Effect of a heat and moisture exchanger on heat loss in isoflurane-anesthetized dogs undergoing single-limb orthopedic procedures.

OBJECTIVE

To determine whether a heat and moisture exchange device (HME) prevents a decrease in body temperature in isoflurane-anesthetized dogs undergoing orthopedic procedures.

DESIGN

Blinded randomized controlled clinical trial.

ANIMALS

60 privately owned dogs weighing at least 15 kg (33 lb).

PROCEDURES

Dogs were randomly assigned to 1 of 3 treatment groups (n = 20/group): HME placed immediately after anesthetic induction with isoflurane, after transfer to the operating room, or not at all. The device consisted of a hygroscopic filter placed between the endotracheal tube and the Y piece of the anesthesia circuit. Each dog was positioned on a circulating warm water blanket and had a forced-air warming blanket placed over its body. Body temperature was monitored after transfer to the operating room with a probe placed in the thoracic aspect of the esophagus.

RESULTS

Study groups did not differ significantly with respect to body weight, body condition score, reproductive status, breed, surgical procedure, preoperative sedative and opioid administration, anesthetic induction drug, local nerve block technique, or operating room assignment. There were no significant differences among groups in esophageal temperature variables, interval between anesthetic induction and surgery, surgery duration, anesthesia duration, or oxygen flow rate. However, the relationship between temperature delta and body weight was significant and relevant (R(2) = 0.23), as was the association between temperature nadir and body weight (R(2)= 0.10). As body weight increased, the temperature delta decreased and temperature nadir increased. No other significant relationships were identified.

CONCLUSIONS AND CLINICAL RELEVANCE

Inclusion of an HME in healthy dogs undergoing anesthesia for an elective orthopedic surgery did not facilitate maintenance of body temperature throughout the procedure.