Transcript Accidental Hypothermia - Calgary Emergency Medicine

Accidental Hypothermia
Cass Djurfors
May 8, 2003
Case
• Three avalanche workers caught in an
avalanche
• One partially buried called on radio repeater
immediately to mobilize rescue team and
local paramedics by helicopter
• Plan to fly direct to local ED (Scene beyond
range of STARS without refuel and nearby
fuel cache buried in winter snow)
• Other two completely buried
Case
• Partially buried victim pulls shovel from
rucksack on back and digs self out,
performs transceiver search to locate
first buried who comes up breathing
• Continues search and digs up second
buried who is VSA and so begins CPR
• Burial time 40 minutes.
Case
• Paramedics land and apply monitor pads to
show sinus bradycardia, confirm VSA,
continue CPR
• Endotracheal intubation, bundle and fly to
nearby regional ED
• Sinus bradycardia deteriorates en route to
ventricular fibrillation
• Pilot does not allow defibrillation in flight
Case
• Local ED prepared with 2 EP’s, 1
anaesthetist, 1 GP surgeon, 7 nurses,
various support personnel
• Patient arrives asystolic
• Initial esophageal temp probe 27.5oC
Case
• Management as follows:
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Confirm ETT placement
Humidified O2
1L NS at 41C by Level One Infuser
Switch Level One Infuser to 3l NS irrigation bags
for pleural lavage via 36F tube left 2nd intercostal
space and second tube 5th intercostal space
Peritoneal lavage
Bladder irrigation
Alternating all three active internal rewarming
modalities between two Infuser chambers allowing
dwell time for all 3 modes
Maximum outflow temp from Infuser approx 41C
Case
• Meanwhile…
– Team leader calls Trauma Centre intensivist re:
transfer for CPB
– Intensivist unclear as to whether CPB warranted in
this case and states “will call back”
– Aggressive rewarming continues to produce a rise
to 28.5C after 30 minutes
– Intensivist calls back to recommend rapid
transport for CP bypass
– Patient transported by ground (now dark outside)
to nearest Trauma Centre
Case
– CPB initiated
– Patient rapidly warms with return of
spontaneous circulation
– Proceeds to develop MODS that results in
death shortly after
Issues from Case
• Resuscitation of hypothermic patient:
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CPR
ACLS
Defibrillation
Medications
• Core temperature measurement
• Rewarming methods, rates, logistics and their
indications
• Prognostic markers of death in hypothermia
Definitions
• Temperature < 35 C
– Mild 32-35 C
– Moderate 28-32 C
– Severe < 28 C
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Primary (cold exposure)
Secondary (disease process, eg. Myxedema)
Acute (rural, outdoor hypothermia)
Chronic (urban, indoor, elderly hypothermia)
Immersion vs. non-immersion (degree of
rapidity)
Epidemiology
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723 deaths per year US 1979-1995
50% older than 65
Male:female 3:1
Socioeconomic factors
Mentally ill 5 times greater risk
Mechanisms of Heat Loss
Mechanism
Approximate % of Heat Loss
Radiation
50
Convection
30
Evaporation
15
Conduction
5
Physiology: Mild
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37.6 normal rectal temperature
37.0 normal oral temperature
36.0 ↑ metabolic rate, bp, and muscle tone
35.0 maximum shivering
34.0 amnesia, poor judgment
33.3 Ataxia, apathy; cold diuresis
Danzl DF. Accidental hypothermia. Wilderness Medicine
Physiology: Moderate
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32.0
31.0
30.0
29.0
stupor
shivering stops
poikilothermia; arrhythmias develop
↓ LOC, HR and RR; dilated pupils
Danzl DF. Accidental hypothermia. Wilderness Medicine
Physiology: Severe
• 28.0 ↓ VF threshold; hypoventilation
• 26.0 no response to pain
• 25.0 cerebral autoregulation fails,
spontaneous VF and asystole
• 24.0 hypotension and bradycardia
• 23.0 areflexic (incl. corneal and doll’s eye)
• 22.0 max VF risk
Danzl DF. Accidental hypothermia. Wilderness Medicine
Physiology: Profound
• 20.0 lowest resumption of cardiac
activity
• 19.0 EEG silent
• 13.7 lowest adult accidental
hypothermia survivor Gilbert et al. Resuscitation from
accidental hypothermia of 13.7oC with circulatory arrest. Lancet 355: 375, 2000.
• 9.0 lowest therapeutic hypothermia
survivor Niazi et al. Profound hypothermia in Man: Report of a case. Annals of
surgery. 147(2): 26466, 1958.
Danzl DF. Accidental hypothermia. Wilderness Medicine
Causes of Hypothermia
1. Decreased Heat
Production
– Neuromuscular
inefficiency
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Impaired shivering
Age
Immobility / inactivity
– Endocrine failure
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Hypopit
Hypothyroid
Adrenal insuff
– Nutritional
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Hypoglycemia
Anorexia
Malnutrition
2. Increased Heat Loss
– Exposure / Immersion
– Dermatologic
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Erythroderma
Burns / TENS
Psoriasis)
– Vasodilation
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ETOH
Toxins
– Iatrogenic
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Emergent deliveries
Cold infusion
Hanania, NA et al. Accidental Hypothermia. Critical
Care Clinics. 15(2): 236-49, 1999
Causes of Hypothermia
3. Impaired
Thermoregulation
– Drugs
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Sedatives
Barbiturates
EtOH
TCA
Peripheral neuropathy
SCI
DM
CNS bleed / trauma
Parkinson's
Anorexia nervosa
4. Miscellaneous
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Sepsis
Pancreatitis
Carcinomatosis
Uremia
Vascular insufficiency
Hanania, NA et al. Accidental Hypothermia. Critical
Care Clinics. 15(2): 236-49, 1999
Diagnosis
• High index of suspicion
• Low reading thermometer
Temperature measurement
• Need an accurate approximation of core
temperature
• Traditionally rectal (at least 10-15cm)
• Rectal temperature lags behind core:
especially during rapid change, cooling
to warming transition
(Terndrup TE. An appraisal of temperature assessment by infrared emission detection
tympanic thermometry. Ann Emerg Med 21:1483-1492, 1992)
Temperature measurement
• Direct tympanic thermometry is
research standard, but not convenient
for ER use
• Indirect infrared tympanic thermometry:
– often doesn’t read below 34oC
– Susceptible to cerumen or water in the
canal
Temperature measurement
• Esophageal
– Falsely elevated with heated inhalation
• Bladder
– Falsely elevated with peritoneal lavage
– Falsely low with cold diuresis
• Oral
– Found to be comparable to tympanic probe in
“hypothermic” trauma patients 35.2-35.6
Kober A et al. Effectiveness of resistive heating compared with passive warming in treating hypothermia associated with minor
trauma: a randomized trial. Mayo Clin Proc;. 76:369-75, 2001.
Diagnosis: Lab
• ABG’s:
– Controversy of historical interest only
– Curve shifts left with colder temps causing pH to
be reported lower and O2, CO2 to be reported as
higher than actual
– Blood gas analyzer runs samples at 37oC
– Current consensus is that use of uncorrected
values provides better outcomes
Corneli HM. Environmental Emergencies. Clinical Pediatric Emergency Medicine.
2(3):179-91, 2001.
Lab
• Coags may be reported as normal if run
at 37oC despite obvious clinical
coagulopathy
• Electrolyte abnormalities are common
and should be addressed
• Hypoglycemia should be treated
ECG
The J or Osborne Wave
• Deflection of the J point: the junction of the
QRS complex and ST segment
• Most common in leads II and V6
• Diagnostic but not prognostic
• Not pathognomonic: can also occur in CNS
lesions, focal cardiac ischemia and sepsis
• Magnitude of J wave inversely correlates with
temperature
Susi U et al. A prospective evaluation of the electrocardiographic manifestations of
hypothermia. Academic Emergency Medicine: 6(11); 1121-26, 1999.
Other ECG findings
Mattu A et al. Electrocardiographic Manifestations of Hypothermia. American Journal of
Emergency Medicine. 20(4); 314-26
• Artifact produced by clinically invisible
preshivering muscle tone may obscure P
waves
• Any arrhythmia (atrial or ventricular) is
possible
• Bradycardia, Afib, VF asystole common
• Treatment of Afib with anticoagulants has not
been studied and should not be undertaken
• ECG changes resembling ischemia can occur
and should only be treated with rewarming
Basic Management: ABC’s
• A/B:
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Supplemental O2, consider ETT
Neuromuscular blocks ineffective < 30 C
May have to use nasotracheal approach if rigid
Unlikely to induce arrhythmias with ETT
• C:
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Continuous monitoring; usually volume depleted
Peripheral lines ideal; Central may precipitate dysrythmias
Avoid PA catheters under 32 C
Bolus in 250-500 cc increments with glucose checks and 5%
dextrose if necessary
– Theoretically avoid ringers lactate due to impaired liver
– <32 C all fluids warmed to 40 to 42 C
Basic Management: ABC’s
• Remove wet clothing
• Avoid rough movement as this may
precipitate VF
• Nasogastric tube to relieve distension
• Foley for monitoring
ACLS in Hypothermia
2000 AHA Guidelines
• For absent pulse or respirations
– Start CPR
– Defibrillate VF/Pulseless VT with MAXIMUM
of 3 shocks 200, 300, 360
– Secure airway, ventilate with warm
humidified oxygen, start IV with warmed
NS
ACLS in Hypothermia
2000 AHA Guidelines
• For core temperature>30oC
– CPR
– IV meds as per ACLS but with extended
dosing intervals
– Repeats defibrillation attempts as temp
rises
ACLS in Hypothermia
2000 AHA Guidelines
• For core temperature<30oC
– CPR
– Withhold IV meds
– No further shocks
– Proceed with active rewarming
CPR
• Can be difficult due to chest wall
inelasticity
• Optimal rate unknown
• Tissue decomposition, rigor mortis,
fixed and dilated pupils are NOT
indications to withhold CPR
Defibrillation
• Hypothermia is known to alter ion
channel function and hence alter
defibrillation efficacy
• Several case reports suggest
hypothermia impairs defibrillation
leading to traditional belief that
defibrillation is largely ineffective below
28oC
Defibrillation
• Case reports of hypothermic VF responsive to
defibrillation do exist:
– Thomas et al. Successful defibrillation in profound
hypothermia. Resuscitation. 47(3): 317-20, 2000.
• Successful defibrillation of hypothermic patient with core
body temperature of 25.6oC
– Cortes et al. Severe accidental hypothermia:
rewarming by total cardiopulmonary bypass.
Revista Espanola de Anestesiologia y Reanimacion.
41(2):109-12, 1994.
• 20-year-old male with profound hypothermia (26oC
presented in deep coma with recurring ventricular
fibrillation that yielded to electrical defibrillation once a
core temperature of 27.4oC was reached
Defibrillation
Ujhelyi et al. Defibrillation energy requirements and electrical heterogeneity during total body
hypothermia. Critical Care Medicine: 29(5), 2001.
• Animal study
• Compared normothermia with
hypothermia of 30oC
• Induced brief VF
• No change in defibrillation energy
requirements in hypothermia
• Fibrillatory threshold noted to be
reduced
Defibrillation
• Bottom Line:
– Attempt a maximum of three shocks at
standard energy settings (200J, 300J,
360J) in the hypothermic VF or pulseless
VT patient with core body temperature
below 30oC
Pacing?
Dixon et al. Transcutaneous pacing in a hypothermic dog model. Annals of Emergency
Medicine. 29(5): 602-6, 1997.
• 20 mongrel dogs core temperature of
27oC
• TCP restored and maintained
hemodynamic stability and allowed the
hypothermic animals to rewarm in half
the time required by their nonpaced
counterparts
• No human studies
Medications in Hypothermic
Arrest
• Generally reported to be ineffective and possibly even
harmful
Corneli HM. Environmental Emergencies. Clinical Pediatric Emergency Medicine.
2(3):179-91, 2001.
• Bretylium, lidocaine, vasopressors all studied with no
consensus
• Kornberger et al. Effects of epinephrine in a pig
model of hypothermic cardiac arrest and closed-chest
cardiopulmonary resuscitation combined with active
rewarming. Resuscitation. 50(3):301-8, 2001.
– Epinephrine did not improve time to spontaneous
perfusion, and even worsened mixed venous
hypercarbic acidosis.
Medications in Hypothermic
Arrest
• Bottom line:
– Avoid in core temp <30oC
Rewarming Methods: Issues
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Severe hypothermia is uncommon
No RCT’s exist in accidental hypothermia
Evidence is primarily from case reports
Rapid rewarming, while intuitive, has never
been proven to improve outcomes
• Human experimental model unethical below
35oC
• Risky to blindly generalize results of animal
studies to humans
Rewarming Methods: Issues
• Rigid treatment protocols are inherently
hazardous
• Clinical circumstances and availability of
resources have to be taken into account
Core Temperature Afterdrop
• The continued decline in a hypothermic
patient’s temperature after removal from the
cold
• Cause is temperature equilibration between
the warmer core and cooler periphery and
countercurrent cooling of blood perfusing the
cold extremities
• Ideally, rewarming strategies would avoid
significant afterdrop
Rewarming Methods
1. Passive external rewarming
2. Active rewarming
1. Active external rewarming
2. Active core rewarming
Passive External Rewarming
• Involves covering patient with insulating
material to prevent further heat loss
• Indicated mainly for mild hypothermia or as
an adjunct in moderate to severe
hypothermia
• Patient must have endogenous
thermogenesis
– Humans are poikilothermic below 30oC
– Shivering stops below 32oC
• Rewarming rates in mild hypothermia with
PER range from 0.5-2.0oC/hr
Hanania et al. Accidental Hypothermia. Critical Care Clinics. 15(2):236-48, 1999
Active Rewarming
• Direct transfer of exogenous heat to the
patient
• Internal or external techniques
• Indications:
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Poikilothermia (T< 32oC)
Cardiovascular instability
Inadequate rate or failure to rewarm
Endocrine insufficiency
Traumatic or toxicologic peripheral vasodilation
Secondary hypothermia impairing
thermoregulation
– Neonatal or infant patients
Active External Rewarming
• Exogenous heat is delivered directly to
the skin
• Forced air rewarming
• Warming blankets or heating pads
• Immersion
• Arteriovenous anastomoses rewarming
Forced Air Rewarming
• e.g. Bair Hugger
• Theoretical concern: vasodilation in
extremities could transport cooler blood
back to core causing afterdrop and
rewarming shock
• Advantages: easy to use, readily
available, low cost, noninvasive
Forced Air Rewarming
• Has been used successfully in accidental
hypothermia (including profound) without
evidence of afterdrop or rewarming shock
• Usually in conjunction with warmed IV fluids
and heated inhalation
• Rewarming rates between 1 to 4.4oC/hr
De Caen, A. Management of profound hypothermia in children without the use of extracorporeal life
support therapy. The Lancet. 360:1394-95, 2002.
Koller R, Schnider TW, Neidhart P: Deep accidental hypothermia and cardiac arrest--rewarming with
forced air. Acta Anaesthesiol Scand 41:1359, 1997
Roggla et al. Severe accidental hypothermia with or without hemodynamic instability: rewarming without
the use of extracorporeal circulation. Wiener Klinische Wochenschrift. 114(8-0):315-20, 2002
Steele et al. Forced air speeds rewarming in accidental hypothermia. Ann Emerg Med. 27:479, 1996
Immersion
• Impractical in ER setting
• Makes monitoring and CPR impossible
Arteriovenous Anastomoses
Rewarming
• Originally described by Vangaard in 1979
• Exogenous heat provided by immersion of
lower parts of extremities (hands, feet,
forearms and calves) in 44-45oC water
• Mechanism:
– Heat opens arteriovenous anastomoses that exist
1mm below epidermal surface in digits
– Results in increased flow of warmed venous SC
blood returning to heart
– Countercurrent heat loss is minimized as
superficial veins are distant from arteries
• Theoretically should minimize afterdrop
Vanggaard L et al. Immersion of distal arms and
legs in warm water (AVA rewarming) effectively
rewarms mildly hypothermic humans. Space
and Environmental Medicine. 70(11):1081-8,
1999
• Voluntary mildly hypothermic subjects warmed
comfortably with AVA technique at a rate of 9.9+/3.2 degrees C with minimal afterdrop
Diathermy
• Experimental technique involving
transmission of heat by ultrasonic and
low frequency microwave radiation
• Animal studies promising
Active Core Rewarming
• Heated inhalation
• Heated infusion
• Lavage
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Gastric
Colonic
Mediastinal
Thoracic
Peritoneal
Bladder
• Hemodialysis
• Extracorporeal methods
Heated Inhalation
• Must be humidified as dry air has little
thermal conductivity
• 40-45oC
• Although rewarming rates have been
reported at 1-2.5oC/hr, primary aim is to
reduce respiratory heat loss
Warmed IV Fluids
• Cold fluid resuscitation is well known to
induce hypothermia in previously
normothermic trauma patients
Kashuk et al. Major abdominal vascular trauma: a unified approach. J trauma. 22:672,
1982
• Heat IV fluids to 40-42oC
• Conductive heat loss is significant through
long IV tubing esp. at low rates
• Level 1 Fluid Warmer ideal
• In theory, 1 L of fluid at 42oC should warm a
70kg patient at 28oC by 0.33oC
Warmed IV Fluids
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New research into superheated fluids at 65oC
Central infusion
Animal studies
No apparent complications
More work needs to be done
Fildes et al. Very hot intravenous fluid in the treatment of hypothermia. J trauma. 35:683,
1993.
Sheaff et al. Safety of 65oC intravenous fluid for the treatment of hypothermia. Am J Surg.
172:52, 1996.
Heated Irrigation
• Gastric, colonic, bladder
– Limited surface area for heat transfer
– Gastric lavage may be complicated by
aspiration
– Average rewarming rates of 1.5-2oC/hr
Hanania et al. Accidental Hypothermia. Critical Care Clinics. 15(2):236-48, 1999
Danzl DF. Accidental hypothermia. Wilderness Medicine
Peritoneal Lavage
• 40-45oC dialysate via minilaparotomy or
percutaneous puncture
• Flow rates of ~6 L/hr
• Rewarming rates of 1-3oC/hr
• Electrolytes must be carefully monitored
Closed Thoracic Lavage
• Procedure:
– Two 36-40F thoracostomy tubes placed in one or
both hemithoraces
– Anterior second or third intercostal space at
midclavicular line
– Posterior axillary line at fifth to sixth intercostal
space
– Infuse NS at 40-42oC into anterior tube, drain by
suction or gravity from posterior tube
Closed Thoracic Lavage
• Potentially hazardous in the non-arrest
patient (precipitate VF)
• Clinical experience is limited
• Rewarming rates average 3-6oC /hr
• Ensure adequate drainage or tension
hydrothorax will ensue
Kangas et al. Treatment of hypothermic circulatory arrest with thoracotomy and pleural lavage.
Annales Chirurgiae et Gynaecologiae. 83(3):258-60, 1994.
Winegard C. Successful treatment of severe hypothermia and prolonged cardiac arrest with
closed thoracic cavity lavage.] Journal of Emergency Medicine. 15(5):629-32, 1997.
Danzl DF. Accidental hypothermia. Wilderness Medicine. P159.
Mediastinal Irrigation
• Standard left thoracotomy
• Irrigation of mediastinum with 40oC fluid
• Also allows for direct cardiac compression and
direct defibrillation
• Only indicated in cardiac arrest
• One uncontrolled, nonrandomized review
reported favourable results with ED
thoracotomy +/- CPB compared to immediate
CPB alone
Brunette et al. Hypothermic cardiac arrest: an 11 year review of ED
management and outcome. Am J Emerg Med. 18(4): 418-22, 2000.
Extracorporeal Rewarming
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Hemodialysis
Arteriovenous rewarming
Venovenous rewarming
Cardiopulmonary bypass
Extracorporeal Rewarming
• Complications
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Vascular injury
Air embolism
Pulmonary edema
Coagulopathy
• Contraindications
– DNR order or obviously lethal injuries present
– Lack of venous return
– Intravascular clots or slush
Hemodialysis
• Best for stable patients with renal failure or
dialyzable toxin
• Has been reported in the literature in a
known dialysis patient who suffered cold
exposure leading to core temp or 24.9oC.
Warmed hemodialysis was performed for an
average temperature rise of 1.9oC/hr
Owda A. Osama S. Hemodialysis in management of hypothermia. American Journal of Kidney Diseases.
38(2):E8, 2001 Aug
Arteriovenous Rewarming
• Femoral artery and contralateral femoral
venous catheters
• Countercurrent fluid warming
• Required SBP>60mmHg
• Heparinization
• Rates of 3-4oC/hr
Venovenous Rewarming
• Countercurrent fluid warming with roller
pump
• Warmed blood is removed from central
line then returned by a second IV site
• No circulatory support
Cardiopulmonary Bypass
• Considered gold standard of rewarming
hypothermic arrest patients
• Preserves oxygenated flow in patients
without mechanical cardiac activity
• Fastest of all rewarming strategies at 12oC every 3 to 5 minutes!!!
Cardiopulmonary Bypass
• Can be lifesaving in cases of profound hypothermia
with prolonged arrest times
– Walpoth et al 1997: 32 arrest patients with mean T=21.8
rewarmed with CPB. 15 long term survivors
– Schwarz et al 2000: 5 arrest patients treated with CPB, 2
survived
– Gilbert et al 2000: 1 arrest patient T=13.7, warmed with
CPB, survived
– Althaus et al 1982: 3 severely hypothermic patients treated
with CPB: all recovered
– Vretnar et al 1994: 68 hypothermic patients (61 arrest)
mean T=21 placed in CPB. 60% survived
– Koller et al 1997: 5 patients (2 arrest) on CPB, all survived
Cardiopulmonary Bypass
• Standard femoral artery-femoral vein
CPB includes vascular catheters,
mechanical pump, membrane or bubble
oxygenator and heat exchanger
• Heparin-coated perfusion equipment
has been developed and used
successfully in patients with
contraindications to heparinization
“No one is dead until they are
warm and dead”
Prognostic Markers
• Survival is difficult to predict
• Literature is littered with case reports of
dramatic saves
• Mortality rate in severe hypothermia 40-75%
• Wide variation in human physiologic
responses to hypothermia
• Accurate triage markers of death are needed
• No validated prognostic indicators in the
literature
Mair et al. Prognostic markers in patients
with severe accidental hypothermia and
cardiocirculatory arrest. Resuscitation;
27:47-54, 1994
• Retrospective study of 22 patients with severe
hypothermia and cardiac arrest treated with CPB
• Found that in avalanche victims
– K>9 mmol/L
– pH<6.50 (central venous)
– Activated clotting time>400s
Were not compatible with re-establishment of
circulation
• Results could not be applied to non-avalanche
causes of hypothermia
Schaller et al. Hyperkalemia: a
prognostic factor during acute severe
hypothermia. JAMA; 264: 1842, 1990.
• Retrospective review of 9 hypothermic
avalanche victims and 15 hypothermic
intoxications
• All avalanche victims were hyperkalemic
(6.8-24.5) and none survived
• All intoxications were not hyperkalemic
(2.7-5.3) and all survived
Segesser et al. Perfusion without
systemic heparinization for rewarming in
accidental hypothermia. Ann Thoracic
Surg. 52:560-561, 1991.
• Reports resuscitation of hypothermic
patient with K=9.5 mmol/L
Wollnek et al. Cold water submersion
and cardiac arrest in treatment of severe
hypothermia with cardiopulmonary
bypass. Resuscitation; 52(3):255-63,
2002.
• Base excess, pH, K
– Not reliable prognostic markers
Bottom Line
• Decision to continue or terminate
resuscitative efforts in hypothermic
arrest patients cannot at this time be
based on lab values
• May be useful to guide judgment in
situations of multiple victims with
limited resources
CHR Protocol
• Mild hypothermia>32oC
– External passive rewarming
• Warm blankets and environment
– External active rewarming:
• Forced air warming blanket
– Internal rewarming
• Warm IV fluids (<45oC)
CHR Protocol
• Moderate hypothermia 28-32oC with
stable hemodynamics
– External active rewarming:
• Forced air warming blanket
– Internal active rewarming:
• Warm IV fluids
• Consult ICU re:
– Warmed humidified ventilation
– Hemodialysis with warm dialysate (esp if intoxication
suspected)
CHR Protocol
• Severe hypothermia <28oC or <32oC
with unstable hemodynamics
– Trauma team activation, Level 1
– Consult CV surgery team:
• Surgeon, nursing staff, anesthetist, perfusionist
and OR, anesthesia tech at 0050
• Take to trauma OR
CHR Protocol
• Severe hypothermia continued:
hemodynamically stable
– External active rewarming
• Forced air warming blanket
– Internal active rewarming
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Warm IV fluids
Warmed humidified ventilation
Warmed peritoneal lavage
Place percutaneous femoral arterial and venous catheters
for extra-corporeal support access in case of
hemodynamic deterioration
• If neurologic or other major bleeding injury ruled out,
consider CPB even if stable with T<28oC
CHR Protocol
• Severe hypothermia continued:
hemodynamically unstable: VT, VF, asystole
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ACLS protocol
CPR
1 series of 3 defibrillations at T<30oC
Withhold other rewarming strategies while
awaiting extra-corporeal support
– Place percutaneous arterial and venous cannulae if
vessels accessed pre-arrest or cutdown if postarrest
CHR Protocol
• Bypass protocol for severe hypothermia
– Neurologic injury suspected
• Establish ECMO
– Minimal dose heparin 0-3000U at time of cannulation
– Heparin bonded extracorporeal circuit and oxygenator
– Arterial and venous cannulae are not heparin bonded:
avoid stasis
– Biomedicus pump
– Heat exchanger
– Heparin – ACT management: risk/benefit
– Continue CPR until circulation established
CHR Protocol
• Bypass protocol for severe hypothermia
– Neurologic injury not suspected
• Regular cardio-pulmonary bypass with full
heparinization
• With femoral cannulation, LV decompression
may be inadequate: continued CPR may be
required until perfusing rhythm re-established
• Sternotomy for difficult femoral access and
pediatric patients
Questions?