Effects Of Mechanical Ventilation In Piglets With Actue Lung Injury Induced By Paraquat

PART Ⅰ:Establishment of piglet model with actue lung injuryinduced by paraquatObjective:To establish the piglet model with actue lung injury (ALI) induced by paraquat(PQ) and provide the conditions for further study on treating paraquat poisoning bymeans of lung protective ventilation strategy.Methods:Ten healthy female piglets were randomly divided into the control group (n=4)and the experimental group (n=6). The experimental group were givenintraperitoneal injections of20%PQ (20ml) and the control group amount of saline.All piglets were dynamically monitored by pulse-indicated continuous cardiac output(PiCCO) monitor about heart rate (HR), mean arterial pressure (MAP), extravascularlung water index (ELWI) and pulmonary vascular permeability index(PVPI) andchanges of arterial blood pH,oxygen partial pressure (PaO2), partial pressure ofcarbon dioxide(PaCO2), oxygenation index (PaO2/FiO2), peak inspiratory pressure (PIP) and platform of the airway pressure (Pplat) were recorded until the oxygenationindex≤300mmHg.Results:Five piglets model with actue lung injury induced by paraquat of theexperimental group were established successfully and the average time ofestablishment was (4.5±0.2)h.The HR,MAP,ELWI,PVPI,PIP and Pplat of theexperimental group increased gradually2.5hours after PQ intraperitoneal injectionand the differences between the two groups were statistically significant (all P<0.05)when the models were established.The pH,PaO2and oxygenation index declinedgradually while the PaCO2increased gradually of the experimental group after PQintraperitoneal injection,the differences between the two groups were statisticallysignificant (all P<0.05) when the models were established.Lung tissue pathologyresults showed obvious damage changes when the models were established.Conclusion:By this method we can establish a stable paraquat-induced ALI piglet model forfurther animal studies. PART Ⅱ:Effects of different tidal volume mechanical ventilationapplying on piglets with actue lung injury induced by paraquatunder pulse indicating continuous cardiac output monitoringObjective:To study the effects of different tidal volume combined with positive end-expiratory pressure(PEEP) mechanical ventilation applying on piglets with actue lunginjury/acute respiratory distress syndrome（ALI/ARDS）induced by paraquat underpulse indicating continuous cardiac output（PiCCO） monitoring. Methods:The ALI/ARDS models were established by means of healthy female pigletswith20%PQ (20ml) intraperitoneal injection and randomly divided into three groupsaccording to tidal volume (VT):small VTgroup(VT=6ml/kg,n=6),middle VTgroup(VT=10ml/kg,n=6) and large VTgroup(VT=15ml/kg,n=6),and the PEEP wereall setup on10cmH2O.The changes of the heart rate (HR), mean arterial pressure(MAP), extravascular lung water index (ELWI) and pulmonary vascular permeabilityindex(PVPI) were monitored by PiCCO monitoring and changes of arterial bloodpH,oxygen partial pressure (PaO2), partial pressure of carbon dioxide(PaCO2),oxygenation index (PaO2/FiO2), peak inspiratory pressure(PIP) and platform of theairway pressure (Pplat) were recorded at time of before the model was made(baseline),time of the model was made (t0) and2h (t2),4h (t4),6h (t6) after t0.Lungtissue of all animals were punctured at time of baseline, t0and t6to be stained byHematoxylin and eosin (HE) and pulmonary pathology were observed under lightmicroscopy.Results:The piglets model ALI/ARDS was established (4.5±0.2)h after PQintraperitoneal injection.The HR and MAP of all animals increased obviouslycompared to time of baseline when the models were established (all P<0.05),and theHR and MAP of all animals declined gradually after mechanical ventilation,thedifferences were statistically significant compared to time of t0(all P<0.05).The pHvalue,PaO2and oxygenation index of all animals declined obviously while the PaCO2increased evidently compared to time of baseline (all P<0.05);the pH value of allanimals declined gradually after mechanical ventilation and the small VTgroupshowed obviously most(P<0.05).The PaO2and oxygenation index of the small VTgroup were apparently higher than the other two groups(all P<0.05),while thePaCO2of all animals rose after mechanical ventilation and the small VTgroup showedobviously most(P<0.05).The ELWI and PVPI of all animals increased obviouslycompared to time of baseline (all P<0.05);The ELWI of all animals increased obviously2h after mechanical ventilation and then the small VTgroup and middle VTgroup declined gradually,the small VTgroup showed obviously most6h aftermechanical ventilation.Three were no significant change about PVPI of all animalsafter mechanical ventilation.The PIP and Pplat of the small VTgroup declinedgradually after mechanical ventilation while the other two groups increased gradually,and the PIP and Pplat of the small VTgroup apparently lower than the other twogroups6h after mechanical ventilation.Lung tissue pathology results showed obviousdamage changes when the models were established（t0）,and the damage aggravated6h after mechanical ventilation with the large VTgroup showing apparently most andthe small VTgroup showing lighter.Conclusion:The small tidal volume combined with PEEP mechanical ventilation canalleviate the actue lung injury induced by paraquat and improve oxygenation. PART Ⅲ: Effects of pressure control and positiveend-expiratorypressure incremental method lung recruitment maneuvers onhaemodynamics in piglets with actue lung injury induced byparaquatObjective:To discuss the effects of pressure control (PC) and positive end-expiratorypressure (PEEP) incremental method lung recruitment maneuvers (RMs) onhaemodynamics in piglets with actue lung injury induced by paraquat (PQ).Methods:The ALI/ARDS models were established by means of ten healthy female piglets with20%PQ (20ml) intraperitoneal injection and randomly divided into two groups:PC lung RMs (RM1, n=5) and PEEP incremental method lung RMs (RM2,n=5). Thechanges of the heart rate (HR), mean arterial pressure (MAP),cardiac functional index(CI),oxygen partial pressure (PaO2), partial pressure of carbon dioxide(PaCO2) andoxygenation index (PaO2/FiO2) between the two groups at time of before the modelwas made (baseline), time of the model was made (t0) and5min (t5),15min (t15) and30min (t30)after RMs. Lung tissue of all animals were punctured at time of baseline,t0and t6to be stained by Hematoxylin and eosin (HE) and pulmonary pathology wereobserved under light microscopy.Results:The HR and MAP of all animals increased obviously while the CI declinedevidently compared to time of baseline when the models were established (allP<0.05), and the HR and MAP of all animals declined gradually after RMs.The HRand MAP of RM1group were significantly lower than that of the RM2group5minafter RMs (all P<0.05),while there was no statistically significant difference betweenthe two groups30min after RMs (all P>0.05).The CI of all animals declined at firstthen ascended after RMs;the RM1group were significantly higher than that of theRM2group5min after RMs (all P<0.05),while there was no statistically significantdifference between the two groups30min after RMs (all P>0.05).The PaO2,PaCO2and oxygenation index rised after RMs but differences between the two groups wereno statistically significant (all P>0.05).the lung tissue of all animals showed a varietyof pathological changes30min after RMs.The main performance were alveolarepithelial cells falling off, alveolar interval widening further and alveolar bloating,andthe alveolar interval being fractured in portion.Conclusion:PC and PEEP incremental method lung RMs both can improve the oxygenationof the piglets with actue lung injury induced by paraquat and the PC lung RMs causeslower effects on haemodynamics.