Effects of moderate hypothermia on alveolar capillary membrane permeability in endotoxin-induced acute lung injury in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of moderate hypothermia on the permeability of alveolar capillary membrane in acute lung injury (ALI) induced by lipopolysaccharide (LPS) .Methods Thirty-four adult male SD rats weighing 300-350g were randomly divided into 4 groups control group (n = 8) ; LPS group (n = 10); hypothermia group (n = 8) and LPS + hypothermia group (n = 8) . The animals were anesthetized with intraperitoneal (i.p.) 1% pentobarbital 30 mg?kg-1, intubated and mechanically ventilated (RR 80 bpm, VT 20 ml?kg-1, I E 12) . Right external jugular vein and left carotid artery were cannulated for BP and CVP monitoring and blood sampling. ALI was induced by LPS 1.0 mg?kg-1 i.p. and 16h later, intratracheal instillation of LPS 1.5 mg?kg-1. ALI was considered established when PaO2/FiO2 ≤300. Hypothermia was induced by surface cooling. Body T0 was reduced to 32.5-33.0℃. In control and hypothermia groups normal saline was given instead of LPS. Arterial blood samples were taken for blood gas analysis and MAP and CVP were recorded before (T0, baseline) and 1, 2, 3, 4 h after ALI (T1-4) . At the end of experiment (4h after ALI was established) the animals were killed by exsanguination. The lungs were removed. Lung lavage was performed and the concentration of albumin in bronchoalveolar lavage fluid (BALF), the left lung wet/dry weight ratio, myeloperoxidase (MPO) activity of lung tissue were measured. Lung tissue was also taken for histologic examination by transmission electron microscopy.Results There was no significant difference in hemodynamics among the 4 groups. PaO2/FiO2 and PaCO2 remained unchanged in the control group and hypothermia group. PaO2 /FiO2 was significantly decreased and PaCO2 was significantly increased as compared to the baseline values (T0) in LPS group (P