• Case Study #4: Hypothermia

    by Alan Batt. Last modified: 05/03/14

    Picture of thermometer reading low temperature

    Patient & Apparent Chief Complaint

    A 70 year old female presents to ambulance crew after emergency call made by family after they found her on the floor of her bedroom.

    Pre-arrival considerations

    An EMT student was present with the crew on this call, and the crew discussed with him the process of hypothermia and treatment priorities. It was explained to the student the importance of gentle handling pf the patient as rough handling could trigger a VF arrest.  Crew ensured the heater in the rear of the ambulance was switched on and working and that there were adequate blankets on hand. Emotional support for the family was also of paramount importance.


    Patient was found on the floor of her house by her family. The last time she had been seen was sometime the morning previous (>24 hours) She felt extremely cold, and was drowsy when the family tried to talk to her.

    Initial Clinical Findings

    • Airway – clear & patent
    • C Spine – suspected (MOI/NOI: found in collapsed state on floor)
    • Breathing – regular, shallow
    • Circulation – Pulse present, regular, tachycardic; skin colour pale, cap refill delayed (>2 sec)
    • Disability – ? LOC before ambulance arrival (according to NOK); patient responsive to pain on arrival.

    Clinical Impression


    AMPLE History

    • A No known allergies
    • Currently taking calcichew, xanax, atenolol
    • P History of HTN, detached retina
    • L Last oral intake unknown
    • E NOK reports patient was lying on floor of bedroom unable to move. She was incontinent of both urine & faeces.


    • Pulse rate 64bpm
    • Pulse rhythm Regular
    • ECG rate 64
    • ECG rhythm NSR
    • Resp rate 12 per minute, regular, shallow
    • Resp quality Normal, equal bilateral air entry
    • SpO2% 88% @ room air
    • Cap Refill >2secs
    • BP 160/90
    • Pupils PEARRL, size 4
    • GCS 9/15 (E2, V3, M4)
    • BGL 5.1mmol/l
    • Physical examination Nil of significance, nil pedal oedema. Patient dry, cold to touch
    • Temperature 29.6°C (severe hypothermia)

    Pre-hospital care & management

    Warmed humidified O2 commenced via non-rebreather mask. 12 Lead ECG showed no abnormality. Patient was extremely cold to touch. She was semi-dressed, incontinent of faeces and urine, lying prone on the floor, unable to move.

    Crew applied collar and secured her to a longboard. Patient covered in blankets and foil blankets, and passive re-warming commenced. Active re-warming commenced with warmed IV fluids. En-route to hospital the patient’s GCS remained at 9/15. Her vital signs remained unchanged.

    In-hospital care & management

    Triaged as Category 2 (Serious Condition) with ? hypothermia. Brought directly to Resus room. 12 lead ECG repeated. Blood tests taken. Urinary catheter inserted. Active re-warming continued. Patient admitted to Intensive Care Unit for observation and management.

    Identification of all interventions and rationale

    • Pulse oximetry – to monitor oxygen saturation levels in the blood
    • Vital signs (HR, RR, SpO2, BM) – to gain a baseline set of vital signs for reference
    • Supplemental oxygen – to re-oxygenate patient
    • 3 Lead ECG – to identify any life-threatening arrhythmias
    • 12 Lead ECG – to identify any life-threatening arrhythmias or ECG changes indicative of myocardial damage (secondary to hypoxia etc.)
    • Spinal immobilisation – with an unreliable history and an altered LOC spinal immobilisation was performed to protect the spinal cord in case of injury
    • Passive re-warming – to re-warm the patient and prevent hypothermia from progressing
    •  Active re-warming – infusion of warmed IV fluids to re-warm the patient’s core, and allow for reversal of the hypothermic process
    • CXR – to identify pneumonia, pleural effusion etc. that may increase morbidity
    • Blood tests – to identify any electrolyte imbalances, cardiac enzymes released due to myocardial damage, clotting factors present in blood etc.
    • Urinary catheter – to monitor urinary output to ensure adequate renal function

    Learning Outcomes


    Hypothermia is a condition in which the patient’s core body temperature drops below 35.0°C. It can be further sub-divided into 3 categories (JRCALC, 2006)

    1. Mild Hypothermia (>34°C)
    2. Moderate Hypothermia (30-34°C)
    3. Severe Hypothermia (<30°C)
    a. Profound Hypothermia (<20°C)

    Hypothermia results in a gradual drop in basal metabolic and oxygen demand. It can also result in lethargy, confusion, tiredness, pupil dilation. As core temperature reduces, respiratory effort becomes depressed, resulting in acidosis due to carbon dioxide retention. It can also be due to increased lactic acid production caused by impaired perfusion of skeletal muscle.

    ECG changes may be seen during hypothermia. The patient may present in AFib or Sinus Bradycardia, and there may be prolonged PQ, QRS and QT intervals (Sisko & Peckler, 2008)

    Hypothermia affects all systemic organs, and can result in a myriad of unwanted consequences. These include diuresis and volume depletion, hyperglycaemia, increased plasma viscosity, coagulopathy (DIC common), renal impairment and electrolyte imbalances, which may all result in increased morbidity and mortality. (AAOS, 2005; Elling et al.,2007; Melhuish, 2009; Yoon et al., 2014; Singh & Hallows, 2013)

    Those at risk include the elderly, poor (Romero-Ortuno et al., 2013), trauma patients (Wang et al, 2005; Waibel, 2012; Lapostelle et al., 2012), young children, and submersion/immersion incidents.

    Video courtesy Wilderness Leadership Institute (WLI) YouTube channel.

    Prehospital management of hypothermia

    Equipment for diagnosing and treating hypothermia is often lacking on vehicles, including both ground and air based assets  – a recent study in Norway found that only 12% of ambulances had thermometers designed for temperature monitoring in hypothermia (Karlsen et al., 2013).

    The management of hypothermia contains passive and active re-warming elements. Warmed, humidified oxygen is a recommended intervention for all hypothermic patients, allowing for a degree of internal re-warming.

    Warmed IV NaCl infusion is indicated for moderate and severe hypothermia patients. Fluids must be warmed to approximately 40°C. It is administered in aliquots of 250ml to a max of 1 litre (adult).

    Treatment is dependent on the class of hypothermia presenting to the prehospital care provider. For example, sweet hot drinks can be provided to a patient with mild hypothermia. It is recommended to handle all hypothermic patients gently, and to not allow them to walk. (AAOS, 2005; Elling et. al, 2007; JRCALC, 2006)

    Further management of hypothermia

    Treatment of hypothermia in-hospital is mainly a continuation of pre-hospital algorithms of re-warming. There are however a number of additional steps taken, and these treatments can be extremely effective. These include:

    • Peritoneal lavage
      • Lavage of the peritoneum with warmed (~43°C) potassium-free fluid, administered 2 litres at a time.
    • Extracorporeal re-warming (via ECMO)
      • The process of removing the patients blood from their system through a heparinized bypass, re-warming and oxygenating it, and re-infusing it to the patient (Morley et al., 2013)
    • Oesophageal warming tubes
      • Rewarming using insertion of a special double-lumen oesophageal tube with warmed water (~42°C) circulating through it.

    (American Heart Association, 2010)

    Cardiac Arrest & Hypothermia

    Misdiagnosis of cardiac arrest in the pre-hospital setting is a hazard, and it is recommended that care providers perform a pulse check for a minimum of 30-45 seconds to prevent misdiagnosis of same (JRCALC, 2006). Commencing CPR on a hypothermic patient mistakenly diagnosed as being in cardiac arrest will almost certainly result in them arresting.

    The compliance of the chest wall and indeed of the myocardium may be compromised, making compressions more difficult and less effective. The patient may also be less responsive to defibrillation, and in general, EMS providers are limited to delivering only 3 shocks in severely hypothermic patients. Paramedics are also precluded from administering medications to a hypothermic patient in cardiac arrest until core temperature has reached 30°C, and must then double the medication administration interval until core temperature reaches 34°C.

    In the ED, re-warming efforts, in general, should be continued until core temperature is at least near normal. Because it may be impossible to identify if the hypothermia was the cause of arrest, or the arrest occurred prior to hypothermia, it is recommended that doctors exhaust all other causes of arrest prior to making a decision on termination of resuscitative efforts in hypothermic patients. (AHA, 2010)

    Indicators of non-salvageable hypothermic patients

    • Elevated serum potassium
    • Core temperature <6°C
    • Core temperature <15°C if no circulation for >2 hours
    • Venous acidosis (pH <6.5) – uncorrected for temperature
    • Severe coagulopathy (DIC common)
    • Clots within heart on thoracotomy
    • Failure to obtain venous return on cardiopulmonary bypass

    (Hauty et al., 1987; Schaller et al., 1990; Mair et al., 1994)

    Disseminated Intravascular Coagulopathy (DIC)

    DIC is a process whereby there is an abnormal activation of clotting factors within the blood vessel, resulting in clotting, with small clots forming in vessels. Once these clots have consumed all available clotting factors, normal clotting processes are abnormally affected, and the patient may begin to bleed from sites such as venepuncture sites, GI tract, respiratory tract, mouth and nose. The small clots that are formed may also interfere with the blood supply to critical organs.

    The only effective treatment for DIC is reversal of the cause. Infusion of fresh frozen plasma, platelets or clotting factors is sometimes attempted. However, these still result in an extremely poor prognosis for the patient with DIC. The moniker “Death Is Coming” has been used colloquially to describe the lack of treatment options for the patient with DIC, and the ultimately worsening prognosis of the condition.

    (Porter, 2006; Scharbert et al., 2009; Staikou et al., 2009; Maegele et al., 2013)

    References (non-PubMed)

    AAOS (2005) Emergency Care and Transportation of the Sick and Injured 9th Edition. Massachusetts: Jones & Bartlett

    AHA – American Heart Association (2000) “Advanced Challenges in Resuscitation: Section 3: Special Challenges in ECC 3A: Hypothermia” Resuscitation (46) 1 p267-271

    Elling B, Caroline N, Smith M (2007) Nancy Caroline’s Emergency Care in the Streets, 6th Edition (UK Edition). London: LWW

    JRCALC (2006) UK Ambulance Service Clinical Practice Guidelines 2006. JRCALC

    Porter R (2006) The Merck Manual of Diagnosis and Therapy. “Bleeding and Clotting Disorders: Disseminated Intravascular Coagulation.”



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    Alan Batt

    Alan Batt

    Paramedic, educator, researcher
    Alan is a critical care paramedic, paramedic educator and prehospital researcher, currently working around the world as an educator and researcher. He has previously worked and studied across Europe, North America and the Middle East. He holds a Graduate Certificate in Intensive Care Paramedic Studies, and an MSc in Critical Care. His main interests are in care of the elderly, end-of-life care, patient safety, professionalism (including role and identity), and paramedic education.

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