ABSTRACT
Thermoregulatory physiological responses are subject to physiological variations such as gender, age, circadian variations, and exercise. They can also be modified by drugs and certain pathological conditions such as obesity, altered thyroid functions, hypothalamic–pituitary abnormalities, and dysautonomia. Hypothermia is characterized by a fall in the core body temperature by a minimum of 1°C from the normal and becomes clinically relevant if the body temperature is less than 36°C. The effects of hypothermia on different systems are given in the "Cerebrovascular system", "Cardiovascular system", "Respiratory System", and "Excretory system". In nonanesthetized patients requiring primary therapeutic hypothermia (PTH) such as stroke, tolerance to hypothermia has to be induced pharmacologically. Avoidance of fever and hyperthermia remains a major aim in the management of patients in neurointensive care units (NICUs). Temperature loss in the intraoperative period has to be reduced to the minimum possible as shivering and vasoconstriction during extubation are more detrimental in neurosurgery patients.
