Normothermia

Normothermia

Objectives

• Verbalize the definition of normothermia
• Identify the VUMC Perioperative Goals for Surgical Patients and expectations
• Define normothermia terminology
• Recognize dangers of hypothermia
• Verbalize common risk factors and causes of hypothermia
• Alter practice to “make warm the norm”

Normothermia

Normothermia is a core temperature range between 36°C and 38°C (or 98.6°F and 100.4°F)

• Active Warming- application of a forced air convection warming system.
• Passive Warming – application of socks, head coverings, warmed blankets, or limiting skin exposure to ambient air.
• Ambient Temperature - The temperature of the surroundings.
• Hypothermia - Core temperature less than 36°C (96.8°F). “Hypothermia may be present regardless of temperature if the patient describes feeling cold or presents with common signs and symptoms of hypothermia, such as, shivering, peripheral vasoconstriction, and piloerection (goosebumps).”
• Normothermia - Core temperature range from 36°C - 38°C (96.8°F - 100.4°F).

Normothermia

Passive vs. Active Warming

Active Warming

Passive Warming

• Application of socks,
• Head coverings,
• Warmed blankets,
• Limiting skin exposure to ambient air

• Forced-air warming blankets,
• Intravenous fluid warming,

• and Circulating-Water Mattresses

Intrinsic Risk Factors for Hypothermia

Ambient room temperature

Preexisting conditions

Extremes of ages

Female sex

Cachexia

Use of cold irrigants

Use of regional anesthesia

Significant fluid shifts

Use of general anesthesia

Perioperative Risk Factors for Hypothermia

Use of general or regional anesthesia

• Medication-induced inhibition of thermoregulation and vasodilation
• Decreased metabolic heat production
• Loss of heat from lungs when un-warmed gases are used
• Administration of un-warmed IV fluids

Perioperative Risk Factors for Hypothermia

• Duration and type of surgical procedure
• Significant fluid shifts
• Use of cold irrigation
• Redistribution of heat within the body
• Low ambient room temperature
• Increased environmental heat loss (exposure of body cavities to room temperature air)

Preoperative Patient Management

Assessment

Interventions

• Use preventive warming measures for patients who are normothermic utilizing an active warming device and warm to patient’s thermal comfort.
• Passive measures may be used in conjunction with active measures.
• Increase in ambient temperature (minimum 20°C - 24°C or 68°F - 75°F).
• Institute active warming measures for patients who are hypothermic.

• Apply passive and active measures.
• Increase the ambient room temperature (minimum 20°C-24°C or 68°F - 75°F).
• Consider warmed IV fluids.

• Obtain baseline temperature (tympanic reading is preferred) .
• Identify patient’s risk factors for unplanned perioperative hypothermia.
• Assess for other signs and symptoms of hypothermia (shivering, piloerection, and/or cold extremities).

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Hypothermia Prevention Intra-op

Intraop Interventions include:

• Maintaining ambient room temperature settings between 68°F and 75°F.
• Room temperature may be adjusted during case only if the patient's core temperature is greater than 36.5°C.
• Anesthesia records temperature during the case, but we all monitor patient temperature to ensure the patient is normothermic!
• Forced-air warming (at 40°C prior to induction and prep) should be utilized during induction of general anesthesia, paused for skin prep, and reinitiated as soon as draping is completed.
• Patient exposure should be minimized as much as possible during and after induction, utilizing the Bair Paws gown until Bair Hugger devices are applied.
• Upper and lower forced air warming devices should be applied whenever the case permits.
• Patient should be covered with Bair Hugger(s) prior to skin prep to avoid air turbulence over the prepped area.
• Draping should be completed prior to activating the forced-air warming to avoid air turbulence over the prepped area.
• Warm fluids: Intravenous and irrigants.
• Humidify and warm anesthetic gases.
• Remove all wet linens before transfer to PACU.

Did You Know

Hypothermia Prevention in the Recovery Room

• The preferred method for temperature measurement for adults in Perioperative Services is temporal scanner or tympanic on admission, within 15 minutes of arrival to recovery.

• Identify patient’s risk factors for unplanned perioperative hypothermia.
• If hypothermic, monitor serial temperatures at a minimum of every 15 minutes until normothermia is achieved.
• If normothermic, assess temperature again prior to discharge.
• Determine patient’s thermal comfort level (ask the patients if they are cold).
• Assess for signs and symptoms of hypothermia (shivering, piloerection, and/or cold extremities

Hypothermia Prevention in the Recovery Room

PACU Interventions for Hypothermia

Initiate warming measures:

• Apply forced air warming system.
• Apply passive insulation: warm blankets, socks, head covering, and limited skin exposure.
• Heat lamps.
• Increase ambient room temperature (at or above 21°C or 69.8°F).
• Nurses contact Anesthesia Provider or Attending Physician if patient core temperature is < 36°C after 30 minutes of active warming measures as listed above.

Signs of Hypothermia

• Shivering,
• Piloerection,
• and/or Cold Extremities

Let's Talk: Forced-Air Warming Devices

• Any heat-regulating device should be used according to the manufacturer’s recommendations.

• Skin integrity should be assessed before, periodically during (when possible), and after use of interventions such as ice packs and temperature-regulating blankets.

Key Points

• Normothermia reduces negative outcomes for perioperative patients.
• Normothermia optimizes wound healing and recovery time.
• Normothermia prevents extended hospitalization (thereby reducing costs and increasing patient satisfaction).

References:

SOP: Normothermia