Effect of insulation with bubble wrap and an absorbent pad on heat loss in anaesthetised cats

Effect of a single intravenous injection of branched chain amino acids on body temperature of cats undergoing general anesthesia

OBJECTIVE

To evaluate the effect of a single intravenous injection of branched chain amino acids (BCAAs) on body temperature in cats undergoing general anesthesia.

STUDY DESIGN

Prospective, blinded, randomized, crossover, experimental study.

ANIMALS

A total of 10 healthy adult cats (five female and five male).

METHODS

Cats were anesthetized three times with three different treatments in a random order: 3 mL kg-1 lactated Ringer's solution (LRS), 100 mg kg-1 BCAAs (B100) or 200 mg kg-1 BCAAs (B200) solution immediately before induction of anesthesia. After induction, rectal temperature was measured every 5 minutes. Blood samples were collected for the measurement of blood glucose (BG) just before induction, at the end of the 90 minute period of anesthesia, and 24 hours after anesthesia induction. The differences between baseline and each subsequent rectal temperature, and BG measurements were analyzed. Areas under the curve (AUCs) for temperature differences were calculated for each animal for the anesthetic period (AUCT0-90). Parametric or nonparametric data were analyzed by one-way repeated measures anova or Friedman test. A value of p < 0.05 was considered significant.

RESULTS

There were no significant differences in AUCT0-90 between groups: 41.6 ± 7.7 for LRS, 43.4 ± 6.9 for B100 and 42.9 ± 7.5 for B200 (p = 0.368). No significant differences were observed in BG between groups at 90 minutes and 24 hours after anesthesia induction (p = 0.283 and p = 0.089, respectively). The incidence of hypoglycemia [BG ≤ 3.17 mmol L-1 (57 mg dL-1)] after anesthesia tended to be higher in both B100 (4/10 cats) and B200 groups (3/10 cats) than in LRS group (1/10 cats).

CONCLUSIONS AND CLINICAL RELEVANCE

A single, preanesthetic intravenous injection of BCAAs did not attenuate heat loss during anesthesia. More cats were hypoglycemic in the BCAA groups than in the LRS group.

Effects of peripheral active warming and passive insulation on core body temperature during feline ovariohysterectomy: a multi-arm randomized clinical trial

OBJECTIVES

Hypothermia is a common complication of anesthesia, particularly in cats. Some veterinarians insulate the extremities of cats as a preventive measure, and there is evidence that heating the extremities of dogs decreases the rate of heat loss from the core. This study investigated whether active warming or passive insulation of the extremities of cats resulted in a slower decrease in rectal temperature during anesthesia.

METHODS

Female cats were assigned via block randomization to passive (cotton toddler socks), active (heated toddler socks) or control group (uncovered extremities). Rectal temperature was monitored every 5 mins from induction through return to trap/carrier (final temperature). Multivariable linear regression models were used to compare temperature (rate change and final) between groups.

RESULTS

There were 164 cats with 1757 temperature readings. Mean total duration of anesthesia was 53 ± 13 mins. The temperature of all groups decreased linearly over time (all P <0.0001), with the rates of temperature decrease being -0.039°F/min (95% confidence interval [CI] -0.043 to -0.035)/-0.022°C (95% CI -0.024 to -0.019), -0.039°F/min (95% CI -0.042 to -0.035)/-0.022°C (95% CI -0.023 to -0.019) and -0.029°F/min (95% CI -0.032 to -0.025)/-0.016°C (95% CI -0.018 to -0.014) for the control, passive and active groups, respectively. The control, passive and active groups had median final temperatures of 98.4°F (interquartile range [IQR] 97.6-99.4)/36.9°C (IQR 36.4-37.4), 98.0°F (IQR 97.2-98.7)/36.7°C (IQR 36.2-37.1) and 99.1°F (IQR 97.7-100.0)/37.3°C (IQR 36.5-37.8), respectively. After controlling for weight, postinduction temperature and duration of anesthesia, and as compared with controls, the final temperature of the active group was predicted to be 0.54°F (95% CI 0.03-1.01)/0.3°C (95% CI 0.02-0.56) greater (P = 0.023), while the passive group was not significantly different (P = 0.130).

CONCLUSIONS AND RELEVANCE

The rate of rectal temperature decrease was significantly slower for the active group compared with the other groups. Although the cumulative difference in final temperature reading was modest, superior materials might enhance performance. Cotton toddler socks alone did not slow the rate of temperature decrease.

Effect of an Insulation Device in Preventing Hypothermia during Magnetic Resonance Imaging Examinations for Dogs and Cats under General Anesthesia

Simple Summary

Magnetic resonance imaging examinations require general anesthesia, and it is difficult to prevent a decrease in body temperature because a machine for warming the body cannot be placed in the magnetic resonance imaging room, which must have a low room temperature. In this study, we created a heat insulating device that does not affect magnetic resonance imaging and examined the effectiveness of this device for dogs and cats undergoing magnetic resonance imaging examinations. In the dogs and cats wearing bubble wrap and down cloth blanket, the decrease in body temperature was minimal. The heat insulating device developed in this study protected the animals from the cold air and prevented heat loss from the body surface, minimizing a decrease in body temperature. The results obtained in this study suggest that dogs and cats requiring magnetic resonance imaging can be protected from hypothermia due to general anesthesia without the need for special machinery.

Abstract

Dogs and cats under general anesthesia may develop hypothermia. When performing a magnetic resonance imaging (MRI) examination, it is not possible to place a magnetic material in the MRI room, and MRI equipment requires a low room temperature. This study investigated the effectiveness of a heat insulating device that prevented hypothermia during MRI examinations in dogs and cats. The animals that underwent MRI examinations under general anesthesia were divided into control groups (no covering) and heat insulating groups (wearing bubble wrap and down cloth blankets), and their body temperatures were measured before and after the MRI examinations. The changes in body temperatures were as follows: control dogs (n = 17), median of −1.0 (from −2.5 to 0.3) °C; heat insulated dogs (n = 7), −0.3 (from −0.8 to 0.2) °C; control cats (n = 14), −1.85 (from −2.7 to −0.6) °C; and heat insulated cats (n = 12), −0.8 (from −1.5 to −0.1) °C. These results revealed that the bubble wrap and down cloth blanket significantly prevented hypothermia and heat loss from the body surface during MRI examinations of dogs and cats.