Monitoring of Temperature During Anesthesia

Considerations for the measurement of core, skin and mean body temperatures

“…Given existing reviews on body-temperature measurement (Woodhead and Varrier-Jones, 1916;Selle, 1952;Vale, 1981;Togawa, 1985;Brengelmann, 1987;Sawka and Wenger, 1988;Fulbrook, 1993;Ogawa, 1997;Moran and Mendal, 2002;Ring, 2006;Byrne and Lim, 2007;Pušnika and Miklaveca, 2009;Wartzek et al, 2011;Langer and Fietz, 2014;Werner, 2014), another contribution might seem unwarranted. However, following a presentation designed for students (Taylor, 2011), and arising from a debate on the cooling of hyperthermic individuals (Casa et al, 2010), it became apparent the assumed common knowledge on temperature measurement was not quite so common, nor could its existence be presumed.…”

Routine Monitoring of Critically I11 Patients

“…Prior to inserting a rectal thermometer, a digital rectal exam should be performed because feces can blunt temperature measurement. Readings are more accurate when the sensor is passed more than 10 cm (4 inches) into the rectum [5]. Rectal temperature correlates well in most patients with distal esophageal, bladder, and tympanic temperatures [12,13].…”

“…A linearity error of up to 4° C may occur throughout the temperature range of 20 to 50° C but can be substantially reduced by mathematical adjustments or by placing a fixed resistance in parallel with the thermistor, which decreases its sensitivity and usable temperature range [4]. Thermistors are more sensitive, faster responding, less linear, and more costly than thermocouples or semiconductors [4,5]. Semiconductors measure temperature by taking advantage of the fact that the base-to-emitter voltage change is temperature dependent when the collector current of the silicon resistor is constant.…”

“…In this manner, the skin beneath the probe is isolated from ambient temperature changes and more directly reflects deep body temperature or core temperature [6,7]. Response time to changes in core temperature is about 10 minutes [7] but may be substantially longer in obese patients [5]. Inaccuracies during hypoperfusion have been reported [5].…”

“…Response time to changes in core temperature is about 10 minutes [7] but may be substantially longer in obese patients [5]. Inaccuracies during hypoperfusion have been reported [5]. Despite its convenience, this type of thermometer remains infrequently used in the clinical setting due to its cost, 30-minute warm-up time, and inadequate data on local variation of deep body temperature at different sites.…”