Effects of APRV-BIPAP ventilation On lung recruitment/open maneuvers in piglets with acute lung injury / 中华急诊医学杂志

ABSTRACT

Objective To study the effects of APBV (airway pressure release ventilation) / BIPAP(bipha-sic positive airway pressure) on lung recmitment/open maneuvers in piglets with acute lung injury. Method The model of acute lung injury (ALI) was induced by E. coll. intraperitoneal injection in piglets. Based APRV/BI-PAP model, the different pressure combinations (Phigh/Plow) of RMs increased gradually, such as RMI(30/15),RM2(35/20), RM3(40/25), RM4(45/30),RM5(50/35), RM6(55/40), RM7(60/45) cmH2O. The effects of stepwise RMs were studied by computed tomography (CT) at iaspiratory phase. Meantime the oxygen index (PaO2/FiO2), hemodynamic parameter and mean pressure of airway (Pmean) were continuously observed. The piglets were killed when RiMs finished and pulmonary pathological examination were done routinely by optical microscope. Data was analyzed by self-contrast method, using SPSS 11.5 software package. Results were expressed as mean ± standard deviation (x±s). Multiple comparisons were made with One-way ANOVA. Pearson correlative analysis was used to describe the relativity of PaO2/FiO2 and the collapsed alveolar area. Changes were considered as statistically significant if P value was less than 0.05. Results Eight piglets with ALl model were successfully made and all of them showed different degree of alveolar collapse under chest CT scan. During RMs their PaO2/FiO2 increased obviously (P<0.05) were decreased obviously (P<0.05) too, specially after RM2 finished (P<0. 05). But the alveolar over-inflatian could be found in some non-diseased area. The heart rate (HR) increased and mean artery blood pressure (MAP) decreased significantly while the pressure combinations (Phigh/Plow) of RMs were added gradual]y ( P<0.05). Meantime the Pmean and Ppeak inspiratory pressure (PIP) of airway and central venous pressure (CVP) were increased significantly ( P<0.05). But when RMs were finished,all of these indexes were hack to the levels of pre-RMs. Even there were no barowaumas happened, such as pneumothorax and pneumomedistinum, the alveolar overdistention and interruption of the alveolar separation still could be seen by pathologic examination. Conclusions RMs could be done well by APRV/BIPAP. Phigh/Plow (35/20cmH2O) would be the best pressure combination with more efficacy of RMs and less influence on hemodynamics,airway pressure indexes and others. When the effect of RMs was satisfied enough, setting Phigh/Plow to 30/15cmH2O for 20 mitt may maintain the good efficacy of RMs.