Effects of mild hypothermia used for protecting neurological function on electrolytes changes in swine model of ventricular fibrillation after cardiopulmonary resuscitation

Abstract

Objective To study the changes of hemodynamic parameters and electrolytes observed within 72 hours of hypothermic therapy in porcine model of cardiac ventricular fibrillation after cardiopulmonary resuscitation （CPR ） in order to provide clinical basis for safe application of mild hypothermia.Methods After typical ventricular fibrillation （VF）for 8 minutes,the survival animals were randomly （random number）divided into two groups,namely normothermia group and hypothermia group. Upon restoration of spontaneous circulation （ROSC ）,swine of the hypothermic group was treated by endovascular cooling device at a rate of 1 ℃/h until 33 ℃ and it was maintained for 12 h,then rewarming was initiated passively at a rate of 0.5 ℃/h until 38 ℃.The neurologic deficit scores （NDS）of swine were used to evaluate neurological function at 24 h and 72 h after recovery.Serum levels of potassium and sodium were measured at 0.5 h,6 h,12 h,24 h and 72 h after recovery.Results ROSC （restoration of spontaneous circulation）rate was 84.2%.The hypothermia group had higher survival rates at 24 h （75%） and 72 h （62.5%）compared to the normothermia group （37.5% and 25%,respectively）,（P〈0.01 ）. There were no significant differences in hemodynamic variables （HR,MAP,CO,PAWP and CVP）between the two groups （P〈0.05 ）,Serum potassium of the hypothermia group was lower obviously at 24 h after recovery （3.41 ±0.11）（P〈0.01）,and there were no significant differences in serum sodium at all the intervals,and there were no significant differences in underlying trend of electrolytes changes over time （P〉0.05）.The mean NDSs at 24 h and 72 h after recovery was 112.5 （98.75 -126.25）and 61 （50-75）, respectively,in the hypothermic group,and 230 （225 -235）and 207.5 （165 -250）,respectively,in the normothermia group （P 〈0.01 ）.Conclusions Hypothermia has little influence on serum levels of potassium and sodium,and mild hypothermia following resuscitation improves neurological function in the porcine models of cardiac fibrillation. Key words: Cardiopulmonary resuscitation; Ventricular fibrillation; Cardiac arrest; Hypothermia therapy; Endovascular cooling; Hemodynamic; Restoration of spontaneous circulation; Neurological Deficit score