Effect of partial liquid ventilation on oleic acid-induced inflammatory responses in piglets

Background Pediatric patients are susceptible to lung injury.Acute lung injury （ALI） in children often results in a high mortality.Partial liquid ventilation （PLV） has been shown to markedly improve oxygenation and reduce histologic evidence of injury in a number of lung injury models.This study aimed to examine the hypothesis that PLV would attenuate the production of local and systemic cytokines in an immature piglet model of ALI induced by oleic acid （OA）.Methods Twelve Chinese immature piglets were induced to develop ALI by oleic acid.The animals were randomly assigned to two groups （n=6）： （1） conventional mechanical ventilation （MV） group and （2） PLV with FC-77 （10 ml/kg） group.Results Compared with MV group, PLV group got better cardiopulmonary variables （P 〈0.05）.These variables included heart rate, mean blood pressure, blood pH, partial pressure of arterial oxygen （PaO2）, PaO2/FiO2 and partial pressure of arterial carbon dioxide （PaCO2）.Partial liquid ventilation reduced IL-1β, IL-6, IL-10 and TN F-α both in plasma and tissue concentrations compared with MV group （P 〈0.05）.Conclusions Partial liquid ventilation provides protective effects against inflammatory responses in the lungs of oleic acid-induced immature piglets.

Partial liquid ventilation decreases tissue and serum tumor necrosis factor-~ concentrations in acute lung injury model of immature piglet induced by oleic acid

Background Pediatric patients are susceptible to lung injury.Acute lung injury in children often results in high mortality.Partial liquid ventilation （PLV） has been shown to markedly improve oxygenation and reduce histologic evidence of injury in a number of lung injury models.This study was designed to examine the hypothesis that PLV would attenuate the production of local and systemic tumor necrosis factor （TNF）-α in an immature piglet model of acute lung injury induced by oleic acid （OA）.Methods Twelve Chinese immature piglets were induced acute lung injury by OA.The animals were randomly assigned to two groups of six animals,（1） conventional mechanical ventilation （MV） group and （2） PLV with 10 ml/kg FC-77 group.Results Compared with MV group,the PLV group had better cardiopulmonary variables （P 〈0.05）.These variables included heart rate,mean blood pressure,blood pH,partial pressure of arterial oxygen （PaO2）,PaO2/inspired O2 fraction （FiO2） and partial pressure of arterial carbon dioxide （PaCO2）.PLV reduced TNF-α levels both in plasma and tissue compared with MV group （P 〈0.05）.Conclusion PLV provides protective effects against TNF-a response in OA-induced acute lung injury in immature piglets.

Effect of partial liquid ventilation on lung function in oleic acid-induced lung injury model of piglets

Background Pediatric patients are susceptible to lung injury that does not respond to traditional therapies.Partial liquid ventilation （PLV） has been developed as an alternative ventilatory strategy for treating severe lung injury.The aim of this study is to investigate the effect of PLV on lung function in immature piglets.Methods Acute lung injury was induced in 12 Chinese immature piglets by oleic acid （OA）.The animals were randomly assigned to two groups （n=6 each group）：（1） conventional mechanical ventilation （MV） group and （2） PLV with FC-77 （10 ml/kg） group.Mean arterial blood pressure （MAP）,mean pulmonary arterial pressure （MPAP）,central venous pressure （CVP）,left atrial pressure （LAP）,systemic vascular resistance （SVR）,pulmonary vascular resistance （PVR）,cardiac output （CO）,mean pressure of airway （Paw）,dynamic lung compliance （Cydn）,and arterial blood gases were measured during the observation period.Results No piglet died in either group with severe lung injury.After four hours of ventilation,pH in the MV group gradually decreased to lower than 7.20,while in the PLV group,pH also gradually decreased but remained higher than 7.20 （P ＜0.05）.Partial pressure of oxygen in artery （PaO2） decreased in both groups,but with a significant difference between the PLV group and MV group （P ＜0.05）.Partial pressure of carbon dioxide in artery （PaCO2） increased in both groups,but with a significant difference between the PLV group and MV group （P ＜0.05）.Paw increased in both groups,but was not significantly different （P ＞0.05）.Cydn decreased in both groups,but without a significant difference （P ＞0.05）.At four hours,heart rate （HR） and MAP in both groups decreased.MPAP in both groups increased,and there was a significant difference between the two groups （P ＜0.05）.CVP was stable in both groups.At four hours,PVR and LAP were increased in both groups.CO was decreased in both groups （P ＜0.05）.SVR was stable during the observation time.Conclusion PLV did not improve outcome in changes of lung function.

Effect of partial pit exhaust ventilation system on ammonia removal ratio and mass transfer coefficients from different emission sources in pig houses

A partial pit exhaust ventilation(PPEV)system installed below the slatted floor has been widely used in fattening pig barns nowadays in Denmark.Experimental tests showed that annually around 50%of ammonia emissions was collected by PPEV system.However,the percent of emissions collected by PPEV system from different emission sources including slurry manure surfaces,top surfaces,bottom surfaces and side surfaces of the slatted floor has not been investigated as well as the mass transfer coefficients.This study applied CFD modeling to investigate the removal ratio of ammonia emissions from four emission surfaces including the top,side,bottom surfaces of the slatted floor and slurry manure surfaces.The CFD model was validated by experimental air speeds measured in a room equipped with two full-scale pigpens.The validated CFD model was further adopted to simulate cases under five ventilation rates(2000-4000 m^(3)/h),four emission sources and two locations of PPEV system exhaust.The results showed that the removal ratios of ammonia emissions by PPEV system from the four emission sources were generally higher for the cases that the PPEV exhaust was installed opposite to the air supplier than the values of those cases that the PPEV exhaust was located at the same side of side wall air supplier.The removal ratios of ammonia emissions were the highest with the emission source of slurry manure surface and generally 30%higher than the values of other cases.The mass transfer coefficients with the emission sources on the side surfaces of the slatted floor were the largest.The results indicated that the airflow patterns and locations of emission sources greatly influenced the removal ratios of ammonia emissions and ammonia mass transfer coefficients.