Effect of continuous hemofiltration on internal environment and survival rate of severe heatstroke dogs with shock

Objective To explore the effect of continuous hemofiltration(CHF) on internal environment and survival rate of severe heatstroke dogs with shock.Methods Sixteen healthy male dogs were randomly divided into heatshock group(HS group,n=8) and continuous hemofiltration group(CHF group,n=8).Severe heatstroke model was established by applying high temperature to whole body,and then the animals were removed from the heating cabin as soon as they presented manifestations of shock.Dogs of HS group were put into an ordinary environment,while dogs of CHF group received CHF treatment.The core temperature(Tc),mean arterial pressure(MAP),blood gas analysis,serum electrolytes and survival rate of dogs in two groups were observed.Results The time from heat exposure to shock was 107.0±28.5min and 111.4±22.2min in HS group and CHF group respectively(t=-0.354,P=0.729).The Tc in CHF group declined to normal level 15 to 30 minitues after CHF treatment,while the Tc in HS group remained at a level higher than that before heat exposure at 90min after shock.The Tc of two groups showed significant difference at each time point after shock(P < 0.01).The MAP of both groups was obviously lowered than that before heatstroke.The MAP of CHF group raised gradually 30 min after treatment,while the MAP of HS group rose very slowly,and it was significantly lower than that of CHF group at each time point after 45min(P < 0.05,P < 0.01).All the dogs in both groups manifested hyperventilation and respiratory alkalosis when shock appeared.After shock,respiratory alkalosis in HS group gradually became metabolic acidosis,with some animals manifested combined metabolic and respiratory acidosis because of respiratory decompensation,while the blood gas levels in CHF group recovered to normal gradually.The blood gas levels of two groups showed significant difference at each time point after shock(P < 0.05,P < 0.01).Hypernatremia,hyperchloraemia and hyperpotassaemia were found in all animals of both groups.In CHF group the electrolyte disturbance recovered gradually and reached normal level at 180min after shock,while it did not recover in HS group.The levels of serum sodium,chlorine and potassium in HS group were significantly higher than those in CHF group at each time point after shock(P < 0.05,P < 0.01).The median survival time of CHF group(180 minutes) was significantly longer than that of HS group(75 minutes,χ2=6.929,P=0.008).Conclusion CHF could improve the prognosis of severe heatstroke dogs with shock,prolong the survival time and reduce the fatality rate.The mechanism may be associated with fast cooling at early stage,maintenance of hemodynamic stability,and correction the acid-base imbalance and electrolyte disturbance.