Suman Saini, DA, DNB
Assistant professor, Department of Anesthesiology & Intensive Care, Vardhman Mahaveer Medical College & Safdarjung Hospital, New Delhi – 110029 (India); Phone: 09891228793; E-mail: firstname.lastname@example.org
Hypothermia is defined as a core temperature of <35 °C.1 Pediatric patients undergoing surgery are more susceptible to UPH since they have less effective thermoregulatory capacity.2,3 This susceptibility also results because of greater body surface area to volume ratio and minimal insulating subcutaneous tissue layer which leads to less heat production and increased heat loss compared to adults. Upto 20% of the patients experience unintended perioperative hypothermia.4 Thermoregulatory system is affected from the very onset of anesthesia with the fastest fall in temperature occurring during the initial period. This makes hypothermia a real possibility, even for short surgical procedures.
A number of methods are being used to prevent hypothermia in pediatric population. Operating room (OR) temperatures of 27 °C and 29 °C are recommended for full term and premature newborns respectively.5 Forced air warmers are one of the most effective means of warming a patient and are best used perioperatively to prevent hypothermia. Other warming modalities aim to prevent radiant heat transfer include circulating hot water blankets and warm cotton blankets. Use of warming mattresses reduces conductive heat loss. Radiant heaters are used during induction of anesthesia and insertion of catheters until the patient is prepared and draped.3 Fluid warmers are commonly used in OR and are recommended whenever blood or large amount of intravenous fluids are administered. In developing countries like ours, many of the above mentioned warming devices may not be available due to lack of priorities or resources.
Keeping this aspect in mind, we developed a simple and economical method to warm the neonates. We use four or five hot (47-48 °C) IV infusion bottles of any type, keep a baby receiving metallic tray (inverted) over these bottles at least 15 minutes prior to the baby is shifted to OR. A cotton layer is spread over the tray. By the time, neonate is received in OT, the whole assembly is warm. Infant is placed over this and again wrapped in cotton after induction of anesthesia. In this way neonates is prevented from hypothermia for 90-120 min. We measured patient’s baseline axillary temperature before induction of anesthesia to be in the range of 36.1-36.6 °C in majority of the neonates. Oral temperature probe (Drager Infinity Vista XL) was used to measure temperatures every 15 min from induction of anesthesia till the completion of surgery. Observed fall in temperature was not more than 0.6-0.9 °C in all the patients at the end of surgery.
- Keatinge WR. Cold, drowning and seasonal mortality. In: Warrel DA, Cox TM, Firth JD, Benz JE, editors. Online Oxford Textbook of Medicine. 4th ed. Oxford (UK): Oxford University Press; 2003.
- Galante D. Intraoperative hypothermia. Relation between general and regional anesthesia, upper- and lower-body warming: what strategies in pediatric anesthesia? Paediatr Anaesth 2007;17:821-82 [PubMed]
- Tander B, Baris S, Karakaya D, Ariturk E, Rizalar R, Bernay F. Risk factors influencing inadvertent hypothermia in infants and neonates during anesthesia. Paediatr Anaesth 2005;15:574-579. [PubMed]
- Kurz A. Physiology of thermoregulation. Best Pract Res Clin Anaesthesiol 2008;22(4):627-644. [PubMed]
- Luginbuehl I,Bissonette B, Davis PJ. Thermoregulation: Physiology and Perioperative Disturbances. In : Motoyama EK, Davis PJ, editors. Smith’s Anesthesia for Infants and Children, 7th edition. Mosby Elesvier; 2006.