Effects of pressure control and positive end-expiratory pressure incremental method lung recruitment maneuvers on haemodynamics in piglets with acute lung injury induced by paraquat

Objective To discuss the effects of pressure control (PC) and positive end-expiratory pressure (PEEP) incremental method lung recruitment maneuver (RM) on haemodynamics in piglets with acute lung injury (ALI) induced by paraquat (PQ) poisoning. Methods The ALI/acute respiratory distress syndrome (ARDS) model was reproduced by intraperitoneal injection of 20% PQ (20 mL) in 10 healthy female piglets, and they were randomly divided into PC lung RM group (RM1 group) and PEEP incremental method lung RM group (RM2 group), with 5 piglets in each group. Heart rate (HR), mean arterial pressure (MAP), and cardiac index (CI) were monitored by pulse-indicated continuous cardiac output (PiCCO) monitoring before model reproduction (baseline), on the time of successfully set up of model and at 5, 15 and 30 minutes after RM. At the same time the arterial partial pressure of oxygen (PaO2) and arterial partial pressure of carbon dioxide (PaCO2) were recorded, and oxygenation index was calculated. Lung tissues were collected before model reproduction, on the time of successfully set up of model, and at 30 minutes after RM respectively, and pulmonary pathology changes were observed after hematoxylin and eosin (HE) staining under light microscopy. Results The HR, MAP, and PaCO2 on the time of successfully set up of model in both groups were increased obviously while CI, PaO2, and oxygenation index were decreased obviously as compared with those at baseline, all of which conformed to the expression of ALI/ARDS. With RM time extended, the HR in both groups was declined while MAP and CI were increased gradually. The HR and MAP at 5 minutes after RM of RM1 group were significantly lower than those of the RM2 group [HR (bpm): 126.8±5.2 vs. 134.0±3.8, MAP (mmHg, 1 mmHg = 0.133 kPa): 98.4±3.3 vs. 102.8±2.6, both P 0.05). The lung tissue in both groups showed a variety of pathological changes at 30 minutes after RM. The main performances were the loss of alveolar epithelial cells, the further wideness of alveolar interval and the distension of alveolar, and the part breakage of alveolar interval. The wideness of alveolar interval was more significant in RM2 group than that of RM1 group, and alveolar cleft was more common too. Conclusion Both PC and PEEP incremental method lung RM can improve the oxygenation of the piglets with ALI/ARDS induced by PQ, and the PC lung RM has less impact on haemodynamics. Key words: Pressure control method; Positive end-expiratory pressure incremental method; Lung recruitment maneuver; Paraquat; Poisoning; Haemodynamics; Piglet