- TEMPERATURE RELATED EMERGENCIES - Flashcards
Identify the principles and the indications for targeted temperature management
- Cooling post resuscitation an improve survival and brain function post cardiac arrest or ischaemic stroke
- reduces brain damage post hypoxic period by decreasing the brain’s oxygen demand, reducing the production of neurotransmitters like glutamate, as well as reducing free radicals that might damage the brain
Define and describe the stages of hypothermia
• Intentional hypothermia: deliberately induced state, aimed at
neuroprotection (e.g. after cardiac arrest),
• Accidental hypothermia: usually results from exposure to cold
with inadequate protection
• Hypothermia has 2 broad causes:
– Primary: exposure to cold
• Immersion induced
• Non‐immersion induced
– Secondary: result of medical illness
• Trauma: multi‐trauma, major burns,
• Drugs – ethanol, sedatives, phenothiazines
• Neurological – Stroke, paraplegia, Parkinson’s disease
• Endocrine – Hypoglycaemia, hypothyroidism, hypoadrenalism
• Systemic illness – sepsis, malnutrition
• Degrees of hypothermia:
– Mild: <35oC
– Moderate <32.2oC
– Severe < 26oC
Discuss the pathophysiology of hypothermia
Hypothermia affects all systems
CARDIAC
- decreased depolarisation of cardiac pacemaker cells
- bradycardia - AV node and action potential disruption
- prolonged QT&QRS - Myocardial irritability
- Dysrhythmias (AF,VF,asystole) - Vasoconstriction
- hypo-perfusion of peripheries
RESPIRATORY
- hypothermia
- left shift on O2/Hb dissoc. curve
- hypo-perfusion to peripheries
- low metabolic rate
- decrease in O2 consumption
RENAL
- inability of kidneys to concentrate urine
- off loading of excess fluids
- hypoperfusion of peripheries
- cold diuresis (volume loss& dehydration)
- haemoconcentration
- increase blood viscosity
- thrombo-emboli
OTHER
- platelet function and coagulation cascade inhibited
- persistant shivering
- slowing circulation
- CNS depression
Discuss the clinical manifestations of hypothermia
35ºC
- cold, pale
- tachypnoea
- shivering
- poor muscle co-ordination
Mild (32-35ºC)
- Shivering may cease
- lethargy, weakness
- Cold or pale skin
- Decreased RR
- slurred speech
- confusion
- poor co-ordination
Moderate (30-32ºC)
- muscle rigidity
- poor reflexes
- dilated pupils
- hypotension
- bradycardia
- coma
Severe (<30ºC)
- flaccid muscles
- fixed, dilated pupils
- dysrhythmias
- cardiac arrest
Discuss the management of hypothermia
• Airway / Breathing
– Consider humidifier if not intubated
• Circulation
– ECG & continuous cardiac monitoring
– Warm IV fluid replacement
– Caution with defibrillation / drugs
• Disability
– Aim to ↑ core temperature by 0.5oC – 2.0oC per hour (may need
aggressive re‐warming)
– Gentle handling as irritable myocardium
– Monitor urine output
– Continuous temperature monitoring via rectal or bladder
thermometer
– Bear hugger
– Warm packs to groin & axilla
– Prevent rewarming shock and after drop
Discuss the complications of re-warming, including re-warming shock
- hypotension caused by rapid and marked vasodilation from warming
Describe cold diuresis
- redirection of blood from extremeties to core
- increase in fluid volume at core
- increase in MAP
- kidney diurese and increase urine production
Differentiate between heat exhaustion and heat stroke
Heat Exhaustion:
- pale, cool, clammy
- profuse sweating
- core temp 37.7-40
- dizzy, light headed
- confused
- cramping
Heat stroke
- flushed, hot, dry
- not sweating (dehydration)
- core temp >40.5
- confusion, hallucinations, combative
- ACS (usually GCS<8)
- BP changes
- hyperventilation
- seizures (often occur during cooling)
Describe the clinical manifestations of heat exhaustion
- pale, cool, clammy
- profuse sweating
- core temp 37.7-40
- dizzy, light headed
- confused
- cramping
Describe the pathophysiology of heatstroke
- vasodilation, excessive sweating
- hypovolaemia
- hypotension, tachycardia, reduced renal blood flow, reduced organ perfusion
- reduced urine output, renal damage
- reduced brain perfusion, ACS, rhabdomyolysis
- cells leaky, endotocins released
- MODS, SIRS
Discuss the clinical manifestations of heatstroke
- flushed, hot, dry
- not sweating (dehydration)
- core temp >40.5
- confusion, hallucinations, combative
- ACS (usually GCS<8)
- BP changes
- hyperventilation
- seizures (often occur during cooling)
Discuss the management of heatstroke
• Goal: normalise core and skin temperature & CNS function as
quickly as possible
• Easier to prevent than treat, therefore patient education is
important
• Airway – Consider intubation – seizures common • Breathing – Supplemental oxygen • Circulation – Fluid replacement – cool fluids – Haemodynamic monitoring – Monitor urine output • Disability – Corticosteroids for cerebral oedema – Active cooling – cold compress, fan, ice
Define malignant hyperthermia
Malignant Hyperthermia = pharmacogenetic disease of skeletal muscle induced by exposure to certain anaesthetic agents, causing hypermetabolism, muscle rigidity, high fever, tachycardia and increased CO2 production
Discuss the clinical manifestations of malignant hyperthermia
(1) increased ETCO2
(2) tachycardia
(3) tachypnoea
(4) masseter spasm (if develops this convert to a MH safe anaesthetic)
(5) muscle rigidity
(6) temp increase (late) – 1 C\15min
Discuss the management of malignant hyperthermia/ drug induced hyperthermia
– Immediate discontinuation of suspected offending agents – Volume resuscitation (if needed), – Active cooling – Benzodiazepines – Paralysis – Cyproheptadine – Chlorpromezine – Dantrolene (malignant hyperthermia)
