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1

Applications of pressure control ventilation volume guaranteed during one-lung ventilation in thoracic surgery  

PubMed Central

Objective: To explore the effects of ventilatory mode “pressure controlled ventilation-volume guaranteed” (PCV-VG) on the inspiratory pressures, oxygenation parameters and hemodynamics of patients during one lung ventilation (OLV) for thoracic surgery, compared with volume controlled ventilation (VCV). Methods: Twenty participants were recruited and equally assigned into two groups in a controlled, randomized, crossover design. Group A: VCV was performed initially and changed into PCV-VG after 30 min; Group B: In the reverse order. Blood gas analysis, peak inspiratory pressure (Ppeak), mean inspiratory pressure (Pmean), plateau inspiratory pressure (Plateau) were measured at four different time points: (1) 30 min after total lung ventilation (TLV); (2) 30 min after one lung ventilation (VCV or PCV-VG); (3) 30 min after shifting to the other ventilatory mode, and (4) 30 min after reconstruction of TLV. Results: The Ppeak, Plateau, and Pmean were significantly lower in PCV-VG compared with VCV. There was significant increase in arterial partial pressure of oxygen under PCV-VG. Conclusion: In patients undergoing thoracic surgery with OLV, pressure controlled volume guaranteed mode of ventilation may have better effects by decreasing inspiratory pressure parameters and improving arterial oxygenation than volume controlled ventilation.

Pu, Jun; Liu, Zhenxiu; Yang, Liye; Wang, Yanan; Jiang, Jingjing

2014-01-01

2

Hepatic effects of lung-protective pressure-controlled ventilation and a combination of high-frequency oscillatory ventilation and extracorporeal lung assist in experimental lung injury  

PubMed Central

Summary Background Ventilation with high positive end-expiratory pressure (PEEP) can lead to hepatic dysfunction. The aim of this study was to investigate the hepatic effects of strategies using high airway pressures either in pressure-controlled ventilation (PCV) or in high-frequency oscillatory ventilation (HFOV) combined with an arteriovenous extracorporeal lung assist (ECLA). Material/Methods Pietrain pigs underwent induction of lung injury by saline lavage. Ventilation was continued for 24 hours either as PCV with tidal volumes of 6 ml/kg and PEEP 3 cmH2O above the lower inflection point of the pressure-volume curve or as HFOV (?12 Hz) with a mean tracheal airway pressure 3 cmH2O above the lower inflection point combined with arteriovenous ECLA (HFOV+ECLA). Fluids and norepinephrine stabilized the circulation. The indocyanine green plasma disappearance rate, serum bilirubin, aspartate aminotransferase, alanine aminotransferase, ?-glutamyltransferase, alkaline phosphatase, glutamate dehydrogenase, lactate dehydrogenase and creatine kinase were determined repeatedly. Finally, liver neutrophils were counted and liver cell apoptosis was assessed by terminal deoxynucleotidyl transferase nick end labeling (TUNEL). Results Aspartate aminotransferase increased in the PCV group about three-fold and in the HFOV+ECLA group five-fold (p<0.001). Correspondingly, creatine kinase increased about two-fold and four-fold, respectively (p<0.001). Lactate dehydrogenase was increased in the HFOV+ECLA group (p<0.028). The number of neutrophils infiltrating the liver tissue and the apoptotic index were low. Conclusions High airway pressure PCV and HFOV with ECLA in the treatment of lavage-induced lung injury in pigs did not cause liver dysfunction or damage. The detected elevation of enzymes might be of extrahepatic origin.

Kredel, Markus; Muellenbach, Ralf M.; Johannes, Amelie; Brederlau, Joerg; Roewer, Norbert; Wunder, Christian

2011-01-01

3

Continuous endotracheal tube cuff pressure control system protects against ventilator-associated pneumonia  

PubMed Central

Introduction The use of a system for continuous control of endotracheal tube cuff pressure reduced the incidence of ventilator-associated pneumonia (VAP) in one randomized controlled trial (RCT) with 112 patients but not in another RCT with 142 patients. In several guidelines on the prevention of VAP, the use of a system for continuous or intermittent control of endotracheal cuff pressure is not reviewed. The objective of this study was to compare the incidence of VAP in a large sample of patients (n?=?284) treated with either continuous or intermittent control of endotracheal tube cuff pressure. Methods We performed a prospective observational study of patients undergoing mechanical ventilation during more than 48 hours in an intensive care unit (ICU) using either continuous or intermittent endotracheal tube cuff pressure control. Multivariate logistic regression analysis (MLRA) and Cox proportional hazard regression analysis were used to predict VAP. The magnitude of the effect was expressed as odds ratio (OR) or hazard ratio (HR), respectively, and 95% confidence interval (CI). Results We found a lower incidence of VAP with the continuous (n?=?150) than with the intermittent (n?=?134) pressure control system (22.0% versus 11.2%; p?=?0.02). MLRA showed that the continuous pressure control system (OR?=?0.45; 95% CI?=?0.22-0.89; p?=?0.02) and the use of an endotracheal tube incorporating a lumen for subglottic secretion drainage (SSD) (OR?=?0.39; 95% CI?=?0.19-0.84; p?=?0.02) were protective factors against VAP. Cox regression analysis showed that the continuous pressure control system (HR?=?0.45; 95% CI?=?0.24-0.84; p?=?0.01) and the use of an endotracheal tube incorporating a lumen for SSD (HR?=?0.29; 95% CI?=?0.15-0.56; p?pressure control system (continuous or intermittent) and endotracheal tube (with or without SSD) was not statistically significant in MLRA (OR?=?0.41; 95% CI?=?0.07-2.37; p?=?0.32) or in Cox analysis (HR?=?0.35; 95% CI?=?0.06-1.84; p?=?0.21). Conclusions The use of a continuous endotracheal cuff pressure control system and/or an endotracheal tube with a lumen for SSD could help to prevent VAP in patients requiring more than 48 hours of mechanical ventilation.

2014-01-01

4

Adaptive control of a pressure-controlled artificial ventilator: a simulator-based evaluation using real COPD patient data.  

PubMed

The paper discusses the application of a direct adaptive controller to a pressure controlled artificial ventilation problem. In pressure controlled ventilators, the manipulated variable is the maximum flow applied to the patient during the active phase (inspiration), and the regulated variable is the peak pressure at end-inspiration. This simulation case study focuses on patients diagnosed with Chronic Obstructive Pulmonary Disease (COPD), which require artificial/mechanical ventilation. An adaptive PID controller ensures peak pressures below critical values, by manipulating the flow delivered by the ventilator. The simulation study is performed on fractional-order models of the respiratory impedance identified from lung function data obtained from 21 COPD patients. Additional simulation studies show the robustness of the controller in presence of varying model parameters from the respiratory impedance of the patient. Possibilities to implement the control strategy as an online adaptive algorithm are also explored. The results show that the design of the control is suitable for this kind of application and provides useful insight on realistic scenarios. PMID:21458877

De Keyser, Robin; Ionescu, Clara

2011-12-01

5

A new design for high stability pressure-controlled ventilation for small animal lung imaging  

NASA Astrophysics Data System (ADS)

We have developed a custom-designed ventilator to deliver a stable pressure to the lungs of small animals for use in imaging experiments. Our ventilator was designed with independent pressure vessels to separately control the Peak Inspiratory Pressure (PIP) and Positive End Expiratory Pressure (PEEP) to minimise pressure fluctuations during the ventilation process. The ventilator was computer controlled through a LabVIEW interface, enabling experimental manipulations to be performed remotely whilst simultaneously imaging the lungs in situ. Mechanical ventilation was successfully performed on newborn rabbit pups to assess the most effective ventilation strategies for aerating the lungs at birth. Highly stable pressures enabled reliable respiratory gated acquisition of projection radiographs and a stable prolonged (15 minute) breath-hold for high-resolution computed tomography of deceased rabbit pups at different lung volumes.

Kitchen, M. J.; Habib, A.; Fouras, A.; Dubsky, S.; Lewis, R. A.; Wallace, M. J.; Hooper, S. B.

2010-02-01

6

Comparison of two protective lung ventilatory regimes on oxygenation during one-lung ventilation: a randomized controlled trial  

PubMed Central

Background The efficacy of protective ventilation in acute lung injury has validated its use in the operating room for patients undergoing thoracic surgery with one-lung ventilation (OLV). The purpose of this study was to investigate the effects of two different modes of ventilation using low tidal volumes: pressure controlled ventilation (PCV) vs. volume controlled ventilation (VCV) on oxygenation and airway pressures during OLV. Methods We studied 41 patients scheduled for thoracoscopy surgery. After initial two-lung ventilation with VCV patients were randomly assigned to one of two groups. In one group OLV was started with VCV (tidal volume 6 mL/kg, PEEP 5) and after 30 minutes ventilation was switched to PCV (inspiratory pressure to provide a tidal volume of 6 mL/kg, PEEP 5) for the same time period. In the second group, ventilation modes were performed in reverse order. Airway pressures and blood gases were obtained at the end of each ventilatory mode. Results PaO2, PaCO2 and alveolar-arterial oxygen difference did not differ between PCV and VCV. Peak airway pressure was significantly lower in PCV compared with VCV (19.9 ± 3.8 cmH2O vs 23.1 ± 4.3 cmH2O; p < 0.001) without any significant differences in mean and plateau pressures. Conclusions In patients with good preoperative pulmonary function undergoing thoracoscopy surgery, the use of a protective lung ventilation strategy with VCV or PCV does not affect the oxygenation. PCV was associated with lower peak airway pressures.

2010-01-01

7

Effect of porcine circovirus type 2 (PCV2) vaccination on PCV2-viremic piglets after experimental PCV2 challenge.  

PubMed

The objective of this study was to evaluate the effect of porcine circovirus type 2 (PCV2) vaccines on PCV2-viremic and -seropositive piglets born from naturally PCV2-infected sows against postnatal PCV2 challenge. The experimental design was aimed at mimicking commercial swine rearing conditions to evaluate the response of the PCV2 vaccine on PCV2-viremic and -seropositive piglets after experimental PCV2 challenge. PCV2a (or 2b)-viremic piglets received a PCV2 vaccine at 21 days of age followed by a PCV2b (or 2a) challenge at 49 days of age (28 days post vaccination). The PCV2 vaccines elicited a high level of humoral (as measured by immunoperoxidase monolayer assay and neutralizing antibody titers) and cellular (as measured by the frequency of PCV2-specific interferon-?-secreting cells) immune response in the PCV2-viremic piglets after vaccination even in the presence of maternally derived antibodies (MDA). The initial infection of PCV2 in the pigs was not affected by PCV2 vaccination, however the challenging PCV2 was reduced by PCV2 vaccination on PCV2-viremic pigs. The results from this study demonstrate that the PCV2 vaccine used in this study is effective at reducing PCV2 viremia and lymphoid PCV2 DNA, even for PCV2-viremic pigs with passively acquired MDA at the time of vaccination. PMID:24484292

Seo, Hwi Won; Park, Changhoon; Han, Kiwon; Chae, Chanhee

2014-01-01

8

Anaesthesia ventilators  

PubMed Central

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits.

Jain, Rajnish K; Swaminathan, Srinivasan

2013-01-01

9

Anaesthesia ventilators.  

PubMed

Anaesthesia ventilators are an integral part of all modern anaesthesia workstations. Automatic ventilators in the operating rooms, which were very simple with few modes of ventilation when introduced, have become very sophisticated with many advanced ventilation modes. Several systems of classification of anaesthesia ventilators exist based upon various parameters. Modern anaesthesia ventilators have either a double circuit, bellow design or a single circuit piston configuration. In the bellows ventilators, ascending bellows design is safer than descending bellows. Piston ventilators have the advantage of delivering accurate tidal volume. They work with electricity as their driving force and do not require a driving gas. To enable improved patient safety, several modifications were done in circle system with the different types of anaesthesia ventilators. Fresh gas decoupling is a modification done in piston ventilators and in descending bellows ventilator to reduce th incidence of ventilator induced volutrauma. In addition to the conventional volume control mode, modern anaesthesia ventilators also provide newer modes of ventilation such as synchronised intermittent mandatory ventilation, pressure-control ventilation and pressure-support ventilation (PSV). PSV mode is particularly useful for patients maintained on spontaneous respiration with laryngeal mask airway. Along with the innumerable benefits provided by these machines, there are various inherent hazards associated with the use of the ventilators in the operating room. To use these workstations safely, it is important for every Anaesthesiologist to have a basic understanding of the mechanics of these ventilators and breathing circuits. PMID:24249886

Jain, Rajnish K; Swaminathan, Srinivasan

2013-09-01

10

Tracheostomy and mechanical ventilation weaning in children affected by respiratory virus according to a weaning protocol in a pediatric intensive care unit in Argentina: an observational restrospective trial  

PubMed Central

We describe difficult weaning after prolonged mechanical ventilation in three tracheostomized children affected by respiratory virus infection. Although the spontaneous breathing trials were successful, the patients failed all extubations. Therefore a tracheostomy was performed and the weaning plan was begun. The strategy for weaning was the decrease of ventilation support combining pressure control ventilation (PCV) with increasing periods of continuous positive airway pressure + pressure support ventilation (CPAP + PSV) and then CPAP + PSV with increasing intervals of T-piece. They presented acute respiratory distress syndrome on admission with high requirements of mechanical ventilation (MV). Intervening factors in the capabilities and loads of the respiratory system were considered and optimized. The average MV time was 69 days and weaning time 31 days. We report satisfactory results within the context of a directed weaning protocol.

2011-01-01

11

A Chimeric Porcine Circovirus (PCV) with the Immunogenic Capsid Gene of the Pathogenic PCV Type 2 (PCV2) Cloned into the Genomic Backbone of the Nonpathogenic PCV1 Induces Protective Immunity against PCV2 Infection in Pigs  

Microsoft Academic Search

Porcine circovirus type 2 (PCV2) is associated with postweaning multisystemic wasting syndrome in pigs, whereas PCV1 is nonpathogenic. We previously demonstrated that a chimeric PCV1-2 virus (with the immu- nogenic capsid gene of PCV2 cloned into the backbone of PCV1) induces an antibody response to the PCV2 capsid protein and is attenuated in pigs. Here, we report that the attenuated

M. Fenaux; T. Opriessnig; P. G. Halbur; F. Elvinger; X. J. Meng

2004-01-01

12

Commercial PCV2a-based vaccines are effective in protecting naturally PCV2b-infected finisher pigs against experimental challenge with a 2012 mutant PCV2.  

PubMed

Current commercial PCV2 vaccines are all based on PCV2a and have been shown to be effective in reducing PCV2a and PCV2b viremia and PCV2-associated lesions and disease. The recent emergence of novel mutant PCV2 (mPCV2) strains and linkage of mPCV2 with cases of porcine circovirus associated disease (PCVAD) in vaccinated herds have raised concerns over emergence of vaccine-escape mutants and reduced efficacy of PCV2a-based vaccines. The aim of this study was to determine the ability of three commercial PCV2a-based vaccines administered in the presence of an ongoing PCV2b infection and passively-acquired anti-PCV2 antibodies to protect conventional pigs against experimental challenge with mPCV2 at 11 weeks of age. Fifty naturally PCV2b-infected 2-week-old pigs were divided into five treatment groups with 10 pigs each. Pigs were unvaccinated (positive and negative controls) or vaccinated at 3 (VAC-A, VAC-B, VAC-C) and at 5 weeks of age (VAC-C). At 11 weeks of age, all pigs except the negative controls were challenged with a 2012 U.S. strain of mPCV2. The experiment was terminated 21 days after challenge. Under the conditions of this study, vaccinated pigs were protected against PCV2 viremia and lesions whereas non-vaccinated pigs were not. Moreover, concurrent PCV2b and mPCV2 infection was demonstrated in all positive controls and 3/10 had microscopic lesions consistent with PCVAD while negative controls infected with PCV2b alone did not develop PCVAD. The results indicate that concurrent PCV2b/mPCV2 infection can trigger PCVAD development and that commercial vaccines are effective in protecting conventional pigs against emerging mPCV2 strains. PMID:24929119

Opriessnig, Tanja; Gerber, Priscilla F; Xiao, Chao-Ting; Halbur, Patrick G; Matzinger, Shannon R; Meng, Xiang-Jin

2014-07-23

13

Porcine circovirus type 2 (PCV2) vaccination is effective in reducing disease and PCV2 shedding in semen of boars concurrently infected with PCV2 and Mycoplasma hyopneumoniae.  

PubMed

The objectives were to determine whether the amount of porcine circovirus type 2 (PCV2) shed in semen increased in boars experimentally coinfected with Mycoplasma hyopneumoniae (MHYO), and whether PCV2 vaccination of boars prior to PCV2 exposure reduced PCV2 viremia and virus shedding in semen. Twelve specific-pathogen-free PCV2- and MHYO-naïve boars were randomly and equally assigned to one of four groups. Six boars were vaccinated against PCV2 (VAC) on Day 0; three PCV2 vaccinated and three non-vaccinated boars were inoculated with MHYO on Day 21, and all boars were challenged with PCV2 on Day 35. The four treatment groups included PCV2-Infected (I), VAC-PCV2-I, MHYO-PCV2-Coinfected (CoI), and VAC-MHYO-PCV2-CoI. Semen, blood swabs, feces, and serum samples were collected weekly until Day 70. All vaccinated boars had seroconverted to PCV2 by Day 35. Between Days 28 and 35, MHYO boars developed moderate respiratory disease, characterized by coughing, respiratory distress, mucopurulent nasal discharge and loss of body condition. One MHYO-PCV2-CoI boar died on Day 50. Boars in the PCV2-I and MHYO-PCV2-CoI groups had significantly higher PCV2 DNA loads in blood swabs than the remaining boars. Moreover, PCV2 vaccination significantly reduced the incidence and amount of PCV2 shedding in semen and feces. In summary, although concurrent MHYO infection did not influence PCV2 shedding patterns, coinfection of boars with PCV2 and MHYO resulted in severe clinical disease and viral shedding was significantly decreased by PCV2 vaccination. PMID:21496897

Opriessnig, T; Madson, D M; Schalk, S; Brockmeier, S; Shen, H G; Beach, N M; Meng, X J; Baker, R B; Zanella, E L; Halbur, P G

2011-07-15

14

Effect of a lung recruitment maneuver by high-frequency oscillatory ventilation in experimental acute lung injury on organ blood flow in pigs  

PubMed Central

Introduction The objective was to study the effects of a lung recruitment procedure by stepwise increases of mean airway pressure upon organ blood flow and hemodynamics during high-frequency oscillatory ventilation (HFOV) versus pressure-controlled ventilation (PCV) in experimental lung injury. Methods Lung damage was induced by repeated lung lavages in seven anesthetized pigs (23–26 kg). In randomized order, HFOV and PCV were performed with a fixed sequence of mean airway pressure increases (20, 25, and 30 mbar every 30 minutes). The transpulmonary pressure, systemic hemodynamics, intracranial pressure, cerebral perfusion pressure, organ blood flow (fluorescent microspheres), arterial and mixed venous blood gases, and calculated pulmonary shunt were determined at each mean airway pressure setting. Results The transpulmonary pressure increased during lung recruitment (HFOV, from 15 ± 3 mbar to 22 ± 2 mbar, P < 0.05; PCV, from 15 ± 3 mbar to 23 ± 2 mbar, P < 0.05), and high airway pressures resulted in elevated left ventricular end-diastolic pressure (HFOV, from 3 ± 1 mmHg to 6 ± 3 mmHg, P < 0.05; PCV, from 2 ± 1 mmHg to 7 ± 3 mmHg, P < 0.05), pulmonary artery occlusion pressure (HFOV, from 12 ± 2 mmHg to 16 ± 2 mmHg, P < 0.05; PCV, from 13 ± 2 mmHg to 15 ± 2 mmHg, P < 0.05), and intracranial pressure (HFOV, from 14 ± 2 mmHg to 16 ± 2 mmHg, P < 0.05; PCV, from 15 ± 3 mmHg to 17 ± 2 mmHg, P < 0.05). Simultaneously, the mean arterial pressure (HFOV, from 89 ± 7 mmHg to 79 ± 9 mmHg, P < 0.05; PCV, from 91 ± 8 mmHg to 81 ± 8 mmHg, P < 0.05), cardiac output (HFOV, from 3.9 ± 0.4 l/minute to 3.5 ± 0.3 l/minute, P < 0.05; PCV, from 3.8 ± 0.6 l/minute to 3.4 ± 0.3 l/minute, P < 0.05), and stroke volume (HFOV, from 32 ± 7 ml to 28 ± 5 ml, P < 0.05; PCV, from 31 ± 2 ml to 26 ± 4 ml, P < 0.05) decreased. Blood flows to the heart, brain, kidneys and jejunum were maintained. Oxygenation improved and the pulmonary shunt fraction decreased below 10% (HFOV, P < 0.05; PCV, P < 0.05). We detected no differences between HFOV and PCV at comparable transpulmonary pressures. Conclusion A typical recruitment procedure at the initiation of HFOV improved oxygenation but also decreased systemic hemodynamics at high transpulmonary pressures when no changes of vasoactive drugs and fluid management were performed. Blood flow to the organs was not affected during lung recruitment. These effects were independent of the ventilator mode applied.

David, Matthias; Gervais, Hendrik W; Karmrodt, Jens; Depta, Arno L; Kempski, Oliver; Markstaller, Klaus

2006-01-01

15

Association of concurrent porcine circovirus (PCV) 2a and 2b infection with PCV associated disease in vaccinated pigs.  

PubMed

Investigations were performed to characterize porcine circovirus (PCV) 2 infection in 10 week old pigs from a case of apparent vaccine failure. Thirty serum samples were collected from affected or non-affected pigs and tested for anti-PCV2 antibodies and PCV2 DNA. To address potential PCV2 vaccine compliance issues, samples were tested for antibodies against baculovirus and Mycoplasma hyopneumoniae antigens present in the PCV2 vaccine utilized in this herd. Both PCV2a and PCV2b DNA were detected in 76.6% (90% positive for PCV2a, 86.6% positive for PCV2b), anti-PCV2 IgG in 90%, anti-baculovirus IgG in 50%, and anti-M. hyopneumoniae IgG in 43.3% of the samples. Frequency of baculovirus and M. hyopneumoniae seropositive pigs was significantly lower in affected pigs. The finding that only 50% of the pigs developed a detectable immune response to vaccination suggests poor vaccine compliance or efficacy. Concurrent PCV2a and PCV2b infection was common and may have resulted in enhanced PCV2 replication. PMID:23829995

Gerber, Priscilla F; Johnson, John; Shen, Huigang; Striegel, Dave; Xiao, Chao-Ting; Halbur, Patrick G; Opriessnig, Tanja

2013-10-01

16

Origin of porcine circovirus type 2 (PCV2) from swine affected by PCV2-associated diseases in Croatia.  

PubMed

Porcine circovirus type 2 (PCV2) causes some of the most significant economic losses in pig production. Several multisystemic syndromes have been attributed to PCV2 infection, which are known as PCV2-associated diseases (PCVDs). This study investigated the origin and evolution of PCV2 sequences in domestic pigs and wild boars affected by PCVDs in Croatia. Viral sequences were recovered from three wild boars diagnosed with PCV2-systemic disease (PCV2-SD), 63 fetuses positive for PCV2 DNA as determined by PCR, 14 domestic pigs affected with PCV2-SD (displaying severe interstitial nephritis) and five domestic pigs with proliferative and necrotising pneumonia. Seventeen complete PCV2 genomes were recovered. Phylogenetic and evolutionary analyses based on median-joining phylogenetic networks, amino acid alignments and principal coordinate analysis were performed using complete genomes, as well as complete and partial ORF sequences for ORF1 and ORF2. Two of the 17 PCV2 sequences belonged to PCV2a, 14 to PCV2b and one was unclustered. PCV2b was the predominant genotype in Croatia and has been linked to international trade as a route of introduction. Correlation between particular viral strains with PCVDs is lacking. PMID:24591478

Novosel, D; Tuboly, T; Csagola, A; Lorincz, M; Cubric-Curik, V; Jungic, A; Curik, I; Segalés, J; Cortey, M; Lipej, Z

2014-04-26

17

Reproduction in porcine circovirus type 2 (PCV2) seropositive gilts inseminated with PCV2b spiked semen  

PubMed Central

Background Since 1999, field evidence of transplacental infection by porcine circovirus type 2 (PCV2) and reproductive failure has been reported in pigs. The objective of this study was to evaluate the clinical and pathological consequences of PCV2 infection in conventional PCV2-seropositive gilts by insemination with PCV2b-spiked semen. Results Six PCV2 seropositive gilts were inseminated with PCV2b-supplemented semen (infected) and three animals with semen and cell culture medium (controls). Only three out of the six infected animals were pregnant by ultrasonography on day 29 after insemination, while two out of the three controls were pregnant. One control gilt aborted on day 23 after insemination but not due to PVC2. Viraemia was demonstrated in four out of six infected and in one control gilt that became infected with PCV2a. Anti-PCV2 antibody titres showed dynamic variations in the infected group throughout the study. Among infected gilts, the animal with the lowest anti-PCV2 titre (1/100) at the beginning of the experiment and another that reached a similar low value during the experiment showed evident seroconversion over time and had also PCV2 positive foetuses. One placenta displayed mild focal necrosis of the chorionic epithelium positively stained by immunohistochemistry for PCV2 antigen. Conclusions PCV2-seropositive gilts can be infected with PCV2 after intrauterine exposure and low maternal antibody titre may increase the probability of a foetal infection.

2012-01-01

18

Alternative protocol to initiate high-frequency oscillatory ventilation: an experimental study  

PubMed Central

Introduction The objective was to study the effects of a novel lung volume optimization procedure (LVOP) using high-frequency oscillatory ventilation (HFOV) upon gas exchange, the transpulmonary pressure (TPP), and hemodynamics in a porcine model of surfactant depletion. Methods With institutional review board approval, the hemodynamics, blood gas analysis, TPP, and pulmonary shunt fraction were obtained in six anesthetized pigs before and after saline lung lavage. Measurements were acquired during pressure-controlled ventilation (PCV) prior to and after lung damage, and during a LVOP with HFOV. The LVOP comprised a recruitment maneuver with a continuous distending pressure (CDP) of 45 mbar for 2.5 minutes, and a stepwise decrease of the CDP (5 mbar every 5 minute) from 45 to 20 mbar. The TPP level was identified during the decrease in CDP, which assured a change of the PaO2/FIO2 ratio < 25% compared with maximum lung recruitment at CDP of 45 mbar (CDP45). Data are presented as the median (25th–75th percentile); differences between measurements are determined by Friedman repeated-measures analysis on ranks and multiple comparisons (Tukey's test). The level of significance was set at P < 0.05. Results The PaO2/FiO2 ratio increased from 99.1 (56.2–128) Torr at PCV post-lavage to 621 (619.4–660.3) Torr at CDP45 (CDP45) (P < 0.031). The pulmonary shunt fraction decreased from 51.8% (49–55%) at PCV post-lavage to 1.03% (0.4–3%) at CDP45 (P < 0.05). The cardiac output and stroke volume decreased at CDP45 (P < 0.05) compared with PCV, whereas the heart rate, mean arterial pressure, and intrathoracic blood volume remained unchanged. A TPP of 25.5 (17–32) mbar was required to preserve a difference in PaO2/FIO2 ratio < 25% related to CDP45; this TPP was achieved at a CDP of 35 (25–40) mbar. Conclusion This HFOV protocol is easy to perform, and allows a fast determination of an adequate TPP level that preserves oxygenation. Systemic hemodynamics, as a measure of safety, showed no relevant deterioration throughout the procedure.

Karmrodt, Jens; David, Matthias; Yuan, Shying; Markstaller, Klaus

2006-01-01

19

Ventilation and ventilators.  

PubMed

The history of ventilation is reviewed briefly and recent developments in techniques of ventilation are discussed. Operating features of ventilators have changed in the past few years, partly as the result of clinical progress; yet, technology appears to have outstripped the clinician's ability to harness it most effectively. Clinical discipline and training of medical staff in the use of ventilators could be improved. The future is promising if clinician and designer can work together closely. Ergonomics of ventilators and their controls and the provision of alarms need special attention. Microprocessors are likely to feature prominently in the next generation of designs. PMID:6754938

Hayes, B

1982-01-01

20

Bench performance of ventilators during simulated paediatric ventilation.  

PubMed

This study compares the accuracy and capabilities of various ventilators using a paediatric acute respiratory distress syndrome lung model. Various compliance settings and respiratory rate settings were used. The study was done in three parts: tidal volume and FiO2 accuracy; pressure control accuracy and positive end-expiratory pressure (PEEP) accuracy. The parameters set on the ventilator were compared with either or both of the measured parameters by the test lung and the ventilator. The results revealed that none of the ventilators could consistently deliver tidal volumes within 1 ml/kg of the set tidal volume, and the discrepancy between the delivered volume and the volume measured by the ventilator varied greatly. The target tidal volume was 8 ml/kg, but delivered tidal volumes ranged from 3.6-11.4 ml/kg and the volumes measured by the ventilator ranged from 4.1-20.6 ml/kg. All the ventilators maintained pressure within 20% of the set pressure, except one ventilator which delivered pressures of up to 27% higher than the set pressure. Two ventilators maintained PEEP within 10% of the prescribed PEEP. The majority of the readings were also within 10%. However, three ventilators delivered, at times, PEEPs over 20% higher. In conclusion, as lung compliance decreases, especially in paediatric patients, some ventilators perform better than others. This study highlights situations where ventilators may not be able to deliver, nor adequately measure, set tidal volumes, pressure, PEEP or FiO2. PMID:23659397

Park, M A J; Freebairn, R C; Gomersall, C D

2013-05-01

21

Comparative Effects of Vaccination against Porcine Circovirus Type 2 (PCV2) and Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) in a PCV2-PRRSV Challenge Model  

PubMed Central

The objective of the present study was to determine the effects of porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) vaccinations in an experimental PCV2-PRRSV challenge model, based on virological (viremia), immunological (neutralizing antibodies [NAs], gamma interferon-secreting cells [IFN-?-SCs], and CD4+ CD8+ double-positive cells), and pathological (lesions and antigens in lymph nodes and lungs) evaluations. A total of 72 pigs were randomly divided into 9 groups (8 pigs per group): 5 vaccinated and challenged groups, 3 nonvaccinated and challenged groups, and a negative-control group. Vaccination against PCV2 induced immunological responses (NAs and PCV2-specific IFN-?-SCs) and reduced PCV2 viremia, PCV2-induced lesions, and PCV2 antigens in the dually infected pigs. However, vaccination against PCV2 did not affect the PRRSV immunological responses (NAs and PRRSV-specific IFN-?-SCs), PRRSV viremia, PRRSV-induced lesions, or PRRSV antigens in the dually infected pigs. Vaccination against PRRSV did not induce immunological responses (PRRSV-specific IFN-?-SCs) or reduce PRRSV viremia, PRRSV-induced lesions, or PRRSV antigens in the dually infected pigs. In addition, vaccination against PRRSV increased PCV2 viremia, PCV2-induced lesions, and PCV2 antigens in the dually infected pigs. In summary, vaccination against PCV2 reduced PCV2 viremia, PCV2-induced lesions, and PCV2 antigens in the dually infected pigs. However, vaccination against PRRSV increased PCV2 viremia, PCV2-induced lesions, and PCV2 antigens in the dually infected pigs. Therefore, the PCV2 vaccine decreased the potentiation of PCV2-induced lesions by PRRSV in dually infected pigs. In contrast, the PRRSV vaccine alone did not decrease the potentiation of PCV2-induced lesions by PRRSV in dually infected pigs.

Park, Changhoon; Oh, Yeonsu; Seo, Hwi Won; Han, Kiwon

2013-01-01

22

Porcine circovirus (PCV) removal by Q sepharose fast flow chromatography.  

PubMed

The recently discovered contamination of oral rotavirus vaccines led to exposure of millions of infants to porcine circovirus (PCV). PCV was not detected by conventional virus screening tests. Regulatory agencies expect exclusion of adventitious viruses from biological products. Therefore, methods for inactivation/removal of viruses have to be implemented as an additional safety barrier whenever feasible. However, inactivation or removal of PCV is difficult. PCV is highly resistant to widely used physicochemical inactivation procedures. Circoviruses such as PCV are the smallest viruses known and are not expected to be effectively removed by currently-used virus filters due to the small size of the circovirus particles. Anion exchange chromatography such as Q Sepharose(®) Fast Flow (QSFF) has been shown to effectively remove a range of viruses including parvoviruses. In this study, we investigated PCV1 removal by virus filtration and by QSFF chromatography. As expected, PCV1 could not be effectively removed by virus filtration. However, PCV1 could be effectively removed by QSFF as used during the purification of monoclonal antibodies (mAbs) and a log10 reduction value (LRV) of 4.12 was obtained. PMID:24039195

Yang, Bin; Wang, Hua; Ho, Cintia; Lester, Philip; Chen, Qi; Neske, Florian; Baylis, Sally A; Blümel, Johannes

2013-01-01

23

Horizontal transmission of porcine circovirus type 2 (PCV2)  

Microsoft Academic Search

Porcine circovirus type 2 (PCV2) is a small, non-enveloped, circular, single stranded DNA virus of economic importance in the swine industry worldwide. The focus of this dissertation was to investigate different aspects of horizontal transmission including the use of serology to accurately detect infection, the infectivity and amount of PCV2 present in various secretions and excretions following experimental or natural

Abby Patterson

2010-01-01

24

Pressure modes of invasive mechanical ventilation.  

PubMed

Pressure modes of invasive mechanical ventilation generate a tidal breath by delivering pressure over time. Pressure control ventilation (PC) is the prototypical pressure mode and is patient- or time-triggered, pressure-limited, and time-cycled. Other pressure modes include pressure support ventilation (PSV), pressure-regulated volume control (PRVC, also known as volume control plus [VC+]), airway pressure release ventilation (APRV), and biphasic ventilation (also known as BiLevel). Despite their complexity, modern ventilators respond to patient effort and respiratory system mechanics in a fairly predictable fashion. No single mode has consistently demonstrated superiority in clinical trials; however, empiric management with a pressure mode may achieve the goals of patient-ventilator synchrony, effective respiratory system support, adequate gas exchange, and limited ventilator-induced lung injury. PMID:21941160

Singer, Benjamin D; Corbridge, Thomas C

2011-10-01

25

Controller modeling and evaluation for PCV electro-mechanical actuator  

NASA Astrophysics Data System (ADS)

Hydraulic actuators are currently used to operate the propellant control valves (PCV) for the space shuttle main engine (SSME) and other rocket engines. These actuators are characterized by large power to weight ratios, large force capabilities, and rapid accelerations, which favor their use in control valve applications. However, hydraulic systems are also characterized by susceptibility to contamination, which leads to frequent maintenance requirements. The Control Mechanisms Branch (EP34) of the Component Development Division of the Propulsion Laboratory at the Marshall Space Flight Center (MSFC) has been investigating the application of electromechanical actuators as replacements for the hydraulic units in PCV's over the last few years. This report deals with some testing and analysis of a PCV electromechanical actuator (EMA) designed and fabricated by HR Textron, Inc. This prototype actuator has undergone extensive testing by EP34 personnel since early 1993. At this time, the performance of the HR Textron PCV EMA does not meet requirements for position tracking.

Parker, Joey K.

1993-11-01

26

Controller modeling and evaluation for PCV electro-mechanical actuator  

NASA Technical Reports Server (NTRS)

Hydraulic actuators are currently used to operate the propellant control valves (PCV) for the space shuttle main engine (SSME) and other rocket engines. These actuators are characterized by large power to weight ratios, large force capabilities, and rapid accelerations, which favor their use in control valve applications. However, hydraulic systems are also characterized by susceptibility to contamination, which leads to frequent maintenance requirements. The Control Mechanisms Branch (EP34) of the Component Development Division of the Propulsion Laboratory at the Marshall Space Flight Center (MSFC) has been investigating the application of electromechanical actuators as replacements for the hydraulic units in PCV's over the last few years. This report deals with some testing and analysis of a PCV electromechanical actuator (EMA) designed and fabricated by HR Textron, Inc. This prototype actuator has undergone extensive testing by EP34 personnel since early 1993. At this time, the performance of the HR Textron PCV EMA does not meet requirements for position tracking.

Parker, Joey K.

1993-01-01

27

Pigs naturally exposed to porcine circovirus type 2 (PCV2) generate antibody responses capable to neutralise PCV2 isolates of different genotypes and geographic origins.  

PubMed

Porcine circovirus type 2 (PCV2) is the essential infectious agent for PCV2-systemic disease (PCV2-SD, formerly known as postweaning multisystemic wasting syndrome) and other pathological conditions. Recent studies indicated antigenic variability amongst different PCV2 isolates and suggested that single amino acid changes within the capsid protein determine differences in the level of neutralization by specific monoclonal antibodies. The objective of the present study was to examine the cross-reactivity of PCV2 antibodies induced in the context of a natural infection against different PCV2 isolates belonging to genotypes PCV2a and PCV2b. Sera taken from several farms from animals of varying health status (PCV2-SD and age-matched healthy pigs and a set of slaughter-aged animals) were assayed for neutralizing activity against four PCV2 isolates from both predominant genotypes (PCV2a and PCV2b) and of differing geographic origins (Europe and North-America). Results showed that most of studied pigs (79 out of 82) contained neutralizing antibodies (NA) able to neutralize all four studied viral strains. Overall, pigs had significantly higher NA titres against PCV2a than against PCV2b (P?PCV2a) than L-33-Sp-10-54 and MO/S-06 strains (PCV2b) (P?PCV2 isolates translate to functional antigenic differences in viral neutralization in vivo. PMID:24602200

Kurtz, Sherry; Grau-Roma, Llorenç; Cortey, Martí; Fort, Maria; Rodríguez, Fernando; Sibila, Marina; Segalés, Joaquim

2014-01-01

28

In vivo characterization of chimeric PCV DNA clones containing heterogeneous capsid protein nuclear localization signals (NLS)  

PubMed Central

Background PCV ORF2 capsid protein was predicted to contribute to the control of replication via an interaction between the Cap and Rep proteins in the nucleoplasm. We previously showed that the nuclear localization signal (NLS) on the capsid protein plays an accessory role in the replication of PCV in vitro. To further evaluate the in vivo characteristics of NLS-chimeric PCV DNA clones, BALB/C mice were inoculated intranasally and intraperitoneally with the DNA clones. Results As expected, no gross lesions were detected during the study of the inoculated animals. The chimeric PCV12-, PCV1-NLS2- and PCV2-NLS1-inoculated animals had significantly fewer and less severe histopathological lesions in lymphoid tissues than the PCV2-inoculated animals (P?PCV12 induced a specific antibody response against PCV2 ORF2 comparable to that induced by wild-type PCV2 but demonstrated a shorter period of viremia and much lower level of virus loads in sera than those in PCV2-inoculated mice. Remarkably, the PCV2-NLS1 and PCV1-NLS2 chimeras replicated in inoculated mice and induced specific antibody responses but failed to produce viral antigens in the lymph nodes or a detectable viremia. Conclusions The chimeric PCV2-NLS1 and PCV1-NLS2 demonstrated a lower replication level as compared with wild type of PCV2 or PCV1 in vivo, suggesting that ORF2 NLSs played an accessory role in PCV replication. The chimeric PCV12 is a good candidate for vaccination against PCV2 infection.

2013-01-01

29

A genetically engineered chimeric vaccine against porcine circovirus type 2 (PCV2) is genetically stable in vitro and in vivo  

Microsoft Academic Search

A vaccine against porcine circovirus type 2 (PCV2), designated PCV1-2 chimera, was recently developed by replacing the capsid gene of the non-pathogenic PCV1 with that of PCV2. The PCV1-2 chimera virus is attenuated in pigs but induces protective immunity against PCV2. In this study, the genetic stability of the PCV1-2 chimera was evaluated for its potential use as a live

J. Gillespie; N. M. Juhan; J. DiCristina; K. F. Key; S. Ramamoorthy; X. J. Meng

2008-01-01

30

Towards the 13-valent pneumococcal conjugate universal vaccination: Effectiveness in the transition era between PCV7 and PCV13 in Italy, 2010-2013.  

PubMed

Pneumococcal disease epidemiology has changed after introduction of pneumococcal conjugate vaccines. Seven-valent vaccine (PCV7) has been effective in reducing invasive pneumococcal disease (IPD). In Europe, PCV13 effectiveness was estimated at 78% (95% CI: -18-96%) for 2-priming doses. In Italy, PCV7 was introduced in 2006 in the childhood immunization schedule and replaced with PCV13 in 2010. In Apulia, vaccination coverage has reached 95.1% (birth-cohort 2010). We estimated PCV program effectiveness and its impact on S. pneumoniae diseases. PCV Effectiveness: We used the screening method. We calculated the Proportion of Population Vaccinated from immunization registries and detected cases through a laboratory-confirmed surveillance among hospitalized children ?60 months. A confirmed IPD case was a child with PCR positive for S. pneumoniae. Differences among children were assessed with the Chi-square or the Fisher exact test (P value<0.05). PCV Impact: We constructed time series using outcome-specific Poisson regression models: hospitalization rate in pre-PCV era and hospitalization risk ratios (RRs) with 95% CIs for both PCV7 and PCV7/PCV13 shifting era. We calculated hospitalization RR with 95% CIs comparing pre-PCV years with vaccination period. The PCV effectiveness was 84.3% (95% CI: 84.0-84.6%). In May 2010-January 2013, we enrolled 159 suspected IPD of whom 4 were confirmed. Two (fully vaccinated) were caused by serotype 9V, 1 (not vaccinated) by serotype 3, 1 (vaccinated with 2 PCV13 doses) by 15B/C. The most important reduction was for pneumococcal pneumonia (RR: 0.43, 95% CI: 0.21-0.90). The PCV program show promising results in terms of both PCV13 effectiveness and its impact in reducing IPD in children<5 years. PMID:24096297

Martinelli, Domenico; Pedalino, Biagio; Cappelli, Maria Giovanna; Caputi, Giovanni; Sallustio, Anna; Fortunato, Francesca; Tafuri, Silvio; Cozza, Vanessa; Germinario, Cinzia; Chironna, Maria; Prato, Rosa; Surveillance Of Pediatric Ipd, Apulian Group For The

2014-01-01

31

First construction of infectious clone for newly emerging mutation porcine circovirus type 2 (PCV2) followed by comparison with PCV2a and PCV2b genotypes in biological characteristics in vitro  

PubMed Central

Background Porcine circovirus type 2 (PCV2), the causative agent of postweaning multisystemic wasting syndrome (PMWS), is a serious economic problem in the swine industry. Different genotypes (PCV2a, PCV2b and PCV2d) of the virus are present in the clinical cases in China, and it is necessary to elucidate the pathogenic difference among different genotypes of PCV2. In this study, four strains of different genotypes were isolated, two were ordinary strains and another two were mutation strains, which there are one and two amino acids elongation in the capsid protein (Cap) of PCV2, respectively. Representative strains of different genotypes of the virus were constructed by infectious molecular clone and biological characterization of the rescued viruses were identified in vitro. Results Four PCV2 isolates (PCV2a/CL, PCV2b/YJ, PCV2b/JF and PCV2d/BDH) of different genotypes were isolated from the clinical cases of PMWS in China. Four infectious clones of PCV2 were constructed and the rescued viruses were harvested after transfection into PK15 cells. The rescued viruses were verified by nucleotide sequence analysis, morphology of the viruses and immunoperoxidase monolayer assay (IPMA). The rescued viruses propagated stably after consecutive incubation for more than ten passages, and virus propagation reached its peak 72h post infection (PI), and the virus titers were up to 105.7 TCID50/ml. By using neutralizing 1D2 monoclonal antibody (mAb) of PCV2, the antigen capture ELISA showed that only the PCV2a/rCL and PCV2b/rJF strains has immunoreactivity with the 1D2 mAb, however, another two rescued strains (PCV2b/rYJ and PCV2d/rBDH) do not, which indicated the antigenic difference among the rescued viruses of different genotypes. In addition, here is the first report of obtaining the newly emerging PCV2 with mutation in vitro by infectious molecular clone technology. Conclusions Conclusions drawn from this study show that PCV2 has prevailing differences in genomic and ORF2 gene length and antigen in swine herds in China. Four representative clones for different genotypes were constructed and rescued, which will facilitate further studies on the pathogenic differences resulting from different subtypes of PCV2.

2011-01-01

32

Ventilation models  

NASA Astrophysics Data System (ADS)

Calculation procedures, used in the design of ventilating systems, which are especially suited for displacement ventilation in addition to linking it to mixing ventilation, are addressed. The two zone flow model is considered and the steady state and transient solutions are addressed. Different methods of supplying air are discussed, and different types of air flow are considered: piston flow, plane flow and radial flow. An evaluation model for ventilation systems is presented.

Skaaret, Eimund

33

The effect of head rotation on efficiency of ventilation and cuff pressure using the PLMA in pediatric patients  

PubMed Central

Background This study examined whether changing the head position from neutral to side can affect expiratory tidal volume (TV) and cuff pressure when the appropriate sizes of a Proseal™ Laryngeal Mask Airway (PLMA)-depending on the body weight -are used in pediatric patients during pressure controlled ventilation (PCV). Methods Seventy-seven children (5-30 kg) were divided into three groups according to their body weight, PLMA#1.5 (group I, n = 24), #2 (group II, n = 26), and #2.5 (group III, n = 27). After anesthesia induction, a PLMA was placed with a cuff-pressure of 60 cmH2O. The TV and existence of leakage at the peak inspiratory pressure (PIP) of 20 cmH2O, and the appropriate PIP for TV 10 ml/kg were examined. Upon head rotation to the left side, the TV, PIP, cuff pressure changes, and the appropriate PIP to achieve a TV 10 ml/kg were evaluated. Results Head rotation of 45 degrees to the left side during PCV caused a significant increase in cuff pressure and a decrease in TV, and there was no definite leakage. Changes in PIP and TV were similar in the three groups. The cuff pressure increased but there was no significant difference between the three groups. Conclusions Although cuff pressure and TV of the PLMA were changed significantly after turning the head from the neutral position to the side, a re-adjustment of the cuff pressure and PIP to maintain a TV of 10 ml/kg can make the placed PLMA useful and successful in pediatric patients under general anesthesia.

Park, Hahck Soo; Kim, Youn Jin

2011-01-01

34

Verification of natural infection of peridomestic rodents by PCV2 on commercial swine farms.  

PubMed

The porcine circovirus-2 (PCV2) is the main agent responsible for porcine circovirus associated diseases (PCVAD). Few studies have been done regarding PCV2 infection in other species. The purpose of this study was to investigate the occurrence of PCV2 infection in the peridomestic rodent species Mus musculus and Rattus rattus on commercial pig farms in Brazil. Immunohistochemistry assay demonstrated PCV2 in the spleen, lung and kidney. Viral DNA was detected in tissues by nested PCR assay. Partial sequences of PCV2 genomes detected in the rodents had strong identity with gene sequences of PCV2 isolates from pigs. These results show that the studied peridomestic rodent species can be naturally infected by PCV2. However, further studies are needed to confirm PCV2 transmission from rodents to pigs. PMID:23141170

Pinheiro, Albanno Leonard Braz Campos; Bulos, Luiz Henrique Silva; Onofre, Thiago Souza; de Paula Gabardo, Michelle; de Carvalho, Otávio Valério; Fausto, Mariana Costa; Guedes, Roberto Maurício Carvalho; de Almeida, Márcia Rogéria; Silva Júnior, Abelardo

2013-06-01

35

Porcine Circovirus type 2 (PCV2) causes apoptosis in experimentally inoculated BALB/c mice  

PubMed Central

Background We have previously described microscopic and electron microscopic alterations in lymphoid organs of PCV2 inoculated mice as apoptosis. In this study we wanted to investigate the molecular pathogenetic mechanism of PCV2-induced apoptosis. Eight-week old BALB/c mice were either sham inoculated (control mice) or inoculated intraperitoneally (ip) and intranasally (in) with a single (sPCV mice) or multiple (mPCV mice) doses of PCV2. Four control mice and 4 sPCV mice were sacrificed 7, 14, 28 and 42 days post inoculation (PI). All 4 mPCV mice were sacrificed 42 days PI. Following necropsy, immunohistochemistry for caspase 3 and in-situ TUNEL assay were performed on sections of spleen, lymph nodes, thymus and ileum from control, sPCV and mPCV mice. In addition, total RNA was extracted from spleens of control, sPCV and mPCV mice for simultaneous detection and semiquantitation of bcl-2 homologues and various caspase mRNAs using a multiprobe RNase protection assay system. Results PCV2 replicated and was associated with apoptosis in spleens, lymph nodes and Peyer's patches of infected BALB/c mice. Upregulation of caspase 1, 2, 3, 6, 7, 8, 11 and 12 and upregulation for the transcripts of apoptosis inhibitors bcl-2, bcl-w and bcl-X and apoptosis promoters' bax, bak and bad was detected in spleens of sPCV and mPCV mice, but not control mice. Apoptosis was further confirmed by light and electron microscopic morphology as well as by positive TUNEL assay and detection of activated caspase 3. PCV2 nucleic acid was detected by in-situ hybridization in the nuclei and cytoplasm of such apoptotic cells. Conclusion The data presented here support the hypothesis that PCV2 induces apoptosis mediated through the activation of caspases 8 and 3 in the spleens of infected mice.

Kiupel, Matti; Stevenson, Gregory W; Galbreath, Elizabeth J; North, Adam; HogenEsch, Harm; Mittal, Suresh K

2005-01-01

36

Porcine Circovirus type 2 (PCV2) causes apoptosis in experimentally inoculated BALB\\/c mice  

Microsoft Academic Search

BACKGROUND: We have previously described microscopic and electron microscopic alterations in lymphoid organs of PCV2 inoculated mice as apoptosis. In this study we wanted to investigate the molecular pathogenetic mechanism of PCV2-induced apoptosis. Eight-week old BALB\\/c mice were either sham inoculated (control mice) or inoculated intraperitoneally (ip) and intranasally (in) with a single (sPCV mice) or multiple (mPCV mice) doses

Matti Kiupel; Gregory W Stevenson; Elizabeth J Galbreath; Adam North; Harm HogenEsch; Suresh K Mittal

2005-01-01

37

Industrial ventilation  

NASA Astrophysics Data System (ADS)

Industrial ventilation design methodology, using computers and using fluid dynamic models, is considered. It is noted that the design of a ventilation system must be incorporated into the plant design and layout at the earliest conceptual stage of the project. A checklist of activities concerning the methodology for the design of a ventilation system for a new facility is given. A flow diagram of the computer ventilation model shows a typical input, the initialization and iteration loop, and the output. The application of the fluid dynamic modeling techniques include external and internal flow fields, and individual sources of heat and contaminants. Major activities for a ventilation field test program are also addressed.

Goodfellow, H. D.

38

Characterisation of PCV2 isolates from Spain, Germany and France  

Microsoft Academic Search

The new isolated circovirus variant PCV-2 is discussed to be the etiological agent of a new emerging swine disease with a variable morbidity and high lethality, postweaning multisystemic wasting syndrome (PMWS). PMWS has been diagnosed in North America and West Europe. Clinical signs include dyspnea, loss of weight, lymph node enlargement and lymphocyte depletion in lymphoid tissues. This report describes

Annette Mankertz; Mariano Domingo; Josep M Folch; Pierre LeCann; André Jestin; Joaquim Segalés; Barbara Chmielewicz; Juan Plana-Durán; Dirk Soike

2000-01-01

39

Two Amino Acid Mutations in the Capsid Protein of Type 2 Porcine Circovirus (PCV2) Enhanced PCV2 Replication In Vitro and Attenuated the Virus In Vivo  

Microsoft Academic Search

Porcine circovirus type 2 (PCV2) is the primary causative agent of postweaning multisystemic wasting syndrome (PMWS) in pigs. To identify potential genetic determinants for virulence and replication, we serially passaged a PCV2 isolate 120 times in PK-15 cells. The viruses harvested at virus passages 1 (VP1) and 120 (VP120) were biologically, genetically, and experimentally characterized. The PCV2 VP120 virus replicated

M. Fenaux; T. Opriessnig; P. G. Halbur; F. Elvinger; X. J. Meng

2004-01-01

40

Blood pressure control during surgical operations  

Microsoft Academic Search

In order to reduce intraoperative blood loss and spare blood transfusion, the authors developed a blood pressure control system using a state-predictive controller. Using adult mongrel dogs, the mean arterial pressure (MAP) was recorded from a femoral artery while trimethaphan camsilate was infused at constant rates. A pure delay plus a first-order delay model was then derived from the dose-response

Eiko Furutani; Mituhiko Araki; S. Maetani

1995-01-01

41

Ventilation Model  

SciTech Connect

The purpose of this analysis and model report (AMR) for the Ventilation Model is to analyze the effects of pre-closure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts and provide heat removal data to support EBS design. It will also provide input data (initial conditions, and time varying boundary conditions) for the EBS post-closure performance assessment and the EBS Water Distribution and Removal Process Model. The objective of the analysis is to develop, describe, and apply calculation methods and models that can be used to predict thermal conditions within emplacement drifts under forced ventilation during the pre-closure period. The scope of this analysis includes: (1) Provide a general description of effects and heat transfer process of emplacement drift ventilation. (2) Develop a modeling approach to simulate the impacts of pre-closure ventilation on the thermal conditions in emplacement drifts. (3) Identify and document inputs to be used for modeling emplacement ventilation. (4) Perform calculations of temperatures and heat removal in the emplacement drift. (5) Address general considerations of the effect of water/moisture removal by ventilation on the repository thermal conditions. The numerical modeling in this document will be limited to heat-only modeling and calculations. Only a preliminary assessment of the heat/moisture ventilation effects and modeling method will be performed in this revision. Modeling of moisture effects on heat removal and emplacement drift temperature may be performed in the future.

H. Yang

1999-11-04

42

Comparison of three commercial one-dose porcine circovirus type 2 (PCV2) vaccines on PCV2 shedding in semen from experimentally infected boars.  

PubMed

This study compared the effects of 3 different types of commercial PCV2 vaccines on PCV2 virus shedding in the semen from infected boars. Twenty-five non-PCV2 viremic and seronegative boars were randomly divided into five groups: three vaccinated and challenged groups, a non-vaccinated and challenged group, and a negative control group. The number of genomic copies of PCV2 in serum and semen samples was significantly decreased in vaccinated and challenged boars compared to non-vaccinated and challenged boars from 14 to 70 days post-inoculation (dpi). The number of PCV2 genomic copy in the semen correlated with the number of PCV2b genomic copy in the blood in vaccinated and challenged boars (r(2)=0.894-0.926, P<0.01), and non-vaccinated and challenged boars (r(2)=0.903, P<0.01). The vaccination protocol reduced the amount of PCV2 DNA shed in the semen. However, there was a significantly different amount of PCV2 DNA shed in semen among the 3 vaccinated and challenged boar groups. PMID:23465837

Seo, Hwi Won; Han, Kiwon; Oh, Yeonsu; Kang, Ikjae; Park, Changhoon; Chae, Chanhee

2013-05-31

43

Transmission of porcine circovirus type 2b (PCV2b) in Kunming mice.  

PubMed

To investigate porcine circovirus type 2b (PCV2b) transmission by contact and vertical infection in Kunming mice (an outbred mouse stock deriving from Swiss albino mice with a high ratio of gene heterozygosis), four mice in cage 6 were inoculated with PCV2b and 25 mice without any treatment were placed into cages 1 to 5 (five mice in each cage). Seven days after being infected, the PCV2-binoculated mice were co-mingled with non-inoculated mice from cages 1 to 5 successively at 7, 14, 21, 28 and 35 days post infection (dpi), respectively, for 3 days. In addition, eleven pregnant mice were injected with PCV2b. Samples were collected from non-inoculated mice and three newborn mice from each litter for PCV2b detection by polymerase chain reaction (PCR) and immunohistochemistry (IHC). The PCR results showed that PCV2b transmission rate among mice in cages 1, 2, 3, 4 and 5 was 0/5, 2/5, 5/5, 5/5 and 1/5, respectively. PCV2b antigen signals generally appeared in most organs of the non-inoculated mice in which viruses were detected by PCR. PCV2b DNA was also detected in newborn mice of PCV2b-infected litters, and viral antigen signals were observed in their organs as well. PCV2b was transmitted in Kunming mice by contact, and it also caused vertical infection through the placenta. PMID:23661391

Deng, Zhi Bang; Yuan, An Wen; Luo, Wei; Wang, Nai Dong; Gong, Qian Long; Yu, Xing Long; Xue, Li Qun

2013-06-01

44

Ventilation Model  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. The purposes of Revision 01 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post-closure thermal models (Section 6.6). (3) To satisfy the remainder of KTI agreement TEF 2.07 (Reamer and Williams 2001b). Specifically to provide the results of post-test ANSYS modeling of the Atlas Facility forced convection tests (Section 7.1.2). This portion of the model report also serves as a validation exercise per AP-SIII.10Q, Models, for the ANSYS ventilation model. (4) To further satisfy KTI agreements RDTME 3.01 and 3.14 (Reamer and Williams 2001a) by providing the source documentation referred to in the KTI Letter Report, ''Effect of Forced Ventilation on Thermal-Hydrologic Conditions in the Engineered Barrier System and Near Field Environment'' (Williams 2002). Specifically to provide the results of the MULTIFLUX model which simulates the coupled processes of heat and mass transfer in and around waste emplacement drifts during periods of forced ventilation. This portion of the model report is presented as an Alternative Conceptual Model with a numerical application, and also provides corroborative results used for model validation purposes (Section 6.3 and 6.4).

V. Chipman

2002-10-05

45

Racial Differences in Blood Pressure Control: Potential Explanatory Factors  

Microsoft Academic Search

PurposePoor blood pressure control remains a common problem that contributes to significant cardiovascular morbidity and mortality, particularly among African Americans. We explored antihypertensive medication adherence and other factors that may explain racial differences in blood pressure control.

Hayden B. Bosworth; Tara Dudley; Maren K. Olsen; Corrine I. Voils; Benjamin Powers; Mary K. Goldstein; Eugene Z. Oddone

2006-01-01

46

Liquid Ventilation  

PubMed Central

Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future.

Tawfic, Qutaiba A.; Kausalya, Rajini

2011-01-01

47

Air Pressure Controlled Mass Measurement System  

NASA Astrophysics Data System (ADS)

Mass measurement is influenced by air pressure, temperature, humidity and other facts. In order to reduce the influence, mass laboratory of National Institute of Metrology, China has developed an air pressure controlled mass measurement system. In this system, an automatic mass comparator is installed in an airtight chamber. The Chamber is equipped with a pressure controller and associate valves, thus the air pressure can be changed and stabilized to the pre-set value, the preferred pressure range is from 200 hPa to 1100 hPa. In order to keep the environment inside the chamber stable, the display and control part of the mass comparator are moved outside the chamber, and connected to the mass comparator by feed-throughs. Also a lifting device is designed for this system which can easily lift up the upper part of the chamber, thus weights can be easily put inside the mass comparator. The whole system is put on a marble platform, and the temperature and humidity of the laboratory is very stable. The temperature, humidity, and carbon dioxide content inside the chamber are measured in real time and can be used to get air density. Mass measurement cycle from 1100 hPa to 200 hPa and back to 1100 hPa shows the effective of the system.

Zhong, Ruilin; Wang, Jian; Cai, Changqing; Yao, Hong; Ding, Jin'an; Zhang, Yue; Wang, Xiaolei

48

Fetal infections and antibody profiles in pigs naturally infected with porcine circovirus type 2 (PCV2)  

PubMed Central

The aim of this study was to describe early infections with porcine circovirus type 2 (PCV2) in naturally infected piglets and the piglets’ serologic profiles. A total of 20 sows (15 PCV2-vaccinated and 5 unvaccinated) and 100 newborn piglets were studied. Colostrum and serum of the sows and serum of the presuckling piglets were obtained on the day of parturition. Milk samples were collected on day 20 postpartum. Blood samples were taken and the piglets weighed on days 1, 20, 42, 63, and 84 postpartum. Colostrum and milk were evaluated for infectious PCV2 and for PCV2 total antibody (TA), neutralizing antibody (NA), and IgA. Serum samples were evaluated for PCV2 TA, NA, IgA, IgM, and DNA. The sows had high levels of TA and NA in serum and colostrum; however, 11 and 5, respectively, of the 20 colostrum and milk samples contained infectious PCV2. In the serum, PCV2 DNA and IgM were detected in 17 and 5, respectively, of the 20 sows. Nine piglets were born with PCV2 antibodies, which indicates in utero transmission of PCV2 after the period of immunocompetence (> 70 d of gestation). On day 1 postpartum, PCV2 DNA was detected in 29 of the 100 serum samples from the piglets. There was no difference between the weights of viremic and nonviremic piglets throughout the study. In conclusion, even on farms with sows that have high PCV2 antibody titers, vertical transmission of PCV2 may occur, resulting in piglet infection.

Gerber, Priscilla F.; Garrocho, Flavia M.; Lana, Angela M.Q.; Lobato, Zelia I.P.

2012-01-01

49

Mycoplasma hyopneumoniae bacterins and porcine circovirus type 2 (PCV2) infection: Induction of postweaning multisystemic wasting syndrome (PMWS) in the gnotobiotic swine model of PCV2-associated disease  

PubMed Central

Groups (5 to 15 per group) of gnotobiotic swine were infected oronasally with porcine circovirus type 2 (PCV2) at 3 days of age and then given 1 of 6 different commercial Mycoplasma hyopneumoniae (M. hyopneumoniae) bacterins as either a single dose (7 d of age, 1 application products) or 2 doses (7 and 21 d of age, 2 application product). Control groups received PCV2 alone (n = 9) or were infected with PCV2 and immunized twice with keyhole limpet hemocyanin (KLH) emulsified in incomplete Freund’s adjuvant (ICFA) (n = 7). Five of 7 (71%) PCV2-infected piglets immunized with KLH/ICFA developed mild or overt PMWS, whereas none of 9 piglets infected with PCV2 alone developed PMWS. Five of 12 (42%) piglets vaccinated with a commercial bacterin containing mineral oil adjuvant developed PMWS following vaccination. None of the PCV2-infected piglets in the other bacterin-vaccinated groups developed PMWS in this model of PCV2-associated disease. This difference in prevalence of PMWS in piglets given the mineral oil-adjuvanted M. hyopneumoniae bacterin and the other M. hyopneumoniae bacterin vaccination groups was statistically significant (P < 0.05).

Krakowka, Steven; Ellis, John; McNeilly, Francis; Waldner, Cheryl; Rings, D. Michael; Allan, Gordon

2007-01-01

50

Automated gate valve operation for pressure control  

NASA Astrophysics Data System (ADS)

An automated pressure control system is described. The components consist of a reversible, geared, ac motor, a gate valve, a Granville-Phillips Stabil-ion pressure gauge with set-points and an electronics switching unit. The reversible motor is attached to the adjustment shaft of the gate valve and the system is operated in conjunction with a diffusion pump. The orifice of the gate valve is varied so that the chamber pressure is maintained between two selected set-points fixed on the control unit of the Stabil-ion pressure gauge. The system is used to control the operating pressure in a chemical vapor deposition process. It has been found to work satisfactorily for both gas and liquid phase precursor materials. The simplicity of the system together with its low cost allows for its use in a variety of low-pressure processes.

Barshilia, Harish C.; Kalmar, Balazs; Windsor, Norman R.; Kershmann, Gordon; O'Brien, James J.

1998-02-01

51

Ventilation systems  

NASA Astrophysics Data System (ADS)

Two different types of ventilation systems and their components are addressed: general ventilation and local or process ventilation. Calculation of the flow rates used in the different systems is addressed. The many different types of flow calculations, how they are used, and some of the computer programs that could be used for these calculations are described. Some calculations start with assumptions regarding air flow rates in rooms and locals. The flow rates can be chosen from rule of thumb or regulations or standards. Thereafter the designer calculates necessary heat and cooling loads, pressure drops, fan effect, etc. The other type of calculation is not very common. By using demands on concentrations, temperatures or air velocities the flow rates are calculated. These calculations include contaminant source generation rates, use of models (physical and theoretical), and computational fluid dynamics. The latter are focused upon.

Olander, L.

52

Nasal ventilation.  

PubMed Central

Nasal intermittent positive pressure ventilation is likely to have an increasing role in the management of acute ventilatory failure, weaning, and chronic ventilatory problems. Further improvements in ventilator and mask design will be seen. Appropriate application is likely to reduce both mortality and admissions to intensive care, while domiciliary use can improve life expectancy and/or quality of life in chronic ventilatory disorders. As with any new technique, enthusiasm should not outweigh clear outcome information, and possible new indications should always be subject to careful assessment. Images Figure 2

Simonds, A. K.

1998-01-01

53

Review of Residential Ventilation Technologies  

SciTech Connect

This paper reviews current and potential ventilation technologies for residential buildings in North America and a few in Europe. The major technologies reviewed include a variety of mechanical systems, natural ventilation, and passive ventilation. Key parameters that are related to each system include operating costs, installation costs, ventilation rates, heat recovery potential. It also examines related issues such as infiltration, duct systems, filtration options, noise, and construction issues. This report describes a wide variety of systems currently on the market that can be used to meet ASHRAE standard 62.2. While these systems generally fall into the categories of supply, exhaust or balanced, the specifics of each system are driven by concerns that extend beyond those in the standard and are discussed. Some of these systems go beyond the current standard by providing additional features (such as air distribution or pressurization control). The market will decide the immediate value of such features, but ASHRAE may wish to consider modifications to the standard in the future.

Russell, Marion L.; Sherman, Max H.; Rudd, Armin

2005-03-01

54

A Porcine Circovirus Type 2 (PCV2) Mutant with 234 Amino Acids in Capsid Protein Showed More Virulence In Vivo, Compared with Classical PCV2a/b Strain  

PubMed Central

Background Porcine circovirus type 2 (PCV2) is considered to be the primary causative agent of postweaning multisystemic wasting syndrome (PMWS), which has become a serious economic problem for the swine industry worldwide. The major genotypes, PCV2a and PCV2b, are highly prevalent in the pig population and are present worldwide. However, another newly emerging PCV2b genotype mutant, which has a mutation in its ORF2-encoded capsid protein, has been sporadically present in China, as well as in other countries. It is therefore important to determine the relative virulence of the newly emerging PCV2b genotype mutant, compared with the existing PCV2a and PCV2b genotypes, and to investigate whether the newly emerging mutant virus induces more severe illness. Methodology/Principal Findings Twenty healthy, 30-day-old, commercial piglets served as controls or were challenged with PCV2a, PCV2b and the newly emerging mutant virus. A series of indexes representing different parameters were adopted to evaluate virulence, including clinical signs, serological detection, viral load and distribution, changes in immune cell subsets in the peripheral blood, and evaluation of pathological lesions. The newly emerging PCV2 mutant demonstrated more severe signs compatible with PMWS, characterized by wasting, coughing, dyspnea, diarrhea, rough hair-coat and depression. Moreover, the pathological lesions and viremia, as well as the viral loads in lymph nodes, tonsils and spleen, were significantly more severe (P<0.05) for piglets challenged with the newly emerging mutant compared with those in the groups challenged with PCV2a and PCV2b. In addition, a significantly lower average daily weight gain (P<0.05) was recorded in the group challenged with the newly emerging PCV2 mutant than in the groups challenged with the prevailing PCV2a and PCV2b. Conclusions This is believed to be the first report to confirm the enhanced virulence of the newly emerging PCV2 mutant in vivo.

Guo, Longjun; Fu, Yujie; Wang, Yiping; Lu, Yuehua; Wei, Yanwu; Tang, Qinghai; Fan, Peihu; Liu, Jianbo; Zhang, Long; Zhang, Feiyan; Huang, Liping; Liu, Dan; Li, Shengbin; Wu, Hongli; Liu, Changming

2012-01-01

55

Porcine circovirus type 2 (PCV2): genetic variation and newly emerging genotypes in China  

PubMed Central

Background Porcine circovirus type 2 (PCV2), the causative agent of postweaning multisystemic wasting syndrome (PMWS), is a serious economic problem for the swine industry in China. In this study, we investigated the genetic variation of PCV2 in China using strains isolated from 2004-2008. Viruses were isolated from samples collected from pigs with multi-systemic lesions and clinical signs of PMWS from different regions of China, and the genomes of these viruses were sequenced. The assembled sequences were used to define the genotypes of these strains; PCR-RFLP methodology was used to distinguish isolates and capture ELISA was used to demonstrate the antigenic changes resulted from ORF2 gene mutation of the isolates. Results We identified 19 PCV2 isolates, including four newly emerging PCV2 mutant strains. The 19 isolates were designated into three genotypes (PCV2a, PCV2b and PCV2d). PCV2d represented a novel genotype and a shift from PCV2a to PCV2b as the predominant genotype in China was identified. This is the first report of 1766 nt PCV2 harboring a base deletion at other new different positions. Amino acid sequence analysis identified two novel ORF2 mutations (resulting in ORF2 sequences 705 and 708 nt in length) in three deletion strains (1766 nt) and one strain with a genome 1767 nt in length. Finding of two amino acids elongation of the ORF2-encoded Cap protein is firstly observed among PCV2 strains all over the world. The isolates were distinguished into different genotypes by PCR-RFLP methodology and antigenic changes were present in Cap protein of mutation isolates by capture ELISA. Conclusions The results of this study provide evidence that PCV2 is undergoing constant genetic variation and that the predominant strain in China as well as the antigenic situation has changed in recent years. Furthermore, the PCR-RFLP method presented here may be useful for the differential identification of PCV2 strains in future studies.

2010-01-01

56

A pressure control analysis of cryogenic storage systems  

NASA Technical Reports Server (NTRS)

Self-pressurization of cryogenic storage tanks due to heat leak through the thermal protection system is examined along with the performance of various pressure control technologies for application in microgravity environments. Methods of pressure control such as fluid mixing, passive thermodynamic venting, and active thermodynamic venting are analyzed using the homogeneous thermodynamic model. Simplified equations suggested may be used to characterize the performance of various pressure control systems and to design space experiments.

Lin, C.-S.; Van Dresar, N. T.; Hasan, M. M.

1991-01-01

57

Chimeric Porcine Circoviruses (PCV) Containing Amino Acid Epitope Tags in the C Terminus of the Capsid Gene Are Infectious and Elicit both Anti-Epitope Tag Antibodies and Anti-PCV Type 2 Neutralizing Antibodies in Pigs?  

PubMed Central

A chimeric porcine circovirus (PCV1-2) with the capsid gene of pathogenic PCV2 cloned into the genomic backbone of nonpathogenic PCV1 is attenuated in pigs but elicits protective immunity against PCV2. In this study, short epitope tags were inserted into the C terminus of the capsid protein of the chimeric PCV1-2 vaccine virus, resulting in a tractable marker virus that is infectious both in vitro and in vivo. Pigs experimentally infected with the epitope-tagged PCV1-2 vaccine viruses produced tag-specific antibodies, as well as anti-PCV2 neutralizing antibodies, indicating that the epitope-tagged viruses could potentially serve as a positive-marker modified live-attenuated vaccine.

Beach, Nathan M.; Smith, Sara M.; Ramamoorthy, Sheela; Meng, Xiang-Jin

2011-01-01

58

Evidence for different patterns of natural inter-genotype recombination between two PCV2 parental strains in the field.  

PubMed

Co-infection with different virus strains is a precondition for genome recombination, which give rise to continuous evolution of porcine circovirus type 2 (PCV2). In the present study, 32 PCV2 positive clinical samples from the diseased and dead pigs were identified by classic PCR. 15 of 32 (46.8%) clinical samples were identified as infection with both PCV2a and PCV2b using genotype-specific PCR. 13/15 of PCV2 strains were identified as recombinants using sequencing analysis, phylogenetic analysis, recombination detection program and base-by-base comparison. Further analyses of the full-length sequences of these strains suggest that the natural recombination events occurred between strains DQ104423 (PCV2a) and AY579893 (PCV2b), yield two new recombinant clusters through different recombination patterns with crossover regions located in ORF2. Recombinant cluster 1 included 3 strains, and recombinant cluster 2 included 10 strains. These results demonstrate that recombination between PCV2a and PCV2b strains can occur in cap protein coding region through different patterns and yield different recombinants. Our study not only provided new evidences that PCV2 strains can undergo recombination through a variety of patterns, but also suggests that recombination events easily occur in the co-existence of different strains of PCV2. PMID:23545543

Huang, Yong; Shao, Meng; Xu, Xingang; Zhang, Xiujuan; Du, Qian; Zhao, Xiaomin; Zhang, Wenlong; Lyu, Yahui; Tong, Dewen

2013-07-01

59

Influence of pressure control levels on the pulse pressure variations: an animal study using healthy piglets.  

PubMed

Pulse pressure variation (PPV) is a promising predictor for volume responsiveness. However, recent studies have criticized its validity during small tidal volume (TV) ventilation. The present study evaluated the influence of pressure control level (PCL) on PPV. Six anesthetized healthy piglets simulating hemorrhagic shock underwent five stages of intravascular volume status change. Each stage comprised four cycles of PCL manipulation. In each cycle, five different PCLs were applied in random order. Among 600 arterial pressure tracings obtained during PCL manipulations, 26 tracings were excluded because of signal artifact or ectopic beats. For the remaining 574 tracings, the percentage of normal beats among total recorded beats in each tracing was 99.80% ± 0.85%. When manipulating PCL causing an abrupt change within -16 ? +8 cmH(2)O, the PPV responded rapidly and stabilized within 60 s after manipulation. With higher increment in PCL (+12 ? +16 cmH(2)O), it required 90 s for PPV to stabilize. Under each cycle of PCL manipulation, the PPVs are linearly correlated to the PCL (r = 0.84 ± 0.21) and TV (r = 0.83 ± 0.22). The PPV as well as the slopes of the trend lines decreased from hypovolemic stages toward hypervolemic stages. Pulse pressure variation responds rapidly to change in ventilator setting and is linearly correlated with the PCL and TV. These characteristics may have important applications in critical care to improve the interpretation of PPV in accord to different ventilator settings. PMID:21921829

Lee, Chih-Hsin; Wu, Yao-Kuang; Wang, Jann-Yuan; Lan, Chou-Chin; Lee, Chun-Yi; Hsu, Kuei-Yao; Chao, Kun-Mao; Chang, Hung

2011-12-01

60

Crankcase ventilator  

SciTech Connect

This patent describes a crankcase ventilator. It comprises: a conduct adapted to be attached to crankcase and a suction means for drawing air containing vapors from the crankcase through the conduit, a temperature sensitive element adapted to be placed in thermal contact with the crankcase, means for continuously varying the rate at which the suction means draws the air containing vapors from the crankcase according to temperature, and means connecting the varying means to the temperature sensitive element for causing the suction means to draw a greater volume of air from the crankcase when the crankcase is hot than when the crankcase is cold.

Pickering, J.J.

1989-11-14

61

Pressure control system to improve power plant efficiency  

US Patent & Trademark Office Database

A system for improving the efficiency of a modem power plant for generating electricity with a water-cooled shell and tube steam condenser with an air removal system is disclosed. An air removal system typically includes an air offtake pipe and a two-stage liquid ring vacuum pump. The operating pressure of this type of air removal system under steady state operation attains equilibrium by itself and cannot be changed. This invention adds a pressure control system to lower the operating pressure at the inlet of the vacuum pump of the air removal system so that an optimum minimum pressure is attained to reduce air inventory inside the condenser. This enhances heat transfer and improves power plant efficiency. The pressure control system contains a pressure control device (e.g. miniature condenser), a chiller, and a pump with variable speed. These components are connected in a loop that circulates cold water. Part of the steam in the steam-air mixture from the condenser is condensed while passing through the pressure control device. The pressure control system adjusts the condensation rate in the pressure control device to yield the optimum minimum pressure. The condensation rate is changed by adjusting either the flow rate or the temperature of water leaving the chiller and flowing to the pressure control device, or by adjusting both.

2000-10-10

62

Shelter Ventilator Studies.  

National Technical Information Service (NTIS)

The report describes the research conducted to determine the applicability of several investigated shelter supplies: ventilator kits, both Kearny pump (KP) and pedal ventilator (PV); novel fantype ventilators; and a motor kit PV attachment. Military speci...

A. L. Kapil C. E. Rathmann

1971-01-01

63

Mechanical ventilator - infants  

MedlinePLUS

Ventilator - infants; Respirator - infants ... WHY IS A MECHANICAL VENTILATOR USED? A ventilator is used to provide breathing support for ill or immature babies. Sick or premature babies are often ...

64

Can Porcine circovirus type 2 (PCV2) infection be eradicated by mass vaccination?  

PubMed

The feasibility to eradicate Porcine circovirus type 2 (PCV2) in a conventional PCV2 infected farm by vaccinating both sows and piglets using a commercially subunit vaccine was assessed. Vaccination strategy implied that all sows, boars and gilts of the farm were vaccinated every four months, and all piglets vaccinated and revaccinated with the same vaccine at 4 and 7 weeks of age, respectively. This vaccination strategy was applied during 12 consecutive months. Blood samples from 15 piglets of 4, 8, 12, 16, 20 and 24 weeks of age and 15 sows were taken monthly PRE, DURING and POST mass vaccination strategy. From all the collected sera (n=1796), a representative proportion of them (n=1235, 69%) were analysed (n=1121 from piglets and n=114 from sows). All these samples were tested by PCV2 ELISA and PCV2 PCR (and quantitative-PCR when PCR positive). All tested sows were negative by PCR but seropositive. ELISA mean OD values of sows decreased throughout the study. Percentages of PCV2 PCR positive samples in piglets were 8% (12/150), 0.9% (6/659) and 3.5% (11/312) PRE, DURING and POST application of the mass vaccination program, respectively. ELISA mean OD values of PCV2 seropositive animals progressively decreased until the end of the mass vaccination period, but a clear seroconversion was observed after stopping such strategy. In conclusion, one year period of mass PCV2 vaccination (without implementing further farm management practices or biosafety measures) was not able to clear out PCV2 infection, and the virus became detectable again when vaccination was stopped. PMID:24906871

Feng, Hua; Blanco, Gerardo; Segalés, Joaquim; Sibila, Marina

2014-08-01

65

Comparison of four commercial one-dose porcine circovirus type 2 (PCV2) vaccines administered to pigs challenged with PCV2 and porcine reproductive and respiratory syndrome virus at 17 weeks postvaccination to control porcine respiratory disease complex under Korean field conditions.  

PubMed

Under Korean field conditions, coinfection with porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) is most commonly observed in porcine respiratory disease complex (PRDC). Despite the wide use of PCV2 vaccination, PRDC remains a serious respiratory problem. Thus, the objective of this study was to determine and compare the efficacy of 4 one-dose PCV2 vaccines on 3-week-old pigs with an experimental PCV2-PRRSV challenge at 17 weeks postvaccination. Regardless of which commercial PCV2 vaccine was used, the vaccination of piglets at 3 weeks of age was efficacious against cochallenge of PCV2 and PRRSV, on the basis of growth performance and PCV2-associated lesions. However, the inactivated chimeric PCV1-2 and the PCV2 vaccines induced higher PCV2-specific neutralizing antibody (NA) titers and PCV2-specific gamma interferon-secreting cells and lower PCV2 viremia levels than the two PCV2 subunit vaccines. The vaccination of piglets against PCV2 at 3 weeks of age was effective in reducing PCV2 viremia and PCV2-associated lesions during the finishing period, which is an age at which pigs are frequently affected by PRDC caused by coinfection with PCV2 and PRRSV under Korean field conditions. PMID:24403524

Park, Changhoon; Seo, Hwi Won; Han, Kiwon; Chae, Chanhee

2014-03-01

66

The growing role of noninvasive ventilation in patients requiring prolonged mechanical ventilation.  

PubMed

For many patients with chronic respiratory failure requiring ventilator support, noninvasive ventilation (NIV) is preferable to invasive support by tracheostomy. Currently available evidence does not support the use of nocturnal NIV in unselected patients with stable COPD. Several European studies have reported benefit for high intensity NIV, in which setting of inspiratory pressure and respiratory rate are selected to achieve normocapnia. There have also been studies reporting benefit for the use of NIV as an adjunct to exercise training. NIV may be useful as an adjunct to airway clearance techniques in patients with cystic fibrosis. Accumulating evidence supports the use of NIV in patients with obesity hypoventilation syndrome. There is considerable observational evidence supporting the use of NIV in patients with chronic respiratory failure related to neuromuscular disease, and one randomized controlled trial reported that the use of NIV was life-prolonging in patients with amyotrophic lateral sclerosis. A variety of interfaces can be used to provide NIV in patients with stable chronic respiratory failure. The mouthpiece is an interface that is unique in this patient population, and has been used with success in patients with neuromuscular disease. Bi-level pressure ventilators are commonly used for NIV, although there are now a new generation of intermediate ventilators that are portable, have a long battery life, and can be used for NIV and invasive applications. Pressure support ventilation, pressure controlled ventilation, and volume controlled ventilation have been used successfully for chronic applications of NIV. New modes have recently become available, but their benefits await evidence to support their widespread use. The success of NIV in a given patient population depends on selection of an appropriate patient, selection of an appropriate interface, selection of an appropriate ventilator and ventilator settings, the skills of the clinician, the motivation of the patient, and the support of the family. PMID:22663966

Hess, Dean R

2012-06-01

67

Investigations of porcine circovirus type 1 (PCV1) in vaccine-related and other cell lines.  

PubMed

Porcine circovirus type 1 (PCV1) is highly prevalent in swine and was recently reported in some rotavirus vaccines. Since animal-derived raw materials, such as cells, trypsin, and serum, can be a major source of introducing virus contamination in biological products, we have investigated PCV1 in several cell lines obtained from ATCC that have broad use in research, diagnostics, or vaccine development. It is expected that these cell lines have been exposed to bovine and porcine viruses during their establishment and passage history due to the use of serum and trypsin that was not qualified according to current testing guidances or processed using new virus-inactivation methods. This study showed that Vero, MRC-5, and CEFs, which represent cell substrates used in some U.S. licensed vaccines, and other cell lines used in investigational vaccines, such as MDCK, HEK-293, HeLa, and A549, were negative for PCV1 using a nested PCR assay; some were also confirmed negative by infectivity analysis. However, MDBK cells, which are used for some animal vaccines, contained PCV1 sequences, although no virus was isolated. Although the results showed that PCV infection may not have occurred under previous culture conditions, the recent cases of vaccine contamination emphasizes the need for continued efforts to reduce the likelihood of introducing viruses from animal-derived materials used in product manufacture. PMID:21835219

Ma, Hailun; Shaheduzzaman, Syed; Willliams, Dhanya K; Gao, Yamei; Khan, Arifa S

2011-10-26

68

Immune responses of mice immunized by DNA plasmids encoding PCV2 ORF 2 gene, porcine IL-15 or the both.  

PubMed

Porcine circovirus type 2 (PCV2) is associated with many kinds of diseases including postweaning multisystemic wasting syndrome (PMWS). It affects the immune system of swine and causes huge epidemic losses every year. In our previous study, we provided evidence that DNA plasmid bearing porcine IL-15 (pVAX-pIL-15) might serve as an immune enhancer for DNA plasmid encoding porcine reproductive and respiratory syndrome virus GP5 gene. In this study, PCV2 open reading frame (ORF)2 gene was cloned into the eukaryotic expression vector pVAX, resulting in the plasmid pVAX-PCV2-ORF2. Transient expression of the plasmid in BHK-21 cells could be detected using immunofluorescence assay. Experimental mice were divided into 5 groups and immunized with PBS, pVAX, pVAX-pIL-15, pVAX-PCV2-ORF2 or pVAX-pIL-15 plus pVAX-PCV2-ORF2. The results showed that the mice co-inoculated with pVAX-PCV2-ORF2 plus pVAX-pIL-15 had higher humoral and cellular immune responses than the others. In addition, DNA plasmid bearing PCV2 ORF2 gene had a protective effect against challenge with PCV2 in mice which could be promoted with the utilization of pIL-15. PMID:24091312

Dong, Bo; Feng, Jing; Lin, Hai; Li, Lanxiang; Su, Dingding; Tu, Di; Zhu, Weijuan; Yang, Qing; Ren, Xiaofeng

2013-11-19

69

Porcine circovirus type 2 (PCV2) induces cell proliferation, fusion, and chemokine expression in swine monocytic cells in vitro.  

PubMed

Granulomatous lymphadenitis is one of the pathognomonic lesions in post-weaning multisystemic wasting syndrome (PMWS)-affected pigs. This unique lesion has not been reported in direct association with viral infection in pigs. The objective of the present study was to evaluate whether porcine circovirus type 2 (PCV2) alone is able to induce functional modulation in porcine monocytic cells in vitro to elucidate its possible role in the development of granulomatous inflammation. It was found that the proliferation activity of blood monocytes (Mo) and monocyte-derived macrophages (MDM) was significantly enhanced by PCV2. During monocyte-macrophage differentiation, the PCV2 antigen-containing rate and formation of multinucleated giant cells (MGC) were significantly increased in MDM when compared to those in Mo. The MDM-derived MGC displayed a significantly higher PCV2 antigen-containing rate than did the mono-nucleated MDM. Supernatants from PCV2-inoculated MDM at 24 h post-inoculation induced an increased tendency of chemotactic activity for blood Mo. At the same inoculation time period, levels of mRNA expression of the monocytic chemokines, monocyte chemoattractant protein-1 and macrophage inflammatory protein-1, also significantly increased in PCV2-inoculated MDM. The results suggest that PCV2 alone may induce cell proliferation, fusion, and chemokine expression in swine monocytic cells. Thus, PCV2 itself may play a significant role in the induction of granulomatous inflammation in PMWS-affected pigs. PMID:20492892

Tsai, Yi-Chieh; Jeng, Chian-Ren; Hsiao, Shih-Hsuan; Chang, Hui-Wen; Liu, Jiuan Judy; Chang, Chih-Cheng; Lin, Chun-Ming; Chia, Mi-Yuan; Pang, Victor Fei

2010-01-01

70

Concurrent porcine circovirus type 2a (PCV2a) or PCV2b infection increases the rate of amino acid mutations of porcine reproductive and respiratory syndrome virus (PRRSV) during serial passages in pigs.  

PubMed

Porcine reproductive and respiratory syndrome virus (PRRSV) has a high degree of genetic and antigenic variability. The purpose of this study was to determine if porcine circovirus type 2 (PCV2) infection increases genetic variability of PRRSV during serial passages in pigs and to determine if there is a difference in the PRRSV mutation rate between pigs concurrently infected with PCV2a or PCV2b. After 8 consecutive passages of PRRSV alone (group 1), PRRSV with PCV2a (group 2), or PCV2b (group 3) in pigs, the sequences of PRRSV structural genes for open reading frame (ORF) 5, ORF6, ORF7 and the partial non-structural protein gene (Nsp) 2 were determined. The total number of identified amino acid mutations in ORF5, ORF6, ORF7 and Nsp2 sequences was 30 for PRRSV infection only, 63 for PRRSV/PCV2a concurrent infection, and 77 for PRRSV/PCV2b concurrent infection when compared with the original VR2385 virus used to infect the passage 1 pigs. Compared to what occurred in pigs infected with PRRSV only, the mutation rates in ORF5 and ORF6 were significantly higher for concurrent PRRSV/PCV2b infected pigs. The PRRSV/PCV2a pigs had a significantly higher mutation rate in ORF7. The results from this study indicated that, besides ORF5 and Nsp2, the PRRSV structural genes ORF6 and ORF7 were shown to mutate at various degrees when the PRRSV was passaged over time in vivo. Furthermore, a significantly higher mutation rate of PRRSV was observed when pigs were co-infected with PCV2 highlighting the importance of concurrent infections on PRRSV evolution and control. PMID:24036229

Yin, Shuang-Hui; Xiao, Chao-Ting; Gerber, Priscilla F; Beach, Nathan M; Meng, Xiang-Jin; Halbur, Patrick G; Opriessnig, Tanja

2013-12-26

71

Line pressure control system for an automatic transmission  

SciTech Connect

A line pressure control system is described for an automatic transmission for a motor vehicle having an engine, a starting motor operated by closing of a starting motor switch for starting the engine, and a microcomputer supplied with voltage from a battery and controlling line pressure in a hydraulic circuit for the automatic transmission in accordance with driving condition of the motor vehicle.

Sakakiyama, R

1989-05-23

72

142. STANDBY PRESSURE CONTROL UNIT FOR FUEL AND LIQUID OXYGEN ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

142. STANDBY PRESSURE CONTROL UNIT FOR FUEL AND LIQUID OXYGEN IN SOUTHWEST PORTION OF CONTROL ROOM (214), LSB (BLDG. 751), FACING WEST - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

73

Variable force solenoid pressure control for an automatic transmission  

Microsoft Academic Search

This patent describes a hydraulic pressure control circuit for an automatic transmission having fluid pressure operated clutch and brake servo. The controlling transmission consists of: a pump and a main pressure regulator valve means for establishing a regulated pressure in the control circuit; a variable force solenoid valve means for developing a pressure proportional to engine torque including a variable

Lemieux

1989-01-01

74

Emergence of a novel mutant PCV2b variant associated with clinical PCVAD in two vaccinated pig farms in the U.S. concurrently infected with PPV2.  

PubMed

Porcine circovirus (PCV) type 2b (PCV2b) emerged in North America in 2005-2006. During May of 2012, PCVAD occurred in 10-18-week-old pigs in two farms within a production system that routinely vaccinated against PCV2. Both farms received replacement gilts from the same multiplier. A mutant PCV2b strain not previously present in North America was identified. The strain was found to be 99.9% identical to a recently described mutant PCV2 isolate reported in China in 2010 and thought to be more virulent than classical PCV2a or PCV2b strains. It is possible that the current PCV2a-based commercial vaccines are not fully protective against this new strain. In addition, emerging porcine parvovirus type 2 (PPV2) was detected in 55% of the serum samples (73/132), perhaps implying that PPV2 could be a cofactor in cases of PCVAD. PMID:23305615

Opriessnig, Tanja; Xiao, Chao-Ting; Gerber, Priscilla F; Halbur, Patrick G

2013-04-12

75

VENTILATION TECHNOLOGY SYSTEMS ANALYSIS  

EPA Science Inventory

The report gives results of a project to develop a systems analysis of ventilation technology and provide a state-of-the-art assessment of ventilation and indoor air quality (IAQ) research needs. (NOTE: Ventilation technology is defined as the hardware necessary to bring outdoor ...

76

Successful treatment of a patient with ARDS after pneumonectomy using high-frequency oscillatory ventilation  

Microsoft Academic Search

High frequency oscillatory ventilation (HFOV) was used in a patient who developed the acute respiratory distress syndrome\\u000a 5 days following a right pneumonectomy for bronchogenic carcinoma. When conventional pressure-controlled ventilation failed\\u000a to maintain adequate oxygenation, HFOV dramatically improved oxygenation within the first few hours of therapy. Pulmonary\\u000a function and gas exchange recovered during a 10-day period of HFOV. No negative

A. M. Brambrink; J. Brachlow; N. Weiler; B. Eberle; D. Elich; T. Joost; M. Koller; R. Huth; W. Heinrichs

1999-01-01

77

Airway pressure release ventilation: what do we know?  

PubMed

Airway pressure release ventilation (APRV) is inverse ratio, pressure controlled, intermittent mandatory ventilation with unrestricted spontaneous breathing. It is based on the principle of open lung approach. It has many purported advantages over conventional ventilation, including alveolar recruitment, improved oxygenation, preservation of spontaneous breathing, improved hemodynamics, and potential lung-protective effects. It has many claimed disadvantages related to risks of volutrauma, increased work of breathing, and increased energy expenditure related to spontaneous breathing. APRV is used mainly as a rescue therapy for the difficult to oxygenate patients with acute respiratory distress syndrome (ARDS). There is confusion regarding this mode of ventilation, due to the different terminology used in the literature. APRV settings include the "P high," "T high," "P low," and "T low". Physicians and respiratory therapists should be aware of the different ways and the rationales for setting these variables on the ventilators. Also, they should be familiar with the differences between APRV, biphasic positive airway pressure (BIPAP), and other conventional and nonconventional modes of ventilation. There is no solid proof that APRV improves mortality; however, there are ongoing studies that may reveal further information about this mode of ventilation. This paper reviews the different methods proposed for APRV settings, and summarizes the different studies comparing APRV and BIPAP, and the potential benefits and pitfalls for APRV. PMID:21762559

Daoud, Ehab G; Farag, Hany L; Chatburn, Robert L

2012-02-01

78

Airway pressure release ventilation: improving oxygenation: indications, rationale, and adverse events associated with airway pressure release ventilation in patients with acute respiratory distress syndrome for advance practice nurses.  

PubMed

Airway pressure release ventilation (APRV) is a mode of ventilation that has been around since the 1980s and was originally viewed as a type of continuous positive pressure mode of ventilation. Conceptually, APRV can be thought of as a type of inverse-ratio, pressure-controlled, intermittent mandatory ventilation during which the maintenance of spontaneous breathing and prolonged application of high mean airway pressure contribute to the clinical benefits. The aim of this review article was to familiarize the bedside clinician working in the intensive care unit with the theory and rationale behind this mode of ventilation. The potential advantages and disadvantages of APRV will also be discussed to empower the advance practice clinician and bedside nurse to advocate for their patient diagnosed with the often-high mortality disease of acute respiratory distress syndrome. PMID:23933639

Ferdowsali, Kameron; Modock, Jacqueline

2013-01-01

79

[Perspectives in mechanical ventilation in ARDS].  

PubMed

Despite more than 25 years of extensive research, the mortality of ARDS patients remains high. The inflammatory process within the lung and the associated gas exchange disturbances require an aggressive ventilatory regimen, which itself may harm the lung. Therapeutic measures which are used to reduce iatrogenic damage to the lung are pressure controlled mechanical ventilation in combination with PEEP and permissive hypercapnia, dehydration and extracorporeal gas exchange. At present, new strategies such as intratracheal instillation of surfactant, partial liquid ventilation and inhalation of nitric oxide (NO) are being evaluated. Surfactant reduces the surface tension, forming a monomolecular layer at the air/tissue interface. It thereby decreases the forces necessary to expand the alveoli and prevents alveoli with small diameter from collapsing. In ARDS, a disturbance of surfactant synthesis, function and re-uptake is the rationale for treatment with exogenous surfactant. Initial clinical results suggest a limited positive effect independently of the surfactant preparation used, the dose and the application mode. Experience with partial liquid ventilation with perfluorocarbons in ARDS has also been reported. Perfluorocarbons are liquids with a high binding capacity for oxygen and carbon dioxide. During normal mechanical ventilation with gas, repetitive doses of perfluorocarbons are instilled into the lungs up to a volume equal to the functional residual capacity. The liquid is pushed into collapsed alveoli and keeps them open by reducing the surface tension. First clinical studies have demonstrated the possible improvement in pulmonary gas exchange. In ARDS, inhalation of NO may cause a predominantly selective vasodilation in blood vessels of ventilated lung regions, resulting in an increase in PaO2 and a decrease in pulmonary artery pressure. The effect of NO on the pulmonary vasculature also induces a reduction in right ventricular afterload and also in pulmonary capillary pressure, which may lead to a faster resolution of pulmonary edema. However, in spite of the promising results of these new strategies, further studies are needed to evaluate their influence on morbidity and mortality. PMID:9289830

Max, M; Kaisers, U; Rossaint, R

1997-06-14

80

The Edgecombe County High Blood Pressure Control Program: the process of medical care and blood pressure control.  

PubMed

As part of the Edgecombe County High Blood Pressure Control Program, a medical record review was conducted within a multispecialty private group practice in the county. The purposes of the review were to assess the relationship between the process of medical care and blood pressure control and to explore the variation in level and impact of medical care by race and sex. At the end of a three-year period, 41 percent of 628 hypertensive patients from the practice had uncontrolled diastolic blood pressure (DBP), as defined by Hypertension Detection and Follow-up Program criteria. The percentage of uncontrolled hypertensives ranged from 53 percent for black men to 34 percent for white women. Hypertensive patients whose physicians were more aggressive in their use of antihypertensive drug therapy were more likely to be controlled. The effect of the level of physician drug aggressiveness tended to be more pronounced for blacks than for whites. Differences by race in exposure to and efficacy of aggressive drug treatment may influence racial variation in blood pressure control. PMID:3453192

Ballard, D J; Strogatz, D S; Wagner, E H; Siscovick, D S; James, S A; Kleinbaum, D G; Williams, C A; Cutchin, L M; Ibrahim, M A

1986-01-01

81

Ventilation Model Report  

SciTech Connect

The purpose of the Ventilation Model is to simulate the heat transfer processes in and around waste emplacement drifts during periods of forced ventilation. The model evaluates the effects of emplacement drift ventilation on the thermal conditions in the emplacement drifts and surrounding rock mass, and calculates the heat removal by ventilation as a measure of the viability of ventilation to delay the onset of peak repository temperature and reduce its magnitude. The heat removal by ventilation is temporally and spatially dependent, and is expressed as the fraction of heat carried away by the ventilation air compared to the fraction of heat produced by radionuclide decay. One minus the heat removal is called the wall heat fraction, or the remaining amount of heat that is transferred via conduction to the surrounding rock mass. Downstream models, such as the ''Multiscale Thermohydrologic Model'' (BSC 2001), use the wall heat fractions as outputted from the Ventilation Model to initialize their post-closure analyses. The Ventilation Model report was initially developed to analyze the effects of preclosure continuous ventilation in the Engineered Barrier System (EBS) emplacement drifts, and to provide heat removal data to support EBS design. Revision 00 of the Ventilation Model included documentation of the modeling results from the ANSYS-based heat transfer model. Revision 01 ICN 01 included the results of the unqualified software code MULTIFLUX to assess the influence of moisture on the ventilation efficiency. The purposes of Revision 02 of the Ventilation Model are: (1) To validate the conceptual model for preclosure ventilation of emplacement drifts and verify its numerical application in accordance with new procedural requirements as outlined in AP-SIII-10Q, Models (Section 7.0). (2) To satisfy technical issues posed in KTI agreement RDTME 3.14 (Reamer and Williams 2001a). Specifically to demonstrate, with respect to the ANSYS ventilation model, the adequacy of the discretization (Section 6.2.3.1), and the downstream applicability of the model results (i.e. wall heat fractions) to initialize post-closure thermal models (Section 6.6). (3) To satisfy the remainder of KTI agreement TEF 2.07 (Reamer and Williams 2001b). Specifically to provide the results of post-test ANSYS modeling of the Atlas Facility forced convection tests (Section 7.1.2). This portion of the model report also serves as a validation exercise per AP-SIII.10Q, Models, for the ANSYS ventilation model. (4) To asses the impacts of moisture on the ventilation efficiency.

V. Chipman; J. Case

2002-12-20

82

Ventilating the English Channel Tunnel  

SciTech Connect

This article describes a unique ventilation system design which ensures a supply of fresh air to 95 miles of tunnels under the English Channel. The topics of the article include a description of the tunnel, a description of the equipment cooling and ventilation systems including provisions for heating of the tunnel ventilation air, ventilation system operation, and ventilation control system.

Dodge, T.M. (Raxcrest Project Management Ltd., Birmingham (United Kingdom))

1993-10-01

83

Memory T cell proliferative responses and IFN-? productivity sustain long-lasting efficacy of a Cap-based PCV2 vaccine upon PCV2 natural infection and associated disease.  

PubMed

Porcine circovirus type 2 (PCV2) vaccination represents an important measure to cope with PCV2 infection; however, data regarding the modulation of the immune cell compartment are still limited, especially under field conditions. This study is aimed at investigating the features of the cellular immune response in conventional piglets induced by vaccination using a capsid (Cap) protein-based PCV2 vaccine compared to unvaccinated animals when exposed to PCV2 natural infection. Immune reactivity was evaluated by quantifying peripheral cell subsets involved in the anti-viral response and characterizing the interferon-gamma (IFN-?) secreting cell (SC) responsiveness both in vivo and upon in vitro whole PCV2 recall. The vaccination triggered an early and intense IFN-? secreting cell response and induced the activation of peripheral lymphocytes. The early increase of IFN-? SC frequencies resulted in a remarkable and transient tendency to increased IFN-? productivity in vaccinated pigs. In vaccinated animals, soon before the onset of infection occurred 15-16 weeks post-vaccination, the recalled PCV2-specific immune response was characterized by moderate PCV2-specific IFN-? secreting cell frequencies and augmented productivity together with reactive CD4+CD8+ memory T cells. Conversely, upon infection, unvaccinated animals showed very high frequencies of IFN-? secreting cells and a tendency to lower productivity, which paralleled with effector CD4-CD8+ cytotoxic cell responsiveness. The study shows that PCV2 vaccination induces a long-lasting immunity sustained by memory T cells and IFN-? secreting cells that potentially played a role in preventing the onset of infection; the extent and duration of this reactivity can be an important feature for evaluating the protective immunity induced by vaccination. PMID:24735253

Ferrari, Luca; Borghetti, Paolo; De Angelis, Elena; Martelli, Paolo

2014-01-01

84

Memory T cell proliferative responses and IFN-? productivity sustain long-lasting efficacy of a Cap-based PCV2 vaccine upon PCV2 natural infection and associated disease  

PubMed Central

Porcine circovirus type 2 (PCV2) vaccination represents an important measure to cope with PCV2 infection; however, data regarding the modulation of the immune cell compartment are still limited, especially under field conditions. This study is aimed at investigating the features of the cellular immune response in conventional piglets induced by vaccination using a capsid (Cap) protein-based PCV2 vaccine compared to unvaccinated animals when exposed to PCV2 natural infection. Immune reactivity was evaluated by quantifying peripheral cell subsets involved in the anti-viral response and characterizing the interferon-gamma (IFN-?) secreting cell (SC) responsiveness both in vivo and upon in vitro whole PCV2 recall. The vaccination triggered an early and intense IFN-? secreting cell response and induced the activation of peripheral lymphocytes. The early increase of IFN-? SC frequencies resulted in a remarkable and transient tendency to increased IFN-? productivity in vaccinated pigs. In vaccinated animals, soon before the onset of infection occurred 15-16 weeks post-vaccination, the recalled PCV2-specific immune response was characterized by moderate PCV2-specific IFN-? secreting cell frequencies and augmented productivity together with reactive CD4+CD8+ memory T cells. Conversely, upon infection, unvaccinated animals showed very high frequencies of IFN-? secreting cells and a tendency to lower productivity, which paralleled with effector CD4–CD8+ cytotoxic cell responsiveness. The study shows that PCV2 vaccination induces a long-lasting immunity sustained by memory T cells and IFN-? secreting cells that potentially played a role in preventing the onset of infection; the extent and duration of this reactivity can be an important feature for evaluating the protective immunity induced by vaccination.

2014-01-01

85

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. GENERAL VIEW SHOWING VENTILATOR NO. 9. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION. - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

86

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

GENERAL VIEW SHOWING VENTILATOR NUMBER NINE. THIS VENTILATOR IS SLIGHTLY MORE ORNATE THAN WAS GENERALLY USED BECAUSE OF ITS LOCATION - Old Croton Aqueduct, Ventilator Number 9, Spring & Everett Streets, Ossining, Westchester County, NY

87

Baculovirus as a PRRSV and PCV2 bivalent vaccine vector: baculovirus virions displaying simultaneously GP5 glycoprotein of PRRSV and capsid protein of PCV2.  

PubMed

The GP5 glycoprotein of PRRSV is the main target for inducing neutralizing antibodies and protective immunity in the natural host. The capsid (Cap) protein is the major immunogenic protein and associated with the production of PCV2-specific neutralizing antibodies. In the present study, one genetic recombinant baculovirus BacSC-Dual-GP5-Cap was constructed. This virus displays simultaneously histidine-tagged GP5 and Cap proteins with the baculovirus glycoprotein gp64 TM and CTD on the virion surface as well as the surface of the virus-infected cells. After infection, the GP5 and Cap proteins were expressed and anchored simultaneously on the plasma membrane of Sf-9 cells, as revealed by Western blot and confocal microscopy. This report demonstrated first that both GP5 and Cap proteins were displayed successfully on the viral surface, revealed by immunogold electron microscopy. Vaccination of swine with recombinant baculovirus BacSC-Dual-GP5-Cap elicited significantly higher GP5 and Cap ELISA antibody titers in swine than the control groups. Virus neutralization test also showed that serum from the BacSC-Dual-GP5-Cap treated swine had significant levels of virus neutralization titers. Lymphocyte proliferation responses could be induced in swine immunized with BacSC-Dual-GP5-Cap than the control groups. These findings demonstrate that the BacSC-Dual-GP5-Cap bivalent subunit vaccine can be a potential vaccine against PRRSV and PCV2 infections. PMID:22172969

Xu, Xin-Gang; Wang, Zhi-Sheng; Zhang, Qi; Li, Zhao-Cai; Ding, Li; Li, Wei; Wu, Hung-Yi; Chang, Ching-Dong; Lee, Long-Huw; Tong, De-Wen; Liu, Hung-Jen

2012-02-01

88

[Blood pressure control in patient with chronic kidney disease].  

PubMed

Several epidemiological studies have indicated that high blood pressure is associated with deterioration of renal function in patients with renal disease. Target blood pressures in patients with renal diseases have been defined and proposed to the community in several national and international guidelines. However, some of these targets have been recently changed to take into account results of studies, including randomized clinical trials. The aim of this paper is to put into perspective the history of ideas regarding adequate blood pressure control in patients with renal disease in the light of these results, and explain how these trials have changed our perception, practice and guidelines. PMID:24952677

Halimi, J-M

2014-06-01

89

Effect of Sophora subprosrate polysaccharide on oxidative stress induced by PCV2 infection in RAW264.7 cells.  

PubMed

In this study, an oxidative stress model was first developed in a mouse macrophage cell line (RAW264.7 cells) by infecting the cells with porcine circovirus type 2 (PCV2). The regulatory effect of Sophora subprosrate polysaccharide (SSP) on PCV2-induced oxidative stress was investigated. The results showed that after infection with PCV2, reactive oxygen species (ROS) and nitric oxide (NO) production, myeloperoxidase (MPO) activity, and inducible nitric oxide synthase (iNOS) expression were significantly increased. Meanwhile, the ratio of reduced glutathione to oxidized glutathione (GSH/GSSG) and hydroxyl radical prevention capacity were greatly reduced. These data indicate successful creation of an oxidative stress model in RAW264.7 cells. A dramatic decrease in cell viability was observed in the cells exposed to oxidative stress compared to the control. When the cells were treated with SSP in concentrations of 100, 200 or 400 ?g/mL post PCV2 infection, an increase in the GSH/GSSG ratio and hydroxyl radical prevention capacity was observed. We also observed decreased ROS and NO production, MPO activity, and iNOS expression in the infected cells. Our results demonstrated that PCV2 infection was able to induce oxidative stress in RAW264.7 cells and that SSP could reduce the negative effects resulting from the PCV2 infection. PMID:24080450

Su, Zi-Jie; Wei, Ying-Yi; Yin, Dan; Shuai, Xue-Hong; Zeng, Yun; Hu, Ting-Jun

2013-11-01

90

Tank pressure control experiment on the space shuttle  

NASA Technical Reports Server (NTRS)

The tank pressure control experiment is a demonstration of NASA intent to develop new technology for low-gravity management of the cryogenic fluids that will be required for future space systems. The experiment will use freon as the test fluid to measure the effects of jet-induced fluid mixing on storage tank pressure and will produce data on low-gravity mixing processes critical to the design of on-orbit cryogenic storage and resupply systems. Basic data on fluid motion and thermodynamics in low gravity is limited, but such data is critical to the development of space transfer vehicles and spacecraft resupply facilities. An in-space experiment is needed to obtain reliable data on fluid mixing and pressure control because none of the available microgravity test facilities provide a low enough gravity level for a sufficient duration to duplicate in-space flow patterns and thermal processes. Normal gravity tests do not represent the fluid behavior properly; drop-tower tests are limited in length of time available; aircraft low-gravity tests cannot provide the steady near-zero gravity level and long duration needed to study the subtle processes expected in space.

1989-01-01

91

Learning about ventilators  

MedlinePLUS

... the ventilator to the trachea). Suctioning is a word you will hear a lot when your loved one is on a ventilator. A small thin tube will be inserted into the tube in their mouth or neck to vacuum out mucus that is ...

92

Initial Effects of the National PCV7 Childhood Immunization Program on Adult Invasive Pneumococcal Disease in Israel  

PubMed Central

Background PCV7 was introduced as universal childhood vaccination in Israel in July 2009 and PCV13 in November 2010. Here we report data on adult invasive pneumococcal disease (IPD), two years post PCV7 implementation and before an expected effect of PCV13. Methods An ongoing nationwide active-surveillance (all 27 laboratories performing blood cultures in Israel), providing all blood & CSF S. pneumoniae isolates from persons >18 y was initiated in July 2009. Capture-recapture method assured reporting of >95% cases. All isolates were serotyped in one central laboratory. IPD outcome and medical history were recorded in 90%. Second year post PCV implementation is compared to the first year. Results During July 2009 to June 2011, 970 IPD cases were reported (annual incidence [/100,000] of 9.17 and 10.16 in the two consecutive years, respectively). Respective case fatality rates (CFRs) were 20% and 19.1%. Incidence of IPD and CFR increased with age and number of comorbidities. Incidence rate was significantly greater during the second winter, 7.79/100,000 vs. 6.14/100,000 in first winter, p?=?0.004, with a non-significant decrease during summer months (3.02 to 2.48/100,000). The proportion of IPD cases due to PCV7-serotypes decreased from 27.5% to 13.1% (first to second year) (p<0.001). Yet, non-PCV13-strains increased from 32.7% to 40.2% (p?=?0.017). The increase in non-PCV13-strains was highly significant in immunocompromised patients and to a lesser degree in non-immunocompromised at risk or in older patients (>64 y). Among younger/healthier patients serotype 5 was the major increasing serotype. Penicillin and ceftriaxone resistance decreased significantly in the second year. Conclusions While overall annual incidence of IPD did not change, the indirect effect of PCV7 vaccination was evident by the significant decrease in PCV7 serotypes across all age groups. Increase in non-VT13 strains was significant in immunocompromised patients. A longer follow-up is required to appreciate the full effect of infant vaccination on annual IPD.

Regev-Yochay, Gili; Rahav, Galia; Riesenberg, Klaris; Wiener-Well, Yonit; Strahilevitz, Jacob; Stein, Michal; Glikman, Daniel; Weber, Gabriel; Potasman, Israel; Dagan, Ron

2014-01-01

93

Porcine circovirus type 2 (PCV2) infection decreases the efficacy of an attenuated classical swine fever virus (CSFV) vaccine  

PubMed Central

The Lapinized Philippines Coronel (LPC) vaccine, an attenuated strain of classical swine fever virus (CSFV), is an important tool for the prevention and control of CSFV infection and is widely and routinely used in most CSF endemic areas, including Taiwan. The aim of this study was to investigate whether PCV2 infection affects the efficacy of the LPC vaccine. Eighteen 6-week-old, cesarean-derived and colostrum-deprived (CDCD), crossbred pigs were randomly assigned to four groups. A total of 105.3 TCID50 of PCV2 was experimentally inoculated into pigs through both intranasal and intramuscular routes at 0 days post-inoculation (dpi) followed by LPC vaccination 12 days later. All the animals were challenged with wild-type CSFV (ALD stain) at 27 dpi and euthanized at 45 dpi. Following CSFV challenge, the LPC-vaccinated pigs pre-inoculated with PCV2 showed transient fever, viremia, and viral shedding in the saliva and feces. The number of IgM+, CD4+CD8-CD25+, CD4+CD8+CD25+, and CD4-CD8+CD25+ lymphocyte subsets and the level of neutralizing antibodies against CSFV were significantly higher in the animals with LPC vaccination alone than in the pigs with PCV2 inoculation/LPC vaccination. In addition, PCV2-derived inhibition of the CSFV-specific cell proliferative response of peripheral blood mononuclear cells (PBMCs) was demonstrated in an ex vivo experiment. These findings indicate that PCV2 infection decreases the efficacy of the LPC vaccine. This PCV2-derived interference may not only allow the invasion of wild-type CSFV in pig farms but also increases the difficulty of CSF prevention and control in CSF endemic areas.

2011-01-01

94

A novel vaccine against Porcine circovirus type 2 (PCV2) and Streptococcus equi ssp. zooepidemicus (SEZ) co-infection.  

PubMed

To develop a vaccine against Porcine circovirus type 2 (PCV2) and Streptococcus equi ssp. zooepidemicus (SEZ) co-infection, the genes of porcine IL-18, capsid protein (Cap) of PCV2 and M-like protein (SzP) of SEZ were inserted into the swinepox virus (SPV) genome by homologous recombination. The recombinant swinepox virus rSPV-ICS was verified by PCR and indirect immunofluorescence assays. To evaluate the immunogenicity of rSPV-ICS, 28 PCV2 and SEZ seronegative Bama minipigs were immunized with rSPV-ICS (n=8), commercial PCV2 vaccine and SEZ vaccine (n=8) or wild type SPV (n=8). The results showed that SzP-specific antibody and PCV2 neutralizing antibody of the rSPV-ICS immunized group increased significantly compared to the wild type SPV treated group after vaccination and increased continuously over time. The levels of IL-4 and IFN-? in the rSPV-ICS immunized group were significantly higher than the other three groups, respectively. After been co-challenged with PCV2 and SEZ, 87.5% piglets in rSPV-ICS immunized group were survived. Significant reductions in gross lung lesion score, histopathological lung lesion score, and lymph node lesion score were noticed in the rSPV-ICS immunized group compared with the wtSPV treated group. The results suggested that the recombinant rSPV-ICS provided piglets with significant protection against PCV2-SEZ co-infection; thus, it offers proof-of-principle for the development of a vaccine for the prevention of these swine diseases. PMID:24726504

Lin, Hui-Xing; Ma, Zhe; Yang, Xu-Qiu; Fan, Hong-Jie; Lu, Cheng-Ping

2014-06-25

95

Efficacy of single dose of an inactivated porcine circovirus type 2 (PCV2) whole-virus vaccine with oil adjuvant in piglets  

PubMed Central

Background Post-weaning multisystemic wasting syndrome (PMWS) associated with PCV2 is one of the most costly diseases currently faced by the swine industry. The development of effective vaccines against PCV2 infection has been accepted as an important strategy in the prophylaxis of PMWS. Methods In the present study, a PK-15 cell-adapted formalin-inactivated prototype vaccine candidate was prepared using a strain of PCV2 from China. Inactivation of the virus was accomplished using a standard formalin inactivation protocol. The protective properties of the inactivated PCV2 vaccine were evaluated in piglets. Ten 28-day-old pigs were randomly assigned to two groups, each with five. Group 1 was vaccinated intramuscularly with the inactivated virus preparation; Group 2 received sterile PBS as a placebo. By 28?days post-vaccination (DPV), Groups 1 and 2 were challenged intranasally and intramuscularly with 5?×?107 TCID50 of a virulent PCV2 isolate. Results The vaccinated pigs seroconverted to PCV2 and had high levels of serum antibodies to PCV2 at 28?days after vaccination, whereas the control pigs remained seronegative. No significant signs of clinical disease were recorded following the challenge with PCV2, but moderate amounts of PCV2 antigen were detected in most lymphoid organs of the control pigs. PCV2 was detected in two out of the five vaccinated pigs. Furthermore, pathological lesions and viremia were milder in the vaccinated group. Conclusions The obtained results indicate that the inactivated PCV2 virus vaccine with an oil adjuvant induce an immunological response in pigs that appears to provide protection from infection with PCV2. The vaccine, therefore, may have the potential to serve as a vaccine aimed to protect pigs from developing PMWS.

2012-01-01

96

A Live-Attenuated Chimeric Porcine Circovirus Type 2 (PCV2) Vaccine Is Transmitted to Contact Pigs but Is Not Upregulated by Concurrent Infection with Porcine Parvovirus (PPV) and Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) and Is Efficacious in a PCV2b-PRRSV-PPV Challenge Model?  

PubMed Central

The live chimeric porcine circovirus type 2 (PCV2) vaccine with the capsid gene of the emerging subtype 2b cloned in the genomic backbone of the nonpathogenic PCV1 is attenuated in vivo and induces protective immunity against PCV2. To further determine the safety and efficacy of this experimental vaccine, we tested for evidence of pig-to-pig transmission by commingling nonvaccinated and vaccinated pigs, determined potential upregulation by simultaneous vaccination and infection with porcine parvovirus (PPV) and porcine reproductive and respiratory syndrome virus (PRRSV), and determined vaccine efficacy by challenging pigs 4 weeks after vaccination with PCV2b, PRRSV, and PPV. Forty-six 21-day-old, PCV2-naïve pigs were randomly assigned to one of six groups. Twenty-nine of 46 pigs were challenged with PCV2b, PRRSV, and PPV at day 28, 8/46 remained nonvaccinated and nonchallenged and served as negative controls, and 9/46 remained nonchallenged and served as vaccination controls. All animals were necropsied at day 49. PCV1-PCV2 viremia was detected in nonvaccinated contact pigs commingled with vaccinated pigs, indicating pig-to-pig transmission; however, PCV1-PCV2 DNA levels remained low in all vaccinated and contact pigs regardless of concurrent infection. Finally, vaccination 28 days before challenge resulted in significantly (P < 0.05) decreased amounts of PCV2 in tissues and sera and significantly (P < 0.05) reduced macroscopic and microscopic lesions. The results of this study indicate that the experimental live-attenuated chimeric PCV2 vaccine, although transmissible to contact pigs, remains attenuated in pigs concurrently infected with PRRSV and PPV and induces protective immunity against PCV2b when it is administered 28 days before PCV2 exposure.

Opriessnig, T.; Shen, H. G.; Pal, N.; Ramamoorthy, S.; Huang, Y. W.; Lager, K. M.; Beach, N. M.; Halbur, P. G.; Meng, X. J.

2011-01-01

97

Colorado Tunnel Ventilation Study.  

National Technical Information Service (NTIS)

Mechanical ventilation of tunnels is costly because of the initial installation and the continued maintenance and operation. However, at some tunnel length corresponding to a particular altitude, traffic configuration and topography there is a need for th...

B. B. Gerhardt D. E. Donnelly R. G. Griffin R. F. LaForce J. L. Sheff

1973-01-01

98

Volume guarantee ventilation.  

PubMed

Recognition that volume, not pressure, is the key factor in ventilator-induced lung injury and the association of hypocarbia with neonatal brain injury demonstrate the importance of better control delivered tidal volume. New microprocessor-based ventilator modalities combine advantages of pressure-limited ventilation with the ability to deliver a more consistent tidal volume. This article discusses automatic weaning of peak inspiratory pressure in response to changing lung compliance and respiratory effort. More consistent tidal volume, fewer excessively large breaths, lower peak pressure, less hypocapnia, shorter duration of mechanical ventilation, and lower levels of inflammatory cytokines have been documented in short-term clinical trials. It remains to be seen if these short-term benefits ultimately lead to a reduced incidence of chronic lung disease. PMID:17394933

Keszler, Martin; Abubakar, Kabir M

2007-03-01

99

Reverse Flow Personal Ventilation.  

National Technical Information Service (NTIS)

The potential contribution of reverse flow personal ventilation for the relief of thermal stress in the aviation field is reviewed. Current evidence is discussed and recommendations are made for further research. (Author)

D. G. Robertson J. Morrison J. R. Allan

1971-01-01

100

What Is a Ventilator?  

MedlinePLUS

... hospitals. Ventilators: Get oxygen into the lungs. Remove carbon dioxide from the body. (Carbon dioxide is a waste gas that can be ... NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings ...

101

Negative Pressure Ventilation  

Microsoft Academic Search

\\u000a In essence, the negative pressure ventilator comprises a rigid shell that partly or completely encloses the patient’s torso,\\u000a the pressure within which can be dropped by means of an attached pump.27 Air enters the lungs as a result of the fall in pleural pressure produced by expansion of the thoracic cage. Expiration is\\u000a passive. Negative pressure ventilators were introduced in

Ashfaq Hasan

102

Conventional mechanical ventilation  

PubMed Central

The provision of mechanical ventilation for the support of infants and children with respiratory failure or insufficiency is one of the most common techniques that are performed in the Pediatric Intensive Care Unit (PICU). Despite its widespread application in the PICUs of the 21st century, before the 1930s, respiratory failure was uniformly fatal due to the lack of equipment and techniques for airway management and ventilatory support. The operating rooms of the 1950s and 1960s provided the arena for the development of the manual skills and the refinement of the equipment needed for airway management, which subsequently led to the more widespread use of endotracheal intubation thereby ushering in the era of positive pressure ventilation. Although there seems to be an ever increasing complexity in the techniques of mechanical ventilation, its successful use in the PICU should be guided by the basic principles of gas exchange and the physiology of respiratory function. With an understanding of these key concepts and the use of basic concepts of mechanical ventilation, this technique can be successfully applied in both the PICU and the operating room. This article reviews the basic physiology of gas exchange, principles of pulmonary physiology, and the concepts of mechanical ventilation to provide an overview of the knowledge required for the provision of conventional mechanical ventilation in various clinical arenas.

Tobias, Joseph D.

2010-01-01

103

Overall Subsurface Ventilation Systems  

SciTech Connect

The purpose of this analysis is to provide a conceptual design for the Subsurface Ventilation System and address the construction, emplacement, monitoring, backfill, and closure ventilation phases. The design will be based on the recently established program requirements for transitioning to the Site Recommendation (SR) design as outlined by ''Approach to Implementing the Site Recommendation Baseline'' (Stroupe 2000) and the Monitored Geologic Repository Project Description Document (CRWMS M and O 1999d) (MGR). This analysis will summarize the ventilation concepts that have developed from the incorporation of recent changes to the Technical Baseline and describe changes to the conceptual ventilation design that have resulted from the thermal management requirements. Ventilation concepts presented in the Viability Assessment Design (VA Design) that have not changed are identified and included. The objective of this analysis is to provide a basis for the System Description Document (SDD) Section 2 that provides input to the SR Consideration Report. The scope of the analysis includes the following tasks: (1) Determine the number of primary shafts based on the emplacement airflow rate required to meet thermal goals and (2) Determine conceptual airflow networks for major repository phases including: Construction; Emplacement; Monitoring; and Closure. In addition evaluate: (1) Radon mitigation concerns and options; (2) Monitoring and control requirement changes needed to meet current guidelines; and (3) The impact on the ventilation system of a radiological release due to a potential subsurface fire involving a waste package.

Edward G. Thomas

2000-05-16

104

Advanced ventilator modes and techniques.  

PubMed

In addition to improving gas exchange by mechanical ventilation, minimizing iatrogenic lung injury and making the patient comfortable are important goals. This article reviews advanced ventilator modes and techniques that might help to accomplish these goals. Small tidal volumes (VT) and low ventilation pressure minimize ventilator-induced lung injury. Airway pressure release ventilation and high-frequency oscillatory ventilation may provide lung-protective ventilation in certain patients with refractory hypoxemia. Adaptive support ventilation (ASV) automatically adjusts VT and rate on the basis of the patient's respiratory mechanics to provide "safe" settings. When ventilator output does not match patient respiratory center timing, patient-ventilator asynchrony occurs. Proportional assist ventilation and neutrally adjusted ventilatory assist are unique modes of ventilation that provide ventilatory support in direct proportion to patient effort and therefore may be able to better match patient need and improve comfort. Weaning protocols reduce duration of ventilation and intensive care unit stay. Certain ventilator modes purport to automate part of the ventilator discontinuance process. The ASV progressively reduces support as the patient's lung condition improves, while SmartCare/pressure support (Dräger, Lübeck, Germany) reduces support and then initiates a spontaneous breathing trial. Further research is required to determine the proper place these new modes have in the intensive care unit. PMID:22157490

Haas, Carl F; Bauser, Kimberly A

2012-01-01

105

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity  

NASA Technical Reports Server (NTRS)

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83% by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/sq m). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 C, respectively. The boiling process during the entire heating period, as well as the jet-induced mixing process for the first 2 min of the mixing period, was also recorded on video. The unique features of the experimental results are the sustainability of high liquid superheats for long periods and the occurrence of explosive boiling at low heat fluxes (0.86 to 1.1 kW/sq m). For a heat flux of 0.97 kW/sq m, a wall superheat of 17.9 C was attained in 10 min of heating. This superheat was followed by an explosive boiling accompanied by a pressure spike of about 38% of the tank pressure at the inception of boiling. However, at this heat flux the vapor blanketing the heating surface could not be sustained. Steady nucleate boiling continued after the explosive boiling. The jet-induced fluid mixing results were obtained for jet Reynolds numbers of 1900 to 8000 and Weber numbers of 0.2 to 6.5. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number.

Hasan, Mohammad M.; Lin, Chin S.; Knoll, Richard H.; Bentz, Michael D.

1996-01-01

106

Perinatal taurine exposure affects adult arterial pressure control.  

PubMed

Taurine is an abundant, free amino acid found in mammalian cells that contributes to many physiologic functions from that of a simple cell osmolyte to a programmer of adult health and disease. Taurine's contribution extends from conception throughout life, but its most critical exposure period is during perinatal life. In adults, taurine supplementation prevents or alleviates cardiovascular disease and related complications. In contrast, low taurine consumption coincides with increased risk of cardiovascular disease, obesity and type II diabetes. This review focuses on the effects that altered perinatal taurine exposure has on long-term mechanisms that control adult arterial blood pressure and could thereby contribute to arterial hypertension through its ability to program these cardiovascular regulatory mechanisms very early in life. The modifications of these mechanisms can last a lifetime and transfer to the next generation, suggesting that epigenetic mechanisms underlie the changes. The ability of perinatal taurine exposure to influence arterial pressure control mechanisms and hypertension in adult life appears to involve the regulation of growth and development, the central and autonomic nervous system, the renin-angiotensin system, glucose-insulin interaction and changes to heart, blood vessels and kidney function. PMID:23070226

Roysommuti, Sanya; Wyss, J Michael

2014-01-01

107

Tank pressure control in low gravity by jet mixing  

NASA Technical Reports Server (NTRS)

The Tank Pressure Control Experiment (TPCE) is a space experiment developed to help meet the need for a critical aspect of cryogenic fluid management technology: control of storage tank pressures in the absence of gravity by forced convective mixing. The experiment used a 13.7-liter tank filled to a constant 83 percent level with refrigerant 113 at near saturation conditions to simulate the fluid dynamics and thermodynamics of cryogenic fluids in space applications. The objectives of TPCE were to characterize the fluid dynamics of axial jet-induced mixing in low gravity, to evaluate the validity of empirical mixing models, and to provide data for use in developing and validating computational fluid dynamic models of mixing processes. TPCE accomplished all of its objectives in flight on Space Shuttle Mission STS-3 in August of 1991. The range of flow patterns photographed generally confirmed a prior correlation based on drop tower tests. A closed-form equation derived from a simple thermodynamic model was found to provide a first-order prediction of the pressure reduction time as a function of mixer parameters, tank size, and fluid thermophysical properties. Low energy mixing jets were found to be effective and reliable at reducing thermal non-uniformities, promoting heat and mass transfer between the phases, and reducing tank pressure.

Bentz, Michael D.

1993-01-01

108

ORF4-protein deficient PCV2 mutants enhance virus-induced apoptosis and show differential expression of mRNAs in vitro.  

PubMed

Porcine circovirus type 2 (PCV2) is the essential infectious agent of PCV associated disease (PCVAD). During previous in vitro studies, 11 RNAs and four viral proteins have been detected in PCV2-infected cells. Open reading frame (ORF) 4 is 180bp in length and has been identified at the transcription and the translation level. It overlaps completely with ORF3, which has a role in virus-induced apoptosis. In this study, start codon mutations (M1-PCV2) or in-frame termination mutations (M2-PCV2) were utilized to construct two ORF4-protein deficient viruses aiming to investigate its role in viral infection. The abilities of M1-PCV2 and M2-PCV2 to replicate, transcribe, express viral proteins, and to cause cellular apoptosis were evaluated. Viral DNA replication curves supported that the ORF4 protein is not essential for viral replication, but inhibits viral replication in the early stage of infection. Comparison of the expression level of ORF3 mRNA among wild-type and ORF4-deficient viruses in infected PK-15 cell demonstrated enhanced ORF3 transcription of both ORF4 mutants suggesting that the ORF4 protein may play an important role by restricting ORF3 transcription thereby preventing virus-induced apoptosis. This is further confirmed by the significantly higher caspase 3 and 8 activities in M1-PCV2 and M2-PCV2 compared to wild-type PCV2. Furthermore, the role of ORF4 in cell apoptosis and a possible interaction with the ORF1 associated Rep protein could perhaps explain the rapid viral growth in the early stage of infection and the higher expression level of ORF1 mRNA in ORF4 protein deficient PCV2 mutants. PMID:24503223

Gao, Zhangzhao; Dong, Qinfang; Jiang, Yonghou; Opriessnig, Tanja; Wang, Jingxiu; Quan, Yanping; Yang, Zongqi

2014-04-01

109

How to ventilate lungs as small as 12.5% of normal: the new technique of intratracheal pulmonary ventilation.  

PubMed

We wished to determine in a laboratory animal model how much residual lung was needed to sustain total gas exchange. In a series of young, healthy lambs weighing approximately 10 kg that were sedated and paralyzed, we progressively excluded from gas exchange all the left lung (a total of 43%), plus the right lower and cardiac lobes (81%), plus the right middle lobe (87.5%). In some studies, the respective lobes were surgically removed; in others, the bronchi and the pulmonary arteries to the respective lobes were ligated. We provided pulmonary ventilation using the pressure control mode (Servo 900 C) at a tidal volume of 20 mL/kg multiplied by the fraction of the remaining lungs, a respiratory rate up to 120/min, a peak inspiratory pressure of 12-15 cm H2O, and a positive end-expiratory pressure of 3 cm H2O. Those lambs with at least both the right upper lobe (RUL) and right middle lobe remaining (19% of total lungs) were weaned to room air on mechanical ventilation within 48 h. Ventilating RUL (12.5% of remaining lung) with the same ventilator required a substantially higher tidal volume and peak inspiratory pressure to result in adequate alveolar ventilation but led to respiratory failure and death within 8 h. We then applied a newly developed system of intratracheal pulmonary ventilation to ventilate the RUL (12.5% of remaining lung) alone. A continuous flow of humidified mixture of air and oxygen was directly passed into the trachea at the level of the carina through a diffuser at a tidal volume of 2.5 mL/kg. A single valve controlled expiration and respiratory rate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8284097

Müller, E E; Kolobow, T; Mandava, S; Jones, M; Vitale, G; Aprigliano, M; Yamada, K

1993-11-01

110

Genetic characterization of porcine circovirus type 2 (PCV2) from pigs in high-seroprevalence areas in southeastern China.  

PubMed

Increasing evidences indicate that porcine circovirus type 2 (PCV2) is the causative agent of the post-weaning multisystemic wasting syndrome (PMWS). In this study, the prevalence of PCV2 infection in swine herds in southeastern China was investigated by ELISA and PCR, as well as the genetic characteristics by nucleic acid sequencing. Seroprevalence of PCV2 in samples collected from 89 swine herds was significantly higher by ELISA in post-weaning (54.1%) and growing piglets (49.9%) than that of suckling pigs (33.3%) with an average rate of 46.0% (819/1779). Seventy-eight cases out of 159 diseased pigs from these herds were PCV2 positive by PCR. Furthermore, the PCV2-positve rate at herds level in 2005 and 2006 were much higher than that in 2004 (65.63% or 69.23% vs. 32.26%, respectively), indicating that PCV-2 infection expanded rapidly over the past two years. To provide new insights into the extent of genetic heterogeneity of PCV2 isolates in southeastern China, the ORF2 genes of 27 isolates from the area during January 2004-March 2007 were sequenced and aligned. While closely related to each other with identity of 98.0-100%, these isolates displayed lower homologies to those from other regions of China (90.6-100%) or to some foreign isolates (91.3-98.9%). Alignment of deduced amino acid sequences of capsid protein identified two major hyper-variable regions (positions 53-91 and 185-215) in isolates obtained in this study, which were within or close to the putative epitope domains. The substitutions consequently resulted in higher hydrophilicity of the epitope region (positions 47-85). Phylogenetic analysis revealed two clusters of 48 isolates including those from Genbank: the large cluster I consisting of two subgroups and cluster II containing most of foreign isolates owing to the residue substitutions in epitope domains (amino acid positions 80, 86, 88 and 91). While the subgroup Ib contained all the isolates with ORF2 of 705 bp in length, the 27 isolates we sequenced were clustered exclusively in subgroup Ia together with some other Chinese strains. We conclude that PCV2 isolates prevailing in southeastern China were genetically different from those of other countries. PMID:17851745

Shuai, Jiangbing; Wei, Wei; Li, Xiaoliang; Chen, Ning; Zhang, Zhanfeng; Chen, Xueyan; Fang, Weihuan

2007-12-01

111

Volume-targeted ventilation.  

PubMed

Recognition that volume, not pressure, is the key factor in ventilator-induced lung injury and the association of hypocarbia and brain injury dictate the need to better control delivered tidal volume. Volume-controlled ventilation, though much improved, still suffers from loss of volume due to endotracheal tube leak and gas compression in the circuit. Recent microprocessor-based modifications of pressure-limited, time-cycled ventilators combine advantages of pressure-limited ventilation with the ability to deliver a more consistent tidal volume. Each of the modes has advantages and disadvantages, with limited data available to judge their effectiveness. The Volume Guarantee mode, studied most thoroughly, provides automatic weaning of peak pressure in response to improving lung compliance and respiratory effort. More consistent tidal volume, fewer excessively large breaths, lower peak pressure, less hypocarbia and lower levels of inflammatory cytokines have been documented. It remains to be seen if these short-term benefits translate into shorter duration of ventilation or reduced incidence of chronic lung disease. PMID:17069993

Keszler, Martin

2006-12-01

112

A proposal on porcine circovirus type 2 (PCV2) genotype definition and their relation with postweaning multisystemic wasting syndrome (PMWS) occurrence  

Microsoft Academic Search

Porcine circovirus type 2 (PCV2) is the essential infectious agent of postweaning multisystemic wasting syndrome (PMWS). Despite first sequencing studies did not find any association between PCV2 sequences and PMWS occurrence, recent works have suggested the opposite. In the present study, 87 open reading frame 2 (ORF2) sequences obtained from pigs with different clinical conditions and coming from farms with

L. Grau-Roma; E. Crisci; M. Sibila; S. López-Soria; M. Nofrarias; M. Cortey; L. Fraile; A. Olvera; J. Segalés

2008-01-01

113

Variable force solenoid pressure control for an automatic transmission  

SciTech Connect

This patent describes a hydraulic pressure control circuit for an automatic transmission having fluid pressure operated clutch and brake servo. The controlling transmission consists of: a pump and a main pressure regulator valve means for establishing a regulated pressure in the control circuit; a variable force solenoid valve means for developing a pressure proportional to engine torque including a variable force solenoid connected to pressure regulating portions of the torque proportional pressure; a torque signal passage connecting to the variable force solenoid valve means with the pressure regulator valve means whereby the regulated pressure level maintained by the main regulator valve means is controlled in response to changes in the torque proportional pressure; and a variable force solenoid pressure relief valve means communicating with the torque signal passage and with the variable force solenoid valve means whereby the variable force solenoid valve means is adapted to regulate and to develop a pressure of reduced value relative to the regulated pressure of the main pressure regulator valve means as it establishes the torque proportional pressure, the solenoid pressure relief valve means comprising a pressure regulating valve spool, a valve chamber receiving the spool. The spool and the valve chamber having registering valve lands, a valve spring on one side of the spool urging the spool in one direction, a first pressure area on the pool being exposed to the torque proportional pressure, a second pressure area on the valve spool exposed to the pressure of reduced value whereby the spring, the pressure of reduced value and the torque proportional pressure establish a balanced force on the spool.

Lemieux, G.E.

1989-05-30

114

Poor Long-Term Blood Pressure Control after Intracerebral Hemorrhage  

PubMed Central

Background and Purpose Hypertension is the most important risk factor associated with intracerebral hemorrhage (ICH). We explored racial differences in blood pressure (BP) control after ICH and assessed predictors of BP control at presentation, 30 days, and 1 year in a prospective cohort study. Methods Subjects with spontaneous ICH were identified from the DiffErenCes in the Imaging of Primary Hemorrhage based on Ethnicity or Race (DECIPHER) Project. Blood pressure was compared by race at each time point. Multivariable linear regression was used to determine predictors of presenting mean arterial pressure (MAP), and longitudinal linear regression was used to assess predictors of MAP at follow-up. Results A total of 162 patients were included (mean age 59, 53% male, 77% black). MAP at presentation was 9.6 mmHg higher in blacks than whites despite adjustment for confounders (p=0.065). Fewer than 20% of patients had normal blood pressure (<120/80 mmHg) at 30 days or 1 year. While there was no difference at 30 days (p=0.331), blacks were more likely than whites to have Stage I/II hypertension at one year (p=0.036). Factors associated with lower MAP at follow-up in multivariable analysis were being married at baseline (p=0.032) and living in a facility (versus personal residence) at the time of BP measurement (p=0.023). Conclusions Long-term blood pressure control is inadequate in patients following ICH, particularly in blacks. Further studies are needed to understand the role of social support and barriers to control to identify optimal approaches to improve blood pressure in this high-risk population.

Zahuranec, Darin B.; Wing, Jeffrey J.; Edwards, Dorothy F.; Menon, Ravi S.; Fernandez, Stephen J.; Burgess, Richard E.; Sobotka, Ian A.; German, Laura; Trouth, Anna J.; Shara, Nawar M.; Gibbons, M. Chris; Boden-Albala, Bernadette; Kidwell, Chelsea S.

2012-01-01

115

Ventilation technologies scoping study  

SciTech Connect

This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the needs of California, determining residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and level of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

Walker, Iain S.; Sherman, Max H.

2003-09-30

116

Ventilation flow: Submerged  

NASA Technical Reports Server (NTRS)

The ventilation system on a submarine is discussed. When the submarine is submerged. The ventilation system provides a conditioned atmosphere in the ship with complete isolation from the outside. A conditioned atmosphere includes not only filtration and temperature and humidity control, but also air purification (removal of potentially harmful quantities of impurities and comtaminants) and revitalization (addition of vital life support oxygen). Carbon dioxide removal, the oxygen system, air conditioning, carbon monoxide removal, hydrogen removal, and atmosphere monitoring systems are among the topics discussed.

Hutchinson, D.

1985-01-01

117

Physiological Effects of Localized Ventilation.  

National Technical Information Service (NTIS)

Localized ventilation was applied frontally to the head and neck of seated, clothed subjects, engaged in a central tracking and peripheral tasks, in a 95F and 50% RH environment. Eight different ventilating jet properties were tested. Thermal and comfort ...

H. C. Leung N. Z. Azer P. E. McNall

1971-01-01

118

Safety and Performance of Ventilators.  

National Technical Information Service (NTIS)

The lung ventilators covered by this study have a wide range of application. They have come into use because of the need for a device that provides patient ventilation or augments inadequate spontaneous breathing and oxygenation. There are many varieties ...

J. K. Mitchell

1978-01-01

119

Pressure Control System Design for a Closed Crop Growth Chamber  

NASA Technical Reports Server (NTRS)

The Controlled Ecological Life Support System (CELSS) is an area of active research at NASA. CELSS is a plant-based bioregenerative life support system for long term manned space flights where resupply is costly or impractical. The plants in a CELSS will function to convert the carbon dioxide (exhaled by the crew) into oxygen, purify non-potable water into potable quality water, and provide food for the crew. Prior to implementing a CELSS life support system, one must have knowledge on growing plants in a closed chamber under low gravity. This information will come from research to be conducted on the CELSS Test Facility that will operate on the Space Station Freedom. Currently a ground-based CELSS Test Facility is being built at NASA Ames Research Center. It is called the EDU (Engineering Development Unit). This system will allow researchers to identify issues that may cause difficulties in the development of the CELSS Test Facility and aid in the development of new needed technologies. The EDU consists of a 1 m2 crop growth chamber that is surrounded by a containment enclosure. The containment enclosure isolates the system so there is very little mass and thermal exchange with the ambient. The leakage rate is on the order of 1 % of the enclosure's volume per day (with 0.2S psi pressure difference). The thermal leakage is less than 0.5% of the electrical power supplied to the system per degree Celsius difference from the surrounding. The pressure in the containment enclosure is regulated at 62.5 Pa below the ambient by an active controller. The goal is to maintain this set point for a variety of conditions, such as a range of operating temperatures, heat load variations that occur when the lights are turned on and off, and fluctuations in ambient pressure. In addition certain transition tracking performance is required. This paper illustrates the application of some advanced systems control methods to the task of synthesizing the EDU's pressure control system.

Tsai, K.; Blackwell, C.; Harper, Lynn D. (Technical Monitor)

1994-01-01

120

Development and evaluation of single-tube nested PCR (STNPCR) for the detection of porcine circovirus type 2 (PCV2).  

PubMed

Porcine circovirus 2 (PCV2) is a common virus in pig population and is associated with the postweaning multisystemic wasting disease (PMWS). In this study, it was developed and evaluated the single-tube nested PCR (STNPCR) method for the detection of PCV2 DNA. PCV2 reference controls and swine tissue samples were used, and primers were selected for targeting specific regions of the viral genome. In comparison of the methods, STNPCR was 10 times more sensitive than conventional PCR and showed the same sensitivity to nested PCR (NPCR), but with reduction in the risk of cross-contamination. In clinical application, 55 tissue samples were analysed by conventional PCR and resulted in 67% (37/55) of positive reactions, while the NPCR and STNPCR were able to identify the presence of viral DNA in 100% (55/55) of the samples. The high sensitivity combined with the elimination of cross-contamination makes the STNPCR method suitable for the epidemiological studies of PCV2 and can aid in the diagnosis of PMWS. PMID:23078249

Pontes, N E; Barbosa, C N; Jesus, A L S; Silva, J G; Freitas, A C

2014-06-01

121

Supercavitation Ventilation Control System.  

National Technical Information Service (NTIS)

A supercavitation ventilation control system is disclosed and includes a vehicle body having a fore end and an aft end. A cavitator is fit to the fore end of the vehicle body, the cavitator generating a gas cavity around the vehicle body. A cavity control...

R. Kuklinski

2002-01-01

122

Laboratory Ventilation and Safety.  

ERIC Educational Resources Information Center

In order to meet the needs of both safety and economy, laboratory ventilation systems must effectively remove air-borne toxic and flammable materials and at the same time exhaust a minimum volume of air. Laboratory hoods are the most commonly used means of removing gases, dusts, mists, vapors, and fumed from laboratory operations. To be effective,…

Steere, Norman V.

1965-01-01

123

Volume-targeted ventilation.  

PubMed

Recognition that volume, not pressure, is the key factor in ventilator-induced lung injury and awareness of the association of hypocarbia and brain injury foster the desire to better control delivered tidal volume. Recently, microprocessor-based modifications of pressure-limited, time-cycled ventilators were developed to combine advantages of pressure-limited ventilation with the ability to deliver a more consistent tidal volume. Each of the modes has advantages and disadvantages, with limited clinical data available to judge their effectiveness. The Volume Guarantee mode has been studied most thoroughly and is the only one that provides automatic weaning of peak pressure in response to improving lung compliance and patient respiratory effort. More consistent tidal volume, fewer excessively large breaths, lower peak pressure, less hypocarbia and lower levels of inflammatory cytokines have been documented. It remains to be seen if these short-term benefits will translate into shorter duration of ventilation or reduced incidence of chronic lung disease. PMID:15861164

Keszler, Martin

2005-05-01

124

Space station ventilation study  

NASA Technical Reports Server (NTRS)

A ventilation system design and selection method which is applicable to any manned vehicle were developed. The method was used to generate design options for the NASA 33-foot diameter space station, all of which meet the ventilation system design requirements. System characteristics such as weight, volume, and power were normalized to dollar costs for each option. Total system costs for the various options ranged from a worst case $8 million to a group of four which were all approximately $2 million. A system design was then chosen from the $2 million group and is presented in detail. A ventilation system layout was designed for the MSFC space station mockup which provided comfortable, efficient ventilation of the mockup. A conditioned air distribution system design for the 14-foot diameter modular space station, using the same techniques, is also presented. The tradeoff study resulted in the selection of a system which costs $1.9 million, as compared to the alternate configuration which would have cost $2.6 million.

Colombo, G. V.; Allen, G. E.

1972-01-01

125

Patient-ventilator dyssynchrony during assisted invasive mechanical ventilation.  

PubMed

Patient-ventilator dyssynchrony is common during mechanical ventilation. Dyssynchrony decreases comfort, prolongs mechanical ventilation and intensive care unit stays, and might lead to worse outcome. Dyssynchrony can occur during the triggering of the ventilator, the inspiration period after triggering, the transition from inspiration to expiration, and the expiratory phase. The most common dyssynchronies are delayed triggering, autotriggering, ineffective inspiratory efforts (which can occur at any point in the respiratory cycle), mismatch between the patient's and ventilator's inspiratory times, and double triggering. At present, the detection of dyssynchronies usually depends on healthcare staff observing ventilator waveforms; however, performance is suboptimal and many events go undetected. To date, technological complexity has made it impossible to evaluate patient-ventilator synchrony throughout the course of mechanical ventilation. Studies have shown that a high index of dyssynchrony may increase the duration of mechanical ventilation. Better training, better ventilatory modes, and/or computerized systems that permit better synchronization of patients' demands and ventilator outputs are necessary to improve patient-ventilator synchrony. PMID:23254162

Murias, G; Villagra, A; Blanch, L

2013-04-01

126

Variable versus conventional lung protective mechanical ventilation during open abdominal surgery: study protocol for a randomized controlled trial  

PubMed Central

Background General anesthesia usually requires mechanical ventilation, which is traditionally accomplished with constant tidal volumes in volume- or pressure-controlled modes. Experimental studies suggest that the use of variable tidal volumes (variable ventilation) recruits lung tissue, improves pulmonary function and reduces systemic inflammatory response. However, it is currently not known whether patients undergoing open abdominal surgery might benefit from intraoperative variable ventilation. Methods/Design The PROtective VARiable ventilation trial (‘PROVAR’) is a single center, randomized controlled trial enrolling 50 patients who are planning for open abdominal surgery expected to last longer than 3 hours. PROVAR compares conventional (non-variable) lung protective ventilation (CV) with variable lung protective ventilation (VV) regarding pulmonary function and inflammatory response. The primary endpoint of the study is the forced vital capacity on the first postoperative day. Secondary endpoints include further lung function tests, plasma cytokine levels, spatial distribution of ventilation assessed by means of electrical impedance tomography and postoperative pulmonary complications. Discussion We hypothesize that VV improves lung function and reduces systemic inflammatory response compared to CV in patients receiving mechanical ventilation during general anesthesia for open abdominal surgery longer than 3 hours. PROVAR is the first randomized controlled trial aiming at intra- and postoperative effects of VV on lung function. This study may help to define the role of VV during general anesthesia requiring mechanical ventilation. Trial registration Clinicaltrials.gov NCT01683578 (registered on September 3 3012).

2014-01-01

127

ASHRAE and residential ventilation  

SciTech Connect

In the last quarter of a century, the western world has become increasingly aware of environmental threats to health and safety. During this period, people psychologically retreated away from outdoors hazards such as pesticides, smog, lead, oil spills, and dioxin to the seeming security of their homes. However, the indoor environment may not be healthier than the outdoor environment, as has become more apparent over the past few years with issues such as mold, formaldehyde, and sick-building syndrome. While the built human environment has changed substantially over the past 10,000 years, human biology has not; poor indoor air quality creates health risks and can be uncomfortable. The human race has found, over time, that it is essential to manage the indoor environments of their homes. ASHRAE has long been in the business of ventilation, but most of the focus of that effort has been in the area of commercial and institutional buildings. Residential ventilation was traditionally not a major concern because it was felt that, between operable windows and envelope leakage, people were getting enough outside air in their homes. In the quarter of a century since the first oil shock, houses have gotten much more energy efficient. At the same time, the kinds of materials and functions in houses changed in character in response to people's needs. People became more environmentally conscious and aware not only about the resources they were consuming but about the environment in which they lived. All of these factors contributed to an increasing level of public concern about residential indoor air quality and ventilation. Where once there was an easy feeling about the residential indoor environment, there is now a desire to define levels of acceptability and performance. Many institutions--both public and private--have interests in Indoor Air Quality (IAQ), but ASHRAE, as the professional society that has had ventilation as part of its mission for over 100 years, is the logical place to provide leadership. This leadership has been demonstrated most recently by the publication of the first nationally recognized standard on ventilation in homes, ASHRAE Standard 62.2-2003, which builds on work that has been part of ASHRAE for many years and will presumably continue. Homeowners and occupants, which includes virtually all of us, will benefit from the application of Standard 62.2 and use of the top ten list. This activity is exactly the kind of benefit to society that the founders of ASHRAE envisioned and is consistent with ASHRAE's mission and vision. ASHRAE members should be proud of their Society for taking leadership in residential ventilation.

Sherman, Max H.

2003-10-01

128

The preparation of porcine circovirus type 2 (PCV2) virus-like particles using a recombinant pseudorabies virus and its application to vaccine development.  

PubMed

Porcine circovirus type 2 (PCV2) is the primary causative agent of an economically important swine disease, now known as porcine-associated disease (PCVAD). The only structural protein of viral capsid, Cap has become the major target for development of PCV2 subunit vaccines. The purpose of this study is to express Cap of PCV2 using a recombinant pseudorabies virus (PRV) that is gE gene deficient, which is a widely used PRV marker vaccine. The recombinant PRV, gE(-)/PCV2cap(+)PRV, was constructed using homologous recombination techniques, in order to replace the upstream of the gE gene with the PCV2 cap gene. The expression of Cap during virus replication was confirmed using immunofluorescence and Western blotting analysis. The expressed Cap protein self-assembled into virus-like particles (VLPs), which was demonstrated using electromicrography. The immunization of mice or guinea pigs with purified VLPs could induce significant, specific antibody responses to PCV2 Cap. These results demonstrate an alternative to PCV2 for the development of a VLP-based subunit vaccine. PMID:24739460

Chi, Jyun-Ni; Wu, Ching-Ying; Chien, Maw-Sheng; Wu, Pei-Ching; Wu, Chi-Ming; Huang, Chienjin

2014-07-10

129

Selection and identification of single-domain antibody fragment against capsid protein of porcine circovirus type 2 (PCV2) from C. bactrianus.  

PubMed

Single-domain variable heavy chain (VHH) antibody fragments are derived from heavy-chain antibodies of Camelids. Their comparatively small size, solubility, high affinity and specificity to the targets antigen make them suitable for many biotechnological applications. In this study, a VHH library was constructed from porcine circovirus type 2 (PCV2) vaccine immunized C. bactrianus and three VHH fragments specific to the capsid protein of PCV2 (PCV2 Cap) were selected and characterized. The selected VHH clones (VHH-c1/c3/c4) were stably expressed as soluble protein in E. coli, and were specific to PCV2 Cap except VHH-c3 which shows binding activity with both PCV1 and PCV2 Cap by ELISA. All the VHH-cs show high association rate constant and dissociation rate constant, which was 1.84 ×10(5)M(-1)s(-1), 9.00×10(-3)s(-1) for VHH-c1, 5.49×10(4)M(-1)s(-1), 9.91×10(-3)s(-1) and 1.46×10(5)M(-1)s(-1), 1.18×10(-3)s(-1) for VHH-c3 and VHH-c4 assessed by surface plasmon resonance (SPR). Additionally, the selected three VHH-cs can bind to different epitopes of PCV2 Cap that was determined by additive ELISA. Our study confirmed that VHHs with high affinity and specificity to PCV2 Cap can be selected from an immune VHH library, and have the potential application for effective and fast diagnostic development of PCV2. PMID:24736187

Yang, Shunli; Shang, Youjun; Yin, Shuanghui; Tian, Hong; Chen, Yan; Sun, Shiqi; Jin, Ye; Liu, Xiangtao

2014-07-15

130

Local laboratory ventilation devices  

SciTech Connect

This article is a discussion of the ``other`` laboratory ventilation devices described in OSHA`s laboratory standard that could be used in lieu of traditional chemical fume hoods. The reference ``local`` or ``other`` ventilation device is used with little or no information provided as to the type, design, or performance criteria appropriate for specific applications, as was done in excruciating detail for their fume hood cousins. Equally curious is the fact that no performance test criteria were established for this category of equipment. Therefore, great care must be taken by the designer to determine the specific application intended for each unit specified and confirm that its use is appropriate for the task. In light of these standards, manufacturers have responded with many new and innovative products.

Koenigsberg, J. [GPR Planners Collaborative, White Plains, NY (United States)

1995-10-01

131

Nursing Education in High Blood Pressure Control. Report of the Task Force on the Role of Nursing in High Blood Pressure Control.  

ERIC Educational Resources Information Center

This curriculum guide on high blood pressure (hypertension) for nursing educators has five sections: (1) Introduction and Objectives provides information regarding the establishment and objectives of the National Task Force on the Role of Nursing in High Blood Pressure Control and briefly discusses nursing's role in hypertension control; (2) Goals…

National Institutes of Health (DHEW), Bethesda, MD. High Blood Pressure Information Center.

132

A model of psychosocial and cultural antecedents of blood pressure control.  

PubMed Central

Hypertension is a major modifiable risk factor for stroke, congestive heart failure, and end-stage renal disease. Hypertension is particularly prevalent and deadly among African Americans. Effective treatment for hypertension has been available for decades, yet only one fourth of all individuals have their blood pressure under control. Despite the potential impact of hypertension, interventions to improve control have had limited success. We present a model of how to understand antecedents of blood pressure control according to three interrelated categories: patient characteristics, social and cultural environment, and medical environment. This theoretical paper was conducted using a literature review and a model to explain psychosocial antecedents of blood pressure control is presented. We conclude that improved understanding of important antecedents of blood pressure control coupled with technological advances, such as tailored interventions, provide clinicians with a tool that may lead to improved blood pressure control. These interventions will require the involvement of clinicians and consideration of sociocultural factors to be successful.

Bosworth, Hayden B.; Oddone, Eugene Z.

2002-01-01

133

Volume-controlled intermittent mandatory ventilation in preterm infants with hypoxemic episodes  

Microsoft Academic Search

Objective  To test the hypothesis in ventilated very low birth weight infants with frequent hypoxemic episodes that volume-controlled\\u000a synchronized intermittent mandatory ventilation (SIMV) vs. pressure-controlled SIMV reduces by at least 20% the time with\\u000a hypoxemia (defined as SpO2ventilated very low birth weight infants with frequent hypoxemic episodes.\\u000a \\u000a \\u000a \\u000a Interventions  The infants

Helmut D. Hummler; Anja Engelmann; Frank Pohlandt; Axel R. Franz

2006-01-01

134

[Certain aspects of continuous ventilation].  

PubMed

The indication of mechanical ventilation is either a failing ventilatory function of the thorax or a failing gas exchange function of the lung. The ventilation affects every organ function in more or less degree. The starting point of long term ventilation is debated, arbitrary. Some ventilatory devices are simulating the natural intrapleural negative pressure principle, but most of them applies intermittent positive pressure into the lung. For improving oxygenation, a moderate level of positive end expiratory pressure, eventually inversed or 1:1 inspiratory:expiratory ratio can be applied. The computerized electronic ventilators offer a big selection of assisting and controlling ventilatory modes, according to the requirements of the patients. For routine use, in ventilatory failure, pressure cycled controlled ventilation, in gas exchange failure, the combination of synchronized intermittent mandatory ventilation, positive end-expiratory pressure and pressure support can be recommended. For special tasks there are existing special ventilatory or other supportive means. In most of the cases some sedation of the ventilated patients is appropriate, muscle paralysing is restricted to a few situations. It is important to humidify the inhaled air. The detailed monitoring of the patients is essential during ventilation. The weaning of the patients from the ventilator is a complex procedure, which involves ventilatory, nutritional, pharmacologic and psychologic interventions. PMID:8233460

Incze, F

1993-10-31

135

Ventilation heterogeneity in obesity.  

PubMed

Obesity is associated with important decrements in lung volumes. Despite this, ventilation remains normally or near normally distributed at least for moderate decrements in functional residual capacity (FRC). We tested the hypothesis that this is because maximum flow increases presumably as a result of an increased lung elastic recoil. Forced expiratory flows corrected for thoracic gas compression volume, lung volumes, and forced oscillation technique at 5-11-19 Hz were measured in 133 healthy subjects with a body mass index (BMI) ranging from 18 to 50 kg/m(2). Short-term temporal variability of ventilation heterogeneity was estimated from the interquartile range of the frequency distribution of the difference in inspiratory resistance between 5 and 19 Hz (R5-19_IQR). FRC % predicted negatively correlated with BMI (r = -0.72, P < 0.001) and with an increase in slope of either maximal (r = -0.34, P < 0.01) or partial flow-volume curves (r = -0.30, P < 0.01). Together with a slight decrease in residual volume, this suggests an increased lung elastic recoil. Regression analysis of R5-19_IQR against FRC % predicted and expiratory reserve volume (ERV) yielded significantly higher correlation coefficients by nonlinear than linear fitting models (r(2) = 0.40 vs. 0.30 for FRC % predicted and r(2) = 0.28 vs. 0.19 for ERV). In conclusion, temporal variability of ventilation heterogeneities increases in obesity only when FRC falls approximately below 65% of predicted or ERV below 0.6 liters. Above these thresholds distribution is quite well preserved presumably as a result of an increase in lung recoil. PMID:24651986

Pellegrino, Riccardo; Gobbi, Alessandro; Antonelli, Andrea; Torchio, Roberto; Gulotta, Carlo; Pellegrino, Giulia Michela; Dellacà, Raffaele; Hyatt, Robert E; Brusasco, Vito

2014-05-01

136

Dose-intensive, Time-compressed Procarbazine, CCNU, Vincristine (PCV) with Peripheral Blood Stem Cell Support and Concurrent Radiation in Patients with Newly Diagnosed High-grade Gliomas  

Microsoft Academic Search

The dose intensity of the PCV regimen can be doubled using peripheral blood stem cell (PBSC) support. This study sought to determine the feasibility of giving dose-intensive PCV concurrently with radiation therapy. Twelve patients, age 3.2–22.7 years, median 7.5 years, with newly diagnosed high grade gliomas were enrolled. Diagnoses included diffuse intrinsic brainstem gliomas (BSG) (n=6), glioblastoma (n=4), anaplastic astrocytoma

Regina I. Jakacki; Joao Siffert; Cheryl Jamison; Linda Velasquez; Jeffrey C. Allen

1999-01-01

137

Tripping over emerging pathogens around the world: a phylogeographical approach for determining the epidemiology of Porcine circovirus-2 (PCV-2), considering global trading.  

PubMed

Porcine circovirus-2 (PCV-2) is an emerging virus associated with a number of different syndromes in pigs known as Porcine Circovirus Associated Diseases (PCVAD). Since its identification and characterization in the early 1990s, PCV-2 has achieved a worldwide distribution, becoming endemic in most pig-producing countries, and is currently considered as the main cause of losses on pig farms. In this study, we analyzed the main routes of the spread of PCV-2 between pig-producing countries using phylogenetic and phylogeographical approaches. A search for PCV-2 genome sequences in GenBank was performed, and the 420 PCV-2 sequences obtained were grouped into haplotypes (group of sequences that showed 100% identity), based on the infinite sites model of genome evolution. A phylogenetic hypothesis was inferred by Bayesian Inference for the classification of viral strains and a haplotype network was constructed by Median Joining to predict the geographical distribution of and genealogical relationships between haplotypes. In order to establish an epidemiological and economic context in these analyses, we considered all information about PCV-2 sequences available in GenBank, including papers published on viral isolation, and live pig trading statistics available on the UN Comtrade database (http://comtrade.un.org/). In these analyses, we identified a strong correlation between the means of PCV-2 dispersal predicted by the haplotype network and the statistics on the international trading of live pigs. This correlation provides a new perspective on the epidemiology of PCV-2, highlighting the importance of the movement of animals around the world in the emergence of new pathogens, and showing the need for effective sanitary barriers when trading live animals. PMID:22056846

Vidigal, Pedro M P; Mafra, Claudio L; Silva, Fernanda M F; Fietto, Juliana L R; Silva Júnior, Abelardo; Almeida, Márcia R

2012-01-01

138

Laboratory and Industrial Ventilation  

NASA Technical Reports Server (NTRS)

This handbook supplements the Facilities Engineering Handbook (NHB 7320.1) and provides additional policies and criteria for uniform application to ventilation systems. It expands basic requirements, provides additional design and construction guidance, and places emphasis on those design considerations which will provide for greater effectiveness in the use of these systems. The provisions of this handbook are applicable to all NASA field installations and the Jet Propulsion Laboratory. Since supply of this handbook is limited, abstracts of the portion or portions applicable to a given requirement will be made for the individual specific needs encountered rather than supplying copies of the handbook as has been past practice.

1972-01-01

139

New Aspects in Mechanical Ventilation  

Microsoft Academic Search

We present a short overview on what is state of the art in mechanical ventilation with emphasis on acute lung injury and acute\\u000a respiratory distress syndrome as well as on some newer trends for weaning of the patients from mechanical ventilation.

Christoph Haberthür; Reto Stocker

2006-01-01

140

Evaluation of building ventilation systems  

SciTech Connect

Over the past several years, NIOSH has responded to health hazard evaluation requests from workers in dozens of office environments. Typically, the employees have complained of headache, eye and upper respiratory tract irritation, dizziness, lethargy and the inability to concentrate. Most often inadequate ventilation has been blamed for these complaints. Of paramount importance in the evaluation and correction of these problems is an effective evaluation of the building's ventilation system. Heating, ventilating and air-conditioning conditions that can cause worker stresses include: migration of odors or chemical hazards between building areas; reentrainment of exhaust from building fume hoods or through heat wheels; buildup of microorganisms in the HVAC system components; and poor odor or environmental control due to insufficient fresh outdoor air or system heating or cooling malfunction. The purpose of this paper is to provide an overview of building ventilation systems, the ventilation problems associated with poorly designed or operating systems, and the methodology for effectively evaluating system performance.

Hughes, R.T.; O'Brien, D.M.

1986-04-01

141

Particle size concentration distribution and influences on exhaled breath particles in mechanically ventilated patients.  

PubMed

Humans produce exhaled breath particles (EBPs) during various breath activities, such as normal breathing, coughing, talking, and sneezing. Airborne transmission risk exists when EBPs have attached pathogens. Until recently, few investigations had evaluated the size and concentration distributions of EBPs from mechanically ventilated patients with different ventilation mode settings. This study thus broke new ground by not only evaluating the size concentration distributions of EBPs in mechanically ventilated patients, but also investigating the relationship between EBP level and positive expiratory end airway pressure (PEEP), tidal volume, and pneumonia. This investigation recruited mechanically ventilated patients, with and without pneumonia, aged 20 years old and above, from the respiratory intensive care unit of a medical center. Concentration distributions of EBPs from mechanically ventilated patients were analyzed with an optical particle analyzer. This study finds that EBP concentrations from mechanically ventilated patients during normal breathing were in the range 0.47-2,554.04 particles/breath (0.001-4.644 particles/mL). EBP concentrations did not differ significantly between the volume control and pressure control modes of the ventilation settings in the mechanically ventilated patients. The patient EBPs were sized below 5 µm, and 80% of them ranged from 0.3 to 1.0 µm. The EBPs concentrations in patients with high PEEP (> 5 cmH?O) clearly exceeded those in patients with low PEEP (? 5 cmH?O). Additionally, a significant negative association existed between pneumonia duration and EBPs concentration. However, tidal volume was not related to EBPs concentration. PMID:24475230

Wan, Gwo-Hwa; Wu, Chieh-Liang; Chen, Yi-Fang; Huang, Sheng-Hsiu; Wang, Yu-Ling; Chen, Chun-Wan

2014-01-01

142

46 CFR 153.312 - Ventilation system standards.  

Code of Federal Regulations, 2013 CFR

...ft) from openings into or ventilation intakes for, accommodation or service spaces. (b) A ventilation system must not recycle vapors from ventilation discharges. (c) Except for the space served by the ventilation duct, a ventilation duct...

2013-10-01

143

The Impact of Endotracheal Suctioning on Gas Exchange and Hemodynamics During Lung-Protective Ventilation in Acute Respiratory Distress Syndrome  

Microsoft Academic Search

OBJECTIVE: To evaluate the respiratory and hemodynamic effects of open suctioning (OS) versus closed suctioning (CS) during pressure-control (PC) and volume-control (VC) ventila- tion, using a lung-protective ventilation strategy in an animal model of acute respiratory distress syndrome (ARDS). SETTING: Animal laboratory in a university hospital. DESIGN: Randomized cross-over evaluation. ANIMALS: Eight female Dorset sheep. INTERVENTIONS: Lung lavage was used

Maria Paula Caramez; Guilherme Schettino; Klaudiusz Suchodolski; Tomoyo Nishida; R Scott Harris; Atul Malhotra; Robert M Kacmarek

2006-01-01

144

Lack of effect of piglet vaccination against Porcine circovirus type 2 (PCV2) on serum viral loads of Torque teno sus virus 2 (TTSuV2).  

PubMed

Anelloviruses are small, non-enveloped viruses with circular single stranded DNA, which infect a number of animal species as well as humans. In pigs, two distinct Torque teno sus virus (TTSuV) species have been described so far, being one of them linked to disease occurrence. Specifically, TTSuV2 loads in serum have been found increased in pigs suffering from postweaning multisystemic wasting syndrome (PMWS). Since this pathological condition is able to be controlled by means of porcine circovirus type 2 (PCV2) vaccination, it was hypothesized the possibility that such vaccination would have an impact on TTSuV2 prevalence and loads. A total of 150 pigs were divided in two study groups. Half of them received a PCV2 commercial vaccine, while the other half remained as non-vaccinated controls. PCV2 infection was monitored at 3-4, 8, 12, 16 and 21 weeks of age by means of an standard PCR, while TTSuV2 loads were determined at 8, 16 and 21 weeks of age by a quantitative PCR. No obvious PMWS clinical signs were observed among studied animals, although PCV2 infection was confirmed in both groups of pigs. Almost all pigs got TTSuV2 infection throughout the study period, independently of the PCV2 vaccination status of animals. Moreover, TTSuV2 load did not show significant differences between different pig groups at each sampling time, but mean viral load increased with age. Taking into account that previous results suggest that TTSuV2 load in serum is increased in the background of PMWS, the present study suggests that this is not the case in a PCV2 subclinical infection scenario. Therefore, vaccination of PCV2 subclinically infected pigs did not modify the outcome of TTSuV2 infection. PMID:22189433

Nieto, D; Aramouni, M; Sibila, M; Fraile, L; Kekarainen, T; Segalés, J

2012-05-25

145

Type 2 diabetes in older people; the importance of blood pressure control.  

PubMed

Diabetes and hypertension often coexist and their coexistence substantially promote cardiovascular disease (CVD) and chronic kidney disease. Control of blood pressure to a level of 140/90 mm Hg in people with diabetes can prevent or at least delay CVD and chronic kidney disease.. In the past many society treatment guidelines have stressed tight blood pressure control (=< 130/80) for people with diabetes. But recommendations for such tight blood pressure control have not been supported by recent large randomized control trials, especially in in elderly. Here we review the recent literature regarding the benefits of blood pressure control in elderly patients with diabetics. We further focus on evidence for specific levels of blood pressure treatment goals, in this population subset.. PMID:23667714

Jindal, Ankur; Whaley-Connell, Adam; Sowers, James R

2013-06-01

146

Simulation and experiment research on the proportional pressure control of water-assisted injection molding  

NASA Astrophysics Data System (ADS)

Water-assisted injection molding (WAIM), a newly developed fluid-assisted injection molding technology has drawn more and more attentions for the energy saving, short cooling circle time and high quality of products. Existing research for the process of WAIM has shown that the pressure control of the injecting water is mostly important for the WAIM. However, the proportional pressure control for the WAIM system is quite complex due to the existence of nonlinearities in the water hydraulic system. In order to achieve better pressure control performance of the injecting water to meet the requirements of the WAIM, the proportional pressure control of the WAIM system is investigated both numerically and experimentally. A newly designed water hydraulic system for WAIM is first modeled in AMEsim environment, the load characteristics and the nonlinearities of water hydraulic system are both considered, then the main factors affecting the injecting pressure and load flow rate are extensively studied. Meanwhile, an open-loop model-based compensation control strategy is employed to regulate the water injection pressure and a feedback proportional integrator controller is further adopted to achieve better control performance. In order to verify the AMEsim simulation results WAIM experiment for particular Acrylonitrile Butadiene Styrene (ABS) parts is implemented and the measured experimental data including injecting pressure and flow rate results are compared with the simulation. The good coincidence between experiment and simulation shows that the AMEsim model is accurate, and the tracking performance of the load pressure indicates that the proposed control strategy is effective for the proportional pressure control of the nonlinear WAIM system. The proposed proportional pressure control strategy and the conclusions drawn from simulation and experiment contribute to the application of water hydraulic proportional control and WAIM technology.

Zhou, Hua; Chen, Yinglong; Zhang, Zengmeng; Yang, Huayong

2012-05-01

147

Clothing ventilation - update and applications.  

PubMed

The Environmental Ergonomics Unit at the P.O.W. provided a forum for the discussion and consolidation of ideas regarding the origins, current progress and the future development of the Clothing Ventilation Index. Crockford et al (1972) first developed the concept of clothing ventilation. The basic technique employs a trace gas dilution method for measuring the ventilation of the clothing microclimate. Ventilation is vital to the removal of sensible and insensible heat and, therefore, an important determinant of thermal comfort. Two techniques (Lotens and Havenith, 1986, 1988; Reischl et al, 1987) have subsequently been developed. The former method results in an average ventilation value for the total clothed-body surface area, whereas the latter method also takes into consideration regional changes in garment design as separate entities from the total ventilation, allowing for local modification in garment design. The Clothing Ventilation Index is a quantitative, relatively inexpensive, fast, reliable and repeatable technique. It can be used in context, in the working environment to predict the effectiveness, preference and suitability of garments and clothing assemblies; firstly, to ensure that protective clothing is worn and used correctly, and secondly, to improve performance by minimising heat strain, sweat retention and thermal discomfort. Further work on validating the techniques in terms of human responses to the thermal environment is required. Questions were also raised as to whether human beings or manikins should be used. The use of human beings in dynamic situations is of paramount importance; however, manikins could be used for purely physical measurements to test various assumptions in evaluating clothing ventilation. It is essential that body dimensions and posture are always specified. The seminar enabled researchers to identify with the proposed techniques, outline the advantages and importance of the Clothing Ventilation Index and focus future studies. PMID:15676838

Lumley, S H; Story, D L; Thomas, N T

1991-12-01

148

Capabilities of a New Pressure Controller for Gas-Controlled Heat Pipes  

Microsoft Academic Search

Pressure control is used in many metrological applications and for the control of thermodynamic quantities. At the Italian\\u000a National Research Institute of Metrology (INRiM), a new pressure controller has been designed and assembled, operating in\\u000a the pressure range between 4 kPa and 400 kPa. This innovative instrument uses a commercial pressure transducer with a sensitivity\\u000a of 10?4 and several electro-valves interposed among

S. Giunta; A. Merlone; S. Marenco; P. Marcarino; A. Tiziani

2008-01-01

149

Impact of routine PCV7 (Prevenar) vaccination of infants on the clinical and economic burden of pneumococcal disease in Malaysia  

PubMed Central

Background Pneumococcal disease is the leading cause of vaccine-preventable death in children younger than 5 years of age worldwide. The World Health Organization recommends pneumococcal conjugate vaccine as a priority for inclusion into national childhood immunization programmes. Pneumococcal vaccine has yet to be included as part of the national vaccination programme in Malaysia although it has been available in the country since 2005. This study sought to estimate the disease burden of pneumococcal disease in Malaysia and to assess the cost effectiveness of routine infant vaccination with PCV7. Methods A decision model was adapted taking into consideration prevalence, disease burden, treatment costs and outcomes for pneumococcal disease severe enough to result in a hospital admission. Disease burden were estimated from the medical records of 6 hospitals. Where local data was unavailable, model inputs were obtained from international and regional studies and from focus group discussions. The model incorporated the effects of herd protection on the unvaccinated adult population. Results At current vaccine prices, PCV7 vaccination of 90% of a hypothetical 550,000 birth cohort would incur costs of RM 439.6 million (US$128 million). Over a 10 year time horizon, vaccination would reduce episodes of pneumococcal hospitalisation by 9,585 cases to 73,845 hospitalisations with cost savings of RM 37.5 million (US$10.9 million) to the health system with 11,422.5 life years saved at a cost effectiveness ratio of RM 35,196 (US$10,261) per life year gained. Conclusions PCV7 vaccination of infants is expected to be cost-effective for Malaysia with an incremental cost per life year gained of RM 35,196 (US$10,261). This is well below the WHO's threshold for cost effectiveness of public health interventions in Malaysia of RM 71,761 (US$20,922).

2011-01-01

150

Detection of porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) antibodies in meat juice samples from Polish wild boar (Sus scrofa L.).  

PubMed

PCV2 and PRRSV are two important pathogens of domestic swine. There is considerable evidence that the infection is also present in wild boars. Meat juice provides an alternative to serum for antibody testing, and it has been used in testing for many important porcine infectious diseases. Samples of brachial muscle were collected from 142 wild boars shot in different regions of Poland during the 2006/2007 and 2007/2008 hunting seasons. Meat juice harvested from muscle samples was tested using an ELISA test specific for PCV2 and PRRSV antibodies. Additionally, IgG and IgM antibodies specific for PCV2 were detected in order to estimate the status of the PCV2 infection. Only one of the tested meat juice samples was positive for PRRSV (0.7%), and 68 out of 142 (47.9%) samples were positive for PCV2. Of the positive animals, 4 (2.8%) had an antibody profile suggesting active infection, 2 (1.4%) early active infection, and 62 (43.7%) late infection. Also, a lack of association between the age of the animals and the presence of antibodies related to the infection was noticed. PMID:23974935

Fabisiak, Micha?; Podgórska, Katarzyna; Skrzypiec, Ewelina; Szczotka, Anna; Stadejek, Tomasz

2013-12-01

151

Cultivation of PCV2 in swine testicle cells using the shell vial technique and monitoring of viral replication by qPCR and RT-qPCR.  

PubMed

Porcine circovirus type 2 (PCV2) is difficult to isolate. Currently, no published articles have used the shell vial technique to isolate PCV2. In addition, the action of d-glucosamine on swine testicle cells (ST) has not been evaluated properly. Thus, the aim of this study was to determine an optimal concentration of d-glucosamine and to test the shell vial technique for PCV2 propagation in ST cells. The optimal concentration of d-glucosamine was determined to be 100mM. Because PCV2 is noncytopathic, the traditional adsorption was compared to the shell vial technique for 15 passages by qPCR, and RT-qPCR for passages 12 through 15. The quantities of viral DNA (P=0.013) and ORF1-mRNA detected with the shell vial technique were two-fold higher than the obtained with traditional adsorption. The levels of ORF2-mRNA were similar for both methods; however, by passage 15, a six-fold increase in levels was observed with the shell vial technique. Therefore, the shell vial technique was more efficient for the cultivation of PCV2, and qPCR/RT-qPCR can be used to monitor viral replication. In addition, a high viral load (>2.7×10(10) DNA copies/ml) and high levels of viral mRNA expression indicated that the ST cells were persistently infected. PMID:24183921

Cruz, Taís F; Araujo, João P

2014-02-01

152

Ventilation Criteria for Aeromedical Evacuation.  

National Technical Information Service (NTIS)

Air evacuation of patients requiring mechanical ventilation exposes these individuals to a barometric pressure that is approximately 25% less than normal. This limits the maximum inspired oxygen tension that can be provided as well as possibly altering ve...

R. A. Klocke A. T. Aquilina B. J. B. Grant A. R. Saltzman P. A. Land

1986-01-01

153

EIGHTH INTERIM STATUS REPORT: MODEL 9975 PCV O-RING FIXTURE LONG-TERM LEAK PERFORMANCE  

SciTech Connect

A series of experiments to monitor the aging performance of Viton® GLT O-rings used in the Model 9975 package has been ongoing since 2004 at the Savannah River National Laboratory. Seventy tests using mock-ups of 9975 Primary Containment Vessels (PCVs) were assembled and heated to temperatures ranging from 200 to 450 ºF. They were leak-tested initially and have been tested periodically to determine if they meet the criterion of leak-tightness defined in ANSI standard N14.5-97. Fourteen additional tests were initiated in 2008 with GLT-S O-rings heated to temperatures ranging from 200 to 400 ºF. High temperature aging continues for 23 GLT O-ring fixtures at 200 – 270 ºF. Room temperature leak test failures have been experienced in all of the GLT O-ring fixtures aging at 350 ºF and higher temperatures, and in 8 fixtures aging at 300 ºF. The remaining GLT O-ring fixtures aging at 300 ºF have been retired from testing following more than 5 years at temperature without failure. No failures have yet been observed in GLT O-ring fixtures aging at 200 ºF for 61 - 85 months, which is still bounding to O-ring temperatures during storage in KArea Complex (KAC). Based on expectations that the fixtures aging at 200 ºF will remain leaktight for a significant period yet to come, 2 additional fixtures began aging in 2011 at an intermediate temperature of 270 ºF, with hopes that they may reach a failure condition before the 200 ºF fixtures. High temperature aging continues for 6 GLT-S O-ring fixtures at 200 – 300 ºF. Room temperature leak test failures have been experienced in all 8 of the GLT-S O-ring fixtures aging at 350 and 400 ºF. No failures have yet been observed in GLT-S O-ring fixtures aging at 200 - 300 ºF for 41 - 45 months. Aging and periodic leak testing will continue for the remaining PCV fixtures.

Daugherty, W. L.

2013-09-03

154

Mechanical ventilation in rural ICUs  

PubMed Central

Background: In recent years, rural hospitals have expanded their scope of specialized services, which has led to the development and staffing of rural intensive care units (ICUs). There is little information about the breadth, quality or outcomes of these services. This is particularly true for specialized ICU services such as mechanical ventilation, where little, if any, information exists specifically for rural hospitals. The long-term objectives of this project were to evaluate the quality of medical care provided to mechanically ventilated patients in rural ICUs and to improve patient care through an educational intervention. This paper reports baseline data on patient and hospital characteristics for both rural and rural referral hospitals. Results: Twenty Iowa hospitals were evaluated. Data collected on 224 patients demonstrated a mean age of 70 years and a mean ICU admission Acute Physiology and Chronic Health Evaluation (APACHE) II score of 22, with an associated 36% mortality. Mean length of ICU stay was 10 days, with 7.7 ventilated days. Significant differences were found in both institutional and patient variables between rural referral hospitals and rural hospitals with more limited resources. A subgroup of patients with diagnoses associated with complex ventilation had higher mortality rates than patients without these conditions. Patients who developed nosocomial events had longer mean ventilator and ICU days than patients without nosocomial events. This study also found ICU practices that frequently fell outside the guidelines recommended by a task force describing minimum standards of care for critically ill patients with acute respiratory failure on mechanical ventilation. Conclusions: Despite distinct differences in the available resources between rural referral and rural hospitals, overall mortality rates of ventilated patients are similar. Considering the higher mortality rates observed in patients with complicated medical conditions requiring complex ventilation management, the data may suggest that this subgroup could benefit from treatment at a tertiary center with greater resources and technology.

Fieselmann, John F; Bock, M Jeanne; Hendryx, Michael S; Wakefield, Douglas; Helms, Charles M; Bentler, Suzanne E

1999-01-01

155

Mechanical ventilation in rural ICUs.  

PubMed

BACKGROUND: In recent years, rural hospitals have expanded their scope of specialized services, which has led to the development and staffing of rural intensive care units (ICUs). There is little information about the breadth, quality or outcomes of these services. This is particularly true for specialized ICU services such as mechanical ventilation, where little, if any, information exists specifically for rural hospitals. The long-term objectives of this project were to evaluate the quality of medical care provided to mechanically ventilated patients in rural ICUs and to improve patient care through an educational intervention. This paper reports baseline data on patient and hospital characteristics for both rural and rural referral hospitals. RESULTS: Twenty Iowa hospitals were evaluated. Data collected on 224 patients demonstrated a mean age of 70 years and a mean ICU admission Acute Physiology and Chronic Health Evaluation (APACHE) II score of 22, with an associated 36% mortality. Mean length of ICU stay was 10 days, with 7.7 ventilated days. Significant differences were found in both institutional and patient variables between rural referral hospitals and rural hospitals with more limited resources. A subgroup of patients with diagnoses associated with complex ventilation had higher mortality rates than patients without these conditions. Patients who developed nosocomial events had longer mean ventilator and ICU days than patients without nosocomial events. This study also found ICU practices that frequently fell outside the guidelines recommended by a task force describing minimum standards of care for critically ill patients with acute respiratory failure on mechanical ventilation. CONCLUSIONS: Despite distinct differences in the available resources between rural referral and rural hospitals, overall mortality rates of ventilated patients are similar. Considering the higher mortality rates observed in patients with complicated medical conditions requiring complex ventilation management, the data may suggest that this subgroup could benefit from treatment at a tertiary center with greater resources and technology. PMID:11056720

Fieselmann; Bock; Hendryx; Wakefield; Helms; Bentler

1999-01-01

156

Controversies in patient-triggered ventilation.  

PubMed

Patient-triggered ventilation is a relatively recent development in neonatal mechanical ventilation. Advances in microprocessor-based technology, transducers, and monitoring have enabled patient-driven ventilator control and synchronization of mechanical ventilation with patient effort. The novelty of the newer ventilatory techniques has generated several controversies that remain to be resolved. Among these are signal detection and transduction, the optimal ventilatory modes, and weaning during patient-triggered ventilation. PMID:9523074

Donn, S M; Sinha, S K

1998-03-01

157

Space Station Environment Control and Life Support System Pressure Control Pump Assembly Modeling and Analysis  

NASA Technical Reports Server (NTRS)

This paper presents the Modeling and Analysis of the Space Station Environment Control and Life Support System Pressure Control Pump Assembly (PCPA). The contents include: 1) Integrated PCPA/Manifold Analyses; 2) Manifold Performance Analysis; 3) PCPA Motor Heat Leak Study; and 4) Future Plans. This paper is presented in viewgraph form.

Schunk, R. Gregory

2002-01-01

158

Pressure controlled reversing valve. [for drill stem test of offshore oil well  

Microsoft Academic Search

In accordance with an illustrative embodiment of the present invention, a pressure controlled reversing valve includes a housing having a flow passage and ports to communicate the passage with the well annulus outside the housing, valve means for normally closing said ports, valve operator means movable upwardly and downwardly in said housing in response to changes in the pressure of

Nutter

1976-01-01

159

DYNAMIC REDESIGN OF A FLOW CONTROL SERVO-VALVE USING A PRESSURE CONTROL PILOT  

Microsoft Academic Search

In this paper, the dynamic performance of an unconventional two-spool flow control servo valve using a pressure control pilot is analyzed. Such valves are less expensive than typical servo- valves but also tend to be limited in their dynamic performance. Based on a previously developed eight state nonlinear model, we develop a simplified linear model which is able to capture

Perry Y. Li; DSC TOC

2001-01-01

160

Ventilation Model and Analysis Report  

SciTech Connect

This model and analysis report develops, validates, and implements a conceptual model for heat transfer in and around a ventilated emplacement drift. This conceptual model includes thermal radiation between the waste package and the drift wall, convection from the waste package and drift wall surfaces into the flowing air, and conduction in the surrounding host rock. These heat transfer processes are coupled and vary both temporally and spatially, so numerical and analytical methods are used to implement the mathematical equations which describe the conceptual model. These numerical and analytical methods predict the transient response of the system, at the drift scale, in terms of spatially varying temperatures and ventilation efficiencies. The ventilation efficiency describes the effectiveness of the ventilation process in removing radionuclide decay heat from the drift environment. An alternative conceptual model is also developed which evaluates the influence of water and water vapor mass transport on the ventilation efficiency. These effects are described using analytical methods which bound the contribution of latent heat to the system, quantify the effects of varying degrees of host rock saturation (and hence host rock thermal conductivity) on the ventilation efficiency, and evaluate the effects of vapor and enhanced vapor diffusion on the host rock thermal conductivity.

V. Chipman

2003-07-18

161

Mechanical ventilator design and function: the trigger variable.  

PubMed

Because of the design characteristics, flow-triggering appears to offer measurable advantages over pressure-triggering, particularly during spontaneous breathing. During the trigger phase, flow-triggering provides a relatively shorter time delay than pressure-triggering. A trigger sensitivity that does not cause autocycling can be set while a short time delay is maintained. It remains to be determined whether flow-triggering has less effect on the pressure-time product than pressure-triggering. During the post-trigger phase, the relatively optimal flow delivery with flow-by results in the maintenance of airway pressure at or above the end-expiratory airway pressure level. This accounts for the lower level of inspiratory muscle work observed with flow-by over that observed with demand-flow. Whether inspiratory muscle work on a demand-flow system with optimal flow delivery will be similar to that on flow-by is not known. With a flow-by or demand-flow system, the circuit pressure-sensing site influences the flow-pressure control algorithm in the post-trigger phase only. In microprocessor-based ventilators, the shortcomings seen with pressure-triggering during the post-trigger phase can unquestionably be overcome with a better ventilator algorithm design or the application of a small amount of pressure support. However, during the trigger phase, the impact of this effort is less clear. PMID:10145700

Sassoon, C S

1992-09-01

162

Detection of probable effects of microwave exposure of blood parameters of RBC, PCV and Hb in rat.  

PubMed

The aim of this preliminary investigation was to assess the probable effects of microwave exposure on Hematological parameters of RBC (Red Blood Cell), PCV (Packed Cell Volume) and Hb (Hemoglobin) in rats. For this study 80 Sprague Dawley rats were exposed to 2450 MHZ microwave field for a period of one year. The experiment groups were divided to 5 groups, each 16 (8 males and 8 female), 4 for treatment and one, for control (D, E, F, G and H). The incident power density of the first two experiment groups was 1 mW m(-2) and for next two groups, was 10 mW cm(-2). The daily exposure time was 5 min for groups F and G and 30 min for groups, D and F. The animals in control group (H) were under normal condition without any microwave exposure. In the end of the study the blood samples were taken from the heart of animals under ether anesthesia and determination of blood parameters were performed by cell counter auto analyzer. According to the statistical results, the level of RBC in male groups of F and G and percentage of PCV in female and male groups of F and content of Hb, in female groups of F, were significantly increased in comparison to the control group and variation of results in other groups were not significant. PMID:19093535

Esfahani, M Sedehi; Radmehr, B; Kohbodi, A

2007-12-15

163

Epitope screening of the PCV2 Cap protein by use of a random peptide-displayed library and polyclonal antibody.  

PubMed

Capsid protein (Cap), the only structural protein of porcine circovirus 2 (PCV2), is involved in the host protective response and is a target for vaccine development. To find a rapid and easy way to fully map the antigenic epitopes of Cap, purified Cap-specific polyclonal antibodies were used to screen a random heptapeptide phage display library. After three rounds of screening, twenty phage clones that had binding activity to Cap-specific antibodies (tested by phage ELISA) were sequenced. When the inserted amino acid sequences were aligned with the Cap protein sequence, eight core regions in Cap ((50)SRTFGYT(56), (62)VRTPSW(67), (68)AVDMMR(73), (79)FLPPGG(84), (86)SNPRSVPF(93), (102)KVEFWP(107), (119)GSSXXXLDDN(128) and (229)PPLNP(233)) were identified, three of which ((50)SRTFGYT(56), (86)SNPRSVPF(93) and (102)KVEFWP(107)) for the first time. Nine phagetopes representing the eight regions were chosen to immunize Kunming mice. All except minotopes (50)SRTFGYT(56) and (229)PPLNP(233) induced antibodies against PCV2 when injected into Kunming mice. PMID:23845304

Ge, Meng; Yan, Ai; Luo, Wei; Hu, Yun-Fei; Li, Run-Cheng; Jiang, Da-Liang; Yu, Xing-Long

2013-10-01

164

Second-line chemotherapy with temozolomide in recurrent oligodendroglioma after PCV (procarbazine, lomustine and vincristine) chemotherapy: EORTC Brain Tumor Group phase II study 26972  

Microsoft Academic Search

BACKGROUND: Oligodendroglial tumors are chemosensitive, with two-thirds of\\u000a patients responding to PCV combination chemotherapy with procarbazine,\\u000a lomustine (CCNU) and vincristine. Temozolomide (TMZ), a new alkylating and\\u000a methylating agent has shown high response rates in recurrent anaplastic\\u000a astrocytoma. We investigated this drug in recurrent oligodendroglial\\u000a tumors (OD) and mixed oligoastrocytomas (OA) after prior PCV chemotherapy\\u000a and radiation therapy. PATIENTS AND METHODS:

Bent van den M. J; O. Chinot; W. Boogerd; J. Bravo Marques; M. J. B. Taphoorn; J. M. Kros; Rijt van der C. C. D; C. J. Vecht; N. De Beule; B. Baron

2003-01-01

165

Inspiratory work and response times of a modified pediatric volume ventilator during synchronized intermittent mandatory ventilation and pressure support ventilation.  

PubMed

Volume ventilation by demand flow ventilators significantly increases work of breathing during inspiration. Although various ventilator modifications and different modes of ventilation have been developed, there have been few studies regarding imposed work of breathing in infants and children. This study was designed to evaluate several modifications of a commercially available demand flow ventilator designed to shorten response time (tr) and decrease the imposed work (Wi) involved in opening the demand valve. Minimum withdrawal volume (Vmin), maximum negative pressure (P mneg), and tr were measured. Wi was defined as the product of Vmin and P mneg. Seven Siemens Servo 900C ventilators were tested under 16 different trial conditions with four variables: 1) mode of ventilation (synchronized intermittent mandatory ventilation [SIMV] vs. pressure support ventilation [PSV]); 2) caliber of circuit tubing (adult vs. pediatric); 3) location of airway pressure monitor (distal vs. proximal); and 4) ventilator trigger sensitivity (0 cm H2O--high vs. -2 cm H2O--low). Vmin, Pmneg, and Wi were all decreased (P less than .05) while tr was unaffected by changing ventilator trigger sensitivity from low to high. Wi was decreased by pediatric tubing and proximal airway pressure monitoring only when low trigger sensitivity was used. PSV and proximal airway monitoring shortened tr. The authors conclude that the use of pediatric circuit tubing and proximal airway pressure monitoring with a Siemens Servo 900C ventilator significantly improved ventilator performance. PMID:2589684

Martin, L D; Rafferty, J F; Wetzel, R C; Gioia, F R

1989-12-01

166

Residential ventilation standards scoping study  

SciTech Connect

The goals of this scoping study are to identify research needed to develop improved ventilation standards for California's Title 24 Building Energy Efficiency Standards. The 2008 Title 24 Standards are the primary target for the outcome of this research, but this scoping study is not limited to that timeframe. We prepared this scoping study to provide the California Energy Commission with broad and flexible options for developing a research plan to advance the standards. This document presents the findings of a scoping study commissioned by the Public Interest Energy Research (PIER) program of the California Energy Commission to determine what research is necessary to develop new residential ventilation requirements for California. This study is one of three companion efforts needed to complete the job of determining the ventilation needs of California residences, determining the bases for setting residential ventilation requirements, and determining appropriate ventilation technologies to meet these needs and requirements in an energy efficient manner. Rather than providing research results, this scoping study identifies important research questions along with the level of effort necessary to address these questions and the costs, risks, and benefits of pursuing alternative research questions. In approaching these questions and corresponding levels of effort, feasibility and timing were important considerations. The Commission has specified Summer 2005 as the latest date for completing this research in time to update the 2008 version of California's Energy Code (Title 24).

McKone, Thomas E.; Sherman, Max H.

2003-10-01

167

Injurious mechanical ventilation in the normal lung causes a progressive pathologic change in dynamic alveolar mechanics  

PubMed Central

Introduction Acute respiratory distress syndrome causes a heterogeneous lung injury, and without protective mechanical ventilation a secondary ventilator-induced lung injury can occur. To ventilate noncompliant lung regions, high inflation pressures are required to 'pop open' the injured alveoli. The temporal impact, however, of these elevated pressures on normal alveolar mechanics (that is, the dynamic change in alveolar size and shape during ventilation) is unknown. In the present study we found that ventilating the normal lung with high peak pressure (45 cmH20) and low positive end-expiratory pressure (PEEP of 3 cmH2O) did not initially result in altered alveolar mechanics, but alveolar instability developed over time. Methods Anesthetized rats underwent tracheostomy, were placed on pressure control ventilation, and underwent sternotomy. Rats were then assigned to one of three ventilation strategies: control group (n = 3, Pcontrol = 14 cmH2O, PEEP = 3 cmH2O), high pressure/low PEEP group (n = 6, Pcontrol = 45 cmH2O, PEEP = 3 cmH2O), and high pressure/high PEEP group (n = 5, Pcontrol = 45 cmH2O, PEEP = 10 cmH2O). In vivo microscopic footage of subpleural alveolar stability (that is, recruitment/derecruitment) was taken at baseline and than every 15 minutes for 90 minutes following ventilator adjustments. Alveolar recruitment/derecruitment was determined by measuring the area of individual alveoli at peak inspiration (I) and end expiration (E) by computer image analysis. Alveolar recruitment/derecruitment was quantified by the percentage change in alveolar area during tidal ventilation (%I – E?). Results Alveoli were stable in the control group for the entire experiment (low %I – E?). Alveoli in the high pressure/low PEEP group were initially stable (low %I – E?), but with time alveolar recruitment/derecruitment developed. The development of alveolar instability in the high pressure/low PEEP group was associated with histologic lung injury. Conclusion A large change in lung volume with each breath will, in time, lead to unstable alveoli and pulmonary damage. Reducing the change in lung volume by increasing the PEEP, even with high inflation pressure, prevents alveolar instability and reduces injury. We speculate that ventilation with large changes in lung volume over time results in surfactant deactivation, which leads to alveolar instability.

Pavone, Lucio A; Albert, Scott; Carney, David; Gatto, Louis A; Halter, Jeffrey M; Nieman, Gary F

2007-01-01

168

Low-g fluid mixing - Further results from the Tank Pressure Control Experiment  

NASA Technical Reports Server (NTRS)

The Tank Pressure Control Experiment (TPCE) made its first space flight on STS-43 in 1991. Its objective was to test the effectiveness of low-energy axial jet mixing at controlling pressures in low gravity. The experiment used refrigerant 113 at near-saturation conditions, at an 83 percent fill level, to simulate the fluid dynamics and thermodynamics of cryogenic fluids in future space applications. Results from this flight were reported previously. TPCE was again flown in space on STS-52 in 1992, this time primarily to study boiling and related thermal phenomena which will be reported elsewhere. However additional mixing and pressure control data were obtained from the reflight that supplement the data from the first flight.

Bentz, M. D.; Knoll, R. H.; Hasan, M. M.; Lin, C. S.

1993-01-01

169

[Pressure control system for the hermetically sealed cabin of the recoverable satellite].  

PubMed

There are many precision instruments and equipment for scientific researches and experiments in the hermetically sealed cabin of satellite. Appropriate pressure must be controlled in the cabin in order to ensure the instruments and equipment from the adverse space environment. This paper describes a pressure control system for the hermetically sealed cabin in the recoverable scientific detect and experimental satellite. The cabin pressure is regulated automatically into the specific levels by venting or supplying the air from or to the cabin during launch, on orbit and before reentry of the satellite. The system has low mass, low power consumption and high reliability. It was used successfully in the recoverable satellite first in September 1987 and had been used many times since then. It is the first active pressure control system for the hermetically sealed cabin of the satellite in China. PMID:11541420

Sun, J; Yao, S; Zhang, X; Zhang, F; Zheng, C; Fu, L

1998-06-01

170

A Study of the Pneumatic Counterweight of Machine Tools Conventional and Active Pressure Control Method  

NASA Astrophysics Data System (ADS)

The pneumatic counterweight method is a suitable counterweight method used for machine tool owing to its high speed and force capacity, combined with low price and clean operation. However, the preset pressure cannot be hold at higher traveling rate if the conventional pneumatic counterweight is applied. In this study, rather than using the conventional pressure compensation method, the active pressure control method was designed as an alternative to the pneumatic counterweight driven by a linear motor. The fuzzy sliding mode controller was designed and implemented for regulating the pressure using the servo valve. The experimental results demonstrate that the variation of the pressure in the pneumatic cylinder can be hold within the range ±15kPa by using active pressure control method.

Tsai, Ming-Hung; Shih, Ming-Chang

171

Incremental Costs associated with Physician and Pharmacist Collaboration to Improve Blood Pressure Control  

PubMed Central

Study Objective To compare costs associated with a physician-pharmacist collaborative intervention with costs for usual care. Design Cost calculation using healthcare utilization and outcomes from prospective, cluster randomized controlled clinical trials. Setting Eleven community-based medical offices in the Midwest. Patients 496 patients with high blood pressure. Interventions A physician-pharmacist collaborative care program to manage hypertension. Measurements and Main Results Total costs included provider time, laboratory tests, and antihypertensive medications. Provider time was calculated based on 1) an online survey of intervention pharmacists and 2) National Ambulatory Medical Care Survey. Cost parameters were taken from the Bureau of Labor Statistics, the Medicare laboratory fee schedule, and a publicly available drug price website. The total costs were adjusted for patient characteristics. Adjusted total costs were $774.90 in the intervention group and $445.75 in the control group (difference = $329.16; p< 0.001). In a sensitivity analysis, the difference in adjusted total costs between the two groups ranged from $224.27 to $515.56. The intervention cost was $1,338.05 ($329.16/24.6% blood pressure control rate) for each additional patient who attained blood pressure control within six months. The cost over 6 months to lower systolic and diastolic blood pressure 1 mm Hg was $36.25 and $94.32, respectively. Conclusions The physician-pharmacist collaborative intervention increased blood pressure control but also increased the cost of care. Additional research, such as a cost-benefit or a cost-minimization analysis, is needed to assess if financial savings related to reduced morbidity and mortality achieved from better blood pressure control outweighs the cost.

Kulchaitanaroaj, Puttarin; Brooks, John M.; Ardery, Gail; Newman, Dana; Carter, Barry L.

2012-01-01

172

Effect of intensive blood pressure control on the course of type 1 diabetic nephropathy  

Microsoft Academic Search

Diabetic nephropathy is the most common cause of end-stage renal disease in the United States. We undertook a study to assess the impact of assignment to different levels of blood pressure control on the course of type 1 diabetic nephropathy in patients receiving angiotensin-converting enzyme (ACE) inhibitor therapy. We also examined the long-term course of this well-characterized cohort of patients

Julia Breyer Lewis; Tomas Berl; Raymond P. Bain; Richard D. Rohde; Edmund J. Lewis

1999-01-01

173

Air flow in snake ventilation.  

PubMed

Ventilation in resting, unrestrained Boa constrictor, Python regius and Thanmophis s. sirtalis was monitored using various combinations of a closed Kopfkappe (head chamber), intratracheal pressure catheters, strain gauges around the trunk, and a flow meter connected to one of the nostrils. Records of intratracheal pressure with and without closing the Kopfkappe show that the latter device induces artifacts in the normal ventilatory pattern. Flow meter readings from quiescent snakes indicate that ventilation is biphasic (outflow-inflow-pause) rather than triphasic (outflow-inflow-outflow-pause), while simultaneous pressure and strain gauge records are variably tri- or quadriphasic. PMID:644149

Clark, B D; Gans, C; Rosenberg, H I

1978-02-01

174

Fracture ventilation by surface winds  

NASA Astrophysics Data System (ADS)

Gas exchange between the Earth subsurface and the atmosphere is an important mechanism, affecting hydrological, agricultural and environmental processes. From a hydrological aspect, water vapor transport is the most important process related to Earth-atmosphere gas exchange. In respect to agriculture, gas transport in the upper soil profile is important for soil aeration. From an environmental aspect, emission of volatile radionuclides, such as 3H, 14C and Rd from radioactive waste disposal facilities; volatile organic components from industrial sources and Rn from natural sources, all found in the upper vadose zone, can greatly affect public health when emissions occur in populated areas. Thus, it is vital to better understand gas exchange processes between the Earth's upper crust and atmosphere. Four major mechanisms are known to transfer gases between ground surface and atmosphere: (1) Diffusion; (2) Pressure gradients between ground pores and atmosphere due to changes in barometric pressure; (3) Density-driven gas flow in respond to thermal gradients in the ground; and (4) Winds above the ground surface. Herein, the wind ventilation mechanism is studied. Whereas the wind's impact on ground ventilation was explored in several studies, the physical mechanisms governing this process were hardly quantified or characterized. In this work the physical properties of fracture ventilation due to wind blowing along land surface were explored and quantified. Both field measurements and Hele-Shaw experiments under controlled conditions in the laboratory were used to study this process. It was found that winds in the range of 0.3 m/s result in fracture ventilation down to a depth of 0.2 m. As wind velocity increases, the depth of the ventilation inside the fracture increases respectively, in a linear manner. In addition, the fracture aperture also affects the depth of ventilation, which grows as fracture aperture increases. For the maximal examined aperture of 2 cm and wind velocity of 1.25 m/s, fracture ventilation was deeper than 0.45 m. This study sheds new light on fracture ventilation, showing that moderate winds may increase evaporation and gas exchange between fractured media and the atmosphere. Even though wind impact is limited to the top 0.5 m below the ground surface, it is an important process as most of the biological activities, as well as important hydrological processes occur in this region. Wind effect should be considered when modeling mass and energy balances between the Earth upper crust and atmosphere.

Nachshon, U.; Dragila, M. I.; Weisbrod, N.

2011-12-01

175

Human versus Computer Controlled Selection of Ventilator Settings: An Evaluation of Adaptive Support Ventilation and Mid-Frequency Ventilation  

PubMed Central

Background. There are modes of mechanical ventilation that can select ventilator settings with computer controlled algorithms (targeting schemes). Two examples are adaptive support ventilation (ASV) and mid-frequency ventilation (MFV). We studied how different clinician-chosen ventilator settings are from these computer algorithms under different scenarios. Methods. A survey of critical care clinicians provided reference ventilator settings for a 70?kg paralyzed patient in five clinical/physiological scenarios. The survey-derived values for minute ventilation and minute alveolar ventilation were used as goals for ASV and MFV, respectively. A lung simulator programmed with each scenario's respiratory system characteristics was ventilated using the clinician, ASV, and MFV settings. Results. Tidal volumes ranged from 6.1 to 8.3?mL/kg for the clinician, 6.7 to 11.9?mL/kg for ASV, and 3.5 to 9.9?mL/kg for MFV. Inspiratory pressures were lower for ASV and MFV. Clinician-selected tidal volumes were similar to the ASV settings for all scenarios except for asthma, in which the tidal volumes were larger for ASV and MFV. MFV delivered the same alveolar minute ventilation with higher end expiratory and lower end inspiratory volumes. Conclusions. There are differences and similarities among initial ventilator settings selected by humans and computers for various clinical scenarios. The ventilation outcomes are the result of the lung physiological characteristics and their interaction with the targeting scheme.

Mireles-Cabodevila, Eduardo; Diaz-Guzman, Enrique; Arroliga, Alejandro C.; Chatburn, Robert L.

2012-01-01

176

Advanced Design of Local Ventilation Systems.  

National Technical Information Service (NTIS)

The aim of this study was to determine the applicability and limitations of more advanced fluid mechanical methods to the design and development of local ventilation systems. The most important factors affecting the performance of local ventilation system...

I. Kulmala

1997-01-01

177

33 CFR 175.201 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...Ventilation. No person may operate a boat built after July 31, 1980, that has a gasoline engine for electrical generation, mechanical power, or propulsion unless it is equipped with an operable ventilation system that meets the requirements...

2013-07-01

178

An Improved Heat Sterilizable Patient Ventilator.  

National Technical Information Service (NTIS)

A modified heat sterilizable patient ventilator is disclosed. The ventilator is characterized by a ported center body, a shell formed of heat sterilizable material mounted on the center body and defining a hermetically sealed reservoir for confining under...

A. S. Irons P. P. Muehter W. D. Kent

1974-01-01

179

Comparative Tests on Calves. Insulation - Ventilation - Heating.  

National Technical Information Service (NTIS)

Comparative tests have been carried out in 3 calf houses, of which one was insulated, mechanically ventilated and heated (KA-1), another was insulated and had an automatically regulated natural ventilation system without heating (KA-2), and the third hous...

K. Hansen

1984-01-01

180

[Mechanical ventilation in acute respiratory distress syndrome].  

PubMed

The goal of mechanically ventilating patients with acute respiratory distress syndrome (ARDS) is to ensure adequate oxygenation and minimal ventilator-associated lung injury. Non-invasive ventilation should be cautiously used in patients with ARDS. Protective ARDS mechanical ventilation strategies with low tidal volumes can reduce mortality. Driving pressure is the most reasonable parameter to optimize tidal volume. Available evidence does not support the routine use of higher positive end expiratory pressure (PEEP) in patients with ARDS. The optimal level of PEEP may be titrated by the inflection point obtained from static pressure-volume curve. Promising therapies include prone position ventilation, high frequency oscillatory ventilation and extracorporeal membrane oxygenation as salvage treatment. While mechanically ventilating, it is also important for ARDS patients to maintain spontaneous breathing via assisted ventilation mode such as bilevel positive airway pressure, pressure support ventilation and neurally adjusted ventilation assist. Exogenous surfactant, inhaled nitric oxide, bronchodilators, airway pressure release ventilation and partial liquid ventilation are not recommended therapies. PMID:23791070

Wang, Ya-Mei; Tao, Yu-Hong

2013-06-01

181

The fluid mechanics of natural ventilation  

Microsoft Academic Search

Natural ventilation of buildings is the flow generated by temperature differences and by the wind. Modern buildings have extreme designs with large, tall open plan spaces and large cooling requirements. Natural ventilation offers a means of cooling these buildings and providing good indoor air quality. The essential feature of ventilation is an exchange between an interior space and the external

Paul Linden

1999-01-01

182

Summary of human responses to ventilation  

Microsoft Academic Search

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated

Olli A. Seppanen; William J. Fisk

2004-01-01

183

AIR FLOW IN SNAKE VENTILATION  

Microsoft Academic Search

Ahstraet. Ventilation in resting, unrestrained Boa constrictor, Python regius and Thamnophi~ s. sirtalis was monitored using various combinations of a closed Kopfkappe (head chamber), intratracheal pressure catheters, strain gauges around the trunk, and a flow meter connected to one of the nostrils. Records of intratracheal pressure with and without closing the Koplkappe show that the latter device induces artifacts in

BRIAN D. CLARK; CARL GANS; H. I. ROSENBERG

1978-01-01

184

Novel modes of mechanical ventilation.  

PubMed

The overarching goal of positive pressure mechanical ventilation is to provide adequate gas exchange support while not causing harm. Indeed, positive pressure mechanical ventilators are only support technologies, not therapeutic technologies. As such they cannot be expected to "cure" disease; they can only "buy time" for other therapies (including the patient's own defenses) to work.Conventional approaches to positive pressure ventilation involve applying ventilatory patterns mimicking normal ones through either masks or artificial airways. This is usually done with modes of support incorporating assist/control breath-triggering mechanisms, gas delivery patterns governed by either a set flow or pressure, and breath cycling based on either a set volume, a set inspiratory time, or a set flow. Often this support includes positive end-expiratory pressure and supplemental oxygen. In recent decades several novel or unconventional approaches to providing mechanical ventilatory support have been introduced. For these to be considered of value, however, it would seem reasonable that they address important clinical challenges and be shown to improve important clinical outcomes (e.g., mortality, duration of ventilation, sedation needs, complications). This article focuses on challenges facing clinicians in providing mechanical ventilatory support and assesses several novel approaches introduced over the last 2 decades in the context of these challenges. PMID:23934718

Al-Hegelan, Mashael; MacIntyre, Neil R

2013-08-01

185

Phylogenetic comparison of porcine circovirus type 2 (PCV2) and porcine reproductive respiratory syndrome virus (PRRSV) strains detected in domestic pigs until 2008 and in 2012 in Croatia  

PubMed Central

Background Porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) have been present for the last 2 decades in Croatia, causing large economical losses in the pig production. The clinical features of the infections are mostly manifested by the development of respiratory problems, weight loss and poor growth performance, as well as reproductive failure in pregnant sows. Even though the infections are continuously recognized in some regions in Croatia, the heterogeneity of the detected viral strains from 2012 has not yet been investigated. The objective of this study was to compare virus strains of PCV2 and PRRSV detected until 2008 in Croatia with strains isolated in 2012 to gain a better epidemiological understanding of these two infections. Results PCV2 and PRRSV strains detected in 2012 in fattening pigs from regions where these two diseases have been previously described were compared to strains that have been detected in the same regions within the past two decades. The phylogenetic analysis revealed that the circulating PCV2 and PRRSV strains are distantly related to the previously described Croatian viral strains. However, when compared to known isolates from the GenBank a high genetic identity of PRRSV isolates with isolates from Hungary, Denmark and the Netherlands was found. Conclusion The results of this study reveal that even though PCV2 and PRRSV are constantly present in the investigated regions in Croatia, the viral strains found in 2012 genetically differ from those detected in earlier years. This indicates that new entries into the pig population appeared with regard to both infections, probably as a result of pig trade.

2014-01-01

186

To ventilate, oscillate, or cannulate?  

PubMed

Ventilatory management of acute respiratory distress syndrome has evolved significantly in the last few decades. The aims have shifted from optimal gas transfer without concern for iatrogenic risks to adequate gas transfer while minimizing lung injury. This change in focus, along with improved ventilator and multiorgan system management, has resulted in a significant improvement in patient outcomes. Despite this, a number of patients develop hypoxemic respiratory failure refractory to lung-protective ventilation (LPV). The intensivist then faces the dilemma of either persisting with LPV using adjuncts (neuromuscular blocking agents, prone positioning, recruitment maneuvers, inhaled nitric oxide, inhaled prostacyclin, steroids, and surfactant) or making a transition to rescue therapies such as high-frequency oscillatory ventilation (HFOV) and/or extracorporeal membrane oxygenation (ECMO) when both these modalities are at their disposal. The lack of quality evidence and potential harm reported in recent studies question the use of HFOV as a routine rescue option. Based on current literature, the role for venovenous (VV) ECMO is probably sequential as a salvage therapy to ensure ultraprotective ventilation in selected young patients with potentially reversible respiratory failure who fail LPV despite neuromuscular paralysis and prone ventilation. Given the risk profile and the economic impact, future research should identify the patients who benefit most from VV ECMO. These choices may be further influenced by the emerging novel extracorporeal carbon dioxide removal devices that can compliment LPV. Given the heterogeneity of acute respiratory distress syndrome, each of these modalities may play a role in an individual patient. Future studies comparing LPV, HFOV, and VV ECMO should not only focus on defining the patients who benefit most from each of these therapies but also consider long-term functional outcomes. PMID:23827735

Shekar, Kiran; Davies, Andrew R; Mullany, Daniel V; Tiruvoipati, Ravindranath; Fraser, John F

2013-10-01

187

The basis and basics of mechanical ventilation.  

PubMed

The development of mechanical ventilators and the procedures for their application began with the simple foot pump developed by Fell O'Dwyer in 1888. Ventilators have progressed through three generations, beginning with intermittent positive pressure breathing units such as the Bird and Bennett device in the 1960s. These were followed by second-generation units--represented by the Bennett MA-2 ventilator--in the 1970s, and the third-generation microprocessor-controlled units of today. During this evolutionary process clinicians recognized Types I and II respiratory failure as being indicators for mechanical ventilatory support. More recently investigators have expanded, clarified, and clinically applied the physiology of the work of breathing (described by Julius Comroe and other pioneers) to muscle fatigue, requiring ventilatory support. A ventilator classification system can help the clinician understand how ventilators function and under what conditions they may fail to operate as desired. Pressure-support ventilation is an example of how industry has responded to a clinical need--that is, to unload the work of breathing. All positive pressure ventilators generate tidal volumes by using power sources such as medical gas cylinders, air compressors, electrically driven turbines, or piston driven motors. Positive end-expiratory pressures, synchronized intermittent mandatory ventilation, pressure support ventilation, pressure release ventilation, and mandatory minute ventilation, are examples of the special functions available on modern ventilators. Modern third-generation ventilators use microprocessors to control operational functions and monitors. Because these units have incorporated the experience learned from earlier ventilators, it is imperative that clinicians understand basic ventilator operation and application in order to most effectively prescribe and assess their use. PMID:2036934

Bone, R C; Eubanks, D H

1991-06-01

188

Flow transport and gas mixing during invasive high frequency oscillatory ventilation.  

PubMed

A large Eddy simulation (LES) based computational fluid dynamics study was performed to investigate gas transport and mixing in patient specific human lung models during high frequency oscillatory ventilation. Different pressure-controlled waveforms (sinusoidal, exponential and square) and ventilator frequencies (15, 10 and 6Hz) were used (tidal volume=50mL). The waveforms were created by solving the equation of motion subjected to constant lung wall compliance and flow resistance. Simulations were conducted with and without endotracheal tube to understand the effect of invasive management device. Variation of pressure-controlled waveform and frequency exhibits significant differences on counter flow pattern, which could lead to a significant impact on the gas mixing efficiency. Pendelluft-like flow was present for the sinusoidal waveform at all frequencies but occurred only at early inspiration for the square waveform at highest frequency. The square waveform was most efficient for gas mixing, resulting in the least wall shear stress on the lung epithelium layer thereby reducing the risk of barotrauma to both airways and the alveoli for patients undergoing therapy. PMID:24656889

Alzahrany, Mohammed; Banerjee, Arindam; Salzman, Gary

2014-06-01

189

Blood Pressure Control in Hypertensive Patients in the "Hiperdia Program": A Territory-Based Study  

PubMed Central

Background Systemic hypertension is highly prevalent and an important risk factor for cardiovascular events. Blood pressure control in hypertensive patients enrolled in the Hiperdia Program, a program of the Single Health System for the follow-up and monitoring of hypertensive patients, is still far below the desired level. Objective To describe the epidemiological profile and to assess blood pressure control of patients enrolled in Hiperdia, in the city of Novo Hamburgo (State of Rio Grande do Sul, Brazil). Methods Cross-sectional study with a stratified cluster random sample, including 383 adults enrolled in the Hiperdia Program of the 15 Basic Health Units of the city of Porto Alegre, conducted between 2010 and 2011. Controlled blood pressure was defined as ?140 mmHg × 90 mmHg. The hypertensive patients were interviewed and their blood pressure was measured using a calibrated aneroid device. Prevalence ratios (PR) with 95% confidence interval, Wald's ?2 test, and simple and multiple Poisson regression were used in the statistical analysis. Results The mean age was 63 ± 10 years, and most of the patients were females belonging to social class C, with a low level of education, a sedentary lifestyle, and family history positive for systemic hypertension. Diabetes mellitus (DM) was observed in 31%; adherence to the antihypertensive treatment in 54.3%; and 33.7% had their blood pressure controlled. DM was strongly associated with inadequate BP control, with only 15.7% of the diabetics showing BP considered as controlled. Conclusion Even for hypertensive patients enrolled in the Hiperdia Program, BP control is not satisfactorily reached or sustained. Diabetic hypertensive patients show the most inappropriate BP control.

de Souza, Clarita Silva; Stein, Airton Tetelbom; Bastos, Gisele Alsina Nader; Pellanda, Lucia Campos

2014-01-01

190

The mechanical ventilator: past, present, and future.  

PubMed

The use of ventilatory assistance can be traced back to biblical times. However, mechanical ventilators, in the form of negative-pressure ventilation, first appeared in the early 1800s. Positive-pressure devices started to become available around 1900 and today's typical intensive care unit (ICU) ventilator did not begin to be developed until the 1940s. From the original 1940s ventilators until today, 4 distinct generations of ICU ventilators have existed, each with features different from that of the previous generation. All of the advancements in ICU ventilator design over these generations provide the basis for speculation on the future. ICU ventilators of the future will be able to integrate electronically with other bedside technology; they will be able to effectively ventilate all patients in all settings, invasively and noninvasively; ventilator management protocols will be incorporated into the basic operation of the ventilator; organized information will be presented instead of rows of unrelated data; alarm systems will be smart; closed-loop control will be present on most aspects of ventilatory support; and decision support will be available. The key term that will be used to identify these future ventilators will be smart! PMID:21801579

Kacmarek, Robert M

2011-08-01

191

Ventilation and anesthetic approaches for rigid bronchoscopy.  

PubMed

Due to growing interest in management of central airway obstruction, rigid bronchoscopy is undergoing a resurgence in popularity among pulmonologists. Performing rigid bronchoscopy requires use of deep sedation or general anesthesia to achieve adequate patient comfort, whereas maintaining oxygenation and ventilation via an uncuffed and often open rigid bronchoscope requires use of ventilation strategies that may be unfamiliar to most pulmonologists. Available approaches include apneic oxygenation, spontaneous assisted ventilation, controlled ventilation, manual jet, and high-frequency jet ventilation. Anesthetic technique is partially dictated by the selected ventilation strategy but most often relies on a total intravenous anesthetic approach using ultra-short-acting sedatives and hypnotics for a rapid offset of action in this patient population with underlying respiratory compromise. Gas anesthetic may be used with the rigid bronchoscope, minimizing leaks with fenestrated caps placed over the ports, although persistent circuit leaks can make this approach challenging. Jet ventilation, the most commonly used ventilatory approach, may be delivered manually using a Sanders valve or via an automated ventilator at supraphysiologic respiratory rates, allowing for an open rigid bronchoscope to facilitate ease of moving tools in and out of the airway. Despite a patient population that often suffers from significant respiratory compromise, major complications with rigid bronchoscopy are uncommon and are similar among modern ventilation approaches. Choice of ventilation technique should be determined by local expertise and equipment availability. Appropriate patient selection and recognition of limitations associated with a given ventilation strategy are critical to avoid procedural-related complications. PMID:24635585

Pathak, Vikas; Welsby, Ian; Mahmood, Kamran; Wahidi, Momen; MacIntyre, Neil; Shofer, Scott

2014-05-01

192

Clinical review: Liberation from mechanical ventilation  

PubMed Central

Mechanical ventilation is the defining event of intensive care unit (ICU) management. Although it is a life saving intervention in patients with acute respiratory failure and other disease entities, a major goal of critical care clinicians should be to liberate patients from mechanical ventilation as early as possible to avoid the multitude of complications and risks associated with prolonged unnecessary mechanical ventilation, including ventilator induced lung injury, ventilator associated pneumonia, increased length of ICU and hospital stay, and increased cost of care delivery. This review highlights the recent developments in assessing and testing for readiness of liberation from mechanical ventilation, the etiology of weaning failure, the value of weaning protocols, and a simple practical approach for liberation from mechanical ventilation.

El-Khatib, Mohamad F; Bou-Khalil, Pierre

2008-01-01

193

Summary of human responses to ventilation  

SciTech Connect

The effects of ventilation on indoor air quality and health is a complex issue. It is known that ventilation is necessary to remove indoor generated pollutants from indoor air or dilute their concentration to acceptable levels. But, as the limit values of all pollutants are not known, the exact determination of required ventilation rates based on pollutant concentrations and associated risks is seldom possible. The selection of ventilation rates has to be based also on epidemiological research (e.g. Seppanen et al., 1999), laboratory and field experiments (e.g. CEN 1996, Wargocki et al., 2002a) and experience (e.g. ECA 2003). Ventilation may also have harmful effects on indoor air quality and climate if not properly designed, installed, maintained and operated as summarized by Seppdnen (2003). Ventilation may bring indoors harmful substances that deteriorate the indoor environment. Ventilation also affects air and moisture flow through the building envelope and may lead to moisture problems that deteriorate the structures of the building. Ventilation changes the pressure differences over the structures of building and may cause or prevent the infiltration of pollutants from structures or adjacent spaces. Ventilation is also in many cases used to control the thermal environment or humidity in buildings. Ventilation can be implemented with various methods which may also affect health (e.g. Seppdnen and Fisk, 2002, Wargocki et al., 2002a). In non residential buildings and hot climates, ventilation is often integrated with air-conditioning which makes the operation of ventilation system more complex. As ventilation is used for many purposes its health effects are also various and complex. This paper summarizes the current knowledge on positive and negative effects of ventilation on health and other human responses. The focus of the paper is on office-type working environment and residential buildings. In the industrial premises the problems of air quality are usually more complex and case specific. They are subject to occupational safety legislation and not discussed here.

Seppanen, Olli A.; Fisk, William J.

2004-06-01

194

Development of a Residential Integrated Ventilation Controller  

SciTech Connect

The goal of this study was to develop a Residential Integrated Ventilation Controller (RIVEC) to reduce the energy impact of required mechanical ventilation by 20percent, maintain or improve indoor air quality and provide demand response benefits. This represents potential energy savings of about 140 GWh of electricity and 83 million therms of natural gas as well as proportional peak savings in California. The RIVEC controller is intended to meet the 2008 Title 24 requirements for residential ventilation as well as taking into account the issues of outdoor conditions, other ventilation devices (including economizers), peak demand concerns and occupant preferences. The controller is designed to manage all the residential ventilation systems that are currently available. A key innovation in this controller is the ability to implement the concept of efficacy and intermittent ventilation which allows time shifting of ventilation. Using this approach ventilation can be shifted away from times of high cost or high outdoor pollution towards times when it is cheaper and more effective. Simulations, based on the ones used to develop the new residential ventilation requirements for the California Buildings Energy code, were used to further define the specific criteria and strategies needed for the controller. These simulations provide estimates of the energy, peak power and contaminant improvement possible for different California climates for the various ventilation systems. Results from a field test of the prototype controller corroborate the predicted performance.

Staff Scientist; Walker, Iain; Sherman, Max; Dickerhoff, Darryl

2011-12-01

195

Passive ventilation for residential air quality control  

SciTech Connect

Infiltration has long served the residential ventilation needs in North America. In Northern Europe it has been augmented by purpose-provided natural ventilation systems--so-called passive ventilation systems--to better control moisture problems in dwellings smaller than their North American counterparts and in a generally wetter climate. The growing concern for energy consumption, and the environmental impacts associated with it, has however led to tighter residential construction standards on both continents and as a result problems associated with insufficient background ventilation have surfaced. Can European passive ventilation systems be adapted for use in North American dwellings to provide general background ventilation for air quality control? This paper attempts to answer this question. The configuration, specifications and performance of the preferred European passive ventilation system--the passive stack ventilation (PSV) system--will be reviewed; innovative components and system design strategies recently developed to improve the traditional PSV system performance will be outlined; and alternative system configurations will be presented that may better serve the climatic extremes and more urban contexts of North America. While these innovative and alternative passive ventilation systems hold great promise for the future, a rational method to size the components of these systems to achieve the control and precision needed to meet the conflicting constraints of new ventilation and air tightness standards has not been forthcoming. Such a method will be introduced in this paper and an application of this method will be presented.

Axley, J.

1999-07-01

196

Particle deposition in ventilation ducts  

SciTech Connect

Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 {micro}m were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the experimental measurements was applied to evaluate particle losses in supply and return duct runs. Model results suggest that duct losses are negligible for particle sizes less than 1 {micro}m and complete for particle sizes greater than 50 {micro}m. Deposition to insulated ducts, horizontal duct floors and bends are predicted to control losses in duct systems. When combined with models for HVAC filtration and deposition to indoor surfaces to predict the ultimate fates of particles within buildings, these results suggest that ventilation ducts play only a small role in determining indoor particle concentrations, especially when HVAC filtration is present. However, the measured and modeled particle deposition rates are expected to be important for ventilation system contamination.

Sippola, Mark R.

2002-09-01

197

Nontraditional modes of mechanical ventilation: progress or distraction?  

PubMed

As technology continues to develop, a wide range of novel and nontraditional modes of mechanical ventilation have become available for the management of critically ill patients. Proportional assist ventilation, neurally adjusted ventilatory assist and adaptive support ventilation are three novel modes of ventilation, which attempt to optimize patient-ventilator synchrony. Improved interactions between patient and ventilator may be important in improving clinical outcomes. Another important priority for mechanically ventilated patients is lung protection, and nontraditional modes of ventilation that may be implemented to minimize ventilator-associated lung injury include airway pressure release ventilation and high-frequency ventilation. Novel and nontraditional modes of ventilation may represent important tools in the critical care environment; however, continued investigation is needed to determine the overall impact of these various approaches on outcomes for mechanically ventilated patients. PMID:22788942

Turner, David A; Rehder, Kyle J; Cheifetz, Ira M

2012-06-01

198

MGMT Promoter Methylation Is Prognostic but Not Predictive for Outcome to Adjuvant PCV Chemotherapy in Anaplastic Oligodendroglial Tumors: A Report From EORTC Brain Tumor Group Study 26951  

PubMed Central

Purpose O6-methylguanine-methyltransferase (MGMT) promoter methylation has been shown to predict survival of patients with glioblastomas if temozolomide is added to radiotherapy (RT). It is unknown if MGMT promoter methylation is also predictive to outcome to RT followed by adjuvant procarbazine, lomustine, and vincristine (PCV) chemotherapy in patients with anaplastic oligodendroglial tumors (AOT). Patients and Methods In the European Organisation for the Research and Treatment of Cancer study 26951, 368 patients with AOT were randomly assigned to either RT alone or to RT followed by adjuvant PCV. From 165 patients of this study, formalin-fixed, paraffin-embedded tumor tissue was available for MGMT promoter methylation analysis. This was investigated with methylation specific multiplex ligation-dependent probe amplification. Results In 152 cases, an MGMT result was obtained, in 121 (80%) cases MGMT promoter methylation was observed. Methylation strongly correlated with combined loss of chromosome 1p and 19q loss (P = .00043). In multivariate analysis, MGMT promoter methylation, 1p/19q codeletion, tumor necrosis, and extent of resection were independent prognostic factors. The prognostic significance of MGMT promoter methylation was equally strong in the RT arm and the RT/PCV arm for both progression-free survival and overall survival. In tumors diagnosed at central pathology review as glioblastoma, no prognostic effect of MGMT promoter methylation was observed. Conclusion In this study, on patients with AOT MGMT promoter methylation was of prognostic significance and did not have predictive significance for outcome to adjuvant PCV chemotherapy. The biologic effect of MGMT promoter methylation or pathogenetic features associated with MGMT promoter methylation may be different for AOT compared with glioblastoma.

van den Bent, Martin J.; Dubbink, Hendrikus J.; Sanson, Marc; van der Lee-Haarloo, Cathleen R.; Hegi, Monika; Jeuken, Judith W.M.; Ibdaih, Ahmed; Brandes, Alba A.; Taphoorn, Martin J.B.; Frenay, Marc; Lacombe, Denis; Gorlia, Thierry; Dinjens, Winand N.M.; Kros, Johan M.

2009-01-01

199

Decrease in Hospitalizations for Pneumonia in Children under Five Years of Age in an Indian Reservation in Panama after the Introduction of the Heptavalent Pneumococcal Conjugate Vaccine (PCV7).  

PubMed

This study quantifies the impact of Heptavalent-Pneumococcal Conjugate Vaccine (PCV7) in Panama on indigenous children younger than 5 years old, based on clinical pneumonia cases. This study demonstrates a significant 41.2% reduction in hospitalizations and 38.6% reduction in referrals for pneumonia following the introduction of PCV7. Burden of disease from pneumonia appears reduced in the ?12-month- and 13-to-24-month-old groups. PMID:23762081

Nieto Guevara, Javier; Daza, Carlos; Smith, Rebecca

2013-01-01

200

Changes in Capsule and Drug Resistance of Pneumococci after Introduction of PCV7, Japan, 2010-2013.  

PubMed

We aimed to clarify changes in serotypes and genotypes mediating ?-lactam and macrolide resistance in Streptococcus pneumoniae isolates from Japanese children who had invasive pneumococcal disease (IPD) after the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into Japan; 341 participating general hospitals conducted IPD surveillance during April 2010-March 2013. A total of 300 pneumococcal isolates were collected in 2010, 146 in 2011, and 156 in 2012. The proportion of vaccine serotypes in infectious isolates decreased from 73.3% to 54.8% to 14.7% during the 3 years. Among vaccine serotype strains, genotypic penicillin-resistant S. pneumoniae strains also declined each year. Among nonvaccine serotype strains, 19A, 15A, 15B, 15C, and 24 increased in 2012. Increases were noted especially in genotypic penicillin-resistant S. pneumoniae isolates of serotypes 15A and 35B, as well as macrolide resistance mediated by the erm(B) gene in 15A, 15B, 15C, and 24. PMID:24960150

Chiba, Naoko; Morozumi, Miyuki; Shouji, Michi; Wajima, Takeaki; Iwata, Satoshi; Ubukata, Kimiko

2014-07-01

201

Changes in Capsule and Drug Resistance of Pneumococci after Introduction of PCV7, Japan, 2010-2013  

PubMed Central

We aimed to clarify changes in serotypes and genotypes mediating ?-lactam and macrolide resistance in Streptococcus pneumoniae isolates from Japanese children who had invasive pneumococcal disease (IPD) after the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into Japan; 341 participating general hospitals conducted IPD surveillance during April 2010–March 2013. A total of 300 pneumococcal isolates were collected in 2010, 146 in 2011, and 156 in 2012. The proportion of vaccine serotypes in infectious isolates decreased from 73.3% to 54.8% to 14.7% during the 3 years. Among vaccine serotype strains, genotypic penicillin-resistant S. pneumoniae strains also declined each year. Among nonvaccine serotype strains, 19A, 15A, 15B, 15C, and 24 increased in 2012. Increases were noted especially in genotypic penicillin-resistant S. pneumoniae isolates of serotypes 15A and 35B, as well as macrolide resistance mediated by the erm(B) gene in 15A, 15B, 15C, and 24.

Chiba, Naoko; Morozumi, Miyuki; Shouji, Michi; Wajima, Takeaki; Iwata, Satoshi

2014-01-01

202

Indirect population impact of universal PCV7 vaccination of children in a 2 + 1 schedule on the incidence of pneumonia morbidity in Kielce, Poland.  

PubMed

The aim of this study was an analysis of the population effects of a seven-valent pneumococcal conjugate vaccine (PCV7) on pneumonia incidence rates in the 5-year follow-up period after the introduction in 2006 of a universal PCV7 vaccination programme in the city of Kielce, Poland. Vaccinations were carried out according to a 2?+?1 schedule. The vaccination compliance rate amounted to approximately 99 %. The age groups 0-2, 30-49, 50-65 and 65+ years were analysed. The Cochran-Armitage test was used to investigate the significance of observed trends in pneumonia morbidity. The significance of deviations from a linear trend was also tested. The importance of the trend was confirmed by the Mantel test. Between 2005 and 2010, the greatest decline, 82.9 % (2005, 25.31/1,000; 2010, 4.34/1,000), in pneumonia morbidity was observed for children <2 years of age. In the 65+ years age group, this amounted to 43.5 %. Lesser declines, but still of statistical significance, were observed for the other age groups: 16.5 % in the 30-49 years group and 40.4 % in the 50-64 years group. All reductions are statistically significant and confirmed by the Mantel test. Five years after the introduction of a universal PCV7 vaccination programme in Kielce, Poland, its effectiveness in pneumonia prevention has been demonstrated in both the <2 years of age group and indirectly for other groups. PMID:22895889

Patrzalek, M; Gorynski, P; Albrecht, P

2012-11-01

203

Porcine CD74 is involved in the inflammatory response activated by nuclear factor kappa B during porcine circovirus type 2 (PCV-2) infection.  

PubMed

Human CD74 induces a signalling cascade that results in the activation of nuclear factor kappa B (NF-?B); however, porcine CD74 has not been widely studied. In this study, we show that porcine CD74 is mainly expressed in cells of the macrophage lineage and can be induced by lipopolysaccharide (LPS), polyinosinic acid-polycytidylic acid [Poly(I:C)], and infection with porcine circovirus type 2 (PCV2) in vitro. In addition, we confirmed that porcine CD74 can activate NF-?B by promoting I?B? degradation and nuclear translocation of p65. Furthermore, the transcription of NF-?B-regulated genes [Interleukin-6 (IL-6), Interleukin-8 (IL-8), and COX-2] was upregulated in response to the overexpression of porcine CD74. In general, porcine CD74 significantly enhanced the inflammatory response by regulating the NF-?B signalling pathway during PCV2 infection, which suggests that porcine CD74 may be implicated in the pathogenesis of PCV2 infection. PMID:23736979

Zhang, Hengling; Liu, Chong; Cheng, Shuang; Wang, Xiaofei; Li, Wentao; Charreyre, Catherine; Audonnet, Jean Christophe; He, Qigai

2013-11-01

204

Genetic Characterisation of Malawian Pneumococci Prior to the Roll-Out of the PCV13 Vaccine Using a High-Throughput Whole Genome Sequencing Approach  

PubMed Central

Background Malawi commenced the introduction of the 13-valent pneumococcal conjugate vaccine (PCV13) into the routine infant immunisation schedule in November 2011. Here we have tested the utility of high throughput whole genome sequencing to provide a high-resolution view of pre-vaccine pneumococcal epidemiology and population evolutionary trends to predict potential future change in population structure post introduction. Methods One hundred and twenty seven (127) archived pneumococcal isolates from randomly selected adults and children presenting to the Queen Elizabeth Central Hospital, Blantyre, Malawi underwent whole genome sequencing. Results The pneumococcal population was dominated by serotype 1 (20.5% of invasive isolates) prior to vaccine introduction. PCV13 is likely to protect against 62.9% of all circulating invasive pneumococci (78.3% in under-5-year-olds). Several Pneumococcal Molecular Epidemiology Network (PMEN) clones are now in circulation in Malawi which were previously undetected but the pandemic multidrug resistant PMEN1 lineage was not identified. Genome analysis identified a number of novel sequence types and serotype switching. Conclusions High throughput genome sequencing is now feasible and has the capacity to simultaneously elucidate serotype, sequence type and as well as detailed genetic information. It enables population level characterization, providing a detailed picture of population structure and genome evolution relevant to disease control. Post-vaccine introduction surveillance supported by genome sequencing is essential to providing a comprehensive picture of the impact of PCV13 on pneumococcal population structure and informing future public health interventions.

Everett, Dean B.; Cornick, Jennifer; Denis, Brigitte; Chewapreecha, Claire; Croucher, Nicholas; Harris, Simon; Parkhill, Julian; Gordon, Stephen; Carrol, Enitan D.; French, Neil; Heyderman, Robert S.; Bentley, Stephen D.

2012-01-01

205

Independent Orbiter Assessment (IOA): Assessment of the atmospheric revitalization pressure control subsystem FMEA/CIL  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA effort first completed an analysis of the atmospheric Revitalization Pressure Control Subsystem (ARPCS) hardware, generating draft failure modes and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The IOA results were then compared to the NASA FMEA/CIL proposed Post 51-L updates based upon the CCB/PRCB presentations and an informal criticality summary listing. A discussion of each discrepancy from the comparison is provided through additional analysis as required. These discrepancies were flagged as issues, and recommendations were made based on the FMEA data available at the time. This report documents the results of that comparison for the Orbiter ARPCS hardware.

Saiidi, M. J.

1988-01-01

206

Development of an expert system for analysis of Shuttle atmospheric revitalization and pressure control subsystem anomalies  

NASA Technical Reports Server (NTRS)

The paper describes the Shuttle Leak Management Expert System (SLMES), a preprototype expert system developed to enable the ECLSS subsystem manager to analyze subsystem anomalies and to formulate flight procedures based on flight data. The SLMES combines the rule-based expert system technology with the traditional FORTRAN-based software into an integrated system. SLMES analyzes the data using rules, and, when it detects a problem that requires simulation, it sets up the input for the FORTRAN-based simulation program ARPCS2AT2, which predicts the cabin total pressure and composition as a function of time. The program simulates the pressure control system, the crew oxygen masks, the airlock repress/depress valves, and the leakage. When the simulation has completed, other SLMES rules are triggered to examine the results of simulation contrary to flight data and to suggest methods for correcting the problem. Results are then presented in form of graphs and tables.

Lafuse, Sharon A.

1991-01-01

207

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 1 of 4  

NASA Technical Reports Server (NTRS)

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 1 of 4.

1996-01-01

208

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 4 of 4  

NASA Technical Reports Server (NTRS)

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 4 of 4.

1996-01-01

209

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 2 of 4  

NASA Technical Reports Server (NTRS)

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 2 of 4.

1996-01-01

210

Tank Pressure Control Experiment: Thermal Phenomena in Microgravity. Video 3 of 4  

NASA Technical Reports Server (NTRS)

The report presents the results of the flight experiment Tank Pressure Control Experiment/Thermal Phenomena (TPCE/TP) performed in the microgravity environment of the space shuttle. TPCE/TP, flown on the Space Transportation System STS-52, was a second flight of the Tank Pressure Control Experiment (TPCE). The experiment used Freon 113 at near saturation conditions. The test tank was filled with liquid to about 83 percent by volume. The experiment consisted of 21 tests. Each test generally started with a heating phase to increase the tank pressure and to develop temperature stratification in the fluid, followed by a fluid mixing phase for the tank pressure reduction and fluid temperature equilibration. The heating phase provided pool boiling data from large (relative to bubble sizes) heating surfaces (0.1046 m by 0.0742 m) at low heat fluxes (0.23 to 1.16 kW/m(exp 2)). The system pressure and the bulk liquid subcooling varied from 39 to 78 kPa and 1 to 3 deg C, respectively. The boiling process during the entire heating period, as well a jet-induced mixing process for the first 2 min. of the mixing period, was also recorded on video. Analyses of data from the two flight experiments (TPCE and TPCE/TP) and their comparison with the results obtained in drop tower experiments suggest that as Bond number approaches zero the flow pattern produced by an axial jet and the mixing time can be predicted by the Weber number. This is video 3 of 4.

1996-01-01

211

Sex differences in blood pressure control during 6° head-down tilt bed rest.  

PubMed

Spaceflight-induced orthostatic intolerance has been studied for decades. Although ?22% of the astronaut corps are women, most mechanistic studies use mostly male subjects, despite known sex differences in autonomic control and postflight orthostatic intolerance. We studied adrenergic, baroreflex, and autonomic indexes during continuous infusions of vasoactive drugs in men and women during a 60-day head-down bed rest. Volunteers were tested before bed rest (20 men and 10 women) and around day 30 (20 men and 10 women) and day 60 (16 men and 8 women) of bed rest. Three increasing doses of phenylephrine (PE) and sodium nitroprusside were infused for 10 min after an infusion of normal saline. A 20-min rest period separated the phenylephrine and sodium nitroprusside infusions. Autonomic activity was approximated by spectral indexes of heart rate and blood pressure variability, and baroreflex sensitivity was measured by the spontaneous baroreflex slope. Parasympathetic modulation and baroreflex sensitivity decreased with bed rest, with women experiencing a larger decrease in baroreflex sensitivity by day 30 than men. The sympathetic activation of men and parasympathetic responsiveness of women in blood pressure control during physiological stress were preserved throughout bed rest. During PE infusions, women experienced saturation of the R-R interval at high frequency, whereas men did not, revealing a sex difference in the parabolic relationship between high-frequency R-R interval, a measurement of respiratory sinus arrhythmia, and R-R interval. These sex differences in blood pressure control during simulated microgravity reveal the need to study sex differences in long-duration spaceflight to ensure the health and safety of the entire astronaut corps. PMID:23396455

Arzeno, Natalia M; Stenger, Michael B; Lee, Stuart M C; Ploutz-Snyder, Robert; Platts, Steven H

2013-04-15

212

Sex differences in blood pressure control during 6? head-down tilt bed rest  

PubMed Central

Spaceflight-induced orthostatic intolerance has been studied for decades. Although ?22% of the astronaut corps are women, most mechanistic studies use mostly male subjects, despite known sex differences in autonomic control and postflight orthostatic intolerance. We studied adrenergic, baroreflex, and autonomic indexes during continuous infusions of vasoactive drugs in men and women during a 60-day head-down bed rest. Volunteers were tested before bed rest (20 men and 10 women) and around day 30 (20 men and 10 women) and day 60 (16 men and 8 women) of bed rest. Three increasing doses of phenylephrine (PE) and sodium nitroprusside were infused for 10 min after an infusion of normal saline. A 20-min rest period separated the phenylephrine and sodium nitroprusside infusions. Autonomic activity was approximated by spectral indexes of heart rate and blood pressure variability, and baroreflex sensitivity was measured by the spontaneous baroreflex slope. Parasympathetic modulation and baroreflex sensitivity decreased with bed rest, with women experiencing a larger decrease in baroreflex sensitivity by day 30 than men. The sympathetic activation of men and parasympathetic responsiveness of women in blood pressure control during physiological stress were preserved throughout bed rest. During PE infusions, women experienced saturation of the R-R interval at high frequency, whereas men did not, revealing a sex difference in the parabolic relationship between high-frequency R-R interval, a measurement of respiratory sinus arrhythmia, and R-R interval. These sex differences in blood pressure control during simulated microgravity reveal the need to study sex differences in long-duration spaceflight to ensure the health and safety of the entire astronaut corps.

Arzeno, Natalia M.; Lee, Stuart M. C.; Ploutz-Snyder, Robert; Platts, Steven H.

2013-01-01

213

Gastroesophageal reflux in mechanically ventilated pediatric patients and its relation to ventilator-associated pneumonia  

Microsoft Academic Search

ABSTRACT: INTRODUCTION: The objective was to determine the frequency of gastroesophageal reflux (GER) in mechanically ventilated pediatric patients and its role as a risk factor for ventilator-associated pneumonia (VAP), which may be enhanced among those patients. METHODS: The study is a prospective cohort study of mechanically ventilated pediatric patients in the pediatric intensive care unit (PICU) of Ain Shams University

Tarek A Abdel-Gawad; Mostafa A El-Hodhod; Hanan M Ibrahim; Yousef W Michael

2009-01-01

214

Carbon Dioxide and Oxygen Levels in Disposable Individually Ventilated Cages after Removal from Mechanical Ventilation  

PubMed Central

Disposable individually ventilated cages have lids that restrict air exchange when the cage is not mechanically ventilated. This design feature may cause intracage CO2 to increase and O2 to decrease (hypercapnic and hypoxic conditions, respectively) when the electrical supply to the ventilated rack fails, the ventilated rack malfunctions, cages are docked in the rack incorrectly, or cages are removed from the ventilated rack for extended periods of time. We investigated how quickly hypercapnic and hypoxic conditions developed within disposable individually ventilated cages after removal from mechanical ventilation and compared the data with nondisposable static cages, disposable static cages, and unventilated nondisposable individually ventilated cages. When disposable individually ventilated cages with 5 adult mice per cage were removed from mechanical ventilation, CO2 concentrations increased from less than 1% at 0 h to approximately 5% at 3 h and O2 levels dropped from more than 20% at 0 h to 11.7% at 6 h. The breathing pattern of the mice showed a prominent abdominal component (hyperventilation). Changes were similar for 4 adult mice per cage, reaching at least 5% CO2 at 4 h and 13.0% O2 at 6 h. For 3 or 2 mice per cage, values were 4.6% CO2 and 14.7% O2 and 3.04% CO2 and 17.1% O2, respectively, at 6 h. These results document that within disposable individually ventilated cages, a hypercapnic and hypoxic microenvironment develops within hours in the absence of mechanical ventilation.

Nagamine, Claude M; Long, C Tyler; McKeon, Gabriel P; Felt, Stephen A

2012-01-01

215

Co-infection of porcine dendritic cells with porcine circovirus type 2a (PCV2a) and genotype II porcine reproductive and respiratory syndrome virus (PRRSV) induces CD4+CD25+FoxP3+ T cells in vitro  

PubMed Central

Porcine circovirus associated disease (PCVAD) is currently one of the most economically important diseases in the global swine industry. Porcine circovirus type 2 (PCV2) is the primary causative agent, however co-infection with other swine pathogens such as porcine reproductive and respiratory syndrome virus (PRRSV) is often required to induce the full spectrum of clinical PCVAD. While the specific mechanisms of viral co-infection that lead to clinical disease are not fully understood, immune modulation by the co-infecting viruses likely plays a critical role. We evaluated the ability of dendritic cells (DC) infected with PRRSV, PCV2 or both to induce regulatory T cells (Tregs) in vitro. DCs infected with PCV2 significantly increased CD4+CD25+FoxP3+ Tregs (p<0.05) and DCs co-infected with PRRSV and PCV2 induced significantly higher numbers of Tregs than with PCV2 alone (p<0.05). Cytokine analysis indicated that the induction of Tregs by co-infected DCs may be dependent on TGF-? and not IL-10. Our data support the immunomodulatory role of PCV2/PRRSV co-infection in the pathogenesis of PCVAD, specifically via Treg mediated immunosuppression.

Cecere, T.E.; Meng, X.J.; Pelzer, K.; Todd, S.M.; Beach, N.M.; Ni, Y.Y.; LeRoith, T.

2012-01-01

216

Studies on the 'Ventilation Effectiveness' and Modification of the Ventilation System in the Waiting Hall of a Railway Station  

Microsoft Academic Search

The concept of ventilation effectiveness for mechanical ventilation of an air space is reviewed and associated parameters for describing the performance of ventilation systems are described. The idea is applied to a study of the thermal environment in the waiting hall of a railway station. Two ventilation schemes: one with a ventilation system only and the other with an air-conditioning

W. K. Chow; W. Y. Fung

1996-01-01

217

High-frequency ventilation and conventional mechanical ventilation in newborn babies with respiratory distress syndrome: A prospective, randomized trial  

Microsoft Academic Search

Objective. Morbidity and mortality remain high amongst babies ventilated for a respiratory distress syndrome (RDS). Whether newly developed ventilators allowing high frequency ventilation such as high frequen- cy flow interrupted ventilation (HFFIV) could decrease the morbidity and the mortality was investigated in a ran- domized study. Design: Preterm babies weighing < 1800 g suffering from RDS and ventilated by conventional

A. Pardou; D. Vermeylen; M. F. Muller; D. Detemmerman

1993-01-01

218

46 CFR 92.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2010 CFR

...VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 92.15-10 Ventilation for closed spaces. (a) Except as...Means shall be provided for stopping all fans in ventilation systems serving machinery and cargo...

2009-10-01

219

46 CFR 72.15-15 - Ventilation for closed spaces.  

Code of Federal Regulations, 2010 CFR

...VESSELS CONSTRUCTION AND ARRANGEMENT Ventilation § 72.15-15 Ventilation for closed spaces. (a) All enclosed...Means shall be provided for stopping all fans in ventilation systems serving machinery and cargo...

2009-10-01

220

46 CFR 190.15-10 - Ventilation for closed spaces.  

Code of Federal Regulations, 2013 CFR

...ventilated. Means shall be provided to close off all vents and ventilators. (b) Means shall be provided for stopping all fans...storerooms, and machinery spaces and for closing all doorways, ventilators, and annular spaces around funnels and other openings...

2013-10-01

221

Mechanical Ventilation and the Kidney  

PubMed Central

Acute lung injury (ALI) and acute kidney injury (AKI) are complications often encountered in the setting of critical illness. Both forms of end-organ injury commonly occur in similar settings of systemic inflammatory response syndrome, shock, and evolving multiple organ dysfunction. Recent elucidation of the pathobiology of critical illness has led to a more basic mechanistic understanding of the complex interplay between injured organs in patients with multiple organ dysfunction syndrome; this has been aptly called ‘the slippery slope of critical illness’ [Kidney Int Suppl 1998;66:S25–S33]. Distant organ effects of apparently isolated injuries to the lungs, gut, and kidneys have all been discovered in recent years. In this article, we will review the harmful bidirectional interaction between ALI and AKI, which appears to be a common clinical syndrome with routine clinical implications. We will review the current understanding of lung-kidney interactions from both perspectives, including the renal effects of ALI and mechanical ventilation, and the pulmonary sequelae of AKI. In this review of the emerging evidence of deleterious bidirectional organ cross talk between lung and kidney, we will focus on the role of ventilator-induced kidney injury in the pathogenesis of AKI in patients with ALI.

Koyner, Jay L.; Murray, Patrick T.

2010-01-01

222

Volume-controlled ventilation. Variations on a theme.  

PubMed

Development of sophisticated transducers and microprocessor-based ventilators now enables the performance of volume-controlled ventilation of newborn infants. Volume-controlled modes include standard intermittent or synchronized intermittent mandatory ventilation; assist-control ventilation; and hybrid modes, such as pressure-support ventilation, pressure-regulated volume-control ventilation, volume-assured pressure support, and volume guarantee. This article describes the concepts and clinical applications of these ventilatory modes. PMID:11570154

Sinha, S K; Donn, S M

2001-09-01

223

Performance of Ventilation Systems in Residential Buildings.  

National Technical Information Service (NTIS)

The aim of the study was to gather information on the performance of ventilation systems in residential buildings. The effect of the ventilation on health, comfort and satisfaction was also studied. Data was also collected of the fullfilment of National B...

R. Roennberg R. Ruotsalainen A. Majanen

1989-01-01

224

IMPACT OF DOUBLE VENTILATED FACADES IN BUILDINGS  

Microsoft Academic Search

Double ventilated façades are becoming quite common in buildings in Europe. The new IEA ECBCS Annex 44 entitled 'Integrating environmentally responsive elements in buildings' will among other elements consider the double ventilated façades. The use of this kind of façades has an impact on several aspects of the building in the design phase as in the exploitation phase of the

Xavier Loncour; Peter Wouters; Marcelo Blasco

225

NUMERICAL EVALUATION OF HYBRID VENTILATION CONTROL STRATEGIES  

Microsoft Academic Search

This paper deals with the development and the evaluation of hybrid ventilation control strategies, using both natural and mechanical modes, in residential buildings using a graphical simulation tool. The description of a library of airflow components and macroscopic pollutants models used to simulate the demand controlled ventilation based on indoor pollutant concentrations is provided. The paper discusses the issue of

David Jreijiry; Ahmad Husaunndee; Christian Inard

2005-01-01

226

46 CFR 116.610 - Ventilation ducts.  

Code of Federal Regulations, 2013 CFR

...minimized. (f) A ventilation duct penetrating an A-Class or...requirements: (1) A ventilation duct must meet the same requirements...to the passage of smoke and flame as the fire control boundary penetrated; (2) A steel duct penetrating an A-Class...

2013-10-01

227

46 CFR 116.610 - Ventilation ducts.  

Code of Federal Regulations, 2010 CFR

...minimized. (f) A ventilation duct penetrating an A-Class or...requirements: (1) A ventilation duct must meet the same requirements...to the passage of smoke and flame as the fire control boundary penetrated; (2) A steel duct penetrating an A-Class...

2010-10-01

228

46 CFR 116.610 - Ventilation ducts.  

Code of Federal Regulations, 2010 CFR

...minimized. (f) A ventilation duct penetrating an A-Class or...requirements: (1) A ventilation duct must meet the same requirements...to the passage of smoke and flame as the fire control boundary penetrated; (2) A steel duct penetrating an A-Class...

2009-10-01

229

Energy recovery using ventilated double glazing  

Microsoft Academic Search

In a heated building, the outflow of some heat energy through windows is inevitable and can be a waste. It is possible to recover some of this heat loss by directing ventilation fresh air along the surface of the window. A modified double glazing unit with ventilation passage has been used to investigate the reduced heat losses with various flow

Raymond Smyth

1981-01-01

230

Increasing energy efficiency of mine ventilation systems  

SciTech Connect

Every year the US mining industry spends millions of dollars on underground ventilation systems. Potential motor-driven system energy savings can be realized by using mature, proven, and cost-effective technologies. Improved energy efficiency also leads to reduced environmental emissions. This paper promotes a systems approach to increase the energy efficiency in mine ventilation.

Papar, Riyaz; Szady, A.; Huffer, W.D.; Martin V.; McKane, A.T.

1999-06-01

231

Preoperational test report, primary ventilation system  

SciTech Connect

This represents a preoperational test report for Primary Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space filtered venting of tanks AY101, AY102, AZ101, AZ102. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-11-04

232

46 CFR 194.10-25 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...inch mesh. Metal watertight closures shall be provided for use when the ventilation system is not in operation. A 2-inch IPS bypass with check valve shall be provided in parallel with at least one of the ventilation closures to prevent pressure...

2009-10-01

233

46 CFR 194.10-25 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...inch mesh. Metal watertight closures shall be provided for use when the ventilation system is not in operation. A 2-inch IPS bypass with check valve shall be provided in parallel with at least one of the ventilation closures to prevent pressure...

2013-10-01

234

Spontaneous breathing during mechanical ventilation in ARDS  

Microsoft Academic Search

The objective of mechanical ventilation used in the management of Acute Respiratory Distress Syn- drome (ARDS) is to ensure adequate tissue oxygen- ation and alveolar ventilation while limiting the pa- tients' work of breathing and preventing further dam- age to the lungs. Although the \\

Ross Freebairn; Keith Hickling

2005-01-01

235

Update on modalities of mechanical ventilators  

Microsoft Academic Search

Recent advances in ventilator technology have often not been confirmed by randomised trials and instead serious shortcomings have been highlighted. Ventilation modes should only be introduced into routine clinical practice when proved efficacious in appropriately designed studies and no adverse outcomes identified by long term follow up.

A Greenough

2002-01-01

236

Development of Two Types of Ventilators.  

National Technical Information Service (NTIS)

The objective of this program was to evaluate two types of ventilator kits for maximum cost effectiveness. The kits shown on the following page are: (1) Pedal Ventilator Kit, and (2) the Kearny Pump Kit. The two units were previously developed by GARD in ...

J. M. Buday R. J. Klima

1979-01-01

237

Characterization and measurement of ventilator performance  

NASA Astrophysics Data System (ADS)

The work of the ISO in drawing up ventilator norms is reviewed, and the scientific and technical difficulties encountered when investigating ventilators are summarized. Difficulties arise from the many forms of energy transfered to the fluid, the diversity of gases used, compressibility effects, the wide variety of equipment size and performance, the different functions required, and the heterogeneity of test methods.

Judetlelacombe, A.

238

Assisted ventilation in severe acute asthma  

Microsoft Academic Search

During the period 1973-85 assisted ventilation was used for the treatment of severe asthma on 48 occasions in 18 patients (one patient was ventilated 29 times). On each occasion arterial blood gas abnormalities were restored to normal as quickly as possible irrespective of peak inflation pressures. One patient was thought to be brain dead on transfer from another hospital but

B Higgins; A P Greening; G K Crompton

1986-01-01

239

Sensor-based demand controlled ventilation.  

National Technical Information Service (NTIS)

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pol...

A. T. De Almeida W. J. Fisk

1997-01-01

240

The basics of industrial ventilation design  

Microsoft Academic Search

HVAC in the industrial environment assumes many roles from general ventilation to process related applications. Because of the variety of applications and the documentation available for the design of each, it is not the intent of this article to review each one. However, industrial clients often have misconceptions that lead to misapplications of ventilation design and equipment. One of the

1996-01-01

241

Mine ventilation and air conditioning. 3. edition  

SciTech Connect

This revised edition presents an engineering design approach to ventilation and air conditioning as part of the comprehensive environmental control of the mine atmosphere. It provides an in-depth look, for practitioners who design and operate mines, into the health and safety aspects of environmental conditions in the underground workplace. The contents include: Environmental control of the mine atmosphere; Properties and behavior of air; Mine air-quality control; Mine gases; Dusts and other mine aerosols; Mine ventilation; Airflow through mine openings and ducts; Mine ventilation circuits and networks; Natural ventilation; Fan application to mines; Auxiliary ventilation and controlled recirculation; Economics of airflow; Control of mine fires and explosions; Mine air conditioning; Heat sources and effect in mines; Mine air conditioning systems; Appendices; References; Answers to selected problems; and Index.

Hartman, H.L. [Univ. of Alabama, University, AL (United States); Mutmansky, J.M.; Ramani, R.V. [Pennsylvania State Univ., University Park, PA (United States); Wang, Y.J. [West Virginia Univ., Morgantown, WV (United States)

1998-12-31

242

The basics of industrial ventilation design  

SciTech Connect

HVAC in the industrial environment assumes many roles from general ventilation to process related applications. Because of the variety of applications and the documentation available for the design of each, it is not the intent of this article to review each one. However, industrial clients often have misconceptions that lead to misapplications of ventilation design and equipment. One of the more common misconceptions is that ventilation equipment should be sized based on volumetric air changes, regardless of the application. This article will review a generalized approach to ventilation calculations, the fallacy of air changes, and the role of HVAC engineers to provide the industrial client a properly applied ventilation design and thorough knowledge of its operational parameters.

Parks, R.L. [McKim and Creed, Raleigh, NC (United States)

1996-11-01

243

The ``Temperature Amplifier'': an Innovative Application of Pressure-Controlled Heat-Pipes for Calibration of PRTs and Thermocouples  

NASA Astrophysics Data System (ADS)

At high temperature (from 600 °C to 962 °C) calibration by comparison of platinum resistance thermometers (PRTs) is limited by the instability and the reliability of the standard high-temperature PRT and by the temperature uniformity in the working volume of furnaces equipped with comparison blocks. To improve its calibration-comparison capability, BNM-INM is studying the possibility of connecting several pressure-controlled heat-pipes, filled with different working fluids, simultaneously to the same pressure control system. The experimental apparatus, called a ``temperature amplifier,'' is composed of three heat-pipes filled with sodium (Na), potassium (K), and dodecane (Do).

Renaot, E.; Elgourdou, M.; Bonnier, G.

2003-09-01

244

Posterior Reversible Encephalopathy Syndrome and Eclampsia: Pressing the Case for More Aggressive Blood Pressure Control  

PubMed Central

OBJECTIVE: To assess the prevalence, clinical presentations, and neuroimaging abnormalities in a series of patients treated for eclampsia at Mayo Clinic in Rochester, MN. PATIENTS AND METHODS: We reviewed the records of all pregnant patients diagnosed as having eclampsia at Mayo Clinic in Rochester, MN, between January 1, 2001, and December 31, 2008. All patients who underwent neuroimaging were identified, and all studies were reviewed by an independent neuroradiologist. Comparisons were made between groups who did and did not undergo imaging to identify differentiating clinical or laboratory variables. RESULTS: Thirteen cases of eclampsia were found, with neuroimaging studies available for 7: magnetic resonance imaging (n=6) and computed tomography (n=1). All 7 patients developed eclamptic seizures, and 2 of 7 patients had severe hypertension, with recorded systolic blood pressures exceeding 180 mm Hg. Neuroimaging showed characteristic changes of posterior reversible encephalopathy syndrome (PRES) in all patients. Follow-up imaging showed resolution in 2 of 3 patients; 1 patient had residual neuroimaging abnormalities. CONCLUSION: Our results suggest that the clinical syndrome of eclampsia is associated with an anatomical substrate that is recognizable by neuroimaging as PRES. The levels of blood pressure elevation are lower than those reported in cases of PRES because of hypertensive encephalopathy. Further studies are needed to determine whether more aggressive blood pressure control and early neuroimaging may have a role in the management of these patients.

Wagner, Steven J.; Acquah, Letitia A.; Lindell, E. Paul; Craici, Iasmina M.; Wingo, Majken T.; Rose, Carl H.; White, Wendy M.; August, Phyllis; Garovic, Vesna D.

2011-01-01

245

Sex-specific differences in cardiovascular risk factors and blood pressure control in hypertensive patients.  

PubMed

Cardiovascular disease (CVD) and cardiovascular risk factors are frequently undertreated in women. However, it is unclear whether the prevalence of additional cardiovascular risk factors and the total cardiovascular risk differ between hypertensive men and women. There are also limited data regarding rates of blood pressure control in the two sexes outside the United States. The authors aimed to compare the cardiovascular risk profile between sexes. A total of 1810 hypertensive patients (40.4% men, age 56.5±13.5 years) attending the hypertension outpatient clinic of our department were studied. Men were more frequently smokers than women and were more heavy smokers than the latter. Serum high-density lipoprotein cholesterol levels were lower and serum triglyceride levels were higher in men. On the other hand, abdominal obesity and chronic kidney disease were more prevalent in women. The estimated cardiovascular risk was higher in men than in women but the prevalence of established CVD did not differ between the sexes. The percentage of patients with controlled hypertension and the number of antihypertensive medications were similar in men and women. In conclusion, hypertensive men have more adverse cardiovascular risk factor profile and greater estimated cardiovascular risk than women. However, the prevalence of established CVD does not differ between sexes. These findings further reinforce current guidelines that recommend that management of hypertension and of other cardiovascular risk factors should be as aggressive in women as in men in order to prevent cardiovascular events. PMID:24621371

Tziomalos, Konstantinos; Giampatzis, Vasilios; Baltatzi, Maria; Efthymiou, Elias; Psianou, Konstantia; Papastergiou, Natalia; Magkou, Dimitra; Bougatsa, Vagia; Savopoulos, Christos; Hatzitolios, Apostolos I

2014-04-01

246

Independent Orbiter Assessment (IOA): Analysis of the atmospheric revitalization pressure control subsystem  

NASA Technical Reports Server (NTRS)

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis/Critical Items List (FMEA/CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Atmospheric Revitalization and Pressure Control Subsystem (ARPCS) are documented. The ARPCS hardware was categorized into the following subdivisions: (1) Atmospheric Make-up and Control (including the Auxiliary Oxygen Assembly, Oxygen Assembly, and Nitrogen Assembly); and (2) Atmospheric Vent and Control (including the Positive Relief Vent Assembly, Negative Relief Vent Assembly, and Cabin Vent Assembly). The IOA analysis process utilized available ARPCS hardware drawings and schematics for defining hardware assemblies, components, and hardware items. Each level of hardware was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

Saiidi, M. J.; Duffy, R. E.; Mclaughlin, T. D.

1986-01-01

247

Ventless pressure control of two-phase propellant tanks in microgravity  

NASA Technical Reports Server (NTRS)

This work studies pressurization and pressure control of a large liquid hydrogen storage tank. A finite element model is developed that couples a lumped thermodynamic formulation for the vapor region with a complete solution of the Navier-Stokes and energy equations for the flow and temperature fields in the liquid. Numerical results show that buoyancy effects are strong, even in microgravity, and can reposition a vapor bubble that is initially at the center of the tank to a region near the tank wall in a relatively short time. Long-term tank pressurization with the vapor bubble at the tank wall shows that after an initial transient lasting about a week, the final rate of pressure increase agrees with a purely thermodynamic analysis of the entire tank. However, the final pressure levels are quite different from thermodynamic predictions. Numerical results also show that there is significant thermal stratification in the liquid due to the effects of natural convection. A subcooled jet is used to provide simultaneous cooling and mixing in order to bring the tank pressure back down to its initial value. Three different jet speeds are examined. Although the lowest jet speed is ineffective at controlling the pressure because of insufficient penetration into the liquid region, the highest jet speed is shown to be quite effective at disrupting thermal stratification and reducing the tank pressure in reasonable time.

Kassemi, Mohammad; Panzarella, Charles H.

2004-01-01

248

Optimization on Emergency Longitudinal Ventilation Design  

NASA Astrophysics Data System (ADS)

Emergency ventilation design in longitudinally ventilated vehicular tunnels is vital to provide safe egress route for tunnel user under fire situations. In this study, the influences of the location of active fan groups on the upstream velocity are investigated using Computational Fluid Dynamics (CFD) techniques. The numeric model was firstly validated again the experimental data from Memorial Tunnel Fire Ventilation Test Program (MTFVTP). Based on the validated model, parametric studies were then preformed attempting to establish a semi-empirical correlation between the location of fan groups and the upstream velocity. In the presence of solid fire, it was found that the buoyant force by the fire source and inertial force by the fans interact with each other and resulted in a ``leveling-off'' characteristic when the inertial force is no longer dominating. Such interaction re-distributed the ventilation flow direction and sequentially reduces the magnitude of the upstream velocity. In other word, the industrial practice of activating furthest fan group may not be able to prevent the backlayering as a consequence of solid fires. Fans closer to the fire source are recommended to be activated for preventing the hazard of backlayering. Furthermore, through the parametric study, location of ventilation fans is found to have significant effect on the upstream velocity. Such finding suggests that other geometrical parameters could also impose adverse effects to the ventilation system. Existing empirical equation could be insufficient to cover all possible ventilation design scenarios.

Se, Camby M. K.; Yuen, Richard K. K.; Cheung, Sherman C. P.; Tu, Jiyuan

2010-05-01

249

Evaluation of intestinal pressure-controlled colon delivery capsule containing caffeine as a model drug in human volunteers  

Microsoft Academic Search

The delivery ability of a pressure-controlled colon delivery capsule (PCDC) containing caffeine as a test drug was evaluated after oral administration to healthy male human volunteers. The driving force causing PCDC disintegration in the intestinal tract is the physiological luminal pressure which results from peristalsis. Three kinds of PCDCs having different thickness of a water-insoluble polymer membrane were prepared by

Motoki Muraoka; Zhaopeng Hu; Tatsuharu Shimokawa; Syu-ichi Sekino; Ri-e Kurogoshi; Yoshiko Kuboi; Yukako Yoshikawa; Kanji Takada

1998-01-01

250

Design and Operation of a Pressure-Controlled Inlet for Airborne Sampling with an Aerodynamic Aerosol Lens  

Microsoft Academic Search

Two pressure-controlled inlets (PCI) have been designed and integrated into the Aerodyne Aerosol Mass Spectrometer (AMS) inlet system containing an aerodynamic aerosol lens system for use in airborne measurements. Laboratory experiments show that size calibration and mass flow rate into the AMS are not affected by changes in upstream pressure (P0) of the PCI as long as the pressure within

Roya Bahreini; Edward J. Dunlea; Brendan M. Matthew; Craig Simons; Kenneth S. Docherty; Peter F. DeCarlo; Jose L. Jimenez; Charles A. Brock; Ann M. Middlebrook

2008-01-01

251

Implementation of a Hybrid Controller for Ventilation Control Using Soft Computing  

SciTech Connect

Many industrial facilities utilize pressure control gradients to prevent migration of hazardous species from containment areas to occupied zones, often using Proportional-Integral-Derivative (PID) control systems. When operators rebalance the facility, variation from the desired gradients can occur and the operating conditions can change enough that the PID parameters are no longer adequate to maintain a stable system. As the goal of the ventilation control system is to optimize the pressure gradients and associated flows for the facility, Linear Quadratic Tracking (LQT) is a method that provides a time-based approach to guiding facility interactions. However, LQT methods are susceptible to modeling and measurement errors, and therefore the additional use of Soft Computing methods are proposed for implementation to account for these errors and nonlinearities.

Craig G. Rieger; D. Subbaram Naidu

2005-06-01

252

Characteristics of coal mine ventilation air flows.  

PubMed

Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and approximately 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide, sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore, this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities. PMID:17239518

Su, Shi; Chen, Hongwei; Teakle, Philip; Xue, Sheng

2008-01-01

253

Neonatal ventilators: how do they differ?  

PubMed

Remarkable technological advances over the past two decades have brought dramatic changes to the neonatal intensive care unit. Microprocessor-based mechanical ventilation has replaced time-cycled, pressure-limited, intermittent mandatory ventilation with almost limitless options for the management of respiratory failure in the prematurely born infant. Unfortunately, much of the infusion of technology occurred before the establishment of a convincing evidence base. This review focuses on the basic principles of mechanical ventilation, nomenclature and the characteristics of both conventional and high-frequency devices. PMID:19399015

Donn, S M

2009-05-01

254

Effect of oral high frequency ventilation by jet or oscillator on minute ventilation in normal subjects.  

PubMed Central

Normal subjects were asked to breathe through an open ended tube while high frequency oscillations were superimposed on tidal breathing via a side arm, either an eight inch (20 cm) loudspeaker or a jet ventilator being used. Both systems were comfortable and well tolerated. Spontaneous minute ventilation fell by 19-46% at frequencies up to 33 Hz without a rise in transcutaneous PCO2. Maximum ventilatory savings occurred at 1.6 Hz with the jet ventilator (p less than 0.01) and at a frequency corresponding to respiratory system resonance with the loudspeaker. This suggests that during oral high frequency ventilation pulmonary gas exchange is improved and leads to more efficient carbon dioxide excretion for a given minute ventilation. This technique provides a practical and simple method of supplementing breathing in conscious subjects, and it may also have application in the management of patients with acute or chronic respiratory failure, where intubation and conventional ventilation might be avoided.

George, R J; Winter, R J; Johnson, M A; Slee, I P; Geddes, D M

1985-01-01

255

Constant Pressure-controlled Extrusion Method for the Preparation of Nano-sized Lipid Vesicles  

PubMed Central

Liposomes are artificially prepared vesicles consisting of natural and synthetic phospholipids that are widely used as a cell membrane mimicking platform to study protein-protein and protein-lipid interactions3, monitor drug delivery4,5, and encapsulation4. Phospholipids naturally create curved lipid bilayers, distinguishing itself from a micelle.6 Liposomes are traditionally classified by size and number of bilayers, i.e. large unilamellar vesicles (LUVs), small unilamellar vesicles (SUVs) and multilamellar vesicles (MLVs)7. In particular, the preparation of homogeneous liposomes of various sizes is important for studying membrane curvature that plays a vital role in cell signaling, endo- and exocytosis, membrane fusion, and protein trafficking8. Several groups analyze how proteins are used to modulate processes that involve membrane curvature and thus prepare liposomes of diameters <100 - 400 nm to study their behavior on cell functions3. Others focus on liposome-drug encapsulation, studying liposomes as vehicles to carry and deliver a drug of interest9. Drug encapsulation can be achieved as reported during liposome formation9. Our extrusion step should not affect the encapsulated drug for two reasons, i.e. (1) drug encapsulation should be achieved prior to this step and (2) liposomes should retain their natural biophysical stability, securely carrying the drug in the aqueous core. These research goals further suggest the need for an optimized method to design stable sub-micron lipid vesicles. Nonetheless, the current liposome preparation technologies (sonication10, freeze-and-thaw10, sedimentation) do not allow preparation of liposomes with highly curved surface (i.e. diameter <100 nm) with high consistency and efficiency10,5, which limits the biophysical studies of an emerging field of membrane curvature sensing. Herein, we present a robust preparation method for a variety of biologically relevant liposomes. Manual extrusion using gas-tight syringes and polycarbonate membranes10,5 is a common practice but heterogeneity is often observed when using pore sizes <100 nm due to due to variability of manual pressure applied. We employed a constant pressure-controlled extrusion apparatus to prepare synthetic liposomes whose diameters range between 30 and 400 nm. Dynamic light scattering (DLS)10, electron microscopy11 and nanoparticle tracking analysis (NTA)12 were used to quantify the liposome sizes as described in our protocol, with commercial polystyrene (PS) beads used as a calibration standard. A near linear correlation was observed between the employed pore sizes and the experimentally determined liposomes, indicating high fidelity of our pressure-controlled liposome preparation method. Further, we have shown that this lipid vesicle preparation method is generally applicable, independent of various liposome sizes. Lastly, we have also demonstrated in a time course study that these prepared liposomes were stable for up to 16 hours. A representative nano-sized liposome preparation protocol is demonstrated below.

Yin, Hang

2012-01-01

256

A new pressure-controlled colon delivery capsule for chronotherapeutic treatment of nocturnal asthma.  

PubMed

The purpose of this study was to prepare a pressure-controlled colon delivery capsule (PCDC) containing theophylline (TPH) dispersion in a lipid matrix as a chronotherapeutic drug delivery system for the treatment of nocturnal asthma. The system was made by film coating using Eudragit S100- based formula over the sealed-hard gelatin capsules containing the drug-lipid dispersion. The lipid formula was composed mainly of Gelucire 33/01 (G33) with different ratios of surfactants (1-10%). The efficiency of the prepared system was evaluated in vitro for its ability to withstand both the gastric and intestinal medium. In addition, the drug plasma concentrations were monitored after single administration to Beagle dogs and compared to that obtained after administration of a reference marketed, generic, sustained-release TPH tablets, Avolen(®) SR. It was found that the optimum lipid formula was GL2 containing 90% G33 and 10% Labrasol. The film-coated capsules showed complete resistance to both the acidic environment (pH 1.2) for 2 hours and phosphate buffer pH 6.8 for 3 hours at 37°C. In vivo evaluation of the TPH-based PCDCs showed longer lag time compared TO the marketed formula followed by sudden increase in TPH blood levels, which recommends the high potential of this system as a chronotherapeutic drug delivery for nocturnal asthma. The prepared PCDCs exhibited a significantly higher C(max) and T(max) and a nonsignificantly different AUC compared with Avolen(®) SR. Higher TPH blood levels from 1 to 8 hours postadministration was detected in the case of the prepared PCDCs. PMID:20681754

Barakat, Nahla S; Al-Suwayeh, Saleh A; Taha, Ehab I; Bakry Yassin, Alaa Eldeen

2011-06-01

257

Unusual outcome of in utero infection and subsequent postnatal super-infection with different PCV2b strains.  

PubMed

VC2002, isolated from postweaning multisystemic wasting syndrome (PMWS)-affected pig, is a mixture of two porcine circovirus genotype 2b (PCV2b) viruses, K2 and K39. Preliminary experiments disclosed short-term adverse effects of K39, but not K2, on porcine foetuses. These findings led to the hypothesis that infection of immuno-incompetent foetuses with K2 confers a status of immunotolerance, and postnatal super-infection with K39 triggers PMWS. To explore this hypothesis, nine 55-day-old foetuses were inoculated in utero (three with K2-10(4.3)TCID50, three with K39-10(4.3)TCID50 and three with medium), and foeto-pathogenicity examined. At 21 days post-inoculation (dpi), K2 did not induce pathology, whereas pathological effects of K39 were evident. Twenty-four 45-day-old foetuses were subsequently inoculated to examine the long-term effect of K2, including six with K2-high dose-10(4.3)TCID50, six with K2-low dose-10(2.3)TCID50 and 12 mock-inoculated controls. Both doses resulted in five mummified foetuses and one live-born piglet each (69dpi). K2 was recovered from all mummies. K2 and K2-specific antibodies were not detected in serum of the two live-born piglets at birth, indicating full control of K2 infection. The K2-low dose-infected piglet was immunostimulated at day 2, but not the K2-high dose-infected piglet. Both non-stimulated and stimulated K2-infected piglets were super-inoculated with K39 at day 6 or 8 (taken as 0 days post super-inoculation). Low viral replication was observed in the non-stimulated K2-K39 piglet (up to 10(3.3)TCID50/g; identified as K39). In contrast, viral replication was extremely high in the stimulated K2-K39 piglet (up to 10(5.6)TCID50/g) and identified as K2, indicating that K2 infection is controlled during foetal life, but emerges after birth upon immunostimulation. However, none of the piglets showed any signs of PMWS. PMID:24950783

Saha, Dipongkor; Karniychuk, Uladzimir U; Huang, Liping; Geldhof, Marc; Vanhee, Merijn; Lefebvre, David J; Meerts, Peter; Ducatelle, Richard; Doorsselaere, Jan V; Nauwynck, Hans J

2014-06-01

258

Principles of mechanical ventilation--a critical review.  

PubMed

This article is the first of a two-part review focusing on mechanical ventilation, with particular emphasis on non-invasive ventilation when managing patients suffering from respiratory failure. This article explores the principles underpinning artificial ventilation, explains the difference between positive and negative pressure ventilation, and differentiates between invasive and non-invasive modes of ventilation. Finally it examines the various operational features, flexibility in use and limitations that artificial ventilation therapy presents. Optimum ventilatory practice requires knowledge to ensure the choosing of the 'right' ventilator. It ensures informed practice and maintains optimum patient safety. PMID:19717989

Pertab, Dhanishwar

259

Demand Controlled Ventilating Systems: Sensor Tests.  

National Technical Information Service (NTIS)

A test program has been designed to evaluate the performance characteristics of sensors for the automatic control of ventilation rates. The test program consists of two main parts, one being the evaluation of sensor performance in laboratory tests and the...

P. Fahlen H. Andersson S. Ruud

1992-01-01

260

46 CFR 194.20-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...shall be of watertight construction. (3) Inlets to exhaust ducts shall be provided and located at points where concentration...of vapor ignition. Terminals shall be fitted with acceptable flame screens. (4) The control for the power ventilation...

2013-10-01

261

Waste tank ventilation system waste material accumulations  

Microsoft Academic Search

This paper calculates the amount of material that accumulates in the ventilation systems of various Tank Waste Remediation System facilities and estimates the amount of material that could be released due to a rapid pressurization.

Van Vleet; Westinghouse Hanford

1996-01-01

262

46 CFR 194.15-5 - Ventilation.  

Code of Federal Regulations, 2013 CFR

...CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS HANDLING, USE, AND CONTROL OF EXPLOSIVES AND OTHER HAZARDOUS MATERIALS Chemistry Laboratory and Scientific Laboratory § 194.15-5 Ventilation. (a) Operations, reactions or...

2013-10-01

263

EVALUATION OF VENTILATION PERFORMANCE FOR INDOOR SPACE  

EPA Science Inventory

The paper discusses a personal-computer-based application of computational fluid dynamics that can be used to determine the turbulent flow field and time-dependent/steady-state contaminant concentration distributions within isothermal indoor space. (NOTE: Ventilation performance ...

264

Shelter Occupancy Studies of Ventilator Utilization.  

National Technical Information Service (NTIS)

The report describes three shelter occupancy experiments designed to investigate shelter management problems involving shelteree needs and responses, control of the shelter environment, shelter organization, and the operation of shelter ventilation equipm...

A. G. Jago J. A. Anderson R. C. Friedman

1970-01-01

265

[The choice of a pediatric anesthesia ventilator].  

PubMed

The technology of anesthesia ventilators has substantially progressed during last years. The choice of a pediatric anesthesia ventilator needs to be led by multiple parameters: requirement, technical (pneumatic performance, velocity of halogenated or oxygen delivery), cost (purchase, in operation, preventive and curative maintenance), reliability, ergonomy, upgradability, and compatibility. The demonstration of the interest of pressure support mode during maintenance of spontaneous ventilation anesthesia makes this mode essential in pediatrics. In contrast, the financial impact of target controlled inhalation of halogenated has not be studied in pediatrics. Paradoxically, complex and various available technologies had not been much prospectively studied. Anesthesia ventilators performances in pediatrics need to be clarified in further clinical and bench test studies. PMID:24209991

Kern, D; Larcher, C; Cottron, N; Ait Aissa, D; Fesseau, R; Alacoque, X; Delort, F; Masquère, P; Agnès, E; Visnadi, G; Fourcade, O

2013-12-01

266

30 CFR 75.333 - Ventilation controls.  

Code of Federal Regulations, 2013 CFR

...for the construction of overcasts, undercasts, shaft partitions, permanent stoppings, and regulators include concrete, concrete block, brick, cinder block, tile, or steel. No ventilation controls installed after November 15, 1992,...

2013-07-01

267

Comparison of prophylactic effects of polyurethane cylindrical or tapered cuff and polyvinyl chloride cuff endotracheal tubes on ventilator-associated pneumonia.  

PubMed

Because microaspiration of contaminated supraglottic secretions past the endotracheal tube cuff is considered to be central in the pathogenesis of pneumonia, improved design of tracheal tubes with new cuff material and shape have reduced the size and number of folds, which together with the addition of suction ports above the cuff to drain pooled subglottic secretions leads to reduced aspiration of oropharyngeal secretions. So we conducted a study to compare the prophylactic effects of polyurethane-cylindrical or tapered cuff and polyvinyl chloride cuff endotracheal tubes (ETT) on ventilator-associated pneumonia. This randomized clinical trial was carried out in a 12 bed surgical intensive care unit. 96 patients expected to require mechanical ventilation more than 96 hours were randomly allocated to one of three following groups: Polyvinyl chloride cuff (PCV) ETT, Polyurethane (PU) cylindrical Sealguard ETT and PU Taperguard ETT. Cuff pressure monitored every three hours 3 days in all patients. Mean cuff pressure didn't have significant difference between three groups during 72 hours. Pneumonia was seen in 11 patients (34%) in group PVC, 8 (25%) in Sealguard and 7 (21%) in Taperguard group. Changes in mean cuff pressure between Sealguard and PVC tubes and also between Taperguard and PVC tubes did not show any significant difference. There was no significant difference in overinflation between three groups. The use of ETT with PU material results in reducing ventilator-associated pneumonia compared to ETT with PVC cuff. In PU tubes Taperguard has less incidence of ventilator-associated pneumonia compared to Sealguard tubes. PMID:23945890

Mahmoodpoor, Ata; Peyrovi-far, Ali; Hamishehkar, Hadi; Bakhtyiari, Zhaleh; Mirinezhad, Mir Mousa; Hamidi, Masoud; Golzari, Samad Eslam Jamal

2013-01-01

268

Sensor-based demand controlled ventilation  

SciTech Connect

In most buildings, occupancy and indoor pollutant emission rates vary with time. With sensor-based demand-controlled ventilation (SBDCV), the rate of ventilation (i.e., rate of outside air supply) also varies with time to compensate for the changes in pollutant generation. In other words, SBDCV involves the application of sensing, feedback and control to modulate ventilation. Compared to ventilation without feedback, SBDCV offers two potential advantages: (1) better control of indoor pollutant concentrations; and (2) lower energy use and peak energy demand. SBDCV has the potential to improve indoor air quality by increasing the rate of ventilation when indoor pollutant generation rates are high and occupants are present. SBDCV can also save energy by decreasing the rate of ventilation when indoor pollutant generation rates are low or occupants are absent. After providing background information on indoor air quality and ventilation, this report provides a relatively comprehensive discussion of SBDCV. Topics covered in the report include basic principles of SBDCV, sensor technologies, technologies for controlling air flow rates, case studies of SBDCV, application of SBDCV to laboratory buildings, and research needs. SBDCV appears to be an increasingly attractive technology option. Based on the review of literature and theoretical considerations, the application of SBDCV has the potential to be cost-effective in applications with the following characteristics: (a) a single or small number of dominant pollutants, so that ventilation sufficient to control the concentration of the dominant pollutants provides effective control of all other pollutants; (b) large buildings or rooms with unpredictable temporally variable occupancy or pollutant emission; and (c) climates with high heating or cooling loads or locations with expensive energy.

De Almeida, A.T. [Universidade de Coimbra (Portugal). Dep. Eng. Electrotecnica; Fisk, W.J. [Lawrence Berkeley National Lab., CA (United States)

1997-07-01

269

Iatrogenic pneumothorax related to mechanical ventilation  

PubMed Central

Pneumothorax is a potentially lethal complication associated with mechanical ventilation. Most of the patients with pneumothorax from mechanical ventilation have underlying lung diseases; pneumothorax is rare in intubated patients with normal lungs. Tension pneumothorax is more common in ventilated patients with prompt recognition and treatment of pneumothorax being important to minimize morbidity and mortality. Underlying lung diseases are associated with ventilator-related pneumothorax with pneumothoraces occurring most commonly during the early phase of mechanical ventilation. The diagnosis of pneumothorax in critical illness is established from the patients’ history, physical examination and radiological investigation, although the appearances of a pneumothorax on a supine radiograph may be different from the classic appearance on an erect radiograph. For this reason, ultrasonography is beneficial for excluding the diagnosis of pneumothorax. Respiration-dependent movement of the visceral pleura and lung surface with respect to the parietal pleura and chest wall can be easily visualized with transthoracic sonography given that the presence of air in the pleural space prevents sonographic visualization of visceral pleura movements. Mechanically ventilated patients with a pneumothorax require tube thoracostomy placement because of the high risk of tension pneumothorax. Small-bore catheters are now preferred in the majority of ventilated patients. Furthermore, if there are clinical signs of a tension pneumothorax, emergency needle decompression followed by tube thoracostomy is widely advocated. Patients with pneumothorax related to mechanical ventilation who have tension pneumothorax, a higher acute physiology and chronic health evaluation?II?score or PaO2/FiO2 < 200 mmHg were found to have higher mortality.

Hsu, Chien-Wei; Sun, Shu-Fen

2014-01-01

270

Iatrogenic pneumothorax related to mechanical ventilation.  

PubMed

Pneumothorax is a potentially lethal complication associated with mechanical ventilation. Most of the patients with pneumothorax from mechanical ventilation have underlying lung diseases; pneumothorax is rare in intubated patients with normal lungs. Tension pneumothorax is more common in ventilated patients with prompt recognition and treatment of pneumothorax being important to minimize morbidity and mortality. Underlying lung diseases are associated with ventilator-related pneumothorax with pneumothoraces occurring most commonly during the early phase of mechanical ventilation. The diagnosis of pneumothorax in critical illness is established from the patients' history, physical examination and radiological investigation, although the appearances of a pneumothorax on a supine radiograph may be different from the classic appearance on an erect radiograph. For this reason, ultrasonography is beneficial for excluding the diagnosis of pneumothorax. Respiration-dependent movement of the visceral pleura and lung surface with respect to the parietal pleura and chest wall can be easily visualized with transthoracic sonography given that the presence of air in the pleural space prevents sonographic visualization of visceral pleura movements. Mechanically ventilated patients with a pneumothorax require tube thoracostomy placement because of the high risk of tension pneumothorax. Small-bore catheters are now preferred in the majority of ventilated patients. Furthermore, if there are clinical signs of a tension pneumothorax, emergency needle decompression followed by tube thoracostomy is widely advocated. Patients with pneumothorax related to mechanical ventilation who have tension pneumothorax, a higher acute physiology and chronic health evaluation?II?score or PaO2/FiO2 < 200 mmHg were found to have higher mortality. PMID:24834397

Hsu, Chien-Wei; Sun, Shu-Fen

2014-02-01

271

Construction of Prediction Module for Successful Ventilator Weaning  

Microsoft Academic Search

Ventilator weaning is the process of discontinuing mechanical ventilation from patients with respiratory failure. Previous\\u000a investigations reported that 39%-40% of the intensive care unit (ICU) patients need mechanical ventilator for sustaining their\\u000a lives. Among them, 90% of the patients can be weaned from the ventilator in several days while other 5%-15% of the patients\\u000a need longer ventilator support. Modern mechanical

Jiin-chyr Hsu; Yung-fu Chen; Hsuan-hung Lin; Chi-hsiang Li; Xiaoyi Jiang

2007-01-01

272

Tracer dating and ocean ventilation  

SciTech Connect

The interpretation of transient tracer observations depends on difficult to obtain information on the evolution in time of the tracer boundary conditions and interior distributions. Recent studies have attempted to circumvent this problem by making use of a derived quantity, age, based on the simultaneous distribution of two complementary tracers, such as tritium and its daughter, helium 3. The age is defined with reference to the surface such that the boundary condition takes on a constant value of zero. The authors use a two-dimensional model to explore the circumstances under which such a combination of conservation equations for two complementary tracers can lead to a cancellation of the time derivative terms. An interesting aspect of this approach is that mixing can serve as a source or sink of tracer based age. The authors define an idealized ventilation age tracer that is conservative with respect to mixing, and they explore how its behavior compares with that of the tracer-based ages over a range of advective and diffusive parameters.

Thiele, G.; Sarmiento, J.L. (Princeton Univ., NJ (United States))

1990-06-15

273

Seismic qualification of ventilation stack  

SciTech Connect

This paper describes the method to be used to qualify the 105 K ventilation stack at the U.S. Department of Energy`s Hanford Site, near Richland, Washington, under seismic and wind loadings. The stack stands at 175 ft (53.34 m), with a diameter tapering from 22 ft (6.71 m) at the foundation to 12.83 ft (3.91 m) at the top. Although the stack is classified as Safety Class 3 (low hazard), it is treated as a Safety Class 1 (high hazard) component, as failure could damage a Safety Class 1 facility (the irradiated fuel storage basin). The evaluation used U.S. Department of Energy criteria specified in UCRL 15910 (1990). The seismic responses of the stack under earthquake loading were obtained from modal analyses with response spectrum input that used the ANSYS (1989) finite-element computer code. The moments and shear forces from the results of seismic analysis were used to qualify the reinforcement capacity of the stack structure by the ultimate-strength method. The wind forces acting on the stack in both along-wind and crosswind directions were also calculated. Presented are evaluations of the soil bearing pressure, the moment, and the shear capacity of the stack foundation.

Chen, W.W.; Huang, S.N.; Lindquist, M.R.

1993-10-01

274

Clinical review: Long-term noninvasive ventilation  

PubMed Central

Noninvasive positive ventilation has undergone a remarkable evolution over the past decades and is assuming an important role in the management of both acute and chronic respiratory failure. Long-term ventilatory support should be considered a standard of care to treat selected patients following an intensive care unit (ICU) stay. In this setting, appropriate use of noninvasive ventilation can be expected to improve patient outcomes, reduce ICU admission, enhance patient comfort, and increase the efficiency of health care resource utilization. Current literature indicates that noninvasive ventilation improves and stabilizes the clinical course of many patients with chronic ventilatory failure. Noninvasive ventilation also permits long-term mechanical ventilation to be an acceptable option for patients who otherwise would not have been treated if tracheostomy were the only alternative. Nevertheless, these results appear to be better in patients with neuromuscular/-parietal disorders than in chronic obstructive pulmonary disease. This clinical review will address the use of noninvasive ventilation (not including continuous positive airway pressure) mainly in diseases responsible for chronic hypoventilation (that is, restrictive disorders, including neuromuscular disease and lung disease) and incidentally in others such as obstructive sleep apnea or problems of central drive.

Robert, Dominique; Argaud, Laurent

2007-01-01

275

Protective ventilation using electrical impedance tomography.  

PubMed

Dynamic thoracic EIT is capable of detecting changes of the ventilation distribution in the lung. Nevertheless, it has yet to become an established clinical tool. Therefore, it is necessary to consider application scenarios wherein fast and distinct changes of the tissue conductivities are to be found and also have a clear diagnostic significance. One such a scenario is the artificial ventilation of patients suffering from the acute respiratory distress syndrome (ARDS). New protective ventilation strategies involving recruitment manoeuvres are associated with noticeable shifts of body fluids and regional ventilation, which can quite easily be detected by EIT. The bedside assessment of these recruitment manoeuvres will help the attending physician to optimize treatment. Hence, we performed an animal study of lavage-induced lung failure and investigated if EIT is capable of qualitatively as well as quantitatively monitoring lung recruitment during a stepwise PEEP trial. Additionally, we integrated EIT into a fuzzy controller-based ventilation system which allows one to perform automated recruitment manoeuvres (open lung concept) based on online PaO2 measurements. We found that EIT is a useful tool to titrate the proper PEEP level after fully recruiting the lung. Furthermore, EIT seems to be able to determine the status of recruitment when combining it with other physiological parameters. These results suggest that EIT may play an important role in the individualization of protective ventilation strategies. PMID:17664639

Luepschen, H; Meier, T; Grossherr, M; Leibecke, T; Karsten, J; Leonhardt, S

2007-07-01

276

Airway pressure release ventilation: an alternative mode of mechanical ventilation in acute respiratory distress syndrome.  

PubMed

Acute respiratory distress syndrome (ARDS) results in collapse of alveoli and therefore poor oxygenation. In this article, we review airway pressure release ventilation (APRV), a mode of mechanical ventilation that may be useful when, owing to ARDS, areas of the lungs are collapsed and need to be reinflated ("recruited"), avoiding cyclic alveolar collapse and reopening. PMID:21285342

Modrykamien, Ariel; Chatburn, Robert L; Ashton, Rendell W

2011-02-01

277

Hydrostatic Hyperbaric Chamber Ventilation System  

NASA Technical Reports Server (NTRS)

The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy (HBOT) available in the developing world for the treatment of a variety of medical conditions. Specifically, HBOT is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. HBOT is simply too expensive and too dangerous to implement in the developing world using standard equipment. The HHC technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system to provide controlled pressurization and adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware, supports sustainability.

Sarguisingh, Miriam J.

2012-01-01

278

Cost-utility analyses of intensive blood glucose and tight blood pressure control in type 2 diabetes (UKPDS 72)  

Microsoft Academic Search

Aims\\/hypothesis  This study estimated the economic efficiency (1) of intensive blood glucose control and tight blood pressure control in patients with type 2 diabetes who also had hypertension, and (2) of metformin therapy in type 2 diabetic patients who were overweight.Methods  We conducted cost-utility analysis based on patient-level data from a randomised clinical controlled trial involving 4,209 patients with newly diagnosed type

P. M. Clarke; A. M. Gray; A. Briggs; R. J. Stevens; D. R. Matthews; R. R. Holman

2005-01-01

279

A study on the improvement of the load pressure feedback mechanism of the proportional pressure control valve  

Microsoft Academic Search

The proportional pressure control valve having versatile functions and higher performance is an essential component in the\\u000a open loop controlled rear wheel steering gear of the four wheel steering system on a passenger car. In this study, the authors\\u000a suggest a new type of load pressure feedback mechanism which can make it easy to change the control range of load

Inho Oh; Jiseong Jang; Illyeong Lee; Daijong Chung; Sunghyun Cho

1999-01-01

280

Regenerative Blower for EVA Suit Ventilation Fan  

NASA Technical Reports Server (NTRS)

Portable life support systems in future space suits will include a ventilation subsystem driven by a dedicated fan. This ventilation fan must meet challenging requirements for pressure rise, flow rate, efficiency, size, safety, and reliability. This paper describes research and development that showed the feasibility of a regenerative blower that is uniquely suited to meet these requirements. We proved feasibility through component tests, blower tests, and design analysis. Based on the requirements for the Constellation Space Suit Element (CSSE) Portable Life Support System (PLSS) ventilation fan, we designed the critical elements of the blower. We measured the effects of key design parameters on blower performance using separate effects tests, and used the results of these tests to design a regenerative blower that will meet the ventilation fan requirements. We assembled a proof-of-concept blower and measured its performance at sub-atmospheric pressures that simulate a PLSS ventilation loop environment. Head/flow performance and maximum efficiency point data were used to specify the design and operating conditions for the ventilation fan. We identified materials for the blower that will enhance safety for operation in a lunar environment, and produced a solid model that illustrates the final design. The proof-of-concept blower produced the flow rate and pressure rise needed for the CSSE ventilation subsystem while running at 5400 rpm, consuming only 9 W of electric power using a non-optimized, commercial motor and controller and inefficient bearings. Scaling the test results to a complete design shows that a lightweight, compact, reliable, and low power regenerative blower can meet the performance requirements for future space suit life support systems.

Izenson, Michael G.; Chen, Weibo; Paul, Heather L.

2010-01-01

281

A Porcine Model for Initial Surge Mechanical Ventilator Assessment and Evaluation of Two Limited Function Ventilators  

PubMed Central

Objective To adapt an animal model of acute lung injury for use as a standard protocol for a screening, initial evaluation of limited function, or “surge,” ventilators for use in mass casualty scenarios. Design Prospective, experimental animal study. Setting University research laboratory. Subjects 12 adult pigs. Interventions 12 spontaneously breathing pigs (6 in each group) were subjected to acute lung injury/acute respiratory distress syndrome (ALI/ARDS) via pulmonary artery infusion of oleic acid. Following development of respiratory failure, animals were mechanically ventilated with a limited function ventilator (Simplified Automatic Ventilator [SAVe] I or II; Automedx) for one hour or until the ventilator could not support the animal. The limited function ventilator was then exchanged for a full function ventilator (Servo 900C; Siemens). Measurements and Main Results Reliable and reproducible levels of ALI/ARDS were induced. The SAVe I was unable to adequately oxygenate 5 animals, with PaO2 (52.0 ± 11.1 torr) compared to the Servo (106.0 ± 25.6 torr; p=0.002). The SAVe II was able to oxygenate and ventilate all 6 animals for one hour with no difference in PaO2 (141.8 ± 169.3 torr) compared to the Servo (158.3 ± 167.7 torr). Conclusions We describe a novel in vivo model of ALI/ARDS that can be used to initially screen limited function ventilators considered for mass respiratory failure stockpiles, and is intended to be combined with additional studies to defintively assess appropriateness for mass respiratory failure. Specifically, during this study we demonstrate that the SAVe I ventilator is unable to provide sufficient gas exchange, while the SAVe II, with several more functions, was able to support the same level of hypoxemic respiratory failure secondary to ALI/ARDS for one hour.

Dickson, Robert P; Hotchkin, David L; Lamm, Wayne JE; Hinkson, Carl; Pierson, David J; Glenny, Robb W; Rubinson, Lewis

2013-01-01

282

WASTE TREATMENT BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT  

SciTech Connect

The Waste Treatment Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Treatment Building (WTB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition to maintaining the proper environmental conditions for personnel comfort and equipment operation, the contamination confinement area ventilation system directs potentially contaminated air away from personnel in the WTB and confines the contamination within high-efficiency particulate air (HEPA) filtration units. The contamination confinement area ventilation system creates airflow paths and pressure zones to minimize the potential for spreading contamination with the building. The contamination confinement ventilation system also protects the environment and the public by limiting airborne releases of radioactive or other hazardous contaminants from the WTB. The Waste Treatment Building Ventilation System confines the radioactive and hazardous material within the building such that the release rates comply with regulatory limits, The system design, operations, and maintenance activities incorporate ALARA (as low as is reasonably achievable) principles to maintain personnel radiation doses to all occupational workers below regulatory limits and as low as is reasonably achievable. The system provides status of important system parameters and equipment operation, and provides audible and/or visual indication of off-normal conditions and equipment failures. The Waste Treatment Building Ventilation System interfaces with the Waste Treatment Building System by being located in the WTB, and by maintaining specific pressure, temperature, and humidity environments within the building. The system also depends on the WTB for normal electric power supply and the required supply of water for heating, cooling, and humidification. Interface with the Waste Treatment Building System includes the WTB fire protection subsystem for detection of fire and smoke. The Waste Treatment Building Ventilation System interfaces with the Site Radiological Monitoring System for continuous monitoring of the exhaust air and key areas within the WTB, the Monitored Geologic Repository Operations Monitoring and Control System for monitoring and control of system operations, and the Site Generated Radiological Waste Handling System and Site Generated Hazardous, Non-Hazardous & Sanitary Waste Disposal System for routing of pretreated toxic, corrosive, and radiologically contaminated effluent from process equipment to the HEPA filter exhaust ductwork and air-cleaning unit.

P.A. Kumar

2000-06-22

283

WASTE HANDLING BUILDING VENTILATION SYSTEM DESCRIPTION DOCUMENT  

SciTech Connect

The Waste Handling Building Ventilation System provides heating, ventilation, and air conditioning (HVAC) for the contaminated, potentially contaminated, and uncontaminated areas of the Monitored Geologic Repository's (MGR) Waste Handling Building (WHB). In the uncontaminated areas, the non-confinement area ventilation system maintains the proper environmental conditions for equipment operation and personnel comfort. In the contaminated and potentially contaminated areas, in addition to maintaining the proper environmental conditions for equipment operation and personnel comfort, the contamination confinement area ventilation system directs potentially contaminated air away from personnel in the WHB and confines the contamination within high-efficiency particulate air (HEPA) filtration units. The contamination confinement areas ventilation system creates airflow paths and pressure zones to minimize the potential for spreading contamination within the building. The contamination confinement ventilation system also protects the environment and the public by limiting airborne releases of radioactive or other hazardous contaminants from the WHB. The Waste Handling Building Ventilation System is designed to perform its safety functions under accident conditions and other Design Basis Events (DBEs) (such as earthquakes, tornadoes, fires, and loss of the primary electric power). Additional system design features (such as compartmentalization with independent subsystems) limit the potential for cross-contamination within the WHB. The system provides status of important system parameters and equipment operation, and provides audible and/or visual indication of off-normal conditions and equipment failures. The Waste Handling Building Ventilation System confines the radioactive and hazardous material within the building such that the release rates comply with regulatory limits. The system design, operations, and maintenance activities incorporate ALARA (as low as is reasonably achievable) principles to maintain personnel radiation doses to all occupational workers below regulatory limits and as low as is reasonably achievable. The Waste Handling Building Ventilation System interfaces with the Waste Handling Building System by being located within the WHB and by maintaining specific pressures, temperatures, and humidity within the building. The system also depends on the WHB for water supply. The system interfaces with the Site Radiological Monitoring System for continuous monitoring of the exhaust air; the Waste Handling Building Fire Protection System for detection of fire and smoke; the Waste Handling Building Electrical System for normal, emergency, and standby power; and the Monitored Geologic Repository Operations Monitoring and Control System for monitoring and control of the system.

P.A. Kumar

2000-06-21

284

Blood pressure control and antihypertensive pharmacotherapy patterns in a hypertensive population of Eastern Central Region of Portugal  

PubMed Central

Background Interventions to improve blood pressure control in hypertension have had limited success in clinical practice despite evidence of cardiovascular disease prevention in randomised controlled trials. The objectives of this study were to evaluate blood pressure control and antihypertensive pharmacotherapy patterns in a population of Eastern Central Region of Portugal, attending a hospital outpatient clinic (ambulatory setting) for routine follow-up. Methods Medical data of all patients that attended at least two medical appointments of hypertension/dyslipidemia in a university hospital over a one and a half year period (from January 2008 to June 2009) were retrospectively analysed. Demographic variables, clinical data and blood pressure values of hypertensive patients included in the study, as well as prescribing metrics were examined on a descriptive basis and expressed as the mean ± SD, frequency and percentages. Student's test and Mann-Whitney rank sum test were used to compare continuous variables and ?2 test and Fisher exact probability test were used to test for differences between categorical variables. Results In all, 37% of hypertensive patients (n = 76) had their blood pressure controlled according to international guidelines. About 45.5% of patients with a target blood pressure <140/90 mmHg (n = 156) were controlled, whereas in patients with diabetes or chronic kidney disease (n = 49) the corresponding figure was only 10.2% (P < 0.001). Among patients initiating hypertension/dyslipidemia consultation within the study period 32.1% had stage 2 hypertension in the first appointment, but this figure decreased to 3.6% in the last consultation (P = 0.012). Thiazide-type diuretics were the most prescribed antihypertensive drugs (67%) followed by angiotensin receptor blockers (60%) and beta-blockers (43%). About 95.9% patients with comorbid diabetes were treated with an angiotensin-converting enzyme inhibitor or an angiotensin receptor blocker. Conclusions Clinically important blood pressure decreases can be achieved soon after hypertension medical appointment initiation. However, many hypertensive patients prescribed with antihypertensive therapy fail to achieve blood pressure control in clinical practice, this control being worse among patients with diabetes or chronic kidney disease. As pharmacotherapy patterns seem to coincide with international guidelines, further research is needed to identify the causes of poor blood pressure control.

2010-01-01

285

Design Feature 7: Continuous Preclosure Ventilation  

SciTech Connect

This design feature (DF) is intended to evaluate the effects of continuous ventilation in the emplacement drifts during preclosure and how the effects, if any, compare to the Viability Assessment (VA) reference design for postclosure long term performance. This DF will be evaluated against a set of criteria provided by the License Application Design Selection (LADS) group. The VA reference design included a continuous ventilation airflow quantity of 0.1 m{sup 3}/s in the emplacement drifts in the design of the repository subsurface facilities. The effects of this continuous ventilation during the preclosure was considered to have a negligible effect on postclosure performance and therefore is not included during postclosure in the assessment of the long term performance. This DF discusses the effects of continuous ventilation on the emplacement drift environment and surrounding rock conditions during preclosure for three increased airflow quantities. The three cases of continuous ventilation systems are: System A, 1.0 m{sup 3}/s (Section 8), System B, 5.0 m{sup 3}/s (Section 9), and System C, 10.0 m{sup 3}/s (Section 10) in each emplacement drift split. An emplacement drift split is half total length of emplacement drift going from the east or west main to the exhaust main. The difference in each system is the quantity of airflow in the emplacement drifts.

A.T. Watkins

1999-06-22

286

Computational fluid dynamics in ventilation: Practical approach  

NASA Astrophysics Data System (ADS)

The potential of computation fluid dynamics (CFD) for conceiving ventilation systems is shown through the simulation of five practical cases. The following examples are considered: capture of pollutants on a surface treating tank equipped with a unilateral suction slot in the presence of a disturbing air draft opposed to suction; dispersion of solid aerosols inside fume cupboards; performances comparison of two general ventilation systems in a silkscreen printing workshop; ventilation of a large open painting area; and oil fog removal inside a mechanical engineering workshop. Whereas the two first problems are analyzed through two dimensional numerical simulations, the three other cases require three dimensional modeling. For the surface treating tank case, numerical results are compared to laboratory experiment data. All simulations are carried out using EOL, a CFD software specially devised to deal with air quality problems in industrial ventilated premises. It contains many analysis tools to interpret the results in terms familiar to the industrial hygienist. Much experimental work has been engaged to validate the predictions of EOL for ventilation flows.

Fontaine, J. R.

287

Prevention of ventilator-associated pneumonia.  

PubMed

Invasive mechanical ventilation (IMV) represents a risk factor for the development of ventilator-associated pneumonia (VAP), which develops at least 48h after admission in patients ventilated through tracheostomy or endotracheal intubation. VAP is the most frequent intensive-care-unit (ICU)-acquired infection among patients receiving IMV. It contributes to an increase in hospital mortality, duration of MV and ICU and length of hospital stay. Therefore, it worsens the condition of the critical patient and increases the total cost of hospitalization. The introduction of preventive measures has become imperative, to ensure control and to reduce the incidence of VAP. Preventive measures focus on modifiable risk factors, mediated by non-pharmacological and pharmacological evidence based strategies recommended by guidelines. These measures are intended to reduce the risk associated with endotracheal intubation and to prevent microaspiration of pathogens to the lower airways. PMID:24674617

Oliveira, J; Zagalo, C; Cavaco-Silva, P

2014-01-01

288

Clinical review: Mechanical ventilation in severe asthma  

PubMed Central

Respiratory failure from severe asthma is a potentially reversible, life-threatening condition. Poor outcome in this setting is frequently a result of the development of gas-trapping. This condition can arise in any mechanically ventilated patient, but those with severe airflow limitation have a predisposition. It is important that clinicians managing these types of patients understand that the use of mechanical ventilation can lead to or worsen gas-trapping. In this review we discuss the development of this complication during mechanical ventilation, techniques to measure it and strategies to limit its severity. We hope that by understanding such concepts clinicians will be able to reduce further the poor outcomes occasionally related to severe asthma.

Stather, David R; Stewart, Thomas E

2005-01-01

289

Pulmonary ventilation teaching aid: part 2  

NSDL National Science Digital Library

Since writing the article titled "Pulmonary ventilation teaching aid" (Stockert B, Adv Physiol Educ 27: 41ÃÂ42, 2003), we have continued to use the salad tongs and rubber band model to teach ventilation mechanics and several clinical correlates. The original article dealt primarily with normal ventilation mechanics and changes in the lungs, i.e., the rubber bands, that occur with common pulmonary disorders, e.g., pulmonary fibrosis and chronic obstructive pulmonary disease. We have developed several additional clinical correlates related to changes in the chest wall, i.e., the salad tongs. Those clinical examples are presented here. The materials needed for this demonstration are several rubber bands and a pair of metal salad tongs with a hinge.

PhD Brad Stockert (University of the Pacific Department of Physical Therapy)

2003-06-01

290

Efficacy of intermittent ventilation for providing acceptable indoor air quality  

SciTech Connect

Ventilation standards and guidelines typically treat ventilation as a constant and specify its value. In many circumstances a designer wishes to use intermittent ventilation, rather than constant ventilation, but there are no easy equivalencies available. This report develops a model of efficacy that allows one to calculate how much intermittent ventilation one needs to get the same indoor air quality as a the continuous value specified. We have found that there is a simple relationship between three dimensionless quantities: the temporal ventilation effectiveness (which we call the efficacy), the nominal turn-over and the under-ventilation fraction. This relationship allows the calculation of intermittent ventilation for a wide variety of parameters and conditions. We can use the relationship to define a critical time that separates the regime in which ventilation variations can be averaged over from the regime in which variable ventilation is of low effectiveness. We have found that ventilation load-shifting, temporary protection against poor outdoor air quality and dynamic ventilation strategies can be quite effective in low-density buildings such as single-family houses or office spaces. The results of this work enable ventilation standards and guidelines to allow this extra flexibility and still provide acceptable indoor air quality.

Sherman, M.H.

2004-10-01

291

Estimated costs of ventilation systems complying with the HUD ventilation standard for manufactured homes  

SciTech Connect

At the request of the US Department of Housing and Urban Development (HUD), the Pacific Northwest Laboratory estimated the material, labor, and operating costs for ventilation equipment needed for compliance with HUD`s proposed revision to the ventilation standard for manufactured housing. This was intended to bound the financial impacts of the ventilation standard revision. Researchers evaluated five possible prototype ventilation systems that met the proposed ventilation requirements. Of those five, two systems were determined to be the most likely used by housing manufacturers: System 1 combines a fresh air duct with the existing central forced-air system to supply and circulate fresh air to conditioned spaces. System 2 uses a separate exhaust fan to remove air from the manufactured home. The estimated material and labor costs for these two systems range from $200 to $300 per home. Annual operating costs for the two ventilation systems were estimated for 20 US cities. The estimated operating costs for System 1 ranged from $55/year in Las Vegas, Nevada, to $83/year in Bismarck, North Dakota. Operating costs for System 2 ranged from a low of $35/year in Las Vegas to $63/year in Bismarck. Thus, HUD`s proposed increase in ventilation requirements will add less than $100/year to the energy cost of a manufactured home.

Miller, J.D.; Conner, C.C.

1993-11-01

292

Open circuit mouthpiece ventilation: Concise clinical review.  

PubMed

In 2013 new "mouthpiece ventilation" modes are being introduced to commercially available portable ventilators. Despite this, there is little knowledge of how to use noninvasive intermittent positive pressure ventilation (NIV) as opposed to bi-level positive airway pressure (PAP) and both have almost exclusively been reported to have been used via nasal or oro-nasal interfaces rather than via a simple mouthpiece. Non-invasive ventilation is often reported as failing because of airway secretion encumbrance, because of hypercapnia due to inadequate bi-level PAP settings, or poor interface tolerance. The latter can be caused by factors such as excessive pressure on the face from poor fit, excessive oral air leak, anxiety, claustrophobia, and patient-ventilator dys-synchrony. Thus, the interface plays a crucial role in tolerance and effectiveness. Interfaces that cover the nose and/or nose and mouth (oro-nasal) are the most commonly used but are more likely to cause skin breakdown and claustrophobia. Most associated drawbacks can be avoided by using mouthpiece NIV. Open-circuit mouthpiece NIV is being used by large populations in some centers for daytime ventilatory support and complements nocturnal NIV via "mask" interfaces for nocturnal ventilatory support. Mouthpiece NIV is also being used for sleep with the mouthpiece fixed in place by a lip-covering flange. Small 15 and 22mm angled mouthpieces and straw-type mouthpieces are the most commonly used. NIV via mouthpiece is being used as an effective alternative to ventilatory support via tracheostomy tube (TMV) and is associated with a reduced risk of pneumonias and other respiratory complications. Its use facilitates "air-stacking" to improve cough, speech, and pulmonary compliance, all of which better maintain quality of life for patients with neuromuscular diseases (NMDs) than the invasive alternatives. Considering these benefits and the new availability of mouthpiece ventilator modes, wider knowledge of this technique is now warranted. This review highlights the indications, techniques, advantages and disadvantages of mouthpiece NIV. PMID:24841239

Garuti, G; Nicolini, A; Grecchi, B; Lusuardi, M; Winck, J C; Bach, J R

2014-01-01

293

Ventilation-perfusion distribution in normal subjects.  

PubMed

Functional values of LogSD of the ventilation distribution (?(V)) have been reported previously, but functional values of LogSD of the perfusion distribution (?(q)) and the coefficient of correlation between ventilation and perfusion (?) have not been measured in humans. Here, we report values for ?(V), ?(q), and ? obtained from wash-in data for three gases, helium and two soluble gases, acetylene and dimethyl ether. Normal subjects inspired gas containing the test gases, and the concentrations of the gases at end-expiration during the first 10 breaths were measured with the subjects at rest and at increasing levels of exercise. The regional distribution of ventilation and perfusion was described by a bivariate log-normal distribution with parameters ?(V), ?(q), and ?, and these parameters were evaluated by matching the values of expired gas concentrations calculated for this distribution to the measured values. Values of cardiac output and LogSD ventilation/perfusion (Va/Q) were obtained. At rest, ?(q) is high (1.08 ± 0.12). With the onset of ventilation, ?(q) decreases to 0.85 ± 0.09 but remains higher than ?(V) (0.43 ± 0.09) at all exercise levels. Rho increases to 0.87 ± 0.07, and the value of LogSD Va/Q for light and moderate exercise is primarily the result of the difference between the magnitudes of ?(q) and ?(V). With known values for the parameters, the bivariate distribution describes the comprehensive distribution of ventilation and perfusion that underlies the distribution of the Va/Q ratio. PMID:22773767

Beck, Kenneth C; Johnson, Bruce D; Olson, Thomas P; Wilson, Theodore A

2012-09-01

294

Regenerative Blower for EVA Suit Ventilation Fan  

NASA Technical Reports Server (NTRS)

Portable life support systems in future space suits will include a ventilation subsystem driven by a dedicated fan. This ventilation fan must meet challenging requirements for pressure rise, flow rate, efficiency, size, safety, and reliability. This paper describes research and development that showed the feasibility of a regenerative blower that is uniquely suited to meet these requirements. We proved feasibility through component tests, blower tests, and design analysis. Based on the requirements for the Constellation Space Suit ventilation fan, we designed the critical elements of the blower. We measured the effects of key design parameters on blower performance using separate effects tests, and used the results of these tests to design a regenerative blower that will meet the ventilation fan requirements. We assembled a proof-of-concept blower and measured its performance at low pressures that simulate a PLSS environment. We obtained head/flow performance curves over a range of operating speeds, identified the maximum efficiency point for the blower, and used these results to specify the design and operating conditions for the ventilation fan. We designed a compact motor that can drive the blower under all anticipated operating requirements and operate with high efficiency during normal operation. We identified materials for the blower that will enhance safety for operation in a lunar environment. We produced a solid model that illustrates the final design. The proof-of-concept blower produced the flow rate and pressure rise needed for the CSSS ventilation subsystem while running at 5400 rpm and consuming only 9 W of electric power and using a non-optimized, commercial motor and controller and inefficient bearings. Scaling the test results to a complete design shows that a lightweight, compact, reliable, and low power blower can meet the performance requirements for future PLSSs.

Paul, Heather; Izenson, Mike; Chen, Weibo

2008-01-01

295

Thermoregulation and ventilation of termite mounds.  

PubMed

Some of the most sophisticated of all animal-built structures are the mounds of African termites of the subfamily Macrotermitinae, the fungus-growing termites. They have long been studied as fascinating textbook examples of thermoregulation or ventilation of animal buildings. However, little research has been designed to provide critical tests of these paradigms, derived from a very small number of original papers. Here I review results from recent studies on Macrotermes bellicosus that considered the interdependence of ambient temperature, thermoregulation, ventilation and mound architecture, and that question some of the fundamental paradigms of termite mounds. M. bellicosus achieves thermal homeostasis within the mound, but ambient temperature has an influence too. In colonies in comparably cool habitats, mound architecture is adapted to reduce the loss of metabolically produced heat to the environment. While this has no negative consequences in small colonies, it produces a trade-off with gas exchange in large colonies, resulting in suboptimally low nest temperatures and increased CO(2) concentrations. Along with the alteration in mound architecture, the gas exchange/ventilation mechanism also changes. While mounds in the thermally appropriate savannah have a very efficient circular ventilation during the day, the ventilation in the cooler forest is a less efficient upward movement of air, with gas exchange restricted by reduced surface exchange area. These results, together with other recent findings, question entrenched ideas such as the thermosiphon-ventilation mechanism or the assumption that mounds function to dissipate internally produced heat. Models trying to explain the proximate mechanisms of mound building, or building elements, are discussed. PMID:12743703

Korb, Judith

2003-05-01

296

[Non invasive ventilation in emergency settings].  

PubMed

The use of non invasive ventilation (NIV) in the emergency setting to treat acute respiratory failure (ARF) has received much attention. To date, large studies support the early administration of continuous positive airway pressure (CPAP) in patients with cardiogenic acute pulmonary edema; and 2) non-invasive positive pressure ventilation (NPPV) for exacerbations of chronic obstructive pulmonary disease (COPD). NIV could also be useful in other types of ARF, but its success rate is dependent on the cause of ARF and patient's characteristics. Use of NIV in the emergency setting should take into account validated indications and local expertise of the nursing staff to minimize the risk of complications. PMID:16152879

Sarasin, F P; Jolliet, P

2005-08-10

297

46 CFR 108.187 - Ventilation for brush type electric motors in classified spaces.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Ventilation for brush type electric motors in classified spaces...Ventilation § 108.187 Ventilation for brush type electric motors in classified spaces. Ventilation for brush type electric motors in classified...

2010-10-01

298

46 CFR 108.187 - Ventilation for brush type electric motors in classified spaces.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 false Ventilation for brush type electric motors in classified spaces...Ventilation § 108.187 Ventilation for brush type electric motors in classified spaces. Ventilation for brush type electric motors in classified...

2009-10-01

299

46 CFR 171.118 - Automatic ventilators and side ports.  

Code of Federal Regulations, 2013 CFR

...STABILITY SPECIAL RULES PERTAINING TO VESSELS CARRYING PASSENGERS Openings in the Side of a Vessel Below the Bulkhead or Weather Deck § 171.118 Automatic ventilators and side ports. (a) An automatic ventilator must not be fitted in the...

2013-10-01

300

46 CFR 108.181 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2013 CFR

...Ventilation for enclosed spaces. 108.181 Section 108.181 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) A-MOBILE OFFSHORE DRILLING UNITS DESIGN AND EQUIPMENT Construction and Arrangement Ventilation §...

2013-10-01

301

Indoor Air Quality: Is Increased Ventilation the Answer?  

ERIC Educational Resources Information Center

Explains how indoor air quality is affected by pollutants in the air and also by temperature, humidity, and ventilation. Increased ventilation alone seldom solves the "sick building syndrome." Lists ways to improve indoor air quality and optimize energy efficiency. (MLF)

Hansen, Shirley

1989-01-01

302

Ventilation/Odor Study, Field Study. Final Report, Volume I.  

National Technical Information Service (NTIS)

The results are presented of field investigations in schools, hospitals, and an office building on the relation between ventilation rate and odor within the buildings. The primary objective of the study was to determine: the reduction in ventilation rates...

R. A. Duffee P. Jann

1981-01-01

303

Post-Polio Health International including International Ventilator Users Network  

MedlinePLUS

... post-polio.org. Check out International Ventilator Users Network Post-Polio Health International's mission is to enhance ... Polio Health International (PHI) Including International Ventilator Users Network 4207 Lindell Blvd., #110, Saint Louis, MO 63108- ...

304

12. NEW YORK SIDE, HUDSON RIVER VENTILATION BUILDING IN FOREGROUND; ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. NEW YORK SIDE, HUDSON RIVER VENTILATION BUILDING IN FOREGROUND; NEW JERSEY SIDE, HUDSON RIVEN VENTILATION BUILDING IN BACKGROUND - Holland Tunnel, Beneath Hudson River between New York & Jersey City, New York, New York County, NY

305

Effect of Positive Pressure Ventilation on a Room Fire.  

National Technical Information Service (NTIS)

Fire departments may use ventilation blowers or fans to pressurize a structure prior to suppressing a fire. This pressurization or positive pressure ventilation (PPV) tactic can assist in the venting of smoke and high temperature combustion products and m...

S. Kerber W. D. Walton

2005-01-01

306

3. LEPLEY VENTILATOR FROM EAST. STEAM ENGINE CYLINDER AT LEFT, ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. LEPLEY VENTILATOR FROM EAST. STEAM ENGINE CYLINDER AT LEFT, AEROVANE FAN HOOD AT RIGHT REAR. - Consolidation Coal Company Mine No. 11, Lepley Ventilator, East side of State Route 936, Midlothian, Allegany County, MD

307

46 CFR 169.315 - Ventilation (other than machinery spaces).  

Code of Federal Regulations, 2013 CFR

...manner suitable for the purpose of the space. (b) A means must be provided...vents and ventilators. (c) Living spaces must be ventilated by a mechanical...vessel's design waterline length times its maximum beam. Living...

2013-10-01

308

46 CFR 185.352 - Ventilation of gasoline machinery spaces.  

Code of Federal Regulations, 2013 CFR

...Ventilation of gasoline machinery spaces. The mechanical exhaust...ventilation of a gasoline machinery space, required by § 182.460...starting gasoline engines for the time sufficient to insure at least one complete change of air in the space...

2013-10-01

309

Automated analysis of Xe-133 pulmonary ventilation (AAPV) in children  

NASA Astrophysics Data System (ADS)

In this study, an automated analysis of pulmonary ventilation (AAPV) was developed to visualize the ventilation in pediatric lungs using dynamic Xe-133 scintigraphy. AAPV is a software algorithm that converts a dynamic series of Xe- 133 images into four functional images: equilibrium, washout halftime, residual, and clearance rate by analyzing pixelbased activity. Compared to conventional methods of calculating global or regional ventilation parameters, AAPV provides a visual representation of pulmonary ventilation functions.

Cao, Xinhua; Treves, S. Ted

2011-03-01

310

Effect of repository underground ventilation on emplacement drift temperature control  

SciTech Connect

The repository advanced conceptual design (ACD) is being conducted by the Civilian Radioactive Waste Management System, Management & Operating Contractor. Underground ventilation analyses during ACD have resulted in preliminary ventilation concepts and design methodologies. This paper discusses one of the recent evaluations -- effects of ventilation on emplacement drift temperature management.

Yang, H.; Sun, Y.; McKenzie, D.G.; Bhattacharyya, K.K. [Morrison Knudson Corporation, Las Vegas, NV (United States)

1996-02-01

311

Ventilation requirements in non-domestic buildings and energy efficiency  

Microsoft Academic Search

This paper focuses on the importance of the level of ventilation requirements on the energy demand of non-domestic buildings. At present, we observe a tremendous difference in the ventilation requirements in various countries as well as at the European level. Variations by a factor of 10 of the ventilation rate requirement can be found in the proposal for European standard

Peter Wouters; David Ducarme; Jan Demeester; Luk Vandaele

1998-01-01

312

Solar chimney for promoting cooling ventilation in southern Algeria  

Microsoft Academic Search

In hot climates ventilation can be a useful means of cooling dwellings, if the outside air is cooler than that inside the dwelling. Often, in hot regions the outside air is so hot during the day that cooling by ventilation is of no benefit until the evening when the outside air cools. Ventilation can then be beneficial, and can be

A. Bouchair

1994-01-01

313

Ventilation planning at Energy West's Deer Creek mine  

SciTech Connect

In 2004 ventilation planning was initiated to exploit a remote area of Deer Creek mine's reserve (near Huntington, Utah), the Mill Fork Area, located under a mountain. A push-pull ventilation system was selected. This article details the design process of the ventilation system upgrade, the procurement process for the new fans, and the new fan startup testing. 5 figs., 1 photo.

Tonc, L.; Prosser, B.; Gamble, G. [Pacific Corp., Huntington, UT (United States)

2009-08-15

314

Treatment of chronic respiratory failure in kyphoscoliosis: oxygen or ventilation?  

Microsoft Academic Search

Treatment of chronic respiratory failure in kyphoscoliosis: oxygen or ventilation? B. Buyse, W. Meersseman, M. Demedts. #ERS Journals Ltd 2003. ABSTRACT: Patients with kyphoscoliosis and chronic respiratory insufficiency are treated either with home oxygen therapy or ventilation. Kyphoscoliotic patients demon- strate impaired ventilatory mechanics, consequently ventilation seems to be the treatment of choice. Yet, no randomised controlled trials (CRT) exist

B. Buyse; W. Meersseman; M. Demedts

2003-01-01

315

Fuzzy ventilation control for zone temperature and relative humidity  

Microsoft Academic Search

Many non-domestic and domestic buildings, built recently around the world, use natural means to provide ventilation for indoor air quality and thermal comfort. The fuzzy ventilation control strategy aims to use the free cooling and dehumidification available due to differences in zone and ambient conditions. This can achieve by changing the proportion of fresh air entering the heating, ventilation and

Mohamed Mahmoud Gouda

2005-01-01

316

Cytokines and ventilator-induced acute lung injury  

Microsoft Academic Search

Mechanical ventilation is an indispensable therapy for patients who need respiratory support. However, im- proper ventilation can lead to acute lung injury, which contributes to the mortality and morbidity of patients with respiratory distress. Mechanical ventilator-induced production of pro-inflammatory mediators, such as cytokines and chemokines, has been suggested to play an important role in mediating acute inflammatory responses in the

Bing HAN; Mingyao LIU

2002-01-01

317

Enclosure Smoke Filling and Management with Mechanical Ventilation  

Microsoft Academic Search

Enclosure smoke filling and management are addressed from the standpoint of the volumetric flow rates commonly used for mechanical ventilation system design. In this context, fire-induced gasexpans ion istreated asa volumetric s ource term. A two-layer analysis developed previously for enclosure smoke filling without mechanical ventilation is extended to consider the impact of mechanical ventilation on smoke layer descent rates

Frederick W. Mowrer

2002-01-01

318

Enclosure Smoke Filling and Management with Mechanical Ventilation  

Microsoft Academic Search

Enclosure smoke filling and management are addressed from the standpoint of the volumetric flow rates commonly used for mechanical ventilation system design. In this context, fire-induced gas expansion is treated as a volumetric source term. A two-layer analysis developed previously for enclosure smoke filling without mechanical ventilation is extended to consider the impact of mechanical ventilation on smoke layer descent

Frederick W. Mowrer

2002-01-01

319

46 CFR 127.250 - Ventilation for enclosed spaces.  

Code of Federal Regulations, 2013 CFR

...ventilated. Means must be provided for closing each vent and ventilator. (b) Means must be provided for stopping each fan in...cargo spaces and for closing, in case of fire, each doorway, ventilator, and annular space around funnels and other openings...

2013-10-01

320

Catheter Tip for Intratracheal Ventilation and Intratracheal Pulmonary Ventilation (Continuation in Part of Serial No. 7-606 967).  

National Technical Information Service (NTIS)

A method and apparatus for intratracheal ventilation (ITV) and intratracheal pulmonary ventilation (ITPV) in which a catheter positioned in a patient's trachea at the carina supplies a constant supply of fresh oxygen containing gas to flush anatomical dea...

T. Kolobow

1991-01-01

321

Night ventilation for building cooling in summer  

Microsoft Academic Search

This paper presents a two-step analysis of night ventilation as a way of cooling office buildings and providing comfort in summer. Experimental data first allows us to discuss some factors which affect the performance of the technique, to show that significant comfort improvement may be obtained in “well-designed” rooms, and to investigate the energy removal from the building by defining

P Blondeau; M Spérandio; F Allard

1997-01-01

322

VENTILATING HORNETS DISPLAY DIFFERENTIAL BODY TEMPERATURE  

Microsoft Academic Search

abdomen bent downward at a 90? angle to the thorax, their antennae vibrating, and their wings beating rapidly for minutes at a time. Eventually these hornets leave their position, either to retreat into the nest or else to fly off to the field, and are replaced by new hornets that assume the ventilation task. Infra-red (IR) photography reveals that in

Jacob S. Ishay; Marian Plotkin; Natalya Ermakov; Alon Goren; David J. Bergman

2006-01-01

323

Interfaces and humidification for noninvasive mechanical ventilation.  

PubMed

During noninvasive ventilation (NIV) for acute respiratory failure, the patient's comfort may be less important than the efficacy of the treatment. However, mask fit and care are needed to prevent skin damage and air leaks that can dramatically reduce patient tolerance and the efficacy of NIV. Choice of interface is a major determinant of NIV success or failure. The number and types of NIV interface has increased and new types are in development. Oronasal mask is the most commonly used interface in acute respiratory failure, followed by nasal mask, helmet, and mouthpiece. There is no perfect NIV interface, and interface choice requires careful evaluation of the patient's characteristics, ventilation modes, and type of acute respiratory failure. Every effort should be made to minimize air leaks, maximize patient comfort, and optimize patient-ventilator interaction. Technological issues to consider when choosing the NIV interface include dead space (dynamic, apparatus, and physiologic), the site and type of exhalation port, and the functioning of the ventilator algorithm with different masks. Heating and humidification may be needed to prevent adverse effects from cool dry gas. Heated humidifier provides better CO(2) clearance and lower work of breathing than does heat-and-moisture exchanger, because heated humidifier adds less dead space. PMID:19111108

Nava, Stefano; Navalesi, Paolo; Gregoretti, Cesare

2009-01-01

324

Metrics for Air Conditioning & Refrigeration, Heating, Ventilating.  

ERIC Educational Resources Information Center

Designed to meet the job-related metric measurement needs of the air conditioning and refrigeration, heating and ventilating student, this instructional package is one of three for the construction occupations cluster, part of a set of 55 packages for metric instruction in different occupations. The package is intended for students who already…

Cooper, Gloria S., Ed.; Magisos, Joel H., Ed.

325

Modeling particle loss in ventilation ducts  

SciTech Connect

Empirical equations were developed and applied to predict losses of 0.01-100 {micro}m airborne particles making a single pass through 120 different ventilation duct runs typical of those found in mid-sized office buildings. For all duct runs, losses were negligible for submicron particles and nearly complete for particles larger than 50 {micro}m. The 50th percentile cut-point diameters were 15 {micro}m in supply runs and 25 {micro}m in return runs. Losses in supply duct runs were higher than in return duct runs, mostly because internal insulation was present in portions of supply duct runs, but absent from return duct runs. Single-pass equations for particle loss in duct runs were combined with models for predicting ventilation system filtration efficiency and particle deposition to indoor surfaces to evaluate the fates of particles of indoor and outdoor origin in an archetypal mechanically ventilated building. Results suggest that duct losses are a minor influence for determining indoor concentrations for most particle sizes. Losses in ducts were of a comparable magnitude to indoor surface losses for most particle sizes. For outdoor air drawn into an unfiltered ventilation system, most particles smaller than 1 {micro}m are exhausted from the building. Large particles deposit within the building, mostly in supply ducts or on indoor surfaces. When filters are present, most particles are either filtered or exhausted. The fates of particles generated indoors follow similar trends as outdoor particles drawn into the building.

Sippola, Mark R.; Nazaroff, William W.

2003-04-01

326

Teaching Alveolar Ventilation with Simple, Inexpensive Models  

ERIC Educational Resources Information Center

When teaching and learning about alveolar ventilation with our class of 300 first-year medical students, we use four simple, inexpensive "models." The models, which encourage research-oriented learning and help our students to understand complex ideas, are distributed to the students before class. The students anticipate something new every day,…

DiCarlo, Stephen E.

2008-01-01

327

Characteristics of coal mine ventilation air flows  

Microsoft Academic Search

Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and ?70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation

Shi Su; Hongwei Chen; Philip Teakle; Sheng Xue

2008-01-01

328

DIFFUSE CEILING VENTILATION FOR FRESH CLASSROOMS  

Microsoft Academic Search

In most Dutch classrooms draught results in insufficient ventilation and poor air quality during the heating season, adversely affecting the well being and performance of pupils. Also a considerable part of the year the risk of overheating is high due to the high internal heat load. New analyses show that over 85% of time the heat load and not minimum

P. Jacobs; B. Knoll

2009-01-01

329

30 CFR 75.333 - Ventilation controls.  

Code of Federal Regulations, 2011 CFR

...MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation...Using A Radiant Heat Energy Source.” This...Using A Radiant Heat Energy Source.” This publication...Using A Radiant Heat Energy Source.” This publication...part 51. (g) Before mining is discontinued...

2011-07-01

330

30 CFR 75.333 - Ventilation controls.  

Code of Federal Regulations, 2010 CFR

...MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Ventilation...Using A Radiant Heat Energy Source.” This...Using A Radiant Heat Energy Source.” This publication...Using A Radiant Heat Energy Source.” This publication...part 51. (g) Before mining is discontinued...

2010-07-01

331

Including Children Dependent on Ventilators in School.  

ERIC Educational Resources Information Center

Guidelines for including ventilator-dependent children in school are offered, based on experience with six such students at a New York State school. Guidelines stress adherence to the medical management plan, the school-family partnership, roles of the social worker and psychologist, orientation, transportation, classroom issues, and steps toward…

Levine, Jack M.

1996-01-01

332

Emergency airway management: common ventilation techniques.  

PubMed

Maintaining a patient's airway and facilitating breathing are the main priorities during any emergency situation in which breathing is compromised. The key to safe management of an airway is thorough assessment, primarily to ensure the airway is patent. In an emergency situation, a bag-valve-mask may be the most effective way to assist ventilation. If ventilation is required for prolonged periods in an emergency situation, then endotracheal intubation should be performed. This involves the placement of a cuffed, endotracheal tube in the trachea, through which ventilation is maintained. Each tracheal intubation event should be anticipated as a potentially difficult intubation. Longer term ventilatory support may be achieved by the use of mechanical ventilators, which are designed to assist the movement of gases (air) into and out of a patient's lungs, while minimising the work and effort of breathing. This article provides nurses with an overview of the techniques and equipment that is most often used within emergency and intensive care units to maintain the patency of a patient's airway and provide ventilatory support. PMID:23588011

Higginson, Ray; Parry, Andy

333

46 CFR 111.15-10 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...REQUIREMENTS Storage Batteries and Battery Chargers: Construction and...locker, and box for storage batteries must be arranged or ventilated...compartment and: (i) Have an explosion-proof motor for a Class...must be interlocked with the battery charger so that the...

2010-10-01

334

46 CFR 111.15-10 - Ventilation.  

Code of Federal Regulations, 2010 CFR

...REQUIREMENTS Storage Batteries and Battery Chargers: Construction and...locker, and box for storage batteries must be arranged or ventilated...compartment and: (i) Have an explosion-proof motor for a Class...must be interlocked with the battery charger so that the...

2009-10-01

335

Anxiety and Agitation in Mechanically Ventilated Patients  

PubMed Central

During an ethnography conducted in an intensive care unit (ICU), we found that anxiety and agitation occurred frequently, and were important considerations in the care of 30 patients weaning from prolonged mechanical ventilation. We conducted a secondary analysis to (a) describe characteristics of anxiety and agitation experienced by mechanically ventilated patients; (b) explore how clinicians recognize and interpret anxiety and agitation and (c) describe strategies and interventions used to manage anxiety and agitation with mechanically ventilated patients. We constructed the Anxiety-Agitation in Mechanical Ventilation Model to illustrate the multidimensional features of symptom recognition and management. Patients’ ability to interact with the environment served as a basis for identification and management of anxiety or agitation. Clinicians’ attributions about anxiety or agitation and “knowing the patient” contributed to their assessment of patient responses. Clinicians chose strategies to overcome either the stimulus or patient’s appraisal of risk of the stimulus. This article contributes to the body of knowledge about symptom recognition and management in the ICU by providing a comprehensive model to guide future research and practice.

Tate, Judith Ann; Dabbs, Annette Devito; Hoffman, Leslie; Milbrandt, Eric; Happ, Mary Beth

2013-01-01

336

Does Mixing Make Residential Ventilation More Effective?  

SciTech Connect

Ventilation dilutes or removes indoor contaminants to reduce occupant exposure. In a multi-zone environment such as a house, there will be different dilution rates and different source strengths in every zone. The total ventilation rate is the most important factor in determining the exposure of occupants to given sources, but the zone- specific distribution of exhaust and supply air, and the mixing of ventilation air can have significant roles. Different types of ventilation systems will provide different amounts of mixing depending on several factors such as air leakage through the building envelope, air distribution systems and the location of sources and occupants. This paper reports recent results of investigations to determine the impact that air mixing has on exposures of residential occupants to prototypical contaminants of concern. Evaluations of existing field measurements and simulations reported in the literature are combined with new analyses to provide an integrated overview of the topic. The results show that for extreme cases additional mixing can be a significant factor but for typical homes looking at average exposures mixing is not helpful and can even make exposures worse.

Sherman, Max; Walker, Iain

2010-08-16

337

Impact of the ventilator bundle on ventilator-associated pneumonia in intensive care unit  

PubMed Central

Objectives The ventilator bundle is being promoted to prevent adverse events in ventilated patients including ventilator-associated pneumonia (VAP). We aimed to: (i) examine adoption of the ventilator bundle elements; (ii) determine effectiveness of individual elements and setting characteristics in reducing VAP; (iii) determine effectiveness of two infection-specific elements on reducing VAP; and, (iv) assess crossover effects of complying with VAP elements on central line-associated bloodstream infections. Design Cross-sectional survey. Setting Four hundred and fifteen ICUs from 250 US hospitals. Participants Managers/directors of infection prevention and control departments. Interventions Adoption and compliance with ventilator bundle elements. Main Outcome Measures VAP rates. Results The mean VAP rate was 2.7/1000 ventilator days. Two-thirds (n = 284) reported presence of the full ventilator bundle policy. However, only 66% (n = 188/284) monitored implementation; of those, 39% (n = 73/188) reported high compliance. Only when an intensive care unit (ICU) had a policy, monitored compliance and achieved high compliance were VAP rates lower. Compliance with individual elements or just one of two infection-related element had no impact on VAP (? = ?0.79, P= 0.15). There was an association between complying with two infection elements and lower rates (? = ?1.81, P< 0.01). There were no crossover effects. Presence of a full-time hospital epidemiologist (HE) was significantly associated with lower VAP rates (? = ?3.62, P< 0.01). Conclusions The ventilator bundle was frequently present but not well implemented. Individual elements did not appear effective; strict compliance with infection elements was needed. Efforts to prevent VAP may be successful in settings of high levels of compliance with all infection-specific elements and in settings with full-time HEs.

Pogorzelska, Monika; Stone, Patricia W.; Furuya, E. Yoko; Perencevich, Eli N.; Larson, Elaine L.; Goldmann, Donald; Dick, Andrew

2011-01-01

338

An Economic Evaluation of Prolonged Mechanical Ventilation  

PubMed Central

Objective Patients who receive prolonged mechanical ventilation (PMV) have high resource utilization and relatively poor outcomes, especially the elderly, and are increasing in number. The economic implications of PMV provision however are uncertain and would be helpful to providers and policymakers. Therefore, we aimed to determine the lifetime societal value of PMV. Design and Patients Adopting the perspective of a healthcare payor, we developed a Markov model to determine the cost-effectiveness of providing mechanical ventilation for at least 21 days to a 65 year-old critically ill base-case patient compared to the provision of comfort care resulting in withdrawal of ventilation. Input data were derived from the medical literature, Medicare, and a recent large cohort study of ventilated patients. Measurements and Main Results We determined lifetime costs and survival, quality-adjusted life expectancy, and cost-effectiveness as reflected by costs per quality-adjusted life year gained ($ per QALY). Providing PMV to the base-case patient cost $55,460 per life-year gained and $82,411 per QALY gained compared to withdrawal of ventilation. Cost-effectiveness ratios were most sensitive to variation in age, hospital costs, and probability of readmission, though less sensitive to post-acute care facility costs. Specifically, incremental costs per QALY gained by PMV provision exceeded $100,000 with age ?68 and when predicted one-year mortality was >50%. Conclusions The cost-effectiveness of PMV provision varies dramatically based on age and likelihood of poor short- and long-term outcomes. Identifying patients likely to have unfavorable outcomes, lowering intensity of care for appropriate patients, and reducing costly readmissions should be future priorities in improving the value of PMV.

Cox, Christopher E.; Carson, Shannon S.; Govert, Joseph A.; Chelluri, Lakshmipathi; Sanders, Gillian D.

2009-01-01

339

Differences in Blood Pressure Control in a Large Population-Based Sample of Older African Americans and Non-Hispanic Whites  

PubMed Central

Background. Cardiovascular disease is the main cause of death in older adults. Uncontrolled blood pressure is an important risk factor for cardiovascular disease. African Americans have poorer blood pressure control than non-Hispanic whites. Little is known about whether this difference persists in older ages or the factors that contribute to this racial gap. Methods. Data were obtained from participants of the Chicago Health and Aging Program. Blood pressure control was defined according to JNC-7 criteria. Univariate chi-square analyses were used to determine racial differences in hypertension and blood pressure control, whereas sequential multivariate logistic regression models were used to determine the effect of race on blood pressure control. Results. African Americans had a higher prevalence of hypertension (74% vs 63%; p < .001), higher awareness of hypertension (81% vs 72%; p < .001), and poorer blood pressure control (45% vs 51%, p < .001) than non-Hispanic whites. Racial differences in blood pressure control persisted after adjustment for socioeconomic status, medical conditions, obesity, and use of antihypertensive medications (odds ratio = 0.84, 95% confidence interval = 0.70–0.94). From 1993 to 2008, blood pressure control improved more among non-Hispanic whites than among African Americans. Conclusions. Racial differences in blood pressure control in older adults were not explained by socioeconomic status. The racial disparity in the prevalence and control of hypertension remained consistent for older hypertensive individuals eligible for Medicare. Although the rates of hypertension control improved for both racial groups, the improvement was greater among whites, thus widening the gap in this older population at high risk for cardiovascular disease.

Jacobs, Elizabeth A.; Lackland, Daniel T.; Evans, Denis A.; de Leon, Carlos F. Mendes

2012-01-01

340

A novel osmotic pressure control fed-batch fermentation strategy for improvement of erythritol production by Yarrowia lipolytica from glycerol.  

PubMed

The effect of osmotic pressure on erythritol and mannitol production by an osmophilic yeast strain of Yarrowia lipolytica CICC 1675 using glycerol as the sole carbon source was investigated. Appropriately high osmotic pressure was found to enhance erythritol production and inhibit mannitol formation. A novel two-stage osmotic pressure control fed-batch strategy based on the kinetic analysis was developed for higher erythritol yield and productivity. During the first 96 h, the osmotic pressure was maintained at 4.25 osmol/kg by feeding glycerol to reduce the inhibition of cell growth. After 132 h, the osmotic pressure was controlled at 4.94 osmol/kg to maintain a high dp(ery)/dt. Maximum erythritol yield of 194.3g/L was obtained with 0.95 g/L/h productivity, which were 25.7% and 2.2%, respectively, improvement over the best results in one-stage fed-batch fermentation. This is the first report that a novel osmotic pressure control fed-batch strategy significantly enhanced erythritol production. PMID:24215768

Yang, Li-Bo; Zhan, Xiao-Bei; Zheng, Zhi-Yong; Wu, Jian-Rong; Gao, Min-Jie; Lin, Chi-Chung

2014-01-01

341

SY Tank Farm ventilation isolation option risk assessment report  

SciTech Connect

The safety of the 241-SY Tank Farm ventilation system has been under extensive scrutiny due to safety concerns associated with tank 101-SY. Hydrogen and other gases are generated and trapped in the waste below the liquid surface. Periodically, these gases are released into the dome space and vented through the exhaust system. This attention to the ventilation system has resulted in the development of several alternative ventilation system designs. The ventilation system provides the primary means of mitigation of accidents associated with flammable gases. This report provides an assessment of various alternatives ventilation system designs.

Powers, T.B.; Morales, S.D.

1994-03-01

342

Emerging modes of ventilation in the intensive care unit.  

PubMed

Potentially harmful effects of positive pressure mechanical ventilation have been recognized since its inception in the 1950s. Since then, the risk factors for and mechanisms of ventilator-induced lung injury (VILI) have been further characterized. Publication of the ARDSnet tidal volume trial in 2000 demonstrated that a ventilator strategy limiting tidal volumes and plateau pressure in patients with acute respiratory distress syndrome was associated with a 22% reduction in mortality. Since then, a variety of ventilator modes have emerged seeking to improve gas exchange, reduce injurious effects of ventilation, and improve weaning from the ventilator. We review here emerging ventilator modes in the intensive care unit (ICU). Airway pressure release ventilation seeks to optimize alveolar recruitment and maintain spontaneous ventilatory effort. It is associated with improved indices of respiratory and cardiovascular physiology, but data to support outcome benefit are lacking. High-frequency oscillatory ventilation is associated with improvements in gas exchange, but outcome data are conflicting. Extracorporeal modes of ventilation continue to evolve, and extra-corporeal CO(2) removal is a technique that could be used in non-specialist ICUs. Proportional-assist ventilation and neutrally adjusted ventilator assist are modes that vary level of assistance with patient ventilatory effort. They result in greater patient-ventilator synchrony, but at present there is no evidence of a reduction in the duration of mechanical ventilation or outcome benefit. Although the use of many of these modes is likely to increase in intensive care units, further evidence of a beneficial effect is desirable before they are recommended. PMID:21613281

Stewart, N I; Jagelman, T A J; Webster, N R

2011-07-01

343

Giant left atrium needed negative pressure ventilation.  

PubMed

Giant left atrium (GLA) is seen in a variety of cardiac conditions. The GLA is diagnosed by combining the patient's history, physical examination, and imaging techniques, along with a computed tomographic chest scan, echocardiogram, and barium swallow test. We recently operated on a severely symptomatic 71-year-old woman with GLA (135 mm x 192 mm). We were forced to anesthetize her with negative pressure ventilation before connecting to the cardiopulmonary bypass circuit. Her postoperative course and long-term follow-up were uneventful. The procedure for GLA reduction is safe, even in very high-risk patients. Negative pressure ventilation may be used successfully as a bridge to cardiopulmonary bypass in certain cases. PMID:20103251

Kachel, Erez; Schaff, Hartzell V; Moussa, Fuad; Preisman, Sergey; Ranani, Ehud; Sternik, Leonid

2010-01-01

344

Sizing the lung of mechanically ventilated patients  

Microsoft Academic Search

Introduction  This small observational study was motivated by our belief that scaling the tidal volume in mechanically ventilated patients\\u000a to the size of the injured lung is safer and more 'physiologic' than scaling it to predicted body weight, i.e. its size before\\u000a it was injured. We defined Total Lung Capacity (TLC) as the thoracic gas volume at an airway pressure of

Jennifer S Mattingley; Steven R Holets; Richard A Oeckler; Randolph W Stroetz; Curtis F Buck; Rolf D Hubmayr

2011-01-01

345

[Anesthesia in spontaneous ventilation for difficult intubation].  

PubMed

Difficult intubation in children is rare and often predictable during anesthesia consultation. This allows to establish a strategy to provide fiberoptic guided tracheal intubation with spontaneous ventilation in function of age and children pathology. A good knowledge of physiologic and anatomic children particularities, of fiberoptic technique and the respect for some principles lead to ensure the security of this procedure. First principle is to use only one anesthetic inhaled or intravenous agent in order to limit an important decrease of ventilation. The anesthetic technique recommended for pediatric fiberoptic guided intubation is inhaled anesthesia with sevoflurane. But it is possible to use an intravenous agent, like propofol, with a continuous infusion (bolus of 0.1 to 0.3 mg/kg then 0.1-0.3mg/kg per hour for maintenance) or with target controlled infusion (Schnider model, initial concentration 2.5 ?g/mL, then increase by 0.5 ?g/mL steps) particularly in children older than 5 years with an anesthetic depth control. Whatever the agent, the dose must to be titrated to maintain spontaneous ventilation. Second principle is to combine an airway local anesthesia with general anesthesia to limit airway reactivity. First, a nose topical anesthesia is administered with lidocaine plus naphazoline in children older than 2 years. Then, a laryngeal topical anesthesia is realized with lidocaine 1% (1-2 mL, 2mg/kg) through operating channel of fiberoptic bronchoscope. Finally, third principle is to ensure patient oxygenation with several techniques like use of endoscopic facial mask or nasopharyngeal tube. The use of laryngeal mask is a rescue technique in case of spontaneous ventilation lost. In conclusion, each institution has to establish an algorithm with his own knowledge, constantly feasible and regularly taught. PMID:24209989

Salvi, N; Orliaguet, G

2013-12-01

346

Reaerosolization of Fluidized Spores in Ventilation Systems  

Microsoft Academic Search

This project examined dry, fluidized spore reaerosolization in a heating, ventilating, and air conditioning duct system. Experiments using spores of Bacillus atrophaeus, a nonpathogenic surrogate for Bacillus anthracis, were conducted to delineate the extent of spore reaerosolization behavior under normal indoor airflow conditions. Short-term (five air-volume exchanges), long-term (up to 21,000 air-volume exchanges), and cycled (on-off) reaerosolization tests were conducted

Paula Krauter; Arthur Biermann

2007-01-01

347

Ventilation during total intravenous anaesthesia with ketamine  

Microsoft Academic Search

Total intravenous anaesthesia with ketamine (TIVAK) is widely used throughout the world especially in precarious conditions.\\u000a Although ketamine is usually considered to provide good respiratory function and may be used with spontaneous ventilation,\\u000a recent studies have shown that desaturations may occur. Seventy-six adults and 64 children scheduled for peripheral surgery\\u000a were randomly allocated to breathe spontaneously room air or 40%

Luc-Marie Joly; Dan Benhamou

1994-01-01

348

Climatic inferences from the ventilated thermocline  

Microsoft Academic Search

Several computed cases of a model of the subtropical gyre with a partially ventilated thermocline (Luytenet al., 1982) are presented to illustrate the sensitivity of the field of density stratification, mean flow and location of unventilated\\u000a regions to slight changes in surface boundary conditions. The structure of the low latitude thermocline is less sensitive\\u000a to climatic change in amount of

J. Luyten; J. Pedlosky; H. Stommel

1983-01-01

349

Noninvasive ventilation for acute respiratory failure.  

PubMed

Noninvasive ventilation (NIV) for acute respiratory failure has gained much academic and clinical interest. Despite this, NIV is underutilized. The evidence strongly supports its use in patients presenting with an exacerbation of COPD and in patients with acute cardiogenic pulmonary edema. As reviewed in this paper, there is now evidence supporting or not supporting the use of NIV in various other presentations of acute respiratory failure. It is important not only to know when to initiate NIV, but also when this therapy is failing. Whether NIV in the setting of acute respiratory failure can be managed appropriately outside the ICU setting is controversial. Although a variety of interfaces are available, the oronasal mask is the best initial interface in terms of leak prevention and patient comfort. Some critical care ventilators have NIV modes that compensate well for leaks, but as a group the ventilators that are designed specifically for NIV have better leak compensation. NIV should be part of the armamentarium of all clinicians caring from patients with acute respiratory failure. PMID:23709194

Hess, Dean R

2013-06-01

350

The physiologic effects of noninvasive ventilation.  

PubMed

The physiologic effects of noninvasive ventilation (NIV) on work of breathing (WOB) and breathing pattern, respiratory-system mechanics, and hemodynamic function were examined via a literature review of clinical studies done between 1990 and 2008. Forty-one relevant studies were found; the majority examined patients with chronic obstructive pulmonary disease, whereas some also included patients with restrictive chest-wall disease or acute hypoxic respiratory failure. NIV reduced WOB in direct proportion to the level of inspiratory pressure-assist, and also by the ability of applied positive end-expiratory pressure (PEEP) to counter intrinsic PEEP. In general an inspiratory pressure-support level of 15 cm H(2)O and a PEEP of 5 cm H(2)O reduced most measures of WOB and inspiratory effort toward normal. When set to the same level of inspiratory pressure-assist, both pressure-support ventilation and proportional-assist ventilation effected comparable reductions in WOB. At high levels of inspiratory pressure-assist, NIV consistently increased dynamic lung compliance and tidal volume, and improved arterial blood gases. The hemodynamic effects of NIV are dependent upon the interplay between the type of mask, the level of inspiratory pressure-assist and PEEP, and the disease state. In general, patients with chronic obstructive pulmonary disease have a higher tendency toward decreased cardiac output at high levels of inspiratory pressure-assist, compared to those with acute lung injury. PMID:19111110

Kallet, Richard H; Diaz, Janet V

2009-01-01

351

Why we ventilate our houses - An historical look  

SciTech Connect

The knowledge of how to ventilate buildings, and how much ventilation is necessary for human health and comfort, has evolved over centuries of trial and error. Humans and animals have developed successful solutions to the problems of regulating temperature and removing air pollutants through the use of ventilation. These solutions include ingenious construction methods, such as engineered passive ventilation (termite mounds and passive stacks), mechanical means (wing-powered, fans), and an evolving effort to identify problems and develop solutions. Ventilation can do more than help prevent building occupants from getting sick; it can provide an improved indoor environment. Codes and standards provide minimum legal requirements for ventilation, but the need for ventilation goes beyond code minima. In this paper we will look at indoor air pollutant sources over time, the evolution of ventilation strategies, current residential ventilation codes and standards (e.g., recently approved ASHRAE Standard 62.2), and briefly discuss ways in which we can go beyond the standards to optimize residential ventilation, reduce indoor air quality problems, and provide corresponding social and economic benefit.

Matson, Nance E.; Sherman, Max H.

2004-05-14

352

Ventilator-induced lung injury in preterm infants  

PubMed Central

In preterm infants, the need for intubation and mechanical ventilation is associated with ventilator-induced lung injuries and subsequent bronchopulmonary dysplasia. The aim of the present review was to improve the understanding of the mechanisms of injury that involve cytokine-mediated inflammation to contribute to the development of new preventive strategies. Relevant articles were retrieved from the PubMed database using the search terms "ventilator-induced lung injury preterm", "continuous positive airway pressure", "preterm", and "bronchopulmonary dysplasia". The resulting data and other relevant information were divided into several topics to ensure a thorough, critical view of ventilation-induced lung injury and its consequences in preterm infants. The role of pro-inflammatory cytokines (particularly interleukins 6 and 8 and tumor necrosis factor alpha) as mediators of lung injury was assessed. Evidence from studies conducted with animals and human newborns is described. This evidence shows that brief periods of mechanical ventilation is sufficient to induce the release of pro-inflammatory cytokines. Other forms of mechanical and non-invasive ventilation were also analyzed as protective alternatives to conventional mechanical ventilation. It was concluded that non-invasive ventilation, intubation followed by early surfactant administration and quick extubation for nasal continuous positive airway pressure, and strategies that regulate tidal volume and avoid volutrauma (such as volume guarantee ventilation) protect against ventilator-induced lung injury in preterm infants.

Carvalho, Clarissa Gutierrez; Silveira, Rita C; Procianoy, Renato Soibelmann

2013-01-01

353

Tidal volume variability during airway pressure release ventilation: case summary and theoretical analysis.  

PubMed

Airway pressure-release ventilation (APRV) is used in the management of patients with severe or refractory respiratory failure. In addition to reversal of inspiratory-expiratory ratios, this pressure control mode also allows unrestricted spontaneous breathing. The spontaneous tidal volume (V(T)), as well as the V(T) resulting from transition between the high and low airway pressures, is uncontrolled. There are limited data on the within-patient variation of actual V(T) and the safety of these modes. The authors present a patient with severe ARDS who was managed with biphasic modes (APRV and bi-level positive airway pressure). Serial V(T) measurements showed that V(T) ranged from 4 to 12 mL/kg predicted body weight. Computed tomography scan images and chest radiographs obtained before and following APRV showed lung parenchyma changes that may be related to ventilator-induced lung injury. We also present a mathematical model that is useful for simulating APRV and demonstrating the issues related to volume delivery for mandatory breaths during the transition between the 2 pressure levels. A key finding of this analysis is the interdependence of release volume, autoPEEP, and the T(low) time setting. Furthermore, it is virtually impossible to target a specific P(aCO(2)) with a desired level V(T) and autoPEEP in a passive model, emphasizing the importance of spontaneous breathing with this mode. This case report suggests caution when using these modes, and that end-inspiratory lung volumes and V(T) should be limited to avoid lung injury. The important point of this case study and model analysis is that the application of APRV is more complex than it appears to be. It requires a lot more knowledge and skill than may be apparent from descriptions in the literature. PMID:22348242

Sasidhar, Madhu; Chatburn, Robert L

2012-08-01

354

Patient–ventilator asynchrony during non-invasive ventilation for acute respiratory failure: a multicenter study  

Microsoft Academic Search

Objective\\u000a   To determine the prevalence of patient–ventilator asynchrony in patients receiving non-invasive ventilation (NIV) for acute\\u000a respiratory failure.\\u000a \\u000a \\u000a \\u000a \\u000a Design\\u000a   Prospective multicenter observation study.\\u000a \\u000a \\u000a \\u000a \\u000a Setting\\u000a   Intensive care units in three university hospitals.\\u000a \\u000a \\u000a \\u000a Methods  Patients consecutively admitted to ICU were included. NIV, performed with an ICU ventilator, was set by the clinician. Airway\\u000a pressure, flow, and surface diaphragmatic electromyography were recorded continuously for

Laurence Vignaux; Frédéric Vargas; Jean Roeseler; Didier Tassaux; Arnaud W. Thille; Michel P. Kossowsky; Laurent Brochard; Philippe Jolliet

2009-01-01

355

[Acute obstruction of an anesthetic gas evacuation system. Ventilation with a Servo Ventilator 900D].  

PubMed

During aorto-coronary bypass surgery acute expiratory airway obstruction occurred in two patients during controlled ventilation with a Servo D ventilator (Siemens Elema) in combination with a Servo EVAC 180 gas evacuation system. In this system expiratory volume passes from the ventilator to the reservoir bag. Distension of the bag will open the valve to the receiving unit by vertical dislocation of the valve spring. The mechanism relies on free mobility of the valve spring within the reservoir bag. We observed an increase in mean expiratory and inspiratory airway pressure above 40 mmHg due to blockage of the expiratory gas outlet by external lateral dislocation of the valve spring. In conclusion, while free mobility of the valve spring within the hanging Evac bag has to be ascertained at all times for safe application of the EVAC 180 system, the manufacturer should provide some appropriate mechanical shelter around the bag. PMID:8363032

Ellmauer, S; Rindfleisch, F; Landauer, B

1993-07-01

356

A pilot prospective study on closed loop controlled ventilation and oxygenation in ventilated children during the weaning phase  

PubMed Central

Introduction The present study is a pilot prospective safety evaluation of a new closed loop computerised protocol on ventilation and oxygenation in stable, spontaneously breathing children weighing more than 7 kg, during the weaning phase of mechanical ventilation. Methods Mechanically ventilated children ready to start the weaning process were ventilated for five periods of 60 minutes in the following order: pressure support ventilation, adaptive support ventilation (ASV), ASV plus a ventilation controller (ASV-CO2), ASV-CO2 plus an oxygenation controller (ASV-CO2-O2) and pressure support ventilation again. Based on breath-by-breath analysis, the percentage of time with normal ventilation as defined by a respiratory rate between 10 and 40 breaths/minute, tidal volume > 5 ml/kg predicted body weight and end-tidal CO2 between 25 and 55 mmHg was determined. The number of manipulations and changes on the ventilator were also recorded. Results Fifteen children, median aged 45 months, were investigated. No adverse event and no premature protocol termination were reported. ASV-CO2 and ASV-CO2-O2 kept the patients within normal ventilation for, respectively, 94% (91 to 96%) and 94% (87 to 96%) of the time. The tidal volume, respiratory rate, peak inspiratory airway pressure and minute ventilation were equivalent for all modalities, although there were more automatic setting changes in ASV-CO2 and ASV-CO2-O2. Positive end-expiratory pressure modifications by ASV-CO2-O2 require further investigation. Conclusion Over the short study period and in this specific population, ASV-CO2 and ASV-CO2-O2 were safe and kept the patient under normal ventilation most of the time. Further research is needed, especially for positive end-expiratory pressure modifications by ASV-CO2-O2. Trial registration ClinicalTrials.gov: NCT01095406

2012-01-01

357

Computational fluid dynamics in ventilation. 4: Commercial application of CFD in ventilation  

NASA Astrophysics Data System (ADS)

In considering the commercial applications of Computational Fluid Dynamics (CFD) in ventilation, the following are addressed: typical markets (airport centers, large theaters, atria, shopping malls, etc.); typical problems to be solved (energy flow, draft, ventilation effectiveness, pressure distribution, etc.); and high priority areas, activities and quantities (fast preprocessing, effective visualization software, etc.). It is stated that the commercial application of CFD may be looked upon as an advanced 'zonal' model. The 'zonal' model concept is outlined and CFD with large control volumes is considered. An illustrated example of air flow simulation in a theater is given.

Nielsen, Peter V.

358

Control of airborne infectious diseases in ventilated spaces.  

PubMed

We protect ourselves from airborne cross-infection in the indoor environment by supplying fresh air to a room by natural or mechanical ventilation. The air is distributed in the room according to different principles: mixing ventilation, displacement ventilation, etc. A large amount of air is supplied to the room to ensure a dilution of airborne infection. Analyses of the flow in the room show that there are a number of parameters that play an important role in minimizing airborne cross-infection. The air flow rate to the room must be high, and the air distribution pattern can be designed to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection, and in some cases, it can also reduce the source of infection. Personalized ventilation can especially be used in hospital wards, aircraft cabins and, in general, where people are in fixed positions. PMID:19740921

Nielsen, Peter V

2009-12-01

359

Control of airborne infectious diseases in ventilated spaces  

PubMed Central

We protect ourselves from airborne cross-infection in the indoor environment by supplying fresh air to a room by natural or mechanical ventilation. The air is distributed in the room according to different principles: mixing ventilation, displacement ventilation, etc. A large amount of air is supplied to the room to ensure a dilution of airborne infection. Analyses of the flow in the room show that there are a number of parameters that play an important role in minimizing airborne cross-infection. The air flow rate to the room must be high, and the air distribution pattern can be designed to have high ventilation effectiveness. Furthermore, personalized ventilation may reduce the risk of cross-infection, and in some cases, it can also reduce the source of infection. Personalized ventilation can especially be used in hospital wards, aircraft cabins and, in general, where people are in fixed positions.

Nielsen, Peter V.

2009-01-01

360

Design and Selection of a Camelid Single-Chain Antibody Yeast Two-Hybrid Library Produced De Novo for the Cap Protein of Porcine Circovirus Type 2 (PCV2)  

PubMed Central

Nanobodies (or variable domain of the heavy chain of the heavy-chain antibodies, VHHs) are single-domain antigen-binding fragments derived from camelid heavy chain antibodies. Their comparatively small size, monomeric behavior, high stability, high solubility, and ability to bind epitopes inaccessible to conventional antibodies make them especially suitable for many therapeutic and biotechnological applications. In this paper, for the first time, we created the immunized Camelus Bactrianus VHH yeast two-hybrid (Y2H) library according to the Clontech Mate & Plate library construction system. The transformation efficiency and titer of the VHH Y2H library were 7.26×106 cfu/3 µg and 2×109 cfu/ml, which met the demand for Y2H library screening. Using as an example the porcine circovirus type 2 (PCV2) Cap protein as bait, we screened 21 positive Cap-specific VHH sequences. Among these sequences, 7 of 9 randomly selected clones were strongly positive as indicated by enzyme-linked immunosorbent assay, either using PCV2 viral lysis or purified Cap protein as coated antigen. Additionally, the immunocytochemistry results further indicated that the screened VHHs could specifically detected PCV2 in the infected cells. All this suggests the feasibility of in vivo VHH throughput screening based on Y2H strategy.

Fu, Xiangjing; Gao, Xiaolong; He, Shengfang; Huang, Di; Zhang, Peng; Wang, Xinglong; Zhang, Shuxia; Dang, Ruyi; Yin, Shuanghui; Du, Enqi; Yang, Zengqi

2013-01-01

361

Use of PCR-based assays for the detection of the adventitious agent porcine circovirus type 1 (PCV1) in vaccines, and for confirming the identity of cell substrates and viruses used in vaccine production.  

PubMed

Safety and quality are important issues for vaccines. Whereas reversion to virulence poses a safety risk with live attenuated vaccines, the potential for the presence of adventitious agents is also an issue of vaccine quality. The recent detection or porcine circovirus type 1 (PCV1) in human vaccines has further highlighted the importance of quality control in vaccine production. The purpose of this study was to use a novel conventional PCR to detect PCV1, and subsequently screen materials used in the manufacture of vaccines at Bharat Biotech International Limited, India. The genome or gene fragments of PCV1 were not detected in any of the vaccines and materials tested, including the live attenuated rotavirus vaccine candidate ROTAVAC(®). Further, the identity of the cells and the viruses used as starting materials in the manufacture of these vaccines was confirmed by species-specific PCR or virus-specific RT-PCR, and no cross-contamination was detected in any case. The methods can be applied for regular in-house quality control screening of raw materials and seeds/banks, as well as formulated vaccines. PMID:22079617

Kumar, Deepak; Beach, Nathan M; Meng, Xiang-Jin; Hegde, Nagendra R

2012-01-01

362

TLR2 Deficiency Aggravates Lung Injury Caused by Mechanical Ventilation.  

PubMed

Innate immunity pathways are found to play an important role in ventilator-induced lung injury. We analyzed pulmonary expression of Toll-like receptor 2 (TLR2) in humans and mice and determined the role of TLR2 in the pathogenesis of ventilator-induced lung injury in mice. Toll-like receptor 2 gene expression was analyzed in human bronchoalveolar lavage fluid (BALF) cells and murine lung tissue after 5 h of ventilation. In addition, wild-type (WT) and TLR2 knockout (KO) mice were ventilated with either lower tidal volumes (VT) of 7 mL/kg with positive end-expiratory pressure (PEEP) or higher VT of 15 mL/kg without PEEP for 5 h. Spontaneously breathing mice served as controls. Total protein and immunoglobulin M levels in BALF, neutrophil influx into the alveolar compartment, and interleukin 6 (IL-6), IL-1?, and keratinocyte-derived chemokine concentrations in lung tissue homogenates were measured. We observed enhanced TLR2 gene expression in BALF cells of ventilated patients and in lung tissue of ventilated mice. In WT mice, ventilation with higher VT without PEEP resulted in lung injury and inflammation with higher immunoglobulin M levels, neutrophil influx, and levels of inflammatory mediators compared with controls. In TLR2 KO mice, neutrophil influx and IL-6, IL-1?, and keratinocyte-derived chemokine were enhanced by this ventilation strategy. Ventilation with lower VT with PEEP only increased neutrophil influx and was similar in WT and TLR2 KO mice. In summary, injurious ventilation enhances TLR2 expression in lungs. Toll-like receptor 2 deficiency does not protect lungs from ventilator-induced lung injury. In contrast, ventilation with higher VT without PEEP aggravates inflammation in TLR2 KO mice. PMID:24667617

Kuipers, Maria Theresa; Jongsma, Geartsje; Hegeman, Maria A; Tuip-de Boer, Anita M; Wolthuis, Esther K; Choi, Goda; Bresser, Paul; van der Poll, Tom; Schultz, Marcus J; Wieland, Catharina W

2014-07-01

363

Single-shell tank ventilation upgrades needs analysis report  

SciTech Connect

This report was written to comply with the objectives of the Hanford Federal Facility Agreement and Consent Order, Tri-Party Agreement Milestone M-43-03 Provide to the Washington State Department of Ecology and Department of Health the Results of the Single-Shell Tank Ventilation Upgrades Needs Analysis. The needs analysis consists of identifying the current type and status of each single-shell tank ventilation system, identifying current and projected authorization basis requirements, and identifying ventilation system compliance deficiencies.

Kriskovich, J.R., Fluor Daniel Hanford

1997-02-03

364

Tracheobronchial dilating effect of high frequency jet ventilation  

Microsoft Academic Search

Effect of high frequency jet ventilation (HFJV) on tracheobronchial tone was examined in anesthetized dogs. Changes in intraluminal\\u000a pressure of water-filled endotracheal cuff (Pcuff) were used as an indicator of tracheal smooth muscle tone. Animals were\\u000a initially ventilated with conventional mechanical ventilation (CMV) to maintain normal$$Pa_{CO_2 } $$. HFJV (2.0 Hz.) was then applied to each animal in such a

Hidenori Toyooka; Keisuke Amaha; Kuninori Yokoyama

1990-01-01

365

12th US/North American mine ventilation symposium  

SciTech Connect

Topics covered include: ventilation planning for metal/non-metal and coal mines, spontaneous combustion, heat and humidity, miner's act and mine seals, numerical modeling, coal mine methane, mine dust, tunnel ventilation, mine fans, diesel emissions control, mine fires, and general ventilation design and monitoring. The papers, talks and presentations are available for free download from the www.smenet.org site; printed copies of the proceedings are no longer available.

Wallace, K.G. (ed.)

2008-07-01

366

Negative pressure ventilation in pediatric critical care setting  

Microsoft Academic Search

Invasive ventilation is associated with both pulmonary and non-pulmonary complications. There has been a renewed interest\\u000a in the use of negative pressure ventilation (NPV) for various medical conditions to minimise the complications associated\\u000a with positive pressure ventilation. The routine use of NPV in an ICU setting still requires further studies and research.\\u000a In this article, the authors review the clinical

Akash Deep; Claudine De Munter; Ajay Desai

2007-01-01

367

Ammonia emissions from two mechanically ventilated UK livestock buildings  

NASA Astrophysics Data System (ADS)

Ammonia emission rates from livestock buildings are required to construct an accurate emission inventory for the UK. Ventilation and ammonia emission rates from a fattening pig unit and a broiler house, both mechanically ventilated, were estimated using fan wheel anemometers and thermal converters with a chemiluminescence NO x-analyser to measure the ventilation rate and the ammonia concentration, respectively. The estimated ammonia emission factors were 46.9 and 16.6 kg lu -1 a -1 for the fattening pig unit and the broiler house, respectively. Both emission factors were within the range reported in the literature. A tracer gas (CO) method, based on a constant tracer release rate, was validated for measuring ventilation rates from naturally ventilated livestock buildings. Air inlets and outlets were identified using the air temperature or tracer concentration in the opening. Tracer concentration was found to be a more suitable criterion than temperature. In both houses, a significant correlation between the estimated ventilation rate using the tracer method and the measured ventilation rate using fan wheel anemometers was found. The ventilation rate was underestimated by 12 and 6% for the piggery and broiler house, respectively. The instantaneous ammonia emission derived from the tracer gas method was lower than the ammonia emission derived from the fan wheel anemometer method by 14 and 16% for the piggery and broiler house, respectively. The ventilation and ammonia emission estimates using the tracer method were within acceptable range from the ventilation and emission rates measured using measuring fans, but because of its accuracy and simplicity the fan wheel anemometer method is preferred for long-term measurements of ventilation rate in mechanically ventilated buildings.

Demmers, T. G. M.; Burgess, L. R.; Short, J. L.; Phillips, V. R.; Clark, J. A.; Wathes, C. M.

368

Recommended Ventilation Strategies for Energy-Efficient Production Homes  

SciTech Connect

This report evaluates residential ventilation systems for the U.S. Environmental Protection Agency's (EPA's) ENERGY STAR{reg_sign} Homes program and recommends mechanical ventilation strategies for new, low-infiltration, energy-efficient, single-family, ENERGY STAR production (site-built tract) homes in four climates: cold, mixed (cold and hot), hot humid, and hot arid. Our group in the Energy Analysis Department at Lawrence Berkeley National Lab compared residential ventilation strategies in four climates according to three criteria: total annualized costs (the sum of annualized capital cost and annual operating cost), predominant indoor pressure induced by the ventilation system, and distribution of ventilation air within the home. The mechanical ventilation systems modeled deliver 0.35 air changes per hour continuously, regardless of actual infiltration or occupant window-opening behavior. Based on the assumptions and analysis described in this report, we recommend independently ducted multi-port supply ventilation in all climates except cold because this strategy provides the safety and health benefits of positive indoor pressure as well as the ability to dehumidify and filter ventilation air. In cold climates, we recommend that multi-port supply ventilation be balanced by a single-port exhaust ventilation fan, and that builders offer balanced heat-recovery ventilation to buyers as an optional upgrade. For builders who continue to install forced-air integrated supply ventilation, we recommend ensuring ducts are airtight or in conditioned space, installing a control that automatically operates the forced-air fan 15-20 minutes during each hour that the fan does not operate for heating or cooling, and offering ICM forced-air fans to home buyers as an upgrade.

Roberson, J.; Brown, R.; Koomey, J.; Warner, J.; Greenberg, S.

1998-12-01

369

NATURAL VENTILATION PERFORRlANCE OF A GREENHOUSE TUNNEL IN SOUTH TUNISIA  

Microsoft Academic Search

After recalling the physical model basis of the natural ventilation, we examine the ventilation performance of a greenhouse tunnel equipped with either roof or door openings or both roof and door openings. Altogether four different ventilation configurations are analyzed. Neural networks of ventilation rate were first developed to select relevant parameters influencing the ventilation performances. It confirms that the surface

L. SBITA; T. BOULARD; M. MERMIER

370

Relationship of blood pressure self-monitoring, medication adherence, self-efficacy, stage of change, and blood pressure control among municipal workers with hypertension.  

PubMed

Uncontrolled blood pressure remains a major public health issue. Medication adherence is a key factor in blood pressure management; however, adherence behavior is not clearly understood and the most significant factors contributing to poor medication adherence and blood pressure control are unknown. The purpose of this study was to determine the relationship of self-monitoring of blood pressure, medication adherence, self-efficacy, stage of change, and blood pressure control among municipal workers with access to health insurance. Stage of change was a significant independent predictor of self-monitoring of blood pressure, but not blood pressure control. A strong relationship was found between medication adherence and medication adherence self-efficacy (r = .549, p < .05). PMID:22767462

Breaux-Shropshire, Tonya L; Brown, Kathleen C; Pryor, Erica R; Maples, Elizabeth H

2012-07-01

371

Relationship of Blood Pressure Self-Monitoring, Medication Adherence, Self-Efficacy, Stage of Change, and Blood Pressure Control Among Municipal Workers With Hypertension  

PubMed Central

Uncontrolled blood pressure remains a major public health issue. Medication adherence is a key factor in blood pressure management; however, adherence behavior is not clearly understood and the most significant factors contributing to poor medication adherence and blood pressure control are unknown. The purpose of this study was to determine the relationship of self-monitoring of blood pressure, medication adherence, self-efficacy, stage of change, and blood pressure control among municipal workers with access to health insurance. Stage of change was a significant independent predictor of self-monitoring of blood pressure, but not blood pressure control. A strong relationship was found between medication adherence and medication adherence self-efficacy (r = .549, p < .05).

Breaux-Shropshire, Tonya L; Brown, Kathleen C.; Pryor, Erica R.; Maples, Elizabeth H.

2013-01-01

372

Flammable gas cloud build up in a ventilated enclosure.  

PubMed

Ventilation is frequently used as a means for preventing the build up of flammable or toxic gases in enclosed spaces. The effectiveness of the ventilation often has to be considered as part of a safety case or risk assessment. In this paper methods for assessing ventilation effectiveness for hazardous area classification are examined. The analysis uses data produced from Computational Fluid Dynamics (CFD) simulations of low-pressure jet releases of flammable gas in a ventilated enclosure. The CFD model is validated against experimental measurements of gas releases in a ventilation-controlled test chamber. Good agreement is found between the model predictions and the experimental data. Analysis of the CFD results shows that the flammable gas cloud volume resulting from a leak is largely dependent on the mass release rate of flammable gas and the ventilation rate of the enclosure. The effectiveness of the ventilation for preventing the build up of flammable gas can therefore be assessed by considering the average gas concentration at the enclosure outlet(s). It is found that the ventilation rate of the enclosure provides a more useful measure of ventilation effectiveness than considering the enclosure air change rate. PMID:20855156

Ivings, M J; Gant, S E; Saunders, C J; Pocock, D J

2010-12-15

373

Airway pressure release ventilation in acute respiratory distress syndrome.  

PubMed

Airway pressure release ventilation (APRV) is an alternative mode of ventilation that is increasingly used in patients with acute respiratory failure, acute lung injury (ALI), and acute respiratory distress syndrome (ARDS). Animal and clinical studies have demonstrated that, compared with conventional ventilation, APRV has beneficial effects on lung recruitment, oxygenation, end-organ blood flow, pulmonary vasoconstriction, and sedation requirements. Further studies, however, are required to directly compare APRV to ARDSnet protocol ventilation, specifically in patients with ALI/ARDS, and to determine whether managing ALI/ARDS with APRV will also achieve mortality reduction. PMID:21742214

Maung, Adrian A; Kaplan, Lewis J

2011-07-01

374

Role of caveolin-1 expression in the pathogenesis of pulmonary edema in ventilator-induced lung injury  

PubMed Central

Caveolin-1 is a key regulator of pulmonary endothelial barrier function. Here, we tested the hypothesis that caveolin-1 expression is required for ventilator-induced lung injury (VILI). Caveolin-1 gene-disrupted (Cav-1-/-) and age-, sex-, and strain-matched wild-type (WT) control mice were ventilated using two protocols: volume-controlled with protective (8 mL/kg) versus injurious (21 mL/Kg) tidal volume for up to 6 hours; and pressure-controlled with protective (airway pressure = 12 cm H2O) versus injurious (30 cm H2O) ventilation to induce lung injury. Lung microvascular permeability (whole-lung 125I-albumin accumulation, lung capillary filtration coefficient [Kf, c]) and inflammatory markers (bronchoalveolar lavage [BAL] cytokine levels and neutrophil counts) were measured. We also evaluated histologic sections from lungs, and the time course of Src kinase activation and caveolin-1 phosphorylation. VILI induced a 1.7-fold increase in lung 125I-albumin accumulation, fourfold increase in Kf, c, significantly increased levels of cytokines CXCL1 and interleukin-6, and promoted BAL neutrophilia in WT mice. Lung injury by these criteria was significantly reduced in Cav-1-/- mice but fully restored by i.v. injection of liposome/Cav-1 cDNA complexes that rescued expression of Cav-1 in lung microvessels. As thrombin is known to play a significant role in mediating stretch-induced vascular injury, we observed in cultured mouse lung microvascular endothelial cells (MLECs) thrombin-induced albumin hyperpermeability and phosphorylation of p44/42 MAP kinase in WT but not in Cav-1-/- MLECs. Thus, caveolin-1 expression is required for mechanical stretch-induced lung inflammation and endothelial hyperpermeability in vitro and in vivo.

Maniatis, Nikolaos A.; Kardara, Matina; Hecimovich, Dan; Letsiou, Eleftheria; Castellon, Maricela; Roussos, Charalambos; Shinin, Vasily; Votta-Vellis, E. Gina; Schwartz, David E.; Minshall, Richard D.

2012-01-01

375

[Mechanical ventilation in chronic ventilatory insufficiency].  

PubMed

Mechanical ventilation has become an important treatment option in chronic ventilatory failure. There are different diseases which lead to ventilatory failure and to home mechanical ventilation (HMV). A primary loss of in- and expiratory muscle strength is the reason for respiratory deterioration in neuromuscular disease. In most of these diseases ventilatory failure develops because of the progressive character of muscular damage. Initially, ventilatory failure can be found during night-time. In the case of hypercapnia at daytime, life expectancy is strongly reduced, especially in amyotrophic lateral sclerosis and Duchenne muscular dystrophy. HMV leads to a prolongation of life and to an increase in quality of life, if bulbar involvement is not severe. Impressive clinical improvements under HMV have been found in restrictive disorders of the rib cage like kyphoscoliosis or posttuberculosis sequelae, with an increase of quality of life, walking distance and a decrease in pulmonary hypertension. Only few data are published about long-term results of HMV in Obesity Hypoventilation. In terms of retrospective analyses of clinical data HMV seems to improve survival in this population. Some patients only need CPAP treatment, but most patients have to be treated with ventilatory support. The application of HMV in patients with chronic ventilatory failure due to chronic obstructive pulmonary disease (COPD) is growing, but there are controversial results in randomised clinical trials. Analysis of these data suggest better results of HMV in patients with severe hypercapnia, with the application of higher effective ventilatory pressure and a ventilator mode with a significant reduction in the work of breathing. Under such conditions HMV leads to a reduction of hypercapnia, an improvement in sleep quality, walking distance and quality of life, but until now there is no evidence in reduction of mortality in COPD. PMID:17620231

Schucher, B; Magnussen, H

2007-10-01

376

Ventilator Gas Flow Rates Affect Inspiratory Time and Ventilator Efficiency Index in Term Lambs  

Microsoft Academic Search

Background: Despite increasing survival in the smallest preterm infants, the incidence of chronic lung disease has not decreased. Research into ventilatory strategies has concentrated on minimising barotrauma, volutrauma and atelectotrauma, but little attention has been paid to the role of bias gas flow rates and the potential for rheotrauma or shear stress injury. Ventilated preterm infants frequently receive relatively high

Katinka P. Bach; Carl A. Kuschel; Mark H. Oliver; Frank H. Bloomfield

2009-01-01

377

Liquid ventilation: an alternative ventilation strategy for management of neonatal respiratory distress.  

PubMed

Perfluorochemical (PFC) liquids have great potential for biomedical use and the support of respiration. Currently, there are several commercially available PFC fluids which meet the physiochemical property requirements as well as purity specifications necessary to perform many of the discussed biomedical applications. Moreover, state-of-the-art fluorine chemistry should enable production of new PFC liquids uniquely sculptured relative to the proposed specific application (ie. vehicle for pulmonary delivery of drugs, a diluent for pulmonary lavage, a medium for respiratory gas exchange). In addition to PFC fluid requirements, there have been several techniques reported for liquid assisted ventilation. These methods include total liquid ventilation, liquid lavage, and partial liquid ventilation. The efficacy of these various techniques is under extensive investigation with respect to specific types of lung dysfunction. Liquid ventilation (LV) techniques have the potential to treat lung disease with less risk of barotrauma and provide the means for direct and uniform delivery of pulmonary agents to injured or dysfunctional sites in the lung. For LV to assume a role in clinical medicine it must be shown to be safe and effective with respect to other therapies or in combination with current therapies. Although the use of LV in animal and initial clinical studies has been impressive to date, better documentation of efficacy in human disease will be required. Further controlled multi-center clinical trials are warranted and are currently in progress. PMID:8839744

Shaffer, T H; Wolfson, M R

1996-08-01

378

Continuous-flow apneic ventilation during thoracotomy.  

PubMed

Continuous-flow apneic ventilation (CFAV) by endobronchial insufflation of conditioned gas was evaluated in dogs during thoracotomy. In Group 1 (n = 6), dogs were anesthetized with pentobarbital (25 mg/kg). An endobronchial catheter (2.5 mm ID) was introduced into each mainstem bronchus using a fiberoptic bronchoscope and held in place by an endotracheal tube. Before the onset of CFAV (total flow 1.01 X kg-1 X min-1, the animals were paralyzed with pancuronium bromide and muscle relaxation was monitored with a peripheral nerve stimulator. The CFAV delivery system consisted of a flow meter, air/oxygen blender, oxygen analyzer, heated humidifier, and ultrasonic spirometer. Blood gas values were measured after 30 min of spontaneous ventilation, and CFAV with: 1) closed chest, fractional inspired O2 concentration (FIO2) 0.21; 2) open chest, FIO2 0.21; 3) open chest, FIO2 0.21, continuous positive airway pressure (CPAP) 5 mmHg; and 4) open chest FIO2 0.4, CPAP 5 mmHg. This last combination resulted in a mean PaO2 of 113.1 +/- 5.5 (SEM) mmHg and a PaCO2 of 35.0 +/- 2.1 (SEM) mmHg. In Group 2 (n = 6), animals with open chests were ventilated with CFAV (FIO2 0.4 and CPAP 5 mmHg) for 5 h. Adequate oxygenation and ventilation were achieved. PaCO2 after 5 h of CFAV was 41.8 +/- 1.9 (SEM) mmHg compared with 40.8 +/- 1.9 (SEM) mmHg during spontaneous breathing. PaO2 after 5 h of CFAV was 138.1 +/- 11.7 (SEM) mmHg. There were no significant changes observed in vascular pressures. Significant differences in other hemodynamic parameters were probably due to pentobarbital anesthesia. Adequate gas exchange can be achieved during CFAV in dogs with open chests for 5 h. PMID:3767038

Babinski, M F; Smith, R B; Bunegin, L

1986-10-01

379

Daily Ultrafiltration Results in Improved Blood Pressure Control and More Efficient Removal of Small Molecules during Hemodialysis  

PubMed Central

Background Although prior studies have shown that frequent hemodialysis (HD) can lead to improved control of dry weight (DW) in ESRD patients, there are no clinical studies examining whether this can improve blood pressure control and can also shorten the dialysis time needed to achieve satisfactory removal of small molecules. Several models of wearable dialysis systems are now under various stages of development. These devices present the possibility of hemodialyzing patients to their dry weights. We have built a prototype of a wearable ultrafiltration (UF) device (WUD) that can provide daily UF. Apart from better fluid control, we hypothesize that separating HD from UF will result in better blood pressure control and adequate weekly small molecule removal could be achieved with a decreased duration of dialysis We tested the hypothesis by in current hemodialysis patients using conventional dialysis equipment. Methods Thirteen patients were selected from a large urban hemodialysis center. The experimental period consisted of 4 weeks of daily UF (4 days/week of UF alone and 2 days/week of HD with UF). The duration of the HD sessions was increased by 15 to 30 minutes to maintain weekly standard Kt/V>2.0. The patients were then returned to their conventional 3 days/week of HD with UF and studied for 4 weeks. The pre-dialysis BPs Interdialytic weight gains, and Kt/V results of the experimental and return periods were compared to those of the 3 month control period. No changes were made in antihypertensive or other medication during the study. Results During the experimental period, mean arterial pressure decreased from 110 mmHg to 95mmHg (P<0.001), systolic BP from 158mmHg to 136mmHg (P<0.001) while interdialytic weight gains were reduced from 3.25 liters to 1.21 liters (p<0.0001). During the experimental period, weekly standard Kt/V of 2.16 was achieved in 8.24 hours/week of HD, as compared to 11.14 hours/week. Conclusions Volume control with daily UF results in improved BP control and, by separating the UF function from HD, adequate weekly standard Kt/V>2 can be achieved with twice weekly HD.

Jones, James P.; Leonard, Edward F.; Sandhu, Gagangeet; Winkel, Gary; Levin, Nathan W.; Cortell, Stanley

2013-01-01

380

Protective lung ventilation in operating room: a systematic review.  

PubMed

Postoperative pulmonary and extrapulmonary complications adversely affect clinical outcomes and healthcare utilization, so that prevention has become a measure of the quality of perioperative care. Mechanical ventilation is an essential support therapy to maintain adequate gas exchange during general anesthesia for surgery. Mechanical ventilation using high tidal volume (VT) (between 10 and 15 mL/kg) has been historically encouraged to prevent hypoxemia and atelectasis formation in anesthetized patients undergoing abdominal and thoracic surgery. However, there is accumulating evidence from both experimental and clinical studies that mechanical ventilation, especially the use of high VT and plateau pressure, may potentially aggravate or even initiate lung injury. Ventilator-associated lung injury can result from cyclic alveolar overdistension of non-dependent lung tissue, and repetitive opening and closing of dependent lung tissue resulting in ultrastructural damage at the junction of closed and open alveoli. Lung-protective ventilation, which refers to the use of lower VT and limited plateau pressure to minimize overdistension, and positive end-expiratory pressure to prevent alveolar collapse at end-expiration, was shown to improve outcome in critically ill patients with acute respiratory distress syndrome (ARDS). It has been recently suggested that this approach might also be beneficial in a broader population, especially in critically ill patients without ARDS at the onset of mechanical ventilation. There is, however, little evidence regarding a potential beneficial effect of lung protective ventilation during surgery, especially in patients with healthy lungs. Although surgical patients are frequently exposed to much shorter periods of mechanical ventilation, this is an important gap in knowledge given the number of patients receiving mechanical ventilation in the operating room. This review developed the benefits of lung protective ventilation during surgery and general anesthesia and offers some recommendations for mechanical ventilation in the surgical context. PMID:24226493

Futier, E; Constantin, J M; Jaber, S

2014-06-01

381

Not-So-Trivial Pursuit: Mechanical Ventilation Risk Reduction  

PubMed Central

As many as half of critically ill patients require mechanical ventilation. In this article, a program of research focused on reduction of risk associated with mechanical ventilation is reviewed. Airway management practices can have profound effects on outcomes in these patients. How patients are suctioned, types of processes used, effects of suctioning in patients with lung injury, and open versus closed suctioning systems all have been examined to determine best practices. Pneumonia is a common complication of mechanical ventilation (ventilator-associated pneumonia), and use of higher backrest elevations reduces risk of pneumonia, although compliance with such recommendations varies. The studies reviewed here describe backrest elevation practices, factors that affect backrest elevation, and the effect of backrest elevation on ventilator-associated pneumonia. Oral care strategies also have been investigated to determine their effect on ventilator-associated pneumonia. Oral care practices are reported to hold a low care priority, vary widely across care providers, and differ in intubated versus nonintubated patients. However, in several studies, oral applications of chlorhexidine have reduced the occurrence of ventilator-associated pneumonia. Although ventilator patients require sedation, sedation is associated with significant risks. The overall goals of sedation are to provide physiological stability, to maintain ventilator synchrony, and to ensure patients' comfort–although methods to evaluate achievement of these goals are limited. Reducing risks associated with mechanical ventilation in critically ill patients is a complex and interdisciplinary process. Our understanding of the risks associated with mechanical ventilation is constantly changing, but care of these patients must be based on the best evidence.

Grap, Mary Jo

2013-01-01

382

A rational framework for selecting modes of ventilation.  

PubMed

Mechanical ventilation is a life-saving intervention for respiratory failure and thus has become the cornerstone of the practice of critical care medicine. A mechanical ventilation mode describes the predetermined pattern of patient-ventilator interaction. In recent years there has been a dizzying proliferation of mechanical ventilation modes, driven by technological advances and market pressures, rather than clinical data. The comparison of these modes is hampered by the sheer number of combinations that need to be tested against one another, as well as the lack of a coherent, logical nomenclature that accurately describes a mode. In this paper we propose a logical nomenclature for mechanical ventilation modes, akin to biological taxonomy. Accordingly, the control variable, breath sequence, and targeting schemes for the primary and secondary breaths represent the order, family, genus, and species, respectively, for the described mode. To distinguish unique operational algorithms, a fifth level of distinction, termed variety, is utilized. We posit that such coherent ordering would facilitate comparison and understanding of modes. Next we suggest that the clinical goals of mechanical ventilation may be simplified into 3 broad categories: provision of safe gas exchange; provision of comfort; and promotion of liberation from mechanical ventilation. Safety is achieved via optimization of ventilation-perfusion matching and pressure-volume relationship of the lungs. Comfort is provided by fostering patient-ventilator synchrony. Liberation is promoted by optimization of the weaning experience. Then we follow a paradigm that matches the technological capacity of a particular mode to achieving a specific clinical goal. Finally, we provide the reader with a comparison of existing modes based on these principles. The status quo in mechanical ventilation mode nomenclature impedes communication and comparison of existing mechanical ventilation modes. The proposed model, utilizing a systematic nomenclature, provides a useful framework to address this unmet need. PMID:22710796

Mireles-Cabodevila, Eduardo; Hatipo?lu, Umur; Chatburn, Robert L

2013-02-01

383

78 FR 70578 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Ventilation...  

Federal Register 2010, 2011, 2012, 2013

...Comment Request; Ventilation Plan and Main Fan Maintenance Record ACTION: Notice...titled, ``Ventilation Plan and Main Fan Maintenance Record,'' to the Office of...authorization for the MSHA Ventilation Plan and Main Fan Maintenance Record information...

2013-11-26

384

75 FR 79026 - Agency Information Collection Activities; Submission for OMB Review; Comment Request; Ventilation...  

Federal Register 2010, 2011, 2012, 2013

...Comment Request; Ventilation Plan and Main Fan Maintenance Record ACTION: Notice...titled, ``Ventilation Plan and Main Fan Maintenance Record,'' to the Office of...comment. In addition, the main ventilation fans for an underground mine must be...

2010-12-17

385

30 CFR 75.324 - Intentional changes in the ventilation system.  

Code of Federal Regulations, 2013 CFR

...the ventilation system. 75.324 Section...Mineral Resources MINE SAFETY AND HEALTH...DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH...STANDARDS-UNDERGROUND COAL MINES Ventilation ...the ventilation system. (a) A...

2013-07-01

386

10 CFR 429.43 - Commercial heating, ventilating, air conditioning (HVAC) equipment.  

Code of Federal Regulations, 2011 CFR

...false Commercial heating, ventilating, air conditioning (HVAC) equipment. 429...43 Commercial heating, ventilating, air conditioning (HVAC) equipment. Link...model of commercial heating, ventilating, air conditioning (HVAC) equipment,...

2014-01-01

387

Design and Development of a Regenerative Blower for EVA Suit Ventilation.  

National Technical Information Service (NTIS)

Ventilation subsystems in future space suits require a dedicated ventilation fan. The unique requirements for the ventilation fan - including stringent safety requirements and the ability to increase output to operate in buddy mode - combine to make a reg...

H. L. Paul M. G. Izenson R. W. Hill S. D. Phillips W. Chen

2011-01-01

388

42 CFR 440.185 - Respiratory care for ventilator-dependent individuals.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Respiratory care for ventilator-dependent individuals. 440.185... § 440.185 Respiratory care for ventilator-dependent individuals. (a) âRespiratory care for ventilator-dependent individualsâ...

2013-10-01

389

The Edgecombe County (NC) High Blood Pressure Control Program: II. Barriers to the use of medical care among hypertensives.  

PubMed Central

As the initial step in a five-year project to improve control of high blood pressure in Edgecombe County, North Carolina, a survey was conducted in 1980 to determine the prevalence of hypertension and to identify factors which might constitute barriers to the use of medical care by hypertensives. This report summarizes the findings for the 539 hypertensives identified through the baseline survey. In general, Black hypertensives reported more access problems than Whites. Within race, however, males and females differed very little on selected measures of potential access to medical care. Among women, lower scores on potential access were strongly associated with being untreated, whereas for men, concerns about the safety of anti-hypertensive drug therapy were associated with being unaware. On a summary measure of the actual use of medical care in response to symptoms, both male and female treated hypertensives scored higher than their untreated counterparts. The implications of these and other findings for community-based blood pressure control activities are discussed.

James, S A; Wagner, E H; Strogatz, D S; Beresford, S A; Kleinbaum, D G; Williams, C A; Cutchin, L M; Ibrahim, M A

1984-01-01

390

The Edgecombe County (NC) High Blood Pressure Control Program: II. Barriers to the use of medical care among hypertensives.  

PubMed

As the initial step in a five-year project to improve control of high blood pressure in Edgecombe County, North Carolina, a survey was conducted in 1980 to determine the prevalence of hypertension and to identify factors which might constitute barriers to the use of medical care by hypertensives. This report summarizes the findings for the 539 hypertensives identified through the baseline survey. In general, Black hypertensives reported more access problems than Whites. Within race, however, males and females differed very little on selected measures of potential access to medical care. Among women, lower scores on potential access were strongly associated with being untreated, whereas for men, concerns about the safety of anti-hypertensive drug therapy were associated with being unaware. On a summary measure of the actual use of medical care in response to symptoms, both male and female treated hypertensives scored higher than their untreated counterparts. The implications of these and other findings for community-based blood pressure control activities are discussed. PMID:6711721

James, S A; Wagner, E H; Strogatz, D S; Beresford, S A; Kleinbaum, D G; Williams, C A; Cutchin, L M; Ibrahim, M A

1984-05-01

391

Inhaled antibiotics in mechanically ventilated patients.  

PubMed

During the last decade, inhaled antibiotics, especially colistin, has been widely used worldwide as a therapeutic option, supplementary to conventional intravenous antibiotics, for the treatment of multidrug-resistant (MDR) Gram-negative nosocomial and ventilator-associated pneumonia (VAP). Antimicrobial aerosols are commonly used in mechanically ventilated patients with VAP, although information regarding their efficacy and optimal technique of administration has been limited. Recent studies showed that the administration of inhaled antibiotics in addition to systemic antibiotics provided encouraging results associated with low toxicity for the management of VAP mainly due to MDR Gram negative bacteria. Although the theory behind aerosolized administration of antibiotics seems to be sound, there are limited data available to support the routine use of this modality since very few randomized controlled trials (RCTs) have still examined the efficacy of this approach in patients with VAP. Additionally, this route of antibiotic delivery has not been approved until now neither by the FDA nor by the European Medicines Agency (EMEA) in patients with VAP. However, since the problem of VAP due to MDR bacteria has been increased worldwide RCTs are urgently needed in order to prove the safety, efficiency and efficacy of inhaled antimicrobial agents administered alone or in conjunction with parenteral antibiotics for the management of VAP in critically ill patients. Indeed, more data are needed to establish the appropriate role of inhaled antibiotics for the treatment of VAP. PMID:24107830

Michalopoulos, A S; Falagas, M E

2014-02-01

392

Active noise attenuation in ventilation windows.  

PubMed

The feasibility of applying active noise control techniques to attenuate low frequency noise transmission through a natural ventilation window into a room is investigated analytically and experimentally. The window system is constructed by staggering the opening sashes of a spaced double glazing window to allow ventilation and natural light. An analytical model based on the modal expansion method is developed to calculate the low frequency sound field inside the window and the room and to be used in the active noise control simulations. The effectiveness of the proposed analytical model is validated by using the finite element method. The performance of the active control system for a window with different source and receiver configurations are compared, and it is found that the numerical and experimental results are in good agreement and the best result is achieved when the secondary sources are placed in the center at the bottom of the staggered window. The extra attenuation at the observation points in the optimized window system is almost equivalent to the noise reduction at the error sensor and the frequency range of effective control is up to 390 Hz in the case of a single channel active noise control system. PMID:21786888

Huang, Huahua; Qiu, Xiaojun; Kang, Jian

2011-07-01

393

Ventilation rate in office buildings and sick building syndrome  

Microsoft Academic Search

OBJECTIVE--To examine the relation between ventilation rate and occurrence of symptoms of the eyes, nose, throat, and skin as well as general symptoms such as lethargy and headache, often termed the sick building syndrome. METHODS--A cross sectional population based study was carried out in 399 workers from 14 mechanically ventilated office buildings without air recirculation or humidification, selected randomly from

J J Jaakkola; P Miettinen

1995-01-01

394

Control of Ventilation Airflow for Tunnel Fire Safety  

Microsoft Academic Search

Behavior of fire-induced heat and smoke movement in a longitudinally ventilated model tunnel is studied experimentally. A gas burner is used as fire source. Ventilation velocity, heal release rate, temperature distributions arc measured under quasi-steady conditions. Flow visualization using incense smoke as a tracer has been carried out to identify some important characteristics of the flow and heat transfer, such

H. XUE; T. C. CHEW; K. L. TAY; Y. M. CHENG

2000-01-01

395

Model Predictive Control of the Hybrid Ventilation for Livestock  

Microsoft Academic Search

In this paper, design and simulation results of model predictive control (MPC) strategy for livestock hybrid ventilation systems and associated indoor climate through variable valve openings and exhaust fans, are presented. The design is based on thermal comfort parameters for poultry in barns and a dynamic model describing the nonlinear behavior of ventilation and associated climate, by applying a so-called

Zhuang Wu; Jakob Stoustrup; Klaus Trangbaek; Per Heiselberg; Martin Riisgaard Jensen

2006-01-01

396

CO2 Monitoring for Demand Controlled Ventilation in Commercial Buildings.  

National Technical Information Service (NTIS)

Carbon dioxide (CO(sub 2)) sensors are often deployed in commercial buildings to obtain CO(sub 2) data that are used, in a process called demand-controlled ventilation, to automatically modulate rates of outdoor air ventilation. The objective is to keep v...

D. Faulkner D. P. Sullivan E. Eliseeva W. J. Fisk

2010-01-01

397

Industrial Education Ventilation Study. Volume 1: Final Report.  

ERIC Educational Resources Information Center

A study assessed aspects of ventilation in industrial education facilities in selected junior and senior highs schools in Alberta (Canada). This report describes the purpose of the study and the four test methods used to acquire school specific information. Also discussed are (1) the results of the instructors' perception survey, the ventilation

Stanley Associates, Edmonton (Alberta).

398

Effectiveness of Medical Resident Education in Mechanical Ventilation  

Microsoft Academic Search

Specific methods of mechanical ventilation management reduce 3), and reduce costs and ICU complications (3) for the nearly mortality and lower health care costs. However, in the face of a 1.5 million U.S. patients who require mechanical ventilation predicted deficit of intensivists, it is unclear whether residency pro- each year (4). Critically ill patients with acute respiratory grams are training

Christopher E. Cox; Shannon S. Carson; E. Wesley Ely; Joseph A. Govert; Joanne M. Garrett; Roy G. Brower; David G. Morris; Edward Abraham; Vincent Donnabella; Antoinette Spevetz; Jesse B. Hall

2003-01-01

399

EVALUATION OF VENTILATION EFFECTIVENESS USING AN IAQ MODEL  

EPA Science Inventory

The paper discusses an evaluation of ventilation effectiveness, using a new ventilation solver that can determine the distributions of a time-averaged flow field, the effective turbulent diffusion coefficient, and the steady-state or time-dependent contaminant concentration distr...

400

Quantitative relationship of sick building syndrome symptoms with ventilation rates  

SciTech Connect

Data from published studies were combined and analyzed to develop best-fit equations and curves quantifying the change in sick building syndrome (SBS) symptom prevalence in office workers with ventilation rate. For each study, slopes were calculated, representing the fractional change in SBS symptom prevalence per unit change in ventilation rate per person. Values of ventilation rate, associated with each value of slope, were also calculated. Linear regression equations were fitted to the resulting data points, after weighting by study size. Integration of the slope-ventilation rate equations yielded curves of relative SBS symptom prevalence versus ventilation rate. Based on these analyses, as the ventilation rate drops from 10 to 5 L/s-person, relative SBS symptom prevalence increases approximately 23percent (12percent to 32percent), and as ventilation rate increases from 10 to 25 L/s-person, relative prevalence decreases approximately 29percent (15percent to 42percent). Variations in SBS symptom types, building features, and outdoor air quality may cause the relationship ofSBS symptom prevalence with ventilation rate in specific situations to differ from the average relationship predicted in this paper.

Fisk, William J.; Mirer, Anna G.; Mendell, Mark J.

2009-01-01

401

Ventilation Control Strategy Using the Supply CO2 Concentration Setpoint  

Microsoft Academic Search

This paper proposes a new ventilation control strategy applied to multiple spaces subject to variable occupancy. The strategy specified for real-time, online ventilation control takes advantage of uninitiated air from some overventilated spaces to be used as fresh outdoor air in order to reduce system energy use while maintaining the indoor air quality (IAQ) in each space. This proposed strategy

Nabil Nassif; Stanislaw Kajl; Robert Sabourin

2005-01-01

402

Experimental Study of Fire Ventilation During Fire Fighting Operations  

Microsoft Academic Search

Fire ventilation measures taken by fire & rescue services, including positive pressure ventilation, were investigated. Fifteen tests were performed in a three-room apartment, with an attached staircase, on the first floor of a training facility. The fire source was a 0.5 m diameter pool of heptane. The temperature and pressure in the apartment, the weight of the fire source, and

Stefan Svensson

2001-01-01

403

Heterogeneity in ventilation during positive end-expiratory pressure  

Microsoft Academic Search

We read with interest the commentary ‘Can heterogeneity in ventilation be good’ [1] and the related article by Zhao and colleagues [2]. We agree with the comments that instead of incremental positive end-expiratory pressure (PEEP) levels, a decremented PEEP titration might be an attractive option for determining optimal PEEP [1,3]. However, we feel that physiological inhomogeneity in ventilation and perfusion

Mukesh Tripathi; Mamta Pandey

2010-01-01

404

Influence of occupants on the energy use of balanced ventilation  

Microsoft Academic Search

SUMMARY In this paper we give an overview of the ways occupants use ventilation systems and describe the results of interviews conducted in households equipped with balanced ventilation. An attempt is made to quantify the effects of occupant behaviour on the final energy use of the household for heating. This energy use is studied for several behaviour scenarios, leading to

Karin Soldaat; Laure Itard

405

An Apparatus for Controlled Artificial Positive-Pressure Pulmonary Ventilation  

Microsoft Academic Search

To study the mechanisms of the voluntary regulation of breathing movements, we used controlled artificial positive-pressure pulmonary ventilation of the lungs [1]. Described here is an apparatus that can be used for detecting similarities and dissimilarities in regulatory mechanisms of the respiratory and nonrespiratory muscles during lung ventilation. To operate the earlier version of the apparatus, the subject had to

M. A. Pogodin; S. P. Romanov; G. N. Mikhailov

2001-01-01

406

Recommending a Ventilation Rate for Gas Compressor Buildings  

Microsoft Academic Search

In cold climates, a building ventilation rate must be selected to control contaminants adequately but must not be excessive. Measurements of natural gas (total hydrocarbons), hydrogen sulfide, and carbon monoxide in 16 gas compressor buildings containing 42 compressors (up to 2000 HP each) showed total hydrocarbons to be the critical material requiring additional control by ventilation (primary control is by

Ian Drummond

1986-01-01

407

13. NEW YORK SIDE, HUDSON RIVER VENTILATION BUILDING ACROSS HUDSON ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

13. NEW YORK SIDE, HUDSON RIVER VENTILATION BUILDING ACROSS HUDSON RIVER IN BACKGROUND, WITH SOUTH WALL OF NEW JERSEY SIDE OF VENTILATION BUILDING IN FOREGROUND - Holland Tunnel, Beneath Hudson River between New York & Jersey City, New York, New York County, NY

408

Ventilation and Its Control during Incremental Exercise in Obesity  

Microsoft Academic Search

Background: In obesity, the addition of mass loading of the chest wall by adipose tissue decreases compliance, but its ventilation does not seem to be a limiting factor to physical performance. Plasma K+ and lactic acid are considered important determinants of ventilation during exercise. Obesity is characterized by insulin resistance. Objectives: The aim of this study was to assess ventilatory

Alberto Salvadori; Paolo Fanari; Ilaria Tovaglieri; Emanuela Giacomotti; Ferruccio Nibbio; Fabiola Belardi; Erminio Longhini

2008-01-01

409

Exhaust Ventilation Energy Saving in Car Manufacturing and Other Industries  

Microsoft Academic Search

The purpose of this article is to describe an innovative on-demand industrial ventilation and supply system for the automotive industry. Similar on-demand systems are already being used in the chemical, metal, and woodworking industries, achieving an average electricity savings of 68 percent over an unregulated system. After analyzing the performance and effectiveness of industrial ventilation systems in automobile manufacturing plants,

Ales Litomisky

2007-01-01

410

The Improvement of Ventilation Behaviours in Kitchens of Residential Buildings  

Microsoft Academic Search

This research investigated resident behaviours in relation to kitchen ventilation in residential buildings in order to improve kitchen indoor air quality (IAQ) in South Korean living spaces. The research involved a survey study of 182 households, which identified resident behaviour with respect to ventilation, their satisfaction level regarding the IAQ, and their use and maintenance of range hoods in the

Hyunsoo Lee; Youn Jae Lee; So Yun Park; Yu Won Kim; Yeunsook Lee

2012-01-01

411

Mechanical Ventilation Drives Inflammation in Severe Viral Bronchiolitis  

PubMed Central

Introduction Respiratory insufficiency due to severe respiratory syncytial virus (RSV) infection is the most frequent cause of paediatric intensive care unit admission in infants during the winter season. Previous studies have shown increased levels of inflammatory mediators in airways of mechanically ventilated children compared to spontaneous breathing children with viral bronchiolitis. In this prospective observational multi-center study we aimed to investigate whether this increase was related to disease severity or caused by mechanical ventilation. Materials and Methods Nasopharyngeal aspirates were collected <1 hour before intubation and 24 hours later in RSV bronchiolitis patients with respiratory failure (n?=?18) and non-ventilated RSV bronchiolitis controls (n?=?18). Concentrations of the following cytokines were measured: interleukin (IL)-1?, IL-1?, IL-6, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-1?. Results Baseline cytokine levels were comparable between ventilated and non-ventilated infants. After 24 hours of mechanical ventilation mean cytokine levels, except for MIP-1?, were elevated compared to non-ventilated infected controls: IL-1? (159 versus 4 pg/ml, p<0.01), IL-1? (1068 versus 99 pg/ml, p<0.01), IL-6 (2343 versus 958 pg/ml, p<0.05) and MCP-1 (174 versus 26 pg/ml, p<0.05). Conclusions Using pre- and post-intubation observations, this study suggests that endotracheal intubation and subsequent mechanical ventilation cause a robust pulmonary inflammation in infants with RSV bronchiolitis.

Hennus, Marije P.; van Vught, Adrianus J.; Brabander, Mark; Brus, Frank; Jansen, Nicolaas J.; Bont, Louis J.

2013-01-01

412

Prototype ventilator and alarm algorithm for the NASA space station  

Microsoft Academic Search

An alarm algorithm was developed to monitor the ventilator on the National Aeronautics and Space Administration space station. The algorithm automatically identifies and interprets critical events so that an untrained user can manage the mechanical ventilation of a critically injured crew member. The algorithm was tested in two healthy volunteers by simulating 260 critical events in each volunteer while the

Josef X. Brunner; Dwayne R. Westenskow; Paul Zelenkov

1988-01-01

413

Toxic Vapors and Ventilation Parameters: Evaluating the Laboratory Atmosphere.  

ERIC Educational Resources Information Center

A significant amount of scientific work is done in laboratories with limited ventilation capabilities. To operate at "acceptable risk", an understanding is needed of what ventilation systems can/cannot do. A simple experiment is described which assesses conditions under which specific experiments should be performed and serves to introduce…

Bayer,