Relationship Between Right Cardiac Function Parameters And Optimal Positive End-expiratory Pressure Titrated After Lung Recruitment In Mechanically Ventilated Patients With Acute Respiratory Distress Syndrome

Objective:To investigate the relationship between right heart function parameters by echocardiography and positive end-expiratory pressure（PEEP）titrated after lung recruitment maneuvers（RM）in mechanically ventilated patients with acute respiratory distress syndrome（ARDS）.Methods:Thirty-five patients diagnosed ARDS in our hospital from october 2016 to august2018 were selected in the study.5 patients were given deletion,because their apical four chamber view were not clearly displayed,and finally 30 patients were included in the study.All patients were intubated,mechanically ventilated,increased sedation depth to RASS score-4.Recruitment maneuvers was carried out first,before recruitment maneuvers,the patient’s airway secretion was cleared,pure oxygen was given,ventilator was adjusted to pressure control mode,peak airway pressure was set to 40 cmH₂O,PEEP was set to 20 cmH₂O,to maintain 2 min for recruitment maneuvers.The pulmonary retraction was immediately terminated when there were SpO₂<88%,heart rate>140 beats/min,or<60 beats/min’mean arterial pressure of 60 mmHg、arrhythmias.Then,according to the principle of small tidal volume ventilation（6～8 mL/kg）,the peak airway pressure was adjusted,blood gas analysis was monitored and echocardiography was performed,and then the PEEP was gradually reduced（2 cmH₂O each time）.After each adjustment,the blood gas analysis of the pulse was performed to find the best PEEP.The blood gas analysis was performed each time during the titration PEEP,the PO₂/Fi O₂ decrease was greater than 10%,and the PEEP+2cmH₂O at this time was considered the best PEEP.At the same time,cardiac color ultrasound was performed at each PEEP level to measure TAPSE,E/e’,Tei index and right ventricular diameter.Results:PEEP corresponding to the maximum TAPSE value and the optimal oxygenated PEEP was analyzed by the paired t test.The mean difference value and the p value（mean of the difference value=1.0,p=0.033）.ICC（Intraclass correlation coefficient）analysis showed that the ICC corresponding to the maximum TAPSE value of PEEP and the optimal PEEP with oxygen method was 0.734（P<0.05）.PEEP corresponding to the minimum Tei index value and the optimal oxygenated PEEP was determined by paired t-test analysis:the mean difference value and the p value（the mean difference value=0.2,p=0.762）;ICC analysis showed that the ICC of the minimum Tei index corresponding to PEEP and the optimal PEEP with oxygen method was 0,（P>0.05）.PEEP corresponding to the minimum RV diameter and the optimal oxygenated PEEP were determined by paired t-test analysis,showing that the mean difference value and the p value（the mean difference value=-1.4,p=0.076）.ICC analysis showed that ICC with the lowest right ventricular diameter corresponding to PEEP and the best oxygen-induced PEEP was 0（P>0.05）.PEEP corresponding to the minimum E/e′value and the optimal oxygenated PEEP were determined by the paired t-test analysis.ICC analysis showed that the minimum value of E/e′corresponding to PEEP and the optimal PEEP with oxygen method was 0.810,（P<0.05）.Conclusion:For ARDS patients,monitoring E/e′by echocardiography can be used as an alternative method of titrating optimal PEEP by oxygen index method after RM.