Heated humidified breathing circuits help keep anesthetized dogs warm

Abstract

OBJECTIVE: To compare the effect of a circulating warm water blanket (WWB) in combination with a heated humidified breathing circuit (HHBC) heated to 45 &#xb0;C on rectal temperature (RT) in dogs undergoing general anesthesia for elective ovariohysterectomies. ANIMALS: 29 healthy dogs. PROCEDURES: Dogs in the experimental group (n = 8) and dogs in the control group (21) were connected to an HHBC and a conventional rebreathing circuit, respectively. All dogs were placed on a WWB in the operating room (OR). The RT was recorded at baseline, premedication, induction, transfer to OR, every 15 minutes during maintenance of anesthesia, and extubation. Incidence of hypothermia (RT < 37 &#xb0;C) at extubation was recorded. Data were analyzed using unpaired t tests, the Fisher exact test, and mixed-effect ANOVA. Statistical significance was defined as P < .05. RESULTS: There was no difference in RT during baseline, premedication, induction, and transfer to OR. The overall RT was higher for the HHBC group during anesthesia (P = .005) and at extubation (37.7 &#xb1; 0.6 &#xb0;C) compared with the control group (36.6 &#xb1; 1.0 &#xb0;C; P = .006). The incidence of hypothermia at extubation was 12.5% for the HHBC group and 66.7% for the control group (P = .014). CLINICAL RELEVANCE: The combination of HHBC and WWB can reduce the incidence of postanesthetic hypothermia in dogs. Use of an HHBC should be considered in veterinary patients.