Morning Report: 1/2/2014

Happy New Year everyone! Morning Report is back with Dr. Paulson presenting the first edition of 2014!

Hypothermia:

From the sunny beaches and 80degree weather in SoCal, to the frigid wasteland that is our beloved Brooklyn…

Skin temp can go down to 90 in cold weather, and down to 70-73 before core temp starts to fall.

Heat lost by conduction, increased x5 in wet clothes, x25 in cold water immersion, convection, increased by wind chill, radiation, evaporation.

Mild: core temp 37-33C ( 91.4 – 98.6F) “the umbles” Mumbles, stumbles, fumbles

Shivering, feel cold, tachycardia, cold diuresis, tachypnea, increased DTRs, red face, muscle incoordination, ataxia, impaired fine motor skills (hands), maladaptive behavior, apathy (“just leave me behind, I’ll catch up”)

Moderate: core temp 33-29C (91.4-85.2F)

Shivering stops, stupor, weakness, AMS, slurred speech, poor judgment, inability to follow commands or walk, paradoxical undressing, vision loss, amnesia, tachy-brady, dilated and weakly reactive pupils, shallow breathing
At 30°C, patients develop a higher risk for arrhythmias. Atrial fibrillation and other atrial and ventricular rhythms become more likely. The pulse continues to slow progressively, and cardiac output is reduced. J wave may be seen on ECG in moderate hypothermia.
Below 27C (80F) 83% are comatose.

Severe: core temp below 29C (85.2F)

Minimal breathing, LOC (coma), decreased brain stem reflexes, no response to noxious stimuli, bradycardia, hypotension
Can no longer control body temp and rapidly cools to ambient temp.

Profound: core temp below 22C (71.6F)

Max risk of V Fib, rigid muscles, loss of vital signs, dilated pupils, they look DEAD
They’re not dead until they’re warm and dead. “Warm”= 32C (90F)

Human Diving Reflex: when face contacts water < 21C (~70F), bradycardia, decreased cardiac output with maintained or increased stroke volume, peripheral vasoconstriction, increased MAP – preserves O2 for brain and heart

Sober: immersion decreased heart rate, increased stroke volume, increased blood pressure, and increased total peripheral resistance.
Drunk: increased pre-immersion heart rate, but did not significantly alter pre-immersion blood pressure or stroke volume. Following immersion heart rate decreased, but not to the same low rate as in the sober state, lesser increase in blood pressure and failed to increase stroke volume significantly.

Rescue

Don’t jerk them around! The burden of rescue is to transport and re-warm the victim in a fashion that does not precipitate v.fib. (ie no exercise).
Take off wet clothing, replace with dry ones, get off the ground, cover head and neck, warm packs on chest, axillae, and groin.
Bradyarrhythmia: atropine and pacing DON’T work
Prevent vent dysrhythmias? Lidocaine DOESN’T work
V Fib: defibrillation DOESN’T work
Prophylactic bretylium? 5mg/kg initially. Not available since 1999… Maybe soon?
Warm IV fluids to 45C (113F), bear hugger, blankets, etc.
More aggressive methods include warmed gastric lavage (2.8°C/h), intravenous solutions heated to 65°C (2.9°C/h), and peritoneal lavage with 45°C fluid at 4 L/h (70 kcal/h or 3°C/h).
Rapid rewarming methods provide heat at levels higher than 100 kcal/h. Methods include thoracic lavage at 500 mL/min (6.1°C/h), cardiopulmonary bypass (400 kcal/h or 18°C/h), thoracic lavage at 2 L/min (19.7°C/h), ECMO, and AV dialysis (1-4 degrees per hour, and warm-water immersion [1500 kcal/h]).
In comparison, endogenous shivering provides rewarming at a rate of 300 kcal/h.

Final word: suspect hypothermia in anyone acting strange in cold weather, and if they look dead or were immersed in water, keep doing CPR until they are warm enough to give meds or shock them back to life.

References:

Auerbach PS MD. Medicine for the Outdoors, The Essential Guide to First Aid and Medical Emergencies. 5^th ed.

Li J, MD, Alcock J MD . Hypothermia Treatment & Management. emedicine.com

Wittmers LE Jr, Pozos RS, Fall G, Beck L. Cardiovascular responses to face immersion (the diving reflex) in human beings after alcohol consumption. Annals of EM 1987 Sep;16(9):1031-6.