ENVIRONMENTAL

ResponseHeat Cramps (Painful, involuntary, spasmodic skeletal contractions) - Mildest
Heat Exhaustion - any heat related illness with volume depletion + normal mentation) - Moderate
Heat Stroke (core temp >40c + CNS dysfunction (+/- anhidrosis) - Severe (20-50% mortality)

Prickly heat (Pruritic, maculopapular, erythematous rash over clothed area of body)

ResponseTemperature >40 with CNS dysfunction (+/- anhidrosis depending on source)
Heat Exhaustion is bad. Can lead to Heatstroke which is worse.

Response3 or more days of high maximum and minimum temperatures that is unusual for that location - BOM
(concept: Prolonged period of high temperature, unusual for that location, resulting in adverse health effects)

ResponseHeat Stroke
Sepsis (LRTI, UTI, Skin etc)
CNS infection - Meningitis/encephalitis
Toxidrome - Anticholinergic, sympathomimetics, NMS less likely
Drug withdrawal - Alcohol, opiates
Neuro - non convulsive status, ICH/thalamic bleed
Metabolic - Dehydration, Thyroid storm, DKA
Lots of of others

ResponseEnvironmental - Prolonged extreme temperatures/humidity
Situational - lack of acclimitisation, poor salt/water intake
Patient factors - extremes of age, poor health (esp. CV and Renal failure - bad meds like diuretics), malnourished, EtOh, Mental health (Keep doing crazy shit in the sun)
Meds - Psychotropics, serotonergics, anticholinergics, sympathomimetics

ResponseDrugs that interfere:
Interfere with sweating - anticholinergics (TCA’s), antihistamines
Interfere with thermorgulation - Psych drugs (antipsychotics, neuroleptics, setotonin drugs), Stimulants, Thyroxine
Decrease thirst - ACE inhibitors
Nephrotoxics - NSAIDS
Worsen hypotension (thus worsening heat illness) - vasodilators (nitrates), CCBs, antihypertensives
Drugs that alter alertness - alcohol, benzo’s etc.
Things that mess up electrolytes: Diuretics, Diarrhoea drugs (Colchicine, antibiotics), Alcohol.

(Lots more… see NSW 2017.2 for extensive list)

ResponseEvaporative
- Simple, available, non invasive, can still assess patient
- Shivering, need fans/spray bottles, monitoring equipment gets wet
Immersion
- non invasive, effective
- Logistically difficult, cumbersome, can’t access pt, can’t monitor, shivering
Ice packs/Cooling blankets
- noninvasive, relatively effective, easy, can combine with other techniques
- Shivering, discomfort, poorly tolerated, need ice
Lavage - Gastric/peritoneal
- effective and rapid
- Invasive, airway risk
Bypass
- Rapid
- Invasive

ResponseRehydration - cool IV fluids, rapid infusion/bolus
Core temperature probe (rectal/oesophageal). Aim temp <38.5 (?<40)
urine output 2mL/kg/h with IDC,
Glucose management for normoglycemia
Monitoring - Core temp, ECG, EUC’s, BSL’s
Seek and treat alternative causes.
? intubate - ?needs airway, paralysis stops shivering, avoid sux.
? benzos if shivering
? empiric IVABx

ResponseSeizure = trigger to be super aggressive with this.
Seizure control - Benzo
RSI (No sux)
Active cooling, aim core temp <38.5
Rectal/peritoneal lavage. Consider ECMO/Dialysis if fails.
Seek and treat hyponatraemia (Can be low or high - but it will be deranged)
Aggressive IV fluids
Diuresis and urinary alkalinisation if above fails

ResponseWon’t raise temperature further by muscle contractions during fasciculations
Potassium likely to be higher from loss from damaged muscle (use with caution)
Ie: Best avoided

ResponseCK ? rhabdo
BSL (loss of regulation)
Coags (INR correlates to outcome, DIC)
Gas - ? electrolytes
FBC - thrombocytopaenia, leukocytosis
LFT’s - multi organ failure
Urinalysis - myoglobin
EUC’s - Hyperkalaemia, Renal failure
ECG - Arrhythmias
CTB - if intracranial cause suspected.

ResponseMultiorgan failure. think “list signs of each organ failing”
MSK - Shivering, Rhabdo
Neurological - delirium, seizure, coma
Cardiac - HF, Arrhythmias, cardiovascular collapse
Resp - NCPO, ARDS
Renal - AKI, Rhabdo
GIT - Hepatitis, hepatic necrosis, mesenteric ischaemia
Metabolic - hyperkalaemia, hypernatraemia, Low Calcium
Haem - DIC

ResponseMin predictor is duration and degree of hyperthermia. Below are all bad
Core temp >41c
AST >1,000 in first 24h
Prolonged coma
Hypotension not responsive to cooling/fluid replacement

• Hypodynamic over hyperdynamic circulation
• Need for pressors in first 24h

Need for intubation
Renal impairment/Hyper K
Altered coags