The Favorable Effect of Hypothermia on Acute Respiratory Distress Syndrome Induced by Lipopolysaccharide in Rats

Objective To study the favorable effect of hypothermia on ARDS induced by lipopolysaccharide in rats.Methods A rat model of acute respiratory distress syndrome(ARDS) was established by intratracheal instillation of lipopolysaccharide at 16 h after LPS intraperitoneal administration.Thirty-four male Sprague Dawley rats were randomly divided into four groups.NS+Normalthermia group(NN),NS+Hypothermia group(NH),ARDS+Hypothermia group(AH),ARDS+Normalthermia group(AN).The changes of PaO_(2)/FiO_(2),MAP,CVP and PaCO_(2) were observed at basic situation,onset of ARDS and 1 h,2 h,3 h after ARDS.At 3 h after ARDS,rats were killed by hemorrhage from carotid artery.Histomorphology of superior lobe of right lung tissue was examined,and the wet weight / dry weight ratio of left lung was measured.Lung lavage was performed,the albumin contents in BALF were measured using spectrophotography.Results Compared with the basic values and the NN group,oxygernation index in the AH and AN groups significantly decreased at the time of ARDS and 1h,2h,3h after ARDS(P0.01),but there were no significant differences between the two groups(P0.05).At the time of 3 h after ARDS,PaCO_(2) in the AH group was significantly lower than that in the AN group(P0.05),and compared with the NN group,there was no significant difference(P0.05).However,at the time of ARDS and 1 h,2 h after ARDS,PaCO_(2) in the AH group was markedly higher than the base values and that in the NN group(P0.05),but there were no significant differences at the time of 3 h after ARDS(P0.05).No significant differences were noted in MAP and CVP among the four groups.In the AH group,the albumin contents in BALF and the lung wet weight/dry weight ratio were much lower than those in the AN group(P0.01),but there were no significant differences compared with the NN group(P0.05).A lot of pint hemorrhagic spots,in the AH group,the histological index of lung tissue were attenuated.Conclusion Hypothermia had favorable effect on ARDS induced by lipopolysaccharide in rats.