Effect of fluid resuscitation for hemorrhagic shock on oxygenation of subjects in early period of first visit of high altitude area, an experimentation on dogs

Abstract

To investigate the effect of fluid resuscitation on oxygenation of subjects with hemorrhagic shock in early period of first visit to area of high altitude, an experiment in dogs was performed. A model of serious hemorrhagic shock was reproduced by exsanguination resulting in a lowering of mean arterial pressure to (35+/-5) mm Hg (1 mm Hg=0.133 kPa) maintain for 1 hour. Thirteen mongrel dogs were carried to an area of 3,780 metres above sea level from an area of 1,510 metres, and they were randomly divided into three groups, namely lactated Ringer's (LR) group, 6% hydroxyethyl starch (HES) group, and control group. The dogs in LR group were infused intravenously LR in 1.5 times the volume of blood loss; those in 6% HES group were given HES in equal volume. No fluid infusion was given in the control group. After 1 hour of resuscitation, LR was intravenously given at 5 ml.kg(-1).h(-1) in all groups as maintenance dose. The changes in oxygenation were observed. All animals in control group were dead after 2 hours. One hour after establishment of shock, the oxygen consumption (VO(2)), oxygen delivery (DO(2)), oxygen extraction ratio (O(2)ER), arterial oxygen saturation (SaO(2)) in two resuscitation groups were significantly lower than those before shock, but venous oxygen saturation (Sv(2)) and alveolar-arterial oxygen difference (A-aDO(2)) were significantly higher (all P<0.05). In LR group, the oxygenation parameters including VO(2), DO(2), O(2)ER, SaO(2) after 2 hours of resuscitation were significantly higher than those 1 hour after shock, while A-aDO(2) was significantly lower (all P<0.05); and in HES group, VO(2), DO(2), O(2)ER were significantly higher than those 1 hour after shock, while SvO(2) was significantly lower (all P<0.05). All dogs with serious hemorrhagic shock would die of hemorrhagic shock in the early period of entering a high altitude area if fluid resuscitation is denied. Two hours after infusion of LR in 1.5 times of quantity of blood loss, oxygenation can be restored to expected normal values. Infusion of 6% HES with an equal volume of blood loss, oxygenation dose not reach expected level 2 hours after resuscitation.