Your patient is a 30 year old dashing ski instructor named Pierre. He is brought in after being trapped in an avalanche for 45 minutes. It’s not believed that his airway was ever obstructed. When he was finally extricated from the snow, he was cold and barely responsive. Per chart review, has no significant medical or surgical history, no allergies, is on no medications.
Pierre is quickly airlifted to the ED where you just so happen to be staffing, and you receive report upon arrival that the patient has not significantly improved since extrication. Keeping calm and cool (hey!), you step into the shock room where Pierre has been transferred onto a bed.
You begin your assessment by examining the vitals and physical exam:
P 42 | BP 78/42 | RR 12 | % Sat 93% (RA) | T 87 F (rectal)
Gen: cold, minimally responsive to painful stimuli
HEENT: Pupils dilated and sluggish response, normocephalic, atraumatic
CV: slow, regular rhythm, no murmurs, rubs or gallops
Pulmonary: Clear to auscultation bilaterally
Abdomen: audible bowel sounds x 4; no guarding, rebound, tenderness
Musk/Neuro: moves all 4 extremities to painful stimuli
With this in mind, what exams would you order to begin his workup?
The patient is not significantly improving, and it's time to take action.
What’s going on?
The patient has been exposed to the cold and is moderately hypothermic to 87F. Patients with core body temperatures below 35C (95F) are considered hypothermic. Per the American Heart Association, mild hypothermia (>34C) can be treated with passive re-warming techniques (removing cold/wet clothing, drying the patient), and those with mild hypothermia (30-34C) will require active re-warming (warm blankets, heated room, warm IV fluids, humidified O2). Patients who have severe hypothermia (<30C) may require advanced measures such as warm water bladder and gastric irrigation, central rewarming and even may benefit from ECMO.
Patients who are severely hypothermic are also more likely to develop ventricular fibrillation, and thus extreme caution must be taken when moving the patient and performing invasive procedures. Sinus bradycardia is usually physiologic, and generally does not require cardiac pacing. Always keep a crash cart nearby when caring for these patients! The data is not definitive on the care for hypothermic patients with presumed cardiac arrest. When moderately or severely hypothermic, patients can become profoundly bradycardic and bradypneic, making it difficult to assess for true arrest. If there is any question, however, CPR/rescue breathing should be started immediately. If the monitor shows VFib or Vtach you should defibrillate the patient per normal ACLS/BLS protocol. During the code it is important that you continue to attempt to rewarm the patient, as this will be your best shot at achieving ROSC. Additionally, profoundly hypothermic patients can present with electrolyte abnormalities, which should be monitored.
The studies on medical management of cardiac arrest in hypothermia are few and far between. In the past, there was ‘theoretical’ concern that patients who are hypothermic have poor peripheral circulation, and administration of vasopressors and other standard ACLS medications could lead to toxic accumulation in the periphery without reaching their intended central targets. A few more recent human and animal studies, however, seem to contradict this study. The AHA currently recommends following standard ACLS protocol.
Hypothermia & the EKG
Hypothermic patients may present with marked changes on their EKG including bradyarrhythmias, Osborn waves (seen in the EKG above), prolongation of PR, QT, and QRS intervals, shivering artifacts and ectopic ventricular beats. The Osborn wave, also known as the J wave, is the positive deflection of the J point and is most prominent in the precordial leads. The height of the Osborn wave is roughly proportional to the degree of hypothermia. However, it is important to know that the J wave can be seen in other scenarios including: normal variant, hypercalcemia, medication effects, intracranial hypertension, subarachnoid hemorrhage and idiopathic VFib. As always, keep the patient’s clinical picture in mind.
Some other links for you refine your knowledge of hypothermia:
- CDEM Curriculum: Hypothermia by Kiran Pandit.
- Life in the Fast Lane: Osborn Wave (J Wave).
- Life in the Fast Lane: EKG Changes in Hypothermia.
- EmCrit: Severe Accidental Hypothermia.