Download - Hypothermia and rewarming techniques
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