Transcript Accidental Hypothermia - Calgary Emergency Medicine

Accidental
Hypothermia
Grand Rounds
Oct 15, 2009
Garth Smith
CCFP-EM
A case
• 68 yo F, hx of dementia
• missing for 7 hours
• found by EMS in drainage ditch,
comatose
A case
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RR 6, pulse not palp,
BP, T, Osat unmeasurable
Glu 5.2
ECG - junctional bradycardia 30-40 bpm
decor posturing, GCS 5, no signs trauma,
pupils dilated/NR, foley temp 22.7C
How to proceed?
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airway - is it safe to intubate a profoundly
hypothermic patient? what about that
irritable mycocardium?
breathing - what rate? Osat not registering
so now what? how do I interpret ABG? what
if I can’t get an ABG?
circulation - choose your ACLS algorithm PEA vs unstable bradycardia vs
hypothermia. dry or wet? afterdrop? CBP?
Objectives
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educate and entertain
a case
review definitions and physiology
common investigation pitfalls or surprises
ACLS / AHA guidelines and algorithm, Calgary
protocol
treatment modalities including some “new” ones
hypothermia zingers
what to expect in the near future
questions
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accidental
hypothermia
approx 100 deaths per year (Stats Can)
overall mortality ~15%. In mod/severe
~40%-80% (depends on underlying
disease)
hospital records “tip of the iceberg”
mortality similar between men and women
men are hypothermic more often (stupid)
extremes of age at greater risk
accidental
hypothermia
• majority of AH patients were drunk,
using sedatives, outdoor exposure, and
male
Danzl D, Pozos R, Auerbach P, et al. Multicenter hypothermia survey. Ann Emerg Med
1987;16:1042-1055
Bizek G. Characteristics and Rates of Rewarming of Emergency Department Patients with
Moderate to Severe Accidental Hypothermia. Annals of Emerg Med. 2008; 52:4
Definitions
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AH - unintentional decline in core temp <35C
therapeutic - intentional, preserve brain &
other organs. CPB, TBI, post Vfib arrest
primary AH - exposure of healthy person to
cold, thermoregulation overwhelmed
secondary AH - disease state interferes with
thermoregulatory process. includes trauma.
Definitions
Most Lit
ACLS
Trauma
Mild
32 - 35
34 - 36
34 - 36
Mod
28 - 32
30 - 34
32 - 34
severe
20 - 28
<30
<32
profound
< 20
Heat Transfer
• test
Heat Transfer
• victims of AH are
exposed to
convection (wind)
and conduction
(water, ground, ice)
• conductivity of
water is 30 x that of
air
Thermoregulation
• test
Production + Retention < Cold = Hypothermia
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The politically
incorrect Bs
babies
baldies (geriatrics)
bums (streetpersons, low socioeconomic)
booze and benzos
blood (low sugar / trauma)
brain - CNS and PNS (chronic and acute)
boneheads
bananas/bonkers (phenothiazines, TCAs, Lithium, impaired adaptive
behaviour)
badness (sepsis, pancreatitis, MI)
barfers (anorexia or general malnourishment)
burns
breakdowns (this is Western Canada after all)
Physiology
• how do you die from hypothermia?
• multi organ failure secondary to
prolonged cardio respiratory arrest
Danzl and Pozos. Accidental hypothermia. NJEM. 1994;26, 331, 1756-1760
Testa. Accidental Hypothermia. From EMRAP Feb 2009
Excitation
Adynamic (slowing down)
Shut down
Danzl and Pozos. Accidental hypothermia. NJEM. 1994;26, 331, 1756-1760
Testa. Accidental Hypothermia. From EMRAP Feb 2009
Coagulopathy
Gardner. accidental hypothermia. emergency medicine reports. 2009;30
Jurkovich. Environmental Cold-induced Injury. Surgical Clinics of N.A. 87 (2007) 247-267
Vfib
• Ventricular fibrillation is rare above a
core temperature of 32 C
• increasingly more likely at lower
temperatures
• literature has numerous hypotheses
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby)
2007Steinman, Cardiopulmonary resuscitation and hypothermia. Circulation. 1986; 74
Afterdrop
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not the same as rewarming shock
AD is physiological response, ↓core T after
rewarming or removal from cold stress
two theories: circulatory, thermal gradient
be aware, reevaluate often, expect ↓T, +/clinical deterioration, rewarm the core first
Webb P. Afterdrop of body temperature during rewarming: an alternative explanation. J Appl Physiol 1986;60:385-39
Giesbrecht G. Prehospital treatment of hypothermia. Wilderness Environ Med. 1999;12:24–31.Vanggaard L, Eyolfson D,
Xu X, Weseen G, Giesbrecht GG. Immersion of distal arms and legs in warm water (AVA rewarming) effectively rewarms
hypothermic humans. Aviat Space Environ Med. 1999;70:1081–108
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby) 2007
Cold diuresis
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etiology multifactorial.
suggested mechanisms: 1. inhibition of
antidiuretic hormone (ADH) release, 2.
decreased renal tubular function, 3. relative
central hypervolemia caused by systemic
vasoconstriction, 4. impaired autoregulation of
the kidney
Cold water immersion ↑ urinary output x 3.5
ETOH impressively increases the diuresis
the rule in AH is that the patient is dry, give
volume
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby) 2007
Coagulopathy
• enzymatic nature of the activated
clotting factors is depressed by cold
• Thrombocytopenia
• cannot be confirmed by laboratory
studies performed at 37° C
• Treatment is rewarming and not simply
administration of clotting factors
Jurkovich. Environmental Cold-induced Injury. Surgical Clinics of N.A. 87 (2007) 247-267
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby) 2007
Investigations and
their Pitfalls
• appropriate include CBC, Lytes, Ur, Cr,
Glu, INR/PTT, ECG, ABG, TSH, Lipase,
LFTs, CXR, UA
• the general rule is not to make any
assumptions. extremely variable
results.
• Many of the tests can provide falsly
reassuring data.
CBC
• underestimates blood loss because of
normal hematocrit
• normal WBC count does not rule out
infection
• normal platelet count does not infer
they are functional
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby) 2007
Hypothermia in the sepsis syndrome and clinical outcome: the Methylprednisolone Severe
Sepsis Study Group. Crit Care Med 1992;20:1395-1401
Lytes
• must be continuously monitored
• K is a tricky little devil
• ↓temp can increase hyperkalemic
cardiac toxicity
• characteristic ECG changes maybe
obscured
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby) 2007
Glu
• must have bedside test immediately
• can be high or low
• all hypoglycemia should be treated
• do not treat hyperglycemia unless it
does not resolve with rewarming
• recheck often during rewarming
Gardner. accidental hypothermia. emergency medicine reports. 2009;30
ECG
• First ↑PR, then
↑QRS, then ↑QTc
• preshivering muscle
tone can obscure P
waves
• Osborn J waves
• below 32C, anything
is possible
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby)
2007Aslam et al. Hypotehrmia: Evaluation, Electorcardiographic Manifestations, and
Management. Am Jn of Med (2006) 119, 297 -301
ABG
• do they need to be
corrected to temp?
• debate about astat vs ph-stat
• uncorrected ABG
provides the most
useful information
Delaney,K. Assessement of Acid Base Disturbances in Hypothermia and their physiologic
consequences. Ann Emerg med. Jan 1989; 18: 72-82
Bradycardia?
Hemodynamic
Status?
Circulation. 2005;112:IV-136-IV-138
back to our case
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patient was intubated and ventilated
CPR was not performed
external rewarming with forced air blanket
warmed IV saline
no pressors, no Abx, no defib, no
atropine, no pacing
pulses palpable 30 min post arrival in ED
Circulation. 2005;112:IV-136-IV-138
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ACLS / AHA
guidelines
do all pulseless patients require CPR?
does defibrillation need to be withheld
until >30C?
do meds need to be withheld until >30C?
what meds are most effective?
does bradycardia need to be treated?
should hemodynamic stability as opposed
to temperature determine interventions?
do all pulseless
patients require
CPR?
• No, if the patient
is in the ED
• the presence of an organized cardiac
electrical rhythm (anything but vfib or
asystole) or U/S evidence of organized
movement should be taken as a sign of
life
• CPR is contraindicated in this situation
• concern is conversion to vfib by CPR
Jurkovich. Environmental Cold-induced Injury. Surgical Clinics of N.A. 87 (2007) 247-267
does defibrillation need to
be withheld until >30C?
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Some authors say NO
some recommend repeated defibrillation
after every 1C rise in core temperature
the AHA is vague - recommends repeat
defibrillation “as core temperature rises”
No evidence was referenced for either set of
recommendations
Gardner. Accidental hypothermia. Emergency medicine reports. 2009;30
Schweitzer. Cold but Not Dead. Air medical Journal. 2008; 27:2
Hanania. Accidental Hypothermia. Critical Care Clinics. 1999;15:2
do meds need to be
withheld until >30C?
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AHA indicates meds to be withheld as they
may accumulate to “toxic levels”
once >30C they can be administered “with
increased intervals between doses”
systematic review of animal models
suggests otherwise
case series suggest otherwise
Wira. Anti-arrhythmic and vasopressor medications for the treatment of ventricular fibrillation in
severe hypothermia: a systematic review of the literature. Resuscitation. 2008; 78, 21-29
Gardner. Accidental hypothermia. Emergency medicine reports. 2009;30
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What meds are
effective?
no quality studies in humans, only case
reports
bertyllium appeared to be effective but was
removed from AHA guidelines in 2000
classically taught that vasoconstrictors are
ineffective and may precipitate vfib
aforementioned animal models and case
reports suggest efficacy of epi and amio
Procainamide may precipitate vfib
Wira. Anti-arrhythmic and vasopressor medications for the treatment of ventricular fibrillation in
severe hypothermia: a systematic review of the literature. Resuscitation. 2008; 78, 21-29
Gardner. Accidental hypothermia. Emergency medicine reports. 2009;30
does bradycardia need
to be treated?
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guidelines say that “profound bradycardia” requires CPR
severe hypothermia results in 50% decrease in HR
most experts agree - CPR should be withheld in the severely hypothermic
patient with a pulse regardless of heart rate or blood pressure.
Cardiac pacing is generally not required for bradyarrhythmias unless the
bradycardia persists despite rewarming
A recent hypothermic dog model study concluded transcutaneous pacing is safe
and effective (improved cardiac index, decreased warming time)
recent case report of 2 human patients successfully treated with transcutaneous
pacing
utility of pacing lies in its ability to augment BP and increase rewarming
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby)
2007
Ahmed F. Hypothermia: Evaluation, Electroradiographic Manifestations, and Management. Am
Jn of Med. 2006; 119: 297-301
Ho J. Successful Transcu. Pacing in 2 Severely Hypothermic Patients. Annals of Emerg Med.
should hemodynamic stability as
opposed to temperature determine
rewarming treatment?
• absolutely*
• stable hemodynamics - noninvasive
• cardiac arrest - CPB, thorasic lavage otherwise
• unstable hemodynamics - debatable
* true evidence-based guidelines do not exist at this time. no
controlled randomized trials comparing rewarming
techniques
Walpoth. Outcome of Survivors of Accidental Deep Hypothermia and circulatory arrest treated
with extracorporeal blood warming. NJEM. 1997; 337:1500-5
Kronger. Important aspects in the treatment of severe accidental hypothermia: The Innsbruck
Experience. Journal of neurosurgical anesthesiology. 1996; 8: 1, 83-87
Sultan N. Treatment of severe accidental hypothermia with intermittent hemodialysis. CJEM.
2009; 11(2)
Roggla M.Wiener Klinische Wochenschrift. 114(8-9):315-20, 2002 May 15
Treatment
Active External
Passive External
Active Internal (invasive, noninvasive)
Extracorporeal
Passive
Active
endovascular rewarming catheter
Ahmed F. Hypothermia: Evaluation, Electroradiographic Manifestations, and Management. Am
Jn of Med. 2006; 119: 297-301
Scary
Not Scary
Open Mediastinal Lavage
Peritoneal Lavage
IV infusions
Intubations and warm air
endovascular catheter
Bair Hugger
CRRT
CAVR
CPB
Closed Thorasic Lavage
Plaisier B. Thoracic lavage in accidental hypothermia with cardiac arrest - report of a case and
review of the literature. Resuscitation. 2005; 66: 99-104
Moss JF. A model for the treatment of accidental severe hypothermia. J Trauma 1986;26:68-74
Otto RJ, Metzler MH. Rewarming from experimental hypothermia: comparison of heated
aerosol inhalation, peritoneal lavage, and pleural lavage. Crit Care Med 1988;16:869-875
Hall KN, Syverud SA. Closed thoracic cavity lavage in the treatment of severe hypothermia in
human beings. Ann Emerg Med 1990;19:204-206Iversen RJ, Atkin SH, Jaker MA, Quadrel MA,
Tortella BJ, Odom JW. Successful CPR in a severely hypothermic patient using continuous
thoracostomy lavage. Ann Emerg Med 1990;19:1335-1337
Handrigan M. Factors and methodology in achieving ideal delivery Temperatures for
intravenous and lavage fluid in hypothermia. Am Jrn of Emerg Med. 1997; 15:4
Sheaff C. Safety of 65C intravenous fluid for the treatment of hypothermia. Am Jrn of Surg.
1996; 172
Danzl DF. Accidental Hypothermia. NEJM. 1994; 331: 1756-60
Gentilello LM. Practical approaches to hypothermia. Adv Trauma Crit Care. 1994; 9:39-79
Steele MT. Forced Air Speeds Rewarming in Accidental Hypothermia. Ann Emerg Med. 1996;
27:479-484
Kornberger E. Forced Air surface rewarming in patients with severe accidental hypothermia.
Resuscitation. 1999; 41(2):105-11
Komatsu S. Severe Accidental Hypothermia successfully treated by rewarming strategy using
CVVHD system. Journal of Trauma. 2007; 62: 775-776
Gentilello LM, Jurkovich GJ, Stark MS, et al. Is hypothermia in the victim of major trauma
protective or harmful? A randomized, prospective study. Ann Surg 1997;226(4):439–47
Walpoth. Outcome of Survivors of Accidental Deep Hypothermia and circulatory arrest treated
with extracorporeal blood warming. NJEM. 1997; 337:1500-5
Endovascular
rewarming catheters
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2 recent case reports
1 small case series
Temperature-adjusted sterile saline
flows within the balloons and exchanges
heat with the blood as it passes by.
Endovascular
rewarming catheters
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5-lumen intravascular catheter
balloons form a closed loop system in 2 of the
catheter's lumen
• remaining 3 lumens are available for infusion
• inserted as per normal CVC
• complications are similar to CVC
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may be helpful in trauma patient
Taylor E. Active intravascular rewarming for hypothermia associated with traumatic injury: early
experience with a new technique. Bayl Univ Med Cent. 2008; 21 (2): 120-126
Ban LH. A novel intravascular rewarming method to treat severe hypothermia. Eur Jr of Emer
Med. 2008; 15: 56-58
Laniewicz M. Rapid endovascular warming for profound hypothermia. Annals of Emer Med.
2008; 51:2
Hypothermia Zingers
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CPR in the field: yes or no?
initiate rewarming in the field or transport cold?
intubation: safe or not?
NG/OG: safe or not?
when should resuscitation be withheld in the ED /
prognostic factors?
when can resuscitation be stopped in the ED?
what is the optimal rewarming rate?
are adjunctive therapies required?
CPR in the field: yes or
no?
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human experimental evidence is absent regarding the
frequency of converting bradycardia to ventricular fibrillation
But even if CPR induces ventricular fibrillation, the
fibrillation is being treated
If spontaneous ventricular fibrillation occurs in the absence
of CPR, the resultant anoxia is not being treated at all
long pulse check: 60 - 180 seconds
if pulse not present, give O2 by BVM
pulse still not present, Do CPR in the field (infers no access
to cardiac monitor or U/S)
Steinman A. Cardiopulmonary resuscitation and hypothermia. Circulation. 1986; 74
Hypothermia Guidelines. Circulation. 2005;112:IV-136-IV-138
CPR in the field: yes or
no?
contraindications for CPR
•non compressible chest
•ice formation in airway
•decapitation or other injury incompatible with
life
•unsafe conditions for rescuers
•signs of life
Gardner. accidental hypothermia. emergency medicine reports. 2009;30
initiate rewarming in the
field or transport cold?
• if in cardiac arrest, perform CPR and
transport cold but perform passive
rewarming (remove wet garments,
horizontal position, etc)
• if pulse present, start rewarming
Giesbrecht G. Emergency treatment of hypothermia. Emergency Medicine. 2001; 13: 9-16
Walpoth. Outcome of Survivors of Accidental Deep Hypothermia and circulatory arrest treated
with extracorporeal blood warming. NJEM. 1997; 337:1500-5
intubation: safe or
not?
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same indications to intubate as in non hypothermic
patient
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endotracheal intubation is appropriate in victims of
cardiac arrest.
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failure to oxygenate, failure to ventilate, decreased
level of consciousness, expected clinical
deterioration
Tracheal intubation was performed without incident
in 117 cases, of which 97 were less than or equal to
32.2 C
ventilate at have normal rates
Danzl D, Pozos R, Auerbach P, et al. Multicenter hypothermia survey. Ann Emerg Med
1987;16:1042-1055
Hypothermia Guidelines. Circulation. 2005;112:IV-136-IV-138
NG/OG: safe or not?
• no consensus
• “nasogastric tube placement should be
avoided because these have been
shown to precipitate ventricular
fibrillation”
• “a nasogastric tube may be placed to
relieve gastric distention”
Schweitzer. Cold but Not Dead. Air medical Journal. 2008; 27:2
Gardner. accidental hypothermia. emergency medicine reports. 2009;30
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when should resuscitation be
withheld in the ED / prognostic
factors?
unreliable: time submerged, age of patient, etoh/tox
ingestion, number of hours CPR, initial temperature,
physical exam
asphyxia (sudden drowning, avalanche with no air pocket)
hypothermic cardiac arrest, K> 9 mmol/L or a pH < 6.50 are
not expected to survive
K> 10 mmol/L during acute hypothermia appears to be a
reliable marker of death
be wary of anyone intubated with depolarizing
neuromuscular blocker
Schaller MD. HyperK, a prognostic factor during acute severe hypothermia. J Am Med Assoc
1990;264:1842-1845
Hauty MG. Prognostic factors in severe accidental hypothermia: experience from the Mt. Hood
tragedy. J Trauma 1987;27:107-112
Kornberger M. Prognostic markers in patients with severe accidental hypothermia and
cardiocirculatory arrest. Resuscitation1994; 27:47–54
when should resuscitation not be
attempted in the ED / prognostic
factors?
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Regardless of the presentation, there are no
validated prognostic indicators of the potential
for recovery from acute severe hypothermia
A decision to continue or terminate
resuscitation cannot be based on laboratory
parameters alone
Survival often appears unpredictable and
unrelated to treatment.
Schaller MD. HyperK, a prognostic factor during acute severe hypothermia. J Am Med Assoc
1990;264:1842-1845
Hauty MG. Prognostic factors in severe accidental hypothermia: experience from the Mt. Hood
tragedy. J Trauma 1987;27:107-112
Kornberger M. Prognostic markers in patients with severe accidental hypothermia and
cardiocirculatory arrest. Resuscitation1994; 27:47–54
when can resuscitation
be stopped in the ED?
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the only definite criterion of death is failure to
respond to resuscitation and rewarming
most experts agree that refractory cardiac
arrest above 32C is indicative of death
the decision to terminate resuscitation must be
individualized by the physician in charge and
should be based on the unique circumstances
of each incident
Danzl DF. Accidental hypothermia. In:Auerbach P, ed.Wilderness Medicine, 5th ed(Mosby)
2007
Weinberg A. Hypothermia. Annals of Emerg Med. 1993; 22
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what is the optimal
rewarming rate?
rapid rewarming does not necessarily improve the
chance of survival, except when cardiac arrest is
present
A rewarming rate of 1.85°C/hour can ↑ O2 extraction up
to 60% →mismatch supply/demand
a safe strategy would be to promote steady but
moderate warming
If perfusing cardiac output target of 1-2ºC per hour
If cardiac arrest, then a faster rate of >2ºC per hour
Komatsu S. Severe Accidental Hypothermia successfully treated by rewarming strategy using
CVVHD system. Journal of Trauma. 2007; 62: 775-776
Giesbrecht G. Prehospital treatment of hypothermia. Wilderness and Environ Med. 2001; 12:
24-31
Davis PR, Byers M. Accidental Hypothermia. J R Army Med Corps 2006;152:223-33
are adjunctive
therapies required?
• empiric steroids, barbiturates, and
antibiotics do not increase survival rates
from hypothermia
• recommendations for the use of empiric
steriods, Abx, insulin, sodium bicarb
are out of date and should not be
routinely used
Ahmed F. Hypothermia: Evaluation, Electroradiographic Manifestations, and Management. Am
Jn of Med. 2006; 119: 297-301
Gardner. accidental hypothermia. emergency medicine reports. 2009;30
what to expect in the
near future
• lots on therapeutic hypothermia
• hypothermia for space flight /
hibernation
• potential therapeutic hypothermia in
trauma, “suspended animation”
• more studies on endovascular
rewarming catheters
• more miraculous case reports
back to our case
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invasive core warming was thought to be indicated
IV fluids, heated ventilation and forced air were not
effective
warm pleural lavage considered, CV surgery consulted
for CPB
endovascular catheter was used instead
normothermia was achieved 5 hours later in ICU
good hemodynamic recovery but minimal neurologic
recovery
family requested comfort care, patient died day 8
Laniewicz M. Rapid endovascular warming for profound hypothermia. Annals of Emer Med.
2008; 51:2
Conclusion
In severe and profound hypothermia,
details regarding CPR, defibrillation,
medications, and other interventions may
be less important than the provision of
appropriate, effective rewarming
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Pearls
important numbers: <36C dynamic phase of hypothermia, 32C
critical temp for trauma patients, 32C can establish warm and
dead, <30C patient is in trouble, >30C where ACLS algorithm
changes
afterdrop: be aware of it, reevaluate patients often, expect ↓T, +/clinical deterioration, rewarm the core first
cold diuresis: AH patient is dry, give volume
coagulopathy: normal INR/PPT does not reflect coagulopathic
state. treatment is rewarming - not clotting factors. elevated
INR/PTT in trauma deserves treatment with FFP and cryo
beware the K: ↓T can ↑hyperkalemic cardiac toxicity. ECG may
not show ↑K changes.
Glucose: treat low glu. do not treat high glu.
ECG: anything is possible. don’t confuse J waves for ↑ST
ABG: don’t correct for temperature. just run it. target ph 7.4
pCO2 40
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Pearls
no pulse: if in the field - long pulse check (up to 3min), give O2, if still no pulse - do CPR.
In the ED - use ECG or U/S to establish presence of organized rhythm. If organized, No
CPR despite no pulse
contraindications to CPR: non compressible chest, ice in airway, decapitation or other
injury incompatible with life, unsafe conditions for rescuers, signs of life
pre hospital rewarming: passive rewarming for everyone. if in cardiac arrest - don’t
rewarm until CPB. everyone else - safe to rewarm, target core, watch for afterdrop
intubation: indications identical to normothermic patient. its safe...proceed if needed.
ventilate at half normal rates
repeat defib: consider giving repeat defib x 1 for every 1C rise of core temp despite being
<30C
resus meds: evidence is lacking: a few case reports and animal models. consider giving
epi or amiodarone despite core temp being <30C. reduce frequency. bertyllium or
procainimide not recommended
adjunctinve therapy: empiric antibiotics, bicarb, steroids do not improve outcomes
OG/NG - no evidence. conflicting opinion if safe or not. concern is irritating myocardium
bradycardia: No CPR if pulse/heart movement, regardless of HR or BP. Pacing not
recommended but transcutaneous may be safe and could improve CO. Intravenous pacing
contraindicated
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Pearls
withhold resus: must be in cardiac arrest. Decapitation,
evisceration or other injuries not in keeping with life.
Consider if multi trauma patient with temp <32C or
asphyxiated patient (definitive history) with K>10
prognostication: there are no validated prognostic
indicators of the potential for recovery from acute severe
hypothermia. Time submerged, age of patient, number of
hours CPR, initial temperature, physical exam are all
unreliable. K>10 has been suggested to indicated death
prior to cooling. (warning: it could be elevated due to
depolarizing NMB)
stop resus: the only definite criterion of death is failure to
respond to resuscitation and rewarming. If initiated resus,
should strive to warm to 32C to establish death
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Pearls
hemodynamics: primary determinant of treatment modality, urgency of
rewarming, and rewarming rate
hemodynamic stable and mild ↓temp: passive external rewarming +/- bair
hugger and IV
cardiac arrest: level 1 trauma. transport to FMC. preferred treatment is CPB.
consult CV surgery. back up method is thorasic lavage (open or closed).
consider underlying disease, comorbidities, and likelihood of meaningful recover
before initiating invasive/heroic measures
hemodynamic stable and severe↓temp: treatment is debatable. No urgency.
Go with least invasive, most familiar, and available
unstable and mod/severe↓temp: treatment is debatable. Some urgency.
Consult ICU/Trauma for possible extracorporeal rewarming. Go with least
invasive, most familiar, and available. likely CRRT for most
endovascular rewarming catheter: effective, easy to use, minimal
complications, portable, rewarms throughout entire resus and work up (CT,
angio, OR). minimal literature. expect more in the future
optimal rewarming rate: no evidence. experts recommend if perfusing 1-2ºC
per hour. If cardiac arrest, fast as possible, >2ºC per hour
Pearls
• look for hypothermia: can occur without cold exposure (ie
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DKA, MI, Sepsis) and is even found in warm situations
(marathon runners)
remember the physiology: bradycardia or coma when
core >30C is abnormal. Tachycardia when core <32C is
abnormal. seek other diseases entities to explain findings
find the other problem: elderly patient usually becomes
hypothermic because of another condition. find and treat
this precipitating condition (often sepsis) in parallel with
hypothermia
landmark studies: Walpoth. Outcome of Survivors of
Accidental Deep Hypothermia and circulatory arrest treated
with extracorporeal blood warming. NJEM. 1997; 337:15005
good review:Gardner. Accidental hypothermia. Emergency
medicine reports. 2009;30
Questions?
Big THANKS to
Dr. Gavin Greenfield
Dr. Andy Kirkpatrick
Dr. Bronwyn Kotyk
Dr. Jason Lord
Dr. Kyle McLaughlin