Carlos Mesquita - Associação Lusitana de Trauma e...

Hypothermia in trauma

Carlos Mesquita

EUROTRAUMA 2009 ANTALYA

Lusitanian Association of Trauma and Emergency Surgery

Coimbra University Hospital - Portugal

Thermoregulation - physiology

• Normal core body temperature ~ 37 C / 99 F

(from the 1911 Encyclopædia Britannica Eleventh Edition)

CM – EUROTRUMA 2009 ANTALYA

http://en.wikipedia.org/wiki/File:1911_Animal_heat.png


• Constant body temperature mantained by

– Basal metabolic rate

– Muscle activity

– Cutaneous vasoconstriction

– Inhibition of perspiration


• Mecanisms of heat loss:


– Conduction

• transfer of heat by physical contact with another object or body

– Convection • transfer of heat via a medium such

as air or water

– Radiation • transfer of heat without any medium

through electromagnetic waves

– Evaporation • absorption of heat by a liquid which

then becomes a gas (perspiration, intra-operative loss /

thoracotomy and laparotomy) CM – EUROTRUMA 2009 ANTALYA

• Primary

– Normal thermoregulation + exposure to extreme environment

• Secondary

– Loss of thermoregulatory mechanisms + mild thermal stress

– Intoxication

– Stroke

– Hypothyroid states

– Severe trauma

Accidental hypothermia


• Depletion of high-energy phosphates (ATP)

+ utilization under anaerobic conditions

= Insufficient heat production organ failure

• Clinical Findings

– Decrease in CNS activity

– Decrease of cardiorespiratory activity • gray, cyanotic • initially cardiovascular stimulation by cathecolamine • later cardiovascular depression

– Increased diuresis (“cold diuresis”)

– Coagulopathy • decrease in platelet function and clotting factor activity

Hypothermia


• Drop in core temperature to < 35 C / 095 F – rapid or slow

– severity:

• Mild < 35 C / 095 F • Moderate < 32 C / 090 F • Severe < 30 C / 086 F

• Increased risk of VF at < 28 C / 082 F • Asystole commonly occurs at < 22 C / 072 F

low-range thermometer required preferably esophageal

Hypothermia in the absence of traumatic injury


• Increased mortality with severity of hypothermia

• Any core temperature < 36 C / 097 F

• If < 32 C / 090 F

LIMIT SITUATION = LETHAL TRIAD


HYpotHermia AcidosIS CoagulopatHY will feed off each other and start a steep downward spiral, toward death, that is difficult to stop


• 1/10 major trauma patients experience it – elderly and children at greater risk – decreased heat production in shock – undressing the patient in ressuscitation room – thermoregulation shut off by general anaesthesia – infusion of cold fluids – prolongued exposure of body cavities

• 3/10 death trauma patients hypothermic on arrival



ATLS Key Questions

• Cold injury:

– How does cold affect my patient?

– How do I recognize a cold injury?

– How do I treat local cold injuries?

– How do I treat a systemic cold injury?


ATLS Key Questions

• How does cold affect my patient?

– Factors

• Temperature / environmental conditions

• Duration of exposure

• Amount of protective clothing

• Patient general state and health

• Immobilization / Moisture

• Vascular disease

• Open wounds


ATLS Key Questions

• How do I treat a systemic cold injury?

– ABCDE / monitor and support vital functions

– Measure core temperature

– Rewarm

– Assess for associated disorders

– Do not delay transfer

– Not dead until warm and dead


Rewarming

• Passive external:

– prevention of further heat loss

• remove from the cold environment

– cover with blankets

– allow endogenous heat production to restore normothermia

• not very effective means of restoring and then maintaining normal body temperature

• can result in a shift to anaerobic metabolism and lactic acidosis


Rewarming

• Active external rewarming

– fluid-circulating heating blankets

– convective air warmers

– reflective blankets

– radiant heat shields


Rewarming

• Active internal / core rewarming:

– warm intravenous fluids

– airway rewarming

– body cavity lavage

– extracorporeal circulatory techniques


What’s coming next?


Round-Trip Journeys to the Afterworld… “… strategies to maintain cerebral and cardiac viability

long enough to gain control of hemorrhage and restore intravascular volume could be life-saving … an entirely new approach to the problem, with emphasis on

– rapid total body preservation, – repair of injuries during metabolic arrest, – and controlled resuscitation,

so-called emergency preservation and resuscitation.”

Shuja F, Almeida JP, Alam HB. Role of hypothermia in hemorrhagic shock. J Organ Dysfunction, 2008;4;3



Carlos Mesquita - Associação Lusitana de Trauma e...

Documents

Transcript of Carlos Mesquita - Associação Lusitana de Trauma e...