Experimental Study On The Effects Of Different Mechanical Ventilation Levels On Right Ventricular Function In Ards Rats

Objective Acute respiratory distress syndrome?ARDS?is a common critical disease in the Department of critical medicine.Although the strategy of lung recruitment combined with lung protective ventilation has been widely implemented in clinical practice,the mortality of patients has not decreased.Right heart function is a new focus in the treatment of ARDS patients with mechanical ventilation.To explore the relationship between respiratory mechanics and right ventricular function during mechanical ventilation treatment of ARDS by establishing animal models of ARDS and implementing different levels of mechanical ventilation,so as to provide theoretical basis for right ventricular protective ventilation strategy.Methods The animal model of ARDS was established by injecting oleic acid into central vein in Beagle dogs?n=6?.The same parameters of mechanical ventilation were given before and after the model establishment.Adopt fixed driving pressure and increase PEEP,adjust PEEP to 2,4,6,8,10,12,14 cmH₂O,maintained for 30min each time,and after the vital signs of beagle dogs are stable,the respiratory mechanics?peak airway pressure,plateau pressure,tidal volume,end inspiratory cross pulmonary pressure,end expiratory cross pulmonary pressure,pulmonary static compliance?,hemodynamics?mean arterial pressure,heart rate,finger pulse oxygen saturation,central venous pressure,mean pulmonary arterial pressure?and right heart function indexes?SV,TAPSE and FAC?of beagle dogs are collected.The changes of respiratory mechanics,hemodynamics and right ventricular function in beagle dogs before and after modeling were analyzed with fixed driving pressure and PEEP.Results In the control group?before modeling?,the peak airway pressure?Ppeak?and plateau pressure?Pplat?increased with the increase of PEEP?F 232.733,196.33,P<0.05?.However,Ptrans-I,Ptrans-E,Cstat and Vt decreased?F 4.524,6.499,64.803,2.31,P<0.05?.The area of change of right ventricle?FAC?became smaller?F 3.09,P<0.05?;SV first increased and then decreased?F 3.24,P<0.05?,CVP and MPAP increased?F19.07,14.81,P<0.05?.There was no significant difference in TAPSE,MAP,HR and SpO2?P>0.05?.In the experimental group?after modeling?,it was found that as PEEP increased,Ppeak,Pplat increased?F 24.829,41.95,P<0.05?.Vt,Ptrans-I,Ptrans-E,Cstat and VT first increased and then decreased?F 2.91,4.29,5.84,48.890,P<0.05?.TAPSE and SV first increased and then decreased?F 6.22,6.54,P<0.05?.CVP and mPAP increased?F 5.23,19.24,P<0.05?.MAP increased first and then decreased?F 5.02,P<0.05?.SpO2 increased?F 2.77,P<0.05?.FAC and HR had no statistical significance?P>0.05?.Conclusion 1.For normal lung,increasing PEEP decreases alveolar stress compliance,enlarges pulmonary volume,increases pulmonary vascular resistance due to compression of extraalveolar vessels,affects cardiac output,and restores basic state when normal ventilation is resumed.2.For ARDS simulation lung,the initial increase of PEEP can increase the transpulmonary pressure and the collapsed alveoli,increase the stroke output and improve the cardiac function to some extent;but in the later stage,peep continues to increase,but the transpulmonary pressure and pulmonary compliance do not continue to increase,and the greater the pulmonary artery pressure,the less the blood flow in the alveoli,and the ventilation/blood flow does not improve.At the same time,due to the increase of pulmonary artery,the right ventricular afterload increases,and the cardiac function is affected.3.The increase of PEEP first affects TAPSE,right ventricular systolic function first affects TAPSE,and compensatory output per stroke increases,but the continued increase of PEEP will lead to the decrease of TAPSE and SV.4.Therefore,real-time monitoring of transpulmonary pressure,TAPSE and intrapulmonary blood flow shunt indicators should be used in ARDS treatment,which can more effectively implement pulmonary recruitment and reduce the impact on right ventricular function and circulation.