Recommendations
Key Recommendations
Assess and manage the patient's airway, breathing, and circulation, and prevent further heat loss. Get urgent support from the critical care team for any patient with severe hypothermia. Supportive measures depend on the patient’s clinical status and severity of hypothermia, and include:
Removal of wet and cold clothing; insulation (e.g., with a warm blanket)
Advanced airway management
Humidified oxygen and warm intravenous fluids, particularly once re-warming has been started
Management of cardiac arrhythmias (with the exception of ventricular fibrillation, these are likely to improve without treatment as the patient’s core temperature increases).[24][4] See our topic Overview of dysrhythmias (cardiac)
Management of hypoglycaemia[4]
Monitoring of core temperature and haemodynamic status during re-warming.
Start re-warming, as long as there is adequate monitoring in place to detect any arrhythmias caused by re-warming. The optimal re-warming method depends on the severity of hypothermia and the patient’s clinical condition. If the patient has:
Moderate or severe hypothermia (core temperature ≤32°C (≤90°F), use external (active and passive) and internal re-warming methods. Consider transferring the patient to an extracorporeal life support (ECLS) centre.
Mild hypothermia (core temperature 32°C to 35°C [90°F to 95°F]), start with passive external re-warming methods initially.
If a patient is in cardiac arrest, or is at risk of imminent cardiac arrest, transfer them to an ECLS centre for re-warming if possible.[24] Key modifications to cardiopulmonary resuscitation (CPR) for a patient with hypothermia are:
If the patient’s core temperature is <30℃ (<86℉):[24]
And they are in ventricular fibrillation (VF) 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; use 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]
In the pre-hospital setting, prioritise:
Prevention of further drops in body temperature; carefully remove the patient from the cold environment, and remove any wet or cold clothes[4]
Stabilisation of the patient following basic life support (BLS) and advanced life support (ALS) protocols
Maintaining the patient in a supine position if they have features of moderate or severe hypothermia (e.g., they have stopped shivering or have a reduced level of consciousness)[24]
Insulation of the patient and stabilisation of their core temperature by starting re-warming measures (as long as there is adequate monitoring in place to detect any arrhythmias caused by re-warming).[24][4]
Transfer of the patient to an appropriate centre for re-warming.[24][4]
If the patient is in cardiac arrest or is at risk of imminent cardiac arrest, ensure transfer to an extracorporeal life support (ECLS) centre for re-warming if possible.[24]
Handle the patient gently during transport because cardiac excitability makes the patient's heart susceptible to arrhythmias.[4]
Avoid exercise as a re-warming strategy (unless core temperature is >35°C [95°F]) due to the risk of fatal arrhythmias secondary to peripheral vasodilation. Exercise can also cause cool blood to return to the central circulation.[32]
However, in practice, if the patient is shivering, they can assist with their own extrication.
Transfer any patient who is in cardiac arrest, or is at risk of imminent cardiac arrest, to an 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]
For immediate management of a patient in cardiac arrest, see Cardiac arrest section below.
Check for vital signs (including a carotid pulse) for up to 1 minute.[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 CO2, and ultrasound should also be used to detect cardiac arrest.[24][4]
If 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 cardiopulmonary resuscitation (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 (VF) 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]
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.[24] Instead, the ERC recommends HOPE or ICE to estimate prognosis.[24]
Give supplemental humidified oxygen therapy (this should be heated, but this is usually only possible if the patient is intubated) if the patient is unable to maintain an adequate oxygen saturation.[4][36] Humidified oxygen reduces heat loss that occurs through respiration but does not actively re-warm the patient.
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 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]
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.
The optimal re-warming method depends on the severity of hypothermia and the patient’s clinical condition. If the patient has:
Moderate or severe hypothermia (core temperature ≤32°C (≤90°F), use external (active and passive) and internal re-warming methods.[25] Get urgent support from the critical care team for any patient with severe hypothermia.
Mild hypothermia (core temperature 32°C to 35°C [90°F to 95°F]), start passive external re-warming methods initially.[25]
In practice, consider active external re-warming methods if the patient’s hypothermia does not respond sufficiently to passive external re-warming measures.
Most patients with mild hypothermia will require transfer to hospital. However, the patient can be managed in a pre-hospital setting if they are alert, shivering, and uninjured.[24]
Transfer any patient who is in cardiac arrest, or is at risk of imminent cardiac arrest, to an 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.
External re-warming methods
Passive external re-warming: remove any wet clothing and insulate the patient (e.g., with warm blankets and dry clothes).[25][11] Give hot sweet drinks; these do not re-warm the patient but will supply energy for shivering.[3]
Active external re-warming: very similar to passive external re-warming. In addition to insulating the patient with warm blankets, apply forced warm air directly to the patient's body. The use of an external warming blanket is a good example of active external re-warming.
Internal re-warming methods
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.
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]
If the patient is not in cardiac arrest, 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]
More info: ECLS re-warming
One retrospective review reported a 47% long-term survival rate among 32 patients who underwent ECLS warming for severe hypothermia (core temperature <28°C) associated with cardiac arrest.[41] Long-term survival may be explained by patient characteristics (young and previously in good health), but it is possible that cardiopulmonary bypass, which offers rapid core re-warming and provides circulatory support that other modalities lack, may have contributed. Emerging evidence suggests that ECLS re-warming offers a better survival outcome than other treatment modalities.[42][43]
If a patient has moderate or severe hypothermia, continuously monitor their core temperature and haemodynamic status during re-warming.[4] In practice, if the patient has mild hypothermia, monitor core temperature regularly, using rectal or tympanic measurements.
In practice aim to re-warm the patient at a rate of 0.5℃ to 2℃ (0.9℉ to 3.6℉) per hour. Bear in mind, however, that if the patient is in cardiac arrest and/or undergoing extracorporeal life support, they will require 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 is likely to 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 CO2 if the patient is intubated.
See Monitoring for more information.
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