Veterinary Anesthesia & Analgesia Support Group
Practical Information for the Compassionate Veterinary Practitioner
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Bob Stein

April 2011

   
 

 

   

Bob Stein

April 2011

     
     
   

Patient core body temperature drops quickly while under anesthesia which leads to peripheral vasoconstriction. Once this vasoconstriction occurs it is incrementally more difficult to regain lost core body temperature. Hypothermia leads to an increase in patient morbidity: lowered drug clearance, slower recoveries, increased risk of wound infection, increased risk of perioperative hemmorhage, and potentially unresponsive severe bradycardias. Although tissue oxygen demand declines during hypothermia, cardiac output and ventilation also decline leading to decreased tissue perfusion and oxygenation. Patient shivering during recovery is a known cause of patient discomfort. Shivering increases tissue oxygen demand which can be a significant problem for patients struggling to adequately provide tissue perfusion and oxygenation.

If you truly wish to maximize the stability of you patient’s core temperature you need to intervene early and you need to intervene effectively; you need a safe and effective patient warming system. Warm water blankets are safe but not particularly effective, especially if covered by towels or blankets. Microwaved rice and oat bags and simplistic electric blankets are extremely dangerous; they are capable of creating some of the most painful conditions; third degree burns; their use has to be considered grounds for medical negligence. The pictures above (mouse-over) are graphic reminders of the severity of the burns that can arise from improper supplemental heat methods.

Thermostatically controlled medical devices are available for patient warming without significant risks. Warm air devices and the Hot Dog® veterinary warming system are the most effective way to manage patient heat loss. Bair Huggers and Warm Touch devices are becoming more common in practice as older human equipment becomes available on the secondary equipment market.

The warm air systems purchased through the secondary market remain the most cost-effective option for a veterinary practice but they have their drawbacks: commercial blankets are not inexpensive, not washable, and reuse unattractive as they quickly pick up hair and other contaminants. The author has been successfully creating and using fabric blankets for over 8 years without adverse incident. Fabric blankets have long lifespans are easily laundered between patient use.

     
     
    Page References:
    Perioperative complications of hypothermia. Reynolds L, Beckmann J, Kurz A. Best Pract Res Clin Anaesthesiol. 2008 Dec;22(4):645-57. Review.
    Postanaesthetic shivering. Epidemiology, pathophysiology and approaches to prevention and management. Alfonsi P. Minerva Anestesiol. 2003 May;69(5):438-42. Review.
    Postoperative hemodynamic and thermoregulatory consequences of intraoperative core hypothermia. Kurz A, Sessler DI, Narzt E, Bekar A, Lenhardt R, Huemer G, Lackner F. J Clin Anesth. 1995 Aug;7(5):359-66.
     
     
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