3265 Biddle Road
Medford, OR 97504
Phone: 541-282-7711
Fax: 541-282-7999

Perioperative hypothermia is a common but treatable complication of general anesthesia.  Hypothermia can cause altered hepatic,cardiac and renal function, as well as affect coagulation and wound healing.

Causes of Hypothermia:

Hypothermia is defined as a decrease in normal body temperature.  The normal canine and feline temperature range is between 100.0-102.5F.  There are multiple causes and predisposing factors that result in perioperative hypothermia.  Preoperative causes of hypothermia include prolonged patient preparation time, insufficient patient warming techniques and general anesthesia.  Intraoperative causes include open thoracic or abdominal surgery and cold IV fluids or lavage fluids.  Often, the surgical suite is kept at a low temperature which can also contribute to patient hypothermia.  The length of anesthesia and longer surgical procedures increase the likelihood and severity of hypothermia.  It has been documented in human literature that postoperative hypothermia has been correlated with an increase in mortality in human patients.

Consequences of Hypothermia:

Hypothermia causes a reduction in hepatic metabolism which in turn may prolong the actions of the anesthetics used.  Cardiovascular effects of hypothermia include changes in heart rate, blood pressure and can lead to arrhythmias.  Renal function can be altered causing a cold diuresis in mild-moderate hypothermia and acute renal tubular necrosis with severe hypothermia.  Mild hypothermia can cause an increase in blood loss during surgery, resulting in an increased need for blood transfusions.  Hypothermia can cause a  decrease in coagulation factor activity and platelet aggregation resulting in prolonged bleeding times and may predispose patients to DIC.

Patient Monitoring:

Patient monitoring is key in being able to evaluate and manage hypothermia.  Rectal or esophageal probes are the most accurate methods available to properly evaluate a patient’s body temperature.  Auricular thermometers made for humans are not accurate in our veterinary patients.  There are auricular thermometers now available for animals which are clinically proven accurate but are fairly expensive.

Blankets placed over the patient and between the patient and the surgery table or cage can decrease heat loss by approximately 30%.  Forced air warming blankets such as Bair Huggers are an excellent way to minimize further heat loss.  Warm peritoneal lavage or pleural lavage (warmed to 104-109F), warm IV fluids (warmed to 104-108F), warm water enemas can be used to further minimize hypothermia.

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