In honor of Mariah Carey's performance in NYC yesterday and the start to our frigid temperatures, I figured I would talk about hypothermia.
For simplicity purposes, hypothermia comes in 3 flavors:
1. Mild Hypothermia: 32-35°C; Use insulating blankets on patient's core and they’ll usually warm 1°C/ hour and that’s a life saved.
2. Moderate Hypothermia: 29-32°C or patients refractory to re-warming as expected. Consider other causes including hypoglycemia, malnutrition, ETOH, Addison’s, sepsis, and myxedema coma! Consider using active rewarming techniques (listed below).
3. Severe Hypothermia: <29°C or those patients in cardiac arrest
So, lets talk about active rewarming techniques
After assessing ABC's in the hypothermic patient, you need core temperature monitoring via an esophageal probe (in the back of Resus 53) or a rectal probe! An esophageal probe is preferable given less breaks if compressions are needed and easier initiation of active rewarming.
Active Internal/ Core Rewarming:
Warm humidified oxygen will raise temperature 1°C/hr via NRB or 1.5°C/hr via ETT
Heated IVFs (40-42°C). Must use warm saline because room temperature saline can worsen hypothermia
Peritoneal irrigation, however this is less common given the chance of bowel injury unless there is ascites
Pleural irrigation with two 32F chest tubes on each side of the chest that can increase temperatures 3-6°C/hr
Chest tube placement: one anterior and one posterior lateral on each side. With the anterior chest tube use the connector from a Salem sump and pump warm fluids into the anterior chest tube and then attach the pleura-vac connected to suction to the posterior lateral chest tube to allow continuous emptyingExtracorporeal blood rewarming
o Venovenous
o Hemodialysis
o Continuous arteriovenous rewarming
o Cardiopulmonary bypass
o Extracorpeal Membrane Oxygenation (ECMO)
Termination of CPR should be considered if K >12 mmol or if asystole persists beyond 32°C
Lastly, since the in-service is coming, here a drop extra on arrhythmias in hypothermia…
Most common arrhythmia for mild hypothermia is bradycardia; Pacing is usually not necessary unless bradycardia persists after patient is rewarmed to 32-35°C
In temperatures below 32°C, bradycardia-->atrial arrhythmias-->ventricular arrhythmias-->asystole
If patient is in cardiac arrest, attempt defibrillation with single shock. If further defibrillation attempts are made, concurrent rewarming should be initiated.
Modified ACLS guidelines:
AHA recommends 3 defibrillations and 3 rounds of epi with further dosing guided by clinical response
Recent consensus suggest only one defibrillation and round of ACLS meds → rewarm 5C → one defib/meds → Repeat
Classic test question: ECG finding for hypothermia is an Osborn (J) Wave, which is a positive deflection at the J point. These waves are not pathognoromic. They also, have no prognostic value, like most tests (just kidding). However, the size of the wave correlates with the degree of hypothermia.
Here is an example of mild hypothermia:
That soon turned into moderate hypothermia:
Okay, all done. Stay warm to stay alive. Please feel free to ask questions and send feedback!
