Effect Of EIT-derived PEEP On Oxygen Delivery Of Ventilated Patients With ARDS

Background Acute respiratory distress syndrome(ARDS)is a life-threatening form of respiratory failure that accounts for 10% of intensive care unit admissions.The lung protective ventilation strategy is considered to be the part of the basic principles of treatment,including low tidal volume ventilation(6-8 ml/kg ideal body weight),plateau pressure<30 cm H2 O and appropriate PEEP..However,mortality from ARDS remains high,ranging from 35% to 46%.An important pathological change of ARDS is the dysfunction of ventilation and oxygen metabolism,which may lead to pathological oxygen supply dependence.So it is important to improve the oxygen delivery when manage the ventilated patients with ARDS.As we all know,oxygen delivery is depended on the respiratory system,circulatory system and blood system.Since appropriate positive end-expiratory pressure(PEEP)may not only increase the arterial blood oxygen content by keeping collapsed regions open and otherwise avoiding aeration but also keep adequate cardiac output in ARDS.It is significant to select a appropriate PEEP in ventilated patients with ARDS.Until now,there is no common sense with appropriate PEEP.In recent years,the Electrical Impedance Tomography(EIT)has emerged to assess the pulmonary gas distribution.It can monitor the lung ventilation through the chest impedance changes and can also provide the mechanics characteristics of local lung tissue.Compared to other methods of titrating PEEP.EIT has many advantages,such as noninvasive,safe,no radiation and bedside viable.Since EIT can be used to monitor the collapse and recruitment of local lung tissues,it is expected to become a convenient and effective bedside tool for PEEP titration.Objective1.To investigate the effect of eit-derived PEEP on oxygen delivery of ventilated patients with ARDS;2.Assess whether EIT is suitable as a new technique for PEEP titration in ventilated patients with ARDS.Methods This study was conducted from January 2017 to January 2018 in intensive care unit(ICU)in the first affiliated hospital of Guangzhou medical university.A total of15 patients who were diagnosed ARDS and expected to receive mechanical ventilation were included in this study.The respiratory mechanics parameters,hemodynamic parameters,gas exchange parameters,gas distribution parameters and oxygen delivery parameter were measured after each step in titrating PEEP from5-8-10-12-14-16-18-20 cm H2O.The interval of each step is about 15-20 minutes.And then comparing parameters with the ARDSnet method and the EIT method.Results(1)EIT-derived PEEP significantly lower than the ARDSnet method(9.40±4.34 cm H2O vs 12.40±3.72 cm H2O,P=0.016).(2)EIT-derived PEEP setting can significantly decrease the plateau pressure than ARDSnet method(21.27±6.01 cm H2O vs 27.60±10.04 cm H2 O,P=0.047).(3)EIT-derived PEEP setting can significantly increase the cardiac index than ARDSnet method(3.35±1.35 l/min/m2 vs 2.90±0.97l/min/m2,P=0.002).(4)EIT-derived PEEP setting method and ARDSnet method have no significant difference in gas exchange parameters(P>0.05).(5)EIT-derived PEEP setting method and ARDSnet method have no significant difference in gas distribution parameters(P>0.05).(6)EIT-derived PEEP setting can significantly increase the oxygen deliver y than ARDSnet method(461.83±113.62ml/min/m2vs406.06±108.98ml/min/m2,p=0.014).Conclusion(1)Compared with the ARDSnet table method,the eit-derived PEEP can improve the oxygen delivery of ARDS patients.(2)The eit-derived PEEP may become a promising method for the ventilated patients with ARDS.