The Effects of Intraoperative Hypothermia Review of the Molecular Mechanisms of Action in Therapeutic Hypothermia

During surgery the patient may lose heat during and after surgery through the contribution of several factors: ambient temperature, cold fluid infusion, the position on the operating table, surgical skin preparation methods, type of surgery, conventional surgery or laparoscopy, and the loss increase of the heat by opening the serous cavities, thoracic or abdominal [1]. They add other factors, depending on patients: the elderly are more prone to heat loss, sex; women lose less heat, the existence of associated diseases, as peripheral vascular diseases, endocrine diseases, cachexia, physical constitution or presence of pregnancy. Temperature of the patient’s body lowers in relation to prolonged patient stay in a cool room of resuscitation. The heat loss of the skin tissue in the operating room is important and is expressed at approximately 100 W [2]. More important than the relationship between temperature of the operating room and patient’s skin, the microclimate, which is established between operators fields and patient. Another important factor is body surface area exposed having significant area reported at weight. Hypothermia is aggravated by cold fluid administration, abdominal or thoracic wounds. The use of cold solutions in urologic surgery exposes the central temperature drop, which is more marked if intervention is performed under epidural anesthesia [3]. In epidural anesthesia, hypothermia is due to redistribution of heat between the center and periphery, the thighs being established to intense vasodilatation and heat loss [4, 5]. All measures taken to prevent heat loss are important for prevention of coagulation disorders. Hypothermia reduces oxygen release in half, reducing the liver’s ability to metabolize citrate and lactic acid and cause arrhythmia. The existence of hypothermia in surgical patient reflects failure thermoregulatory mechanisms [1-3].