Effects Of Different Mechanical Ventilation Modes Combined With Pulmonary Surfactant On Lung Histology And Apoptosis In Rabbits With Steam Inhalation Injury

Objective To investigate the effects of high frequency oscillatory ventilation (HFOV) and conventional mechanical ventilation (CMV) and their combination with pulmonary surfactant(PS) therapies on steam inhalation injury.Methods Thirty-two New Zealand rabbits were randomly divided into four groups after acute respiratory failure models caused by severe steam inhalation injury were established.Then they were ventilated by CMV , HFOV , CMV+PS or HFOV+PS,respectively. Femoral arterial blood samples were obtained respectively at 0.5,1.5,2.5,3.5 h treatment timepoints for blood gas examination.After the expenrimetal period,the middle lobe in the right lung were excised for histological sections.Part of the lowest lobe of the excised right lung tissue was collected to test apoptotic rate.Results (A) PaO2 in the four groups all decreased below 60mmHg and PaO2 of postinjury had statistical significance comparing with pre-injury at the same group(P<0.01).(B) PaO2 in the four groups had increased since 1.5h treatment timepont,and values of PaO2 sustained continuously within 3.5 h treatment time.PaO2 in the HFOV and HFOV+PS groups were higher than the corresponding data in CMV and CMV+PS groups respectively (P<0.01,P<0.05).PaO2 in the CMV+PS group at 1.5h treatment timepoint and PaO2 in HFOV+PS group at 1.5h and 2.5h treatment timepoints showed significant advantages over the data in the corresponding non-PS groups at the same timepoints (P<0.05).The PaCO2 had no significant difference in the four groups at different treatment timepoints (P>0.05) and also there were no obvious differences in apoptotic rates(P>0.05). (C) Histological injury found the HFOV groups were more alleviated than the CMV group,the lowest in the HFOV+PS group and the highest in the CMV group.Conclusion HFOV combined with exogenous PS can improve arterial oxygenation,alleviate pulmonary edema and injury,with no obvious changes on apoptotic rate.