VN April 2023

Vetnuus | April 2023 8 Temperature An important priority for every anesthetist is to maintain normothermia. 31 A fall in body temperature, or hypothermia, is extremely common during anesthesia, but is of particular concern in young, growing animals, patients in poor body condition, and in small patients with a high body surface-to-mass ratio (Table 2). 17,30 Hypothermia can adversely affect the central nervous system, as well as the cardiopulmonary, gastrointestinal, and metabolic systems, resulting in a host of physiologic effects, including acidosis, bradypnea, decreasedminute ventilation and tidal volume, bradycardia, cardiac instability, and arrhythmia. 10,17,32 The minimum alveolar concentration (MAC) decreases as body temperature falls, and hypothermia also adversely affects the speed and quality of recovery. 2 Hypothermia can also directly influence surgical site healing. 33 Severe and prolonged hypothermia can even have potentially fatal consequences. 3,6,24 Body temperature is one of the simplest vital signs to monitor during anesthesia. 6 A rectal thermometer can be used; however, this measurement often underestimates core temperature and the readings from a standard thermometer may not go low enough for some reptile patients. 6 If a thermometer is used, monitor body temperature every 5 minutes. 17 Preferably core body temperature should be measured using an esophageal or rectal/cloacal temperature probe with continuous display (Fig 2). 2,6,9,24,31 If an esophageal temperature probe is used, gently advance the probe into the thoracic esophagus to avoid the cooling effects of respiratory gases. The probe should not be advanced past the level of the thoracic inlet as it could enter the stomach or crop and receive false readings from gastric contents or feed material. 6 Leading Article Categories Method Evaporative Clipping or plucking Surgical preparation Introduction of cold anesthetic gases Conductive Placement on cold surgical tables Convective Open body cavities Cold irrigation solutions Radiant Table 2. Causes of heat loss during the pre- and perianesthetic period 10 Figure 2: Rectal temperature probe placed in an anesthetized rat (Rattus norvegicus). Photo credit: Katrina Lafferty, CVT, VTS.