Perioperative thermoregulation and heat balance
Daniel I Sessler
Core body temperature is normally tightly regulated to within a few tenths of a degree. The major thermoregulatory defences in humans are sweating, arteriovenous shunt vasoconstriction, and shivering. The core temperature triggering each response defines its activation threshold. General anaesthetics greatly impair thermoregulation, synchronously reducing the thresholds for vasoconstriction and shivering. Neuraxial anaesthesia also impairs central thermoregulatory control, and prevents vasoconstriction and shivering in blocked areas. Consequently, unwarmed anaesthetised patients become hypothermic, typically by 1–2°
Maintaining intraoperative normothermia: A meta-analysis of outcomes with costs
Christine Brown Mahoney, Jan Odom
Abstract: The present study used a meta-analysis to examine 4 questions about intraoperative hypothermia. The questions addressed were as follows: (1) Is the difference in adverse patient outcomes between normothermic and mildly hypothermic patient groups significant across studies and within studies? (2) What is the magnitude of the difference in adverse patient outcomes across studies? (3) What are the costs resulting from the difference in adverse patient outcomes? (4) Does a significant difference exist in effectiveness of modality for maintaining intraoperative normothermia? The results of this meta-analytic study provide evidence that the difference in adverse patient outcomes between the normothermic and mildly hypothermic patients is significant across studies for all adverse outcomes examined.
Preventing Inadvertent Perioperative Hypothermia
Alexander Torossian, Anselm Bräuer, Jan Höcker, Berthold Bein, Hinnerk Wulf, Ernst-Peter Horn
Background: 25–90% of all patients undergoing elective surgery suffer from inadvertent postoperative hypothermia, i.e., a core body temperature below 36°C. Compared to normothermic patients, these patients have more frequent wound infections (relative risk [RR] 3.25, 95% confidence interval [CI] 1.35–7.84), cardiac complications (RR 4.49, 95% CI 1.00–20.16), and blood transfusions (RR 1.33, 95% CI 1.06–1.66). Hypothermic patients feel uncomfortable, and shivering raises oxygen consumption by about 40%.
The Safe and Efficient Use of Forced-Air Warming Systems
Maintaining perioperative normothermia is important to ensure that a patient does not experience inadvertent hypothermia and its consequences, such as increased blood loss, cardiac abnormalities, prolonged recovery, and increased risk for wound infection. Many clinical guidelines recommend the use of forced-air warming as one of several techniques to prevent inadvertent perioperative hypothermia. Safe use of forced-air warming devices includes choosing the right device, assessing the patient for risks, protecting the patient from burn injuries, appropriately maintaining the patient’s body temperature, and using the device as directed by the manufacturer’s recommendations.