- Warm hypothermic MWDs rapidly but carefully. Anticipate possible complications. Cardiovascular support (principally IV fluid therapy), management of co-existing problems, and prevention of rewarming complications are necessary (See Table 13).
- Rewarm MWDs at a target rate of increase of 2-4° F per hour.
- Use a combination of methods based on the severity of hypothermia and the MWD’s status.
- Rewarm MWDs with mild hypothermia and normovolemia using passive surface warming. Apply external blankets, towels, or other devices to prevent heat loss while the animal ‘self-generates’ heat. These measures will not be effective as sole measures if shivering is absent.1
- Rewarm MWDs with moderate hypothermia using active surface warming.
- Use externally-applied heat sources such as forced-air devices, warm water bottles, or warm-water circulating heating pads to provide heat to offset the patient’s inability to generate heat.
- Provide IV fluid volume support to maintain normotension and prevent rewarming shock (See CPG 6, Figure 33).
- Apply heat to the thorax and abdomen, and not the extremities, as this avoids peripheral vasodilatation and prevents the decreased thermoregulatory response seen when extremities are warmed, both of which contribute to persistent hypothermia and “afterdrop.”1,5
- Rewarm MWDs with severe or profound hypothermia using active core warming.
- Always use active surface warming concurrently with active core warming.1
- Use warmed IV fluids. The temperature of intravenous fluids should not exceed 108° F to avoid injury to cellular components of the peripheral blood.1,5
- If the MWD is intubated and warming humidifiers are available on anesthesia circuits, use warmed inhaled air.
- Given potential complications with use, HCPs should not use warm peritoneal or pleural lavage or urinary bladder or rectal lavage with warmed fluids.
- Warm hypothermic MWDs to a temperature of 98.5° F, and then cease use of all warming methods except passive warming, while providing blood volume support (i.e., IV fluids) at relatively moderate rates to avoid volume overload (10-15 mL/kg/h) that is possible due to earlier cold diuresis 1,5 in hypothermic MWDs being rewarmed.
Table 13. Management of Hypothermia