Rewarming And Primary Biological Effects Of Far-infrared Electrothermal Rewarming Method For Treatment Of Hypothermia

Background:Over 70% surface of the earth is covered by sea. Excluding the areas near the equator, most seas of the world have the low temperature of water below that of the human body. Military personnel are most likely to suffer form hypothermia during their deployment, especially on wartime when they fighting in the sea areas. Accidental hypothermia is defined as an unintentional decrease in core body temperature to below 35℃. For the high mortality rate of the moderate and severe hypothermia, the treatments of hypothermia have become one of the most important topics of emergency medicine and military medicine.Objective:To investigate the rewarming effect and the biological mechanism of far-infrared electrothemal rewarming. The animal model of hypothermia has been established, and the effects of three different rewarming methods have been compared. Then to provide scientific basis for investigating a new external rewarming method for treatment of hypothermia.Methods:30 healthy New Zealand rabbits were randomly divided into 3 groups:the spontaneous rewarming group, the warm bath rewarming group and the far-infrared rewarming group. All the rabbits were immersed by artificial sea water(21.0±0.5℃) to a stable rectal temperature of 30℃and each group were then rewarmed by the following rewarming methods: (1) Spontaneous rewarming; (2) Warm bath(42℃); (3) Electric heating with far-infrared induced by composite carbon fiber device. The blood in the jugular vein was collected to measure the level of the lactate, MDA and SOD in the plasma and the activity of erythrocyte membrane ATPase after 3h of rewarming.Results:About 35 minutes after being immersed by artificial sea water, the rectal temperature of rabbits were dropped from 39.4℃to 30.0℃, animal models of hypothermia were established. Rewarming time:the spontaneous rewarming group 225.00±8.72min, the warm bath rewarming group 67.75±3.11min, the far-infrared rewarming group 78.63±4.69min. There were statistical differences among the mean rewarming time of three groups(P <0.01). After-drop range: the spontaneous rewarming group 1.85±0.13℃, the warm bath rewarming group 0.95±0.30℃, the far-infrared rewarming group 0.53±0.17℃. The after-drop range of the far-infrared rewarming group was significantly shorter than that of the warm bath rewarming and the spontaneous rewarming groups(P<0.01). Activity of erythrocyte membrane ATPase:the spontaneous rewarming group 27.88±2.01 U/gHb, the warm bath rewarming group 31.98±1.65 U/gHb, the far-infrared rewarming group 36.47±2.67 U/gHb. The activity of erythrocyte membrane ATPase of the far-infrared rewarming group was significantly higher than that of the warm bath rewarming and the spontaneous rewarming groups(P<0.01). The level of lactate:the spontaneous rewarming group 10.25±0.72 mmol/L, the warm bath rewarming group 8.43±0.91 mmol/L, the far-infrared rewarming group 6.58±0.66 mmol/L. The level of lactate of the far-infrared rewarming group was significantly less than that of the warm bath rewarming and the spontaneous rewarming groups(P<0.01). The level of SOD:the spontaneous rewarming group 254.75±12.38 U/ml, the warm bath rewarming group 262.23±13.89 U/ml, the far-infrared rewarming group291.99±12.40 U/ml. The level of SOD in the plasma of the far-infrared rewarming group was significantly higher than that of the warm bath rewarming and the spontaneous rewarming groups(P<0.01). The level of MDA: the spontaneous rewarming group 9.16±0.56nmol/ml, the warm bath rewarming group8.40±0.49nmol/ml, the far-infrared rewarming group 5.76±0.64nmol/ml. The level of MDA of the far-infrared rewarming group was significantly less than that of the warm bath rewarming and the spontaneous rewarming groups(P<0.01).Conclusions:Compared with the spontaneous rewarming and the warm bath rewarming methods, the far-infrared electrothermal rewarming method is more effective for treatment of hypothermia. It has faster rewarming speed and shorter after-drop range. This method can improve the energy metabolism and reduce the lipid peroxidation more conspicuously. It is a new kind of external rewarming method for treatment of hypothermia.