Temperature Monitoring and Perioperative Thermoregulation

Abstract

Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature measuring sites are completely non-invasive and easy to use — especially in patients not having general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients having general anesthesia exceeding 30 minutes in duration, and in patients having major operations under neuraxial anesthesia. Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature triggering cold defenses including arterio-venous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, and the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extant than general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown.

Comparison of the Effects of Intrathecal Meperidine and Morphine on Incidence and Intensity of Shivering After Caesarean Sections Under Spinal Anesthesia: A Randomized Controlled Trial

“…The etiology of shivering under regional anesthesia is still obscure, however some of the proposed likely hypotheses are as followed; redistribution of internal body temperature produced by vasodilatation under the level of block, failure of thermoregulatory vasoconstriction under the level of blockade area that could intensify heat loss from the body surface due to the extreme thermo genesis, and lessening of vasoconstriction threshold and simultaneously mild increase in the sweat threshold (15,16).…”

“…Firstly, we monitored axillary temperature instead of core body temperature. The axillary temperature, however, may be used to measure the core temperature, except for extreme body temperature changes (16). Secondly, study registration was done retrospectively.…”

Recommendations for standards of monitoring during anaesthesia and recovery 2015 : Association of Anaesthetists of Great Britain and Ireland

“…If it is necessary to continue anaesthesia without a particular device, the anaesthetist must record the reasons for this in the anaesthetic record and only proceed where the benefits or clinical urgency outweigh the risks. The following are considered minimum monitoring for anaesthesia: Pulse oximeterNIBPECGInspired and expired oxygen, carbon dioxide, nitrous oxide and volatile anaesthetic agent if used (see below)Airway pressurePeripheral nerve stimulator if neuromuscular blocking drugs used (see Appendix 3)Temperature for any procedure > 30 min duration 20. …”

Randomized non-inferiority trial of the vitalHEAT™ Temperature Management System vs the Bair Hugger® warmer during total knee arthroplasty

“…A substantial body of literature exists on this topic, including recent reviews on the physiology of thermoregulation, 8 perioperative temperature monitoring, 9 the effects of mild hypothermia on blood loss and transfusion requirements, 10 and complications of hypothermia. 11 The vitalHEAT TM (vH 2TM ) Temperature Management System is one of several commercially available warming devices that seek to prevent and treat intraoperative hypothermia.…”