Cold critters: Assessing, preventing, and treating hypothermia - Veterinary Medicine
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Cold critters: Assessing, preventing, and treating hypothermia
You've likely seen many solutions for rewarming hypothermia patients, but which method is best in which situation? This specialst provides guidance and helps you avoid complications.


VETERINARY MEDICINE


COMPLICATIONS OF REWARMING

Rewarming complications are common. After-drop describes the phenomenon characterized by a continued decrease in core body temperature after the onset of rewarming. Cold blood from the body's periphery returns to the core while warmed core blood moves to the periphery.5,8

Rewarming shock is a condition caused by rapid rewarming that induces vasodilation and places great metabolic demands on affected patients, both of which may readily overwhelm an already compromised circulatory system.5,9

Cats with hypovolemic shock will frequently present with three distinct clinical signs: hypothermia, hypotension, and bradycardia.5 Indeed, this constellation of signs is profound, is indicative of a life-threatening disease, and is anecdotally referred to as the triad of death. Previous research documented altered adrenergic reactivity in hypothermic cats.10 With effective treatment of hypothermia, adrenergic reactivity and vascular responsiveness are restored; thus, patients treated with large volumes of crystalloids are at risk for hypervolemia and pulmonary edema. Conservative fluid therapy with concurrent aggressive rewarming is an essential part of shock resuscitation therapy in hypothermic cats to help avoid the development of pulmonary edema.

CONCLUSION

Hypothermia is a lowering of the body's temperature. The body's ability to reestablish normothermia lessens and is ultimately abolished with progressive hypothermia. As body core temperature drops, multiple body systems suffer from the effects of the reduced temperature.

The primary treatment goal for hypothermic patients is to reestablish a normal core body temperature through passive surface, active surface, or active core rewarming interventions. To achieve a successful outcome, be prepared to monitor for and treat complications of both hypothermia and rewarming interventions. For a case example of how to treat hypothermia, see Rewarming a stray kitten.

Christopher G. Byers, DVM, DACVECC, DACVIM (small animal internal medicine)
MidWest Veterinary Specialty Hospital
9706 Mockingbird Drive
Omaha, NE 68127

REFERENCES

1. Greer RJ, Cohn LA, Dodam JR, et al. Comparison of three methods of temperature measurement in hypothermic, euthermic, and hyperthermic dogs. J Am Vet Med Assoc 2007;230:1841-1848.

2. Sousa MG, Carareto R, Pereira-Junior VA, et al. Comparison between auricular and standard rectal thermometers for the measurement of body temperature in dogs. Can Vet J 2011;52:403-406.

3. Franklin MA, Rochat MC, Payton ME, et al. Comparison of three intraoperative patient warming systems. J Am Anim Hosp Assoc 2012;48:18-24.

4. Frank SM, Fleisher LA, Breslow MJ, et al. Perioperative maintenance of normothermia reduces the incidence of morbid cardiac events. A randomized clinical trial. JAMA 1997;277:1127-1134.

5. Oncken A, Kirby R, Rudloff E. Hypothermia in critically ill dogs and cats. Compend Contin Educ Pract Vet 2001;23:506-521.

6. Armstrong SR, Roberts BK, Aronsohn M. Perioperative hypothermia. J Vet Emerg Crit Care 2005;15:32-37.

7. Gentilello LM, Moujaes S. Treatment of hypothermia in trauma victims: thermodynamic considerations. J Intensive Care Med 1995;10:5-14.

8. Reuler JB. Hypothermia: pathophysiology, clinical settings, and management. Ann Intern Med 1978;89:519-527.

9. Bessen H. Hypothermia. In: Tintinalli J, Kelen G, Stapczynski J, eds. Emergency medicine. 5th ed. New York City: McGraw-Hill, 2000;1231-1235.

10. Kitagawa H, Akiyama T, Yamazaki T. Effects of moderate hypothermia on in situ cardiac sympathetic nerve endings. Neurochem Int 2002;40:235-242.


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