Effects Of Prone Position On Oxygenation Index In Patients With Severe ARDS Supported By VVECMO

BackgroundAcute respiratory distress syndrome(ARDS)is an acute diffuse lung injury characterized by refractory hypoxemia.Mortality rates for ARDS are high:27%for mild,32%for moderate,and 45%for severe ARDS.In the past,many guidelines and treatment strategies have been developed to reduce mortality and improve the quality of life for survivors.Lung protective ventilation strategies:low tide volume,high end-expiratory positive pressure ventilation(PEEP),low platform pressure<30 cm H2O and lung retentions,etc.,improved the survival rate of ARDS patients.However,these measures do not always provide satisfactory gas exchange.Other advanced support,such as prone position(PP)and VVECMO support,is available if the oxygenation level remains low with a higher level of lung protective ventilation strategy and PEEP.Prone ventilation is an important part of the treatment of ARDS patients.In the 2019 ARDS management guidelines,it is recommended that prone positioning should be used in ARDS patients with PaO2/FIO2 ratio<150 mmHg to reduce mortality(>16h/d).For patients with ECMO,since there is still blood flow in the lungs during ECMO,prone position ventilation is of theoretical value for the improvement of oxygenation.Currently,prone position(PP)is usually performed before VVECMO,and the data of the application of the two is rare.ObjectiveThe purpose of this study is to explore the effect of prone position on OI in patients with severe ARDS supported by VVECMO.MethodsEighty-six patients with severe ARDS supported by VVECMO in ICU of our hospital were eventually included as the study objects,including 43 patients in the prone position group(group P)and 43 patients in the supine position group(group C).Patients in both groups received VVECMO adjuvant therapy after endotracheal intubation.Patients in group P were given prone position ventilation for 4h,with an interval of 2h(4 cycles).If there were irreversible hemodynamic fluctuations during the prone position,they were immediately changed to supine position.Group C was given the conventional supine position.OI values were recorded before(T0),after(T1),and before(T2),3(T3),and 5(T4)days before and after the prone position of the two groups.Arterial blood gas index(pH,PaCO2,PaO2,SaO2);Respiratory mechanical indicators:lung static compliance(Cst),airway peak pressure(Ppeak),airway platform pressure(Pplat);Indicators of infection:plasma calcitonin(PCT),interleukin 6(IL-6);Record the support time of ECMO and the probability of successful withdrawal of ECMO;Death rates at 7,14,and 28 days were recorded in both groups.SPSS21.0 statistical software was used for data analysis.Results(1)There was no statistically significant difference in general data between the two groups(P>0.05);(2)The Mauchly sphericity test was performed on OI values at T0,T1,T2,T3 and T4 in the two groups,P=0.000<0.05,the data was asymmetric,and the multivariate test results were selected.The time-point effect was significant(F=9715.148,P<0.05),indicating that OI in the two groups changed significantly with the time point.In terms of grouping effect,there was no statistically significant difference in T0 and T1 between the two groups(t=0.409,1.122,P=0.684,0.265),and the difference was significant in T2,T3 and T4(t=-9.691,-16.090,-11.710,all P<0.05),and the group OI was higher than the group C.In terms of time point effect:OI values of the two groups at different time points were not the same,and further pin-wise comparison showed that OI values of the two groups at each time point were significantly different(P<0.05).Combined with the interaction graph,the overall OI value of the two groups showed an upward trend,and the rate of rise was faster in group P.(3)There was no statistically significant difference in the pH,PaCO2 and SaO2 of T1,T2,T3 and T4 between the two groups(P>0.05).There was an interaction effect in the overall PaO2 analysis of the two groups(F=1301.289,P=0.000<0.05).There were significant differences at the time points of T2,T3 and T4 in separate effect analysis(P<0.05).The interactive graph showed that the overall PaO2 of the two groups presented an upward trend,and the rate of rise was faster in group P.(4)There was no statistically significant difference in Ppeak and Pplat at time points T1,T2,T3 and T4 between the two groups(P>0.05).There was an interaction effect in the overall analysis of Cst in the two groups(F=352.272,P=0.000<0.05).There were significant differences at the time points of T2,T3 and T4 in separate effect analysis(P<0.05).The interaction diagram showed that the overall Cst of patients in the two groups showed an upward trend,and the rate of increase in group P was faster than that in group C.(5)There was an interaction effect in the overall analysis of PCT and IL-6in the two groups(F=126.534,3992.092,both P=0.000<0.05),indicating that PCT and IL-6 in the two groups changed significantly with the time point.The group effect was significant(F=47.199,46.708,P=0.000<0.05),indicating that PCT and IL-6 in the two groups changed significantly with the time point.The interaction diagram shows that the overall PCT and IL-6 in the two groups showed a downward trend,and the rate of decline was faster in group P.(6)Comparison of patients' time on ECMO in the two groups:compared with the group C,the support time on ECMO in the group P was lower than that in the group C,and the difference was statistically significant(P<0.05).(7)The withdrawal probability of group P was significantly higher than that of group C(74%vs 67%).Kaplan-Meier analysis showed that the mortality rate at 7,14 and 28 days in group P was significantly lower than that in group C(7%vs 16.3%;25.9%vs 39.4%;37.6%vs 56.8%),the difference was statistically significant(P<0.05).Overall comparison[Log Rank(mantel-cox)]:P<0.05,indicating a significant difference between group P and group C;The survival function graph showed that group P had better survival results than group C,with significant difference(P<0.05).Conclusions(1)Prone position ventilation can significantly improve the oxygenation index of patients with severe ARDS supported by VVECMO;(2)Prone position ventilation improved the static lung compliance and shortened the support time of VVECMO;(3)Prone position ventilation can reduce the death rate of patients with severe ARDS supported by VVECMO at 7,14 and 28 days.