Experimental Study Of PEEP And Tidal Volume Evaluation And Seletion After Recruitment Maneuver In Acute Lung Injury

Part1. Relationship of stress index, lung recruitment and gas exchange in dogs with acute respiratory distress syndromeObjective To determine the relationship of stress index, lung recruitment and gas exchange in different canine model with acute respiratory distress syndrome (ARDS). Methods Canine ARDS model were induced by oleic acid intravenous, saline lavage and hydrochloric acid aspiration. During volume control ventilation with constant inspiratory flow,the pressure-tine (P-t) curve was fitted to a power equation:P=a×timeb+c,where coefficient b (stress index) describes the shape of the curve:b=1,straight curve;b<1,progressive increase in slope;and b>1,progressive decrease in slope. Tidal volume (VT) was 6 ml/kg,and positive end-expiratory pressure (PEEP) was set to obtain a b value between 0.9 and 1.1 before (b=1) and after(b=1 after recruiting maneuver) application of a recruiting maneuver (RM). PEEP was changed to obtain 0.6