Hypothermia andHypothermia andrewarming techniquesrewarming techniques

Albury Wodonga Teaching Program 2013Albury Wodonga Teaching Program 2013

hypothermia predisposes to hypothermia predisposes to a physiological state of:a physiological state of:

hypotensionhypotension

hypoventilationhypoventilationdepressed mental state and depressed mental state and

bradycardia.bradycardia.

Key pointsKey points

domestic victims are generally elderly and domestic victims are generally elderly and femalefemale

non-domestic victims are male aged 13-65non-domestic victims are male aged 13-65

invasive techniques are for severe invasive techniques are for severe hypothermia with circulatory compromisehypothermia with circulatory compromise

non-invasive techniques are effectivenon-invasive techniques are effective

Key pointsKey points

Deaths from hypothermia are predominantly Deaths from hypothermia are predominantly domesticdomestic

Co-morbid disease can precipitate hypothermiaCo-morbid disease can precipitate hypothermia

e.g. overdose, trauma, MI, strokee.g. overdose, trauma, MI, stroke

These conditions need specific treatmentThese conditions need specific treatment

Managing hypothermia may reverse Managing hypothermia may reverse physiological abnormalitiesphysiological abnormalities

HypothermiaHypothermia

Incidence of death low - 0.07% of all causes Incidence of death low - 0.07% of all causes

Incidence of hospitalisation 13X rate of deathIncidence of hospitalisation 13X rate of death

Occurs at extremes of age and in young malesOccurs at extremes of age and in young males

Domestic fatalities predominantly occur in the Domestic fatalities predominantly occur in the elderlyelderly

Non-residential fatalities occur in young malesNon-residential fatalities occur in young males

Epidemiology of hypothermia: fatalities and hospitalisations in New Zealand Epidemiology of hypothermia: fatalities and hospitalisations in New Zealand Aust N Z J Med. 1994 Dec;24(6):705-10.Aust N Z J Med. 1994 Dec;24(6):705-10.

In AustraliaIn Australia

Pathology. 2008 Jan;40(1):46-51.Pathology. 2008 Jan;40(1):46-51.

Hypothermia fatalities in a temperate climate: Hypothermia fatalities in a temperate climate: Sydney, AustraliaSydney, Australia

Case report of 24 fatalities 2001-2005Case report of 24 fatalities 2001-2005

Predominantly domestic, female and elderlyPredominantly domestic, female and elderly

Risk factorsRisk factorsburn injuriesburn injuries

extremes of ageextremes of age

ethanol intoxicationethanol intoxication

dehydrationdehydration

major psychiatric illnessmajor psychiatric illness

traumatrauma

use of intoxicantsuse of intoxicants

significant blood losssignificant blood loss

sleep deprivationsleep deprivation

malnutritionmalnutrition

co-existing medical conditionsco-existing medical conditions

How cold is cold?How cold is cold?

Mild 32Mild 32oo - 35 - 35oo

Moderate 29Moderate 29oo - 32 - 32oo

Severe <29Severe <29oo

Poikilothermia - cooled to ambient temperaturePoikilothermia - cooled to ambient temperature

Lowest recorded temperature for a survivor of Lowest recorded temperature for a survivor of accidental hypothermia is 9accidental hypothermia is 9ooCC

Response to coolingResponse to cooling

metabolic rate drops 2-3X with every 10metabolic rate drops 2-3X with every 10o o dropdrop

cerebral blood flow decreases 6-7% per 1cerebral blood flow decreases 6-7% per 1o o

dropdrop

shivering - down to about 34shivering - down to about 34oo

gluconeogenesis - via adrenaline releasegluconeogenesis - via adrenaline release

peripheral vasoconstriction ➜ cold diuresis via peripheral vasoconstriction ➜ cold diuresis via central hypertension and ADH inhibitioncentral hypertension and ADH inhibition

What happens as you What happens as you cool?cool?34-3534-35oo

CVSCVS RSRS CNSCNS

TachycardiaTachycardia TachypnoeaTachypnoea LethargyLethargy

↑↑ afterloadafterload ↑ ↑ minute minute ventilationventilation Mild confusionMild confusion

↑↑BPBPLoss of fine Loss of fine motor co-motor co-ordinationordination

What happens as you What happens as you cool?cool?30-3430-34oo

CVSCVS RSRS CNSCNS

Progressive Progressive bradycardiabradycardia

Increased Increased bronchial bronchial secretionssecretions

DeleriumDelerium

↓ ↓ cardiac cardiac outputoutput ↓ ↓ gag reflexgag reflex Slowed reflexesSlowed reflexes

HypotensionHypotension ↓ ↓ cough cough responseresponse Muscle rigidityMuscle rigidity

lengthening of lengthening of cardiac cardiac conductionconduction

Abnormal EEGAbnormal EEG

atrial/atrial/ventricular ventricular dysrhythmiasdysrhythmias

What happens as you What happens as you cool?cool?< 30< 30oo

CVSCVS RSRS CNSCNS

Spontaneous VFSpontaneous VF RR to ↓ 5 bpmRR to ↓ 5 bpm AreflexiaAreflexia

Osborne ‘J’ Osborne ‘J’ waveswaves ComaComa

Fixed pupilsFixed pupils

EEG ‘silent’ at EEG ‘silent’ at 1919oo

‘‘J’ waves have no prognostic or predictive valueJ’ waves have no prognostic or predictive value

ED Management ED Management prioritiespriorities

Prevent further coolingPrevent further cooling

Establish a safe rewarming rateEstablish a safe rewarming rate

Maintain cardiopulmonary stabilityMaintain cardiopulmonary stability

Provide physiological supportProvide physiological support

Other factors to Other factors to considerconsider

Cardiac arrestCardiac arrest

Acid baseAcid base

CoagulopathiesCoagulopathies

PharmacodynamicsPharmacodynamics

Cardiac arrestCardiac arrest

numerous case reports of survivalnumerous case reports of survival

optimal compression rate not known - likely to be lessoptimal compression rate not known - likely to be less

duration unknownduration unknown

core temp >34core temp >34oo

pH >6.5pH >6.5

K < 10K < 10

May consider admission to ICU for prolonged May consider admission to ICU for prolonged attemptsattempts

Acid-baseAcid-base

↓↓11ooC ➔ C ➔

pH ↑ 0.015pH ↑ 0.015

pCOpCO22 ↓ 4.4% ↓ 4.4%

pOpO2 2 ↓ 7.2% ↓ 7.2%

current theories suggest not correcting for current theories suggest not correcting for temperaturetemperature

arterial pH no a prognostic guidearterial pH no a prognostic guide

CoagulpathiesCoagulpathies

from impaired clot formationfrom impaired clot formation

inhibition of thromboxane B2 (platelet function)inhibition of thromboxane B2 (platelet function)

hypothermia induced platelet aggregation seen hypothermia induced platelet aggregation seen in surgical patients causing neurological deficitin surgical patients causing neurological deficit

PharmacodynamicsPharmacodynamics

drug kinetics are altereddrug kinetics are altered

negative effects on renal and hepatic negative effects on renal and hepatic metabolismmetabolism

avoid digoxinavoid digoxin

magnesium, lignocaine and propanolol have magnesium, lignocaine and propanolol have been usedbeen used

use bicarb and pressors in smaller dosesuse bicarb and pressors in smaller doses

ED Management ED Management prioritiespriorities

Rate and method of Rate and method of rewarming is determined by rewarming is determined by the degree of hypothermia the degree of hypothermia

and severity of clinical and severity of clinical conditioncondition

Start points for Start points for treatmenttreatment

core temp. >32core temp. >32oo

Passive external rewarmingPassive external rewarming

core temp. <32core temp. <32

Active external rewarmingActive external rewarming

Active core rewarmingActive core rewarming

Core temperature Core temperature measurementmeasurement

Bladder probes - available, reliableBladder probes - available, reliable

Rectal probes - lag time, faecesRectal probes - lag time, faeces

Oesophageal probes - may be influenced by Oesophageal probes - may be influenced by warmed airwarmed air

Tympanic membrane - less reliableTympanic membrane - less reliable

Passive external Passive external rewarmingrewarming

Remove wet clothingRemove wet clothing

Warmed blanketsWarmed blankets

Resistive heating blankets (space blanket)Resistive heating blankets (space blanket)

Active external warmingActive external warming

Heated air blanketsHeated air blankets

Warmed IV fluidsWarmed IV fluids

limited role due to reduced circulating limited role due to reduced circulating volumevolume

Immersion therapyImmersion therapy

‘‘afterdrop’ phenomenaafterdrop’ phenomena

not more effective than heated air blanketnot more effective than heated air blanket

Warming rate Warming rate ooC/hrC/hr

Passive Passive externaexterna

ll

Active Active externaexterna

ll

Inhaled Inhaled warm warm

airair

PeritonePeritoneal al

lavagelavage

Colon/Colon/Gastric/Gastric/Bladder Bladder lavagelavage

1st hr1st hr 1.41.4 1.51.5 1.51.5 1.51.5 1.31.3

2nd hr2nd hr 1.41.4 2.42.4 2.02.0 2.52.5 1.71.7

3rd hr3rd hr 1.81.8 2.02.0 1.91.9 3.23.2 1.81.8

From Danzl D, Pozos RS: From Danzl D, Pozos RS: Multicenter hypothermia study.Multicenter hypothermia study. Ann Emerg Med 16:1042, Ann Emerg Med 16:1042, 19871987

Active core rewarmingActive core rewarming

generally a treatment in the face of circulatory generally a treatment in the face of circulatory failurefailure

allows more rapid increase in core temperatureallows more rapid increase in core temperature

some techniques are not technically possible some techniques are not technically possible depending on situationdepending on situation

Active core rewarmingActive core rewarming

Heated humidified oxygenHeated humidified oxygen

Peritoneal lavagePeritoneal lavage

Bladder irrigationBladder irrigation

Thoracic cavity lavageThoracic cavity lavage

ECMO/bypassECMO/bypass

Microwaves / total liquid ventilation(TLV) / hot Microwaves / total liquid ventilation(TLV) / hot IV fluidsIV fluids

Heated Humidified Heated Humidified OxygenOxygen

can be performed via mask or ETTcan be performed via mask or ETT

can be used pre-hospitalcan be used pre-hospital

needs careful monitoring of temperature and needs careful monitoring of temperature and humidificationhumidification

can be used routinely to complement external can be used routinely to complement external techniquestechniques

temperatures >50temperatures >50oo may cause mucosal burns may cause mucosal burns

Warming fluidWarming fluid

ideal temperature 40-42ideal temperature 40-42oo

IV fluid warmersIV fluid warmers

only certain devices are suitable for only certain devices are suitable for adequately warming large volumes for rapid adequately warming large volumes for rapid infusioninfusion

microwaving fluids is not recommendedmicrowaving fluids is not recommended

Peritoneal lavagePeritoneal lavage

can achieve rates up to 2-3can achieve rates up to 2-3oo /hr /hr

infra-umbilical incision/seldinger techniqueinfra-umbilical incision/seldinger technique

rapid infuser device, two catheters to increase rapid infuser device, two catheters to increase flowflow

theoretically less successful than thoracic theoretically less successful than thoracic lavagelavage

wouldn’t interfere with CPRwouldn’t interfere with CPR

may help in overdosemay help in overdose

Bladder irrigationBladder irrigation

good rates of core rewarminggood rates of core rewarming

equipment readily available, saline or equipment readily available, saline or HartmannsHartmanns

smaller volumes possible - max. prob. 200mlssmaller volumes possible - max. prob. 200mls

1-2 minute dwell times1-2 minute dwell times

less risk to patient than more invasive less risk to patient than more invasive techniquestechniques

may interfere with core temp. monitoringmay interfere with core temp. monitoring

Thoracic cavity lavageThoracic cavity lavage

used in setting of cardiac arrestused in setting of cardiac arrest

closed or openclosed or open

CPR can continue with eitherCPR can continue with either

rates of 6-7rates of 6-7oo in 20 minutes have been in 20 minutes have been describeddescribed

caution in coagulpathycaution in coagulpathy

continue until 35continue until 35oo

ECMO/bypassECMO/bypass

high level of expertise/equipment/support high level of expertise/equipment/support neededneeded

1-21-2oo every 3 to 5 minutes every 3 to 5 minutes

may take some time to set upmay take some time to set up

anticoagulation required may complicate active anticoagulation required may complicate active CPRCPR

can allow oxygenationcan allow oxygenation

consider in asystole or VFconsider in asystole or VF

Microwaves/TLV/hot IV Microwaves/TLV/hot IV fluidsfluids

Microwave rewarming equivalent to passive Microwave rewarming equivalent to passive rewarming in volunteer study. rewarming in volunteer study. Resuscitation 29:203, 1995Resuscitation 29:203, 1995

TLV in animal models using warmed oxygenated TLV in animal models using warmed oxygenated perflurocarbon. Shorter rewarming times, no perflurocarbon. Shorter rewarming times, no afterdrop phenomena and no lactate rise. afterdrop phenomena and no lactate rise. Mil Med Mil Med 166:853, 2001166:853, 2001

6060oo IV fluids appear to cause little complications. IV fluids appear to cause little complications. Role in accidental hypothermia not defined. Role in accidental hypothermia not defined. J J Trauma 42:1112, 1997Trauma 42:1112, 1997