Effects of different ventilation modes on efficacy of exogenous pulmonary surfactant for treatment of rats with ventilator-induced lung injury

Abstract

Objectlve To investigate the effects of different ventilation modes on the efficacy of exogenous pulmonary surfactant(PS)for the treatment of rats with ventilator-induced lung injury(VILI).Methods Forty-two male Wistar rats weighing 310-356 g were randomly divided into 6 groups(n=7 each):group CVT6,group SVT6,group CVT10,group SVT10,group CVT14 and group SVT14.The tidal volume(VT)was set at 6,10 and 14 ml/kg respectively and the respiratory rate(RR) was 75,45 and 32 bpm respectively.The animals were anesthetized with intraperitoneal 3% Pentobarbital 50 mg/kg,then tracheostomized and intubated.VILI model was induced by high-pressure ventilation (HPV) with peak inspimtory pressure (PIP) 40 cm H2O and without positive end-expiratory pressure (PEEP).The air was injected into the trachea via the airway at the end ofexpiration before HPV (T0,baseline value) and 15-25 min of HPV,the airway pressure monitored and the lung compliance(C) calculated.When C was decreased to half of the baseline value,PEEP was increased to 7.5 cm H20.After the tracheal edema fluid was removed,the PS 100 mg/kg was immediately injected into the trachea in group SVT6,SVT10 and SVT14.The equal volume of air was injected into the trachea in group CVT6,CVT10 and CVr14 instead of PS.Then the rats in different groups were ventilated with the corresponding ventilation modes.MAP was monitored and blood samples were token from femoral artery for blood gas analysis at T0, 5 min after HPV (T1 ), and 15, 30, 60, 90, 120 min (T2-6) after administration of PS. The tracheal edema fluid was collected at T1 and T6.The rats were killed at T6 and the lung tissues taken for microscopic examination. Results With the same ventilation mode, the VILI was significantly alleviated after administration of PS. With different ventilation modes,the lung injury was significantly reduced in group SVT 10 compared with the other groups. Conclusion The efficacy of PS for the treatment of rats with VILI is good using the ventilation strategy with VT of 10 ml/kg and RR of 45 bpm. Key words: Pulmonary surfactant-associated protein B; Pulmonary surfactant-associated protein C; Respiratory distress syndrome, adult; Respiration, artificial