Accidental hypothermia

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

moderate or severe hypothermia in cardiac arrest: ≤32°C (≤90°F)

1st line – cardiopulmonary resuscitation (CPR) ± advanced life support

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1st line –

cardiopulmonary resuscitation (CPR) ± advanced life support

Check for vital signs (including a carotid pulse) for up to 1 minute and get urgent support from the critical care team.[24][4]

Be aware that vital signs may be very difficult to detect in a patient with hypothermia, especially in the pre-hospital setting; a very hypothermic patient may appear dead but still survive with resuscitation.[24][4]
Where possible, ECG monitoring, end-tidal CO ₂, and ultrasound should also be used to detect cardiac arrest.[24][4]
- I f you cannot feel a pulse and the patient has an organised rhythm on ECG monitoring, this may be pulseless electrical activity, or a perfusing rhythm with very weak pulses.[4]
- Do not start CPR in a patient with an organised, perfusing rhythm because this can risk conversion to ventricular fibrillation (a non-perfusing rhythm).[4]

Start CPR promptly and continue it without interruption if:

You cannot detect vital signs after 1 minute[24][4]
and/or
A non-perfusing rhythm such as ventricular tachycardia, ventricular fibrillation, or asystole can be detected on ECG monitoring.[24]

Chest compressions and ventilation rate should generally follow the same advanced life support algorithm as for a normothermic patient (using a compression-to-breath ratio of 30:2 for adults).[24][4][33]

However, there are key differences in CPR for a patient with hypothermia:[24]

If the patient’s core temperature is <30℃ (<86℉):[24]
- And they are in ventricular fibrillation which persists after three shocks, do not give further shocks until their core temperature is >30℃ (>86℉)
- Do not give adrenaline (epinephrine) or other vasoactive drugs
If the patient’s core temperature is >30℃ (>86℉):[24]
- Double the intervals for administration of vasoactive drugs compared with those for a normotheric patient.
- Follow cardiac arrest algorithms as for a normothermic patient.[4]
In the pre-hospital setting:[24]
- If the patient’s core temperature is <28℃ (<82.4℉), delay CPR if it is too dangerous or not possible in the current setting; consider using intermittent CPR if continuous CPR is not possible.
- Use a mechanical CPR device, if available, particularly if the patient has a long transfer to hospital or the terrain is difficult.[4]

Consider withholding or terminating CPR if:

There are obvious signs of irreversible death (e.g., decapitation, frozen chest wall that is not compressible, ice in the airway)[24]
The patient has a valid ‘Do Not Attempt CPR’ (DNACPR) decision in place[24]
The patient has been buried in an avalanche for >60 minutes, has evidence of an obstructed airway (e.g., airway packed with snow), and is in asystole[24]
In the pre-hospital setting, conditions are unsafe for the rescuers.[24]

Transfer any patient who is in cardiac arrest, or is at risk of imminent cardiac arrest, to an extracorporeal life support (ECLS) centre for re-warming if possible.[24]

Patients are at risk of imminent cardiac arrest if they have any of the following:[24]
- Core temperature <30℃ (<86℉), or <32℃ (<89.6℉) if the patient is frail with multiple comorbidities
- Ventricular arrhythmia
- Systolic blood pressure <90 mmHg
If an ECLS centre cannot be reached within 6 hours, non-ECLS re-warming should be started in a peripheral hospital.[24]

In hospital, use the HOPE (Hypothermia Outcome Prediction after ECLS re-warming for hypothermic arrested patients) or ICE score to estimate the patient’s prognosis and aid decision-making around ECLS.[24] HOPE score Opens in new window In practice, these scores should be used in combination with discussion with the multidisciplinary team (which should include critical care).

Note that the Wilderness Medical Society and the International Alpine Commission recommend withholding or terminating CPR if the patient’s potassium level is >12 mmol/L (12 mEq/L); hyperkalaemia is associated with a poor prognosis.[4][34][35] However, the European Resuscitation Council (ERC) does not recommend using potassium levels to estimate a patient’s prognosis (even when combined with measurement of core temperature) because the ERC deems this unreliable. Instead the ERC recommends HOPE or ICE to estimate prognosis.[24]

Plus – supportive care

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Plus –

supportive care

Treatment recommended for ALL patients in selected patient group

Get urgent support from the critical care team for any patient with severe hypothermia.

Move the patient very carefully and keep them in a supine position. This is crucial, because movement can precipitate ventricular fibrillation, especially if the patient’s temperature is <28℃ (<82.4℉).[4]

Remove the patient's wet and cold clothing and insulate them (e.g., with warm blankets).

Secure the patient’s airway with an advanced airway (e.g., tracheal tube or supraglottic airway device).[4] Advanced airway placement should be attempted only by those with appropriate training and experience.[24][33]

Place a nasogastric or orogastric tube to decompress the stomach and allow placement of an oesophageal temperature probe.[4]
Ventilate the patient at half the standard normothermic rate.[4]

Practical tip

Be aware that intubation can cause ventricular fibrillation (VF) if the patient has severe hypothermia.[3][4] However, this risk is small and the benefits of intubation outweigh the risk of VF.[3][4]

If the patient is hypoglycaemic, give glucose.[4] Hypoglycaemia can stop shivering (because the central control of shivering is dependent on glucose), leading to subsequent heat loss.[29]

Do not give insulin initially if the patient is hyperglycaemic; hyperglycaemia has not been shown to be detrimental to patients with hypothermia.[4]

Instead, monitor the patient’s glucose level closely. In practice, start treatment for hyperglycaemia if their glucose level is rising, there is associated ketosis, or if hyperglycaemia persists once the patient has been successfully re-warmed.
However, if the patient has type 1 diabetes and is hyperglycaemic, do not delay giving insulin as usual; seek expert advice on the insulin dose and timing.

Monitor the patient’s core temperature and haemodynamic status continuously during re-warming.[4]

In practice, the rate of re-warming for a patient in cardiac arrest or undergoing extracorporeal life support requires a tailored approach by a specialist.
Heat redistribution within the body can cause a continued fall in core temperature after removing the patient from a cold environment.
Avoid hyperthermia during and after re-warming.[38]
The patient will also require large volumes of fluids because vasodilation during re-warming causes expansion of the intravascular space. Infusing warmed intravenous fluid also offers an additional advantage of improved absorption of administered drugs.

In addition, monitor:

Other vital signs:
- Pulse rate
- Blood pressure
- Respiratory rate
- Oxygen saturations
Blood gases
- Ensure resolution of hypoxia and normalisation of pH.
End-tidal CO ₂ if the patient is intubated.

Plus – humidified oxygen

Plus – warmed intravenous fluids

Back

Plus –

warmed intravenous fluids

Treatment recommended for ALL patients in selected patient group

Give warm intravenous fluids using normal saline solution, especially once re-warming measures have been started, and titrate the fluids according to the patient’s heart rate and blood pressure. This helps to prevent heat loss but does not actively re-warm the patient.[4]

Obtain intravenous access using a peripheral intravenous cannula.[4] If this is not immediately possible, use intraosseous access instead.[4]
Warm intravenous/intraosseous fluids to 38℃ to 42℃ (100℉ to 107.6℉).[24] This temperature range is used in practice in the UK and is recommended by the European Resuscitation Council. However, the Wilderness Medical Society recommends warming fluids to a slightly higher temperature of at least 40℃ (104℉), and preferably 42℃ (107.6℉).[4] Check your local protocols.
Do not give Hartmann’s solution (also known as Ringer’s lactate) to a patient with hypothermia because their liver will be unable to metabolise lactate.[4]
Monitor the patient carefully for signs of fluid overload and volume depletion.[4] The patient is likely to require large volumes of fluids because vasodilation during re-warming causes expansion of the intravascular space.

Plus – extracorporeal life support (ECLS) re-warming

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Plus –

extracorporeal life support (ECLS) re-warming

Treatment recommended for ALL patients in selected patient group

If the patient is in cardiac arrest, use ECLS re-warming as the preferred method of active internal re-warming.[24]

In hospital, use the HOPE (Hypothermia Outcome Prediction after ECLS re-warming for hypothermic arrested patients) or ICE score to estimate the patient’s prognosis and aid decision-making around ECLS.[24] HOPE score Opens in new window In practice, use HOPE or ICE score in combination with discussion with the multidisciplinary team (which should include critical care).
ECLS re-warming should be performed preferably with extracorporeal membrane oxygenation (ECMO) over cardiopulmonary bypass (CPB).
ECLS re-warming provides sufficient circulation and oxygenation while the core body temperature is increased by 8°C to 12°C (14°F to 22°F), and increases core temperature by 1°C to 2°C (1.8°F to 3.6°F) every 3-5 minutes.[37][38]
ECLS requires heparinisation.[24]

Consider – haemofiltration

moderate or severe hypothermia not in cardiac arrest: ≤32°C (≤90°F)

1st line – supportive care

Back

1st line –

supportive care

Remove the patient's wet and cold clothing and insulate them (e.g., with warm blankets).

Place a nasogastric or orogastric tube to decompress the stomach and allow placement of an oesophageal temperature probe.[4]
Ventilate the patient at half the standard normothermic rate.[4]

Practical tip

Be aware that intubation can cause ventricular fibrillation (VF) if the patient has severe hypothermia.[3][4] However, this risk is small and the benefits of intubation outweigh the risk of VF.[3][4]

Manage any cardiac arrhythmias.[4] See our topic Overview of dysrhythmias (cardiac).

All arrhythmias apart from ventricular fibrillation (particularly atrial arrhythmias) are likely to improve without treatment as the patient’s core temperature increases.[24][4] However, if the patient has bradycardia and hypotension that is disproportionate to their hypothermia, organise transcutaneous pacing.[4]

If the patient is hypoglycaemic, give glucose.[4] Hypoglycaemia can stop shivering (because the central control of shivering is dependent on glucose), leading to subsequent heat loss.[29]

Do not give insulin initially if the patient is hyperglycaemic; hyperglycaemia has not been shown to be detrimental to patients with hypothermia.[4]

Instead, monitor the patient’s glucose level closely. In practice, start treatment for hyperglycaemia if their glucose level is rising, there is associated ketosis, or if hyperglycaemia persists once the patient has been successfully re-warmed.
However, if the patient has type 1 diabetes and is hyperglycaemic, do not delay giving insulin as usual; seek expert advice on the insulin dose and timing.

Monitor the patient’s core temperature and haemodynamic status continuously during re-warming.[4]

In practice (unless the patient is in cardiac arrest and/or undergoing extracorporeal life support as this requires a tailored approach by a specialist), aim to re-warm the patient at a rate of 0.5℃ to 2℃ (0.9℉ to 3.6℉) per hour.
Heat redistribution within the body can cause a continued fall in core temperature after removing the patient from a cold environment.
Avoid hyperthermia during and after re-warming.[38]
The patient will also require large volumes of fluids because vasodilation during re-warming causes expansion of the intravascular space. Infusing warmed intravenous fluid also offers an additional advantage of improved absorption of administered drugs.

In addition, monitor:

Other vital signs:
- Pulse rate
- Blood pressure
- Respiratory rate
- Oxygen saturations
Blood gases
- Ensure resolution of hypoxia and normalisation of pH.
End-tidal CO ₂ if the patient is intubated.

Plus – humidified oxygen

Plus – warmed intravenous fluids

Back

Plus –

warmed intravenous fluids

Treatment recommended for ALL patients in selected patient group

Obtain intravenous access using a peripheral intravenous cannula.[4] If this is not immediately possible, use intraosseous access instead.[4]
Warm intravenous/intraosseous fluids to 38℃ to 42℃ (100℉ to 107.6℉).[24] This temperature range is used in practice in the UK and is recommended by the European Resuscitation Council. However, the Wilderness Medical Society recommends warming fluids to a slightly higher temperature of at least 40℃ (104℉), and preferably 42℃ (107.6℉).[4] Check your local protocols.
Do not give Hartmann’s solution (also known as Ringer’s lactate) to a patient with hypothermia because their liver will be unable to metabolise lactate.[4]

Monitor the patient carefully for signs of fluid overload and volume depletion.[4] The patient is likely to require large volumes of fluids because vasodilation during re-warming causes expansion of the intravascular space and subsequent hypotension.

In practice, vasoactive drugs are generally avoided when managing hypotension in a patient with significant hypothermia, unless the hypotension is due to other causes (e.g., sepsis) or in highly specialist scenarios (e.g., if the patient is undergoing extracorporeal life support). Always seek urgent advice from the critical care team before giving vasoactive drugs. If indicated, vasoactive drugs should be withheld until the patient’s core temperature is at least ≥30°C (≥86°F).[24][4]

Plus – active external re-warming

Plus – active internal re-warming

Back

Plus –

active internal re-warming

Treatment recommended for ALL patients in selected patient group

Active internal (also known as active core) re-warming is the most aggressive strategy. Use active internal re-warming alone or in combination with active external re-warming.

Take a step-wise approach:

Irrigation with warm saline (lavage), which can be peritoneal, pleural, gastric, bladder, or colonic.[3][15][37][39][40] In UK practice, bladder lavage is commonly used because it is less invasive than the other techniques.
ECLS re-warming (if the patient has cardiac instability that is refractory to medical management).[24]

ECLS re-warming should be performed preferably with extracorporeal membrane oxygenation (ECMO) over cardiopulmonary bypass (CPB).[24]

ECLS re-warming provides sufficient circulation and oxygenation while the core body temperature is increased by 8°C to 12°C (14°F to 22°F), and increases core temperature by 1°C to 2°C (1.8°F to 3.6°F) every 3-5 minutes.[37][38]
ECLS requires heparinisation.[24]

Consider – haemofiltration

mild hypothermia: >32°C to 35°C (>90°F to 95°F)

1st line – passive external re-warming

Plus – supportive care

Back

Plus –

supportive care

Treatment recommended for ALL patients in selected patient group

If the patient cannot maintain or protect the airway, secure it using an advanced airway (e.g., tracheal tube or supraglottic airway device).[4] Advanced airway placement should be attempted only by those with appropriate training and experience.[24][33]

Place a nasogastric or orogastric tube to decompress the stomach and allow placement of an oesophageal temperature probe.[4]
Ventilate the patient at half the standard normothermic rate.[4]

Practical tip

Be aware that intubation can cause ventricular fibrillation (VF) if the patient has severe hypothermia.[3][4] However, this risk is small and the benefits of intubation outweigh the risk of VF.[3][4]

Manage any cardiac arrhythmias.[4] See our topic Overview of dysrhythmias (cardiac).

All arrhythmias apart from ventricular fibrillation (particularly atrial arrhythmias) are likely to improve without treatment as the patient’s core temperature increases.[24][4] However, if the patient has bradycardia and hypotension that is disproportionate to their hypothermia, organise transcutaneous pacing.[4]

If the patient is hypoglycaemic, give glucose.[4] Hypoglycaemia can stop shivering (because the central control of shivering is dependent on glucose), leading to subsequent heat loss.[29]

Do not give insulin initially if the patient is hyperglycaemic; hyperglycaemia has not been shown to be detrimental to patients with hypothermia.[4]

Instead, monitor the patient’s glucose level closely. In practice, start treatment for hyperglycaemia if their glucose level is rising, there is associated ketosis, or if hyperglycaemia persists once the patient has been successfully re-warmed.
However, if the patient has type 1 diabetes and is hyperglycaemic, do not delay giving insulin as usual; seek expert advice on the insulin dose and timing.

In practice, monitor core temperature regularly, using rectal or tympanic measurements.

Aim to re-warm the patient at a rate of 0.5℃ to 2℃ (0.9℉ to 3.6℉) per hour.
Heat redistribution within the body can cause a continued fall in core temperature after removing the patient from a cold environment.
Avoid hyperthermia during and after re-warming.[38]

In addition, monitor:

Other vital signs:
- Pulse rate
- Blood pressure
- Respiratory rate
- Oxygen saturations
Blood gases
- Ensure resolution of hypoxia and normalisation of pH.
End-tidal CO ² if the patient is intubated.

Consider – active external re-warming

Consider – warmed intravenous fluids

Back

Consider –

warmed intravenous fluids

Additional treatment recommended for SOME patients in selected patient group

Give warm intravenous fluids, especially once re-warming measures have been started, and titrate the fluids according to the patient’s heart rate and blood pressure. This helps to prevent heat loss but does not actively re-warm the patient.[4]

Obtain intravenous access using a peripheral intravenous cannula.[4] In practice, intraosseous access may be used if intravenous access is not possible and access is vital.
Warm intravenous/intraosseous fluids to 38℃ to 42℃ (100℉ to 107.6℉).[24] This temperature range is used in practice in the UK and is recommended by the European Resuscitation Council. However, the Wilderness Medical Society recommends warming fluids to a slightly higher temperature of at least 40℃ (104℉), and preferably 42℃ (107.6℉).[4] Check your local protocols.
Use normal saline solution.[4] Do not give Hartmann’s solution (also known as Ringer’s lactate) to a patient with hypothermia because their liver will be unable to metabolise lactate.[4]
Monitor the patient carefully for signs of fluid overload and volume depletion.[4] The patient is likely to require large volumes of fluids because vasodilation during re-warming causes expansion of the intravascular space.

Consider – humidified oxygen

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Accidental hypothermia

Treatment algorithm

moderate or severe hypothermia in cardiac arrest: ≤32°C (≤90°F)

cardiopulmonary resuscitation (CPR) ± advanced life support

supportive care

Practical tip

humidified oxygen

warmed intravenous fluids

extracorporeal life support (ECLS) re-warming

haemofiltration

moderate or severe hypothermia not in cardiac arrest: ≤32°C (≤90°F)

supportive care

Practical tip

humidified oxygen

warmed intravenous fluids

active external re-warming

active internal re-warming

haemofiltration

mild hypothermia: >32°C to 35°C (>90°F to 95°F)

passive external re-warming

supportive care

Practical tip

active external re-warming

warmed intravenous fluids

humidified oxygen