Influence of recruitment maneuvers with pressure control ventilation on repeated derecruitment associated lung injury in rabbits

Objective:To evaluate the influence of recruitment maneuvers(RM) with pressure control ventilation(PCV) on repeated derecruitment associated lung injury in rabbits.Methods:The rabbit models of acute respiratory distress syndrome(ARDS) were duplicated using saline alveoli-lavaged,and the rabbits were divided into three groups:(1) LP group:tidal volume(tidal volume,Vt) 6 mL /kg,PEEP(positive end-expiratory pressure,PEEP) was set based on low turning point in the level(lower inflection point in static pressure-volume curve,LIP) of static pressure-volume curve;(2) DR group:the ventilation condition was the same as LP group,derecruitment was repeatedly induced by intentional disconnection of the ventilatory circuit for 1 min every 10 min for 3 h;(3) PCV group:using PCV for RM after derecruitment,setting the mode of ventilator as PCV,inspiratory pressure set to 30 cmH2O,PEEP levels set to LIP level,I:E = 1:2,time of maintenance 90 s.Arterial blood gas parameters and respiratory mechanics were monitored during mechanical ventilation;the rabbits were sacrificed 3h after mechanical ventilation to determine the lung wet/dry weight ratio(W/D) and underwent pathological score of lung tissue injury.Results:PaO2 in group DR was significant lower than that in group LP and PCV at the same time(P all 0.05) 1,2 and 3 h after derecruitmen;PaO2 showed no significant differences between LP and PCV at the same time(P all 0.05);static lung compliance(Cst) and airway platform pressure(Pplat) between group DR and group LP and PCV at the same time had no significant differences(P all 0.05);lung W/D between DR group and LP group and PCV group showed no significant differences(P 0.05);pathological injury score of lung tissue 3 h after mechanical ventilation in group DR was(10.9 ± 0.8),which was significant higher than that in group LP and group PCV(P all 0.05),There was no significant difference between group LP and group PCV(P all 0.05).Conclusion:Repeated derecruitment deteriorates oxygenation markedly and aggravates lung tissue injury of ARDS;recruitment maneuvers with PCV may reduce derecruitment associated lung injury.