Hypothermia following prolonged outdoor exposure

Patient Information

Dispatch: You are called to a patient (Ronald Hatch, 75YO male) found seated on a bench outside the main grandstand. Bystanders report he has been sitting in the cold and wind for over two hours and is now difficult to rouse.
Patient: Ronald Hatch — 75yr (75kg)
Incident History: Pt attended the ANZAC Day dawn service at Langley Park. After the ceremony he sat on a bench and friends were unable to get him to stand up. Pt is lethargic, speaking slowly, and is wet from early morning drizzle. Bystanders unsure how long he has been unresponsive to questions.
Emergency Contact: Margaret Hatch (Wife) — 0412 554 871

Initial Rapid Assessment

Response: Voice
Airway: Patent. Nil airway obstruction. Nil stridor. Airway self-maintained at this time.
Breathing: Shallow and slow. Decreased respiratory rate. Mild reduction in chest excursion. Nil audible wheeze or crackle.
Circulation: Weak and slow radial pulse. Skin pale, cold and dry to touch. Nil active bleeding. Peripheral vasoconstriction noted — fingers and lips pale.
Disability: GCS 11 (E3V3M5). Confused and disoriented to time and place. Slurred speech. Responds to voice but does not follow complex commands.
Exposure: Patient is wearing a thin dress shirt and trousers — both visibly wet from rain. No visible trauma. Mild generalised muscle weakness noted on brief assessment. No rash, no wounds.

Vitals

Time	SpO2	Resp Dist	RR	Pulse	BP	CRT	GCS	PERL	Temp	BGL	Pain
Initial	93% (RA)	Mild	9	46	88/58	4s	11	4 4 SL	31.8	3.6 mmol/L	2
10 mins	96% (O2 NRB 15L)	Nil	12	52	96/62	3s	13	4 4 SL	32.4	3.6 mmol/L	1

History Taking

Treatment Response

Diagnosis

This patient is suffering from moderate hypothermia (estimated core temperature 30–32°C) with associated bradycardia, hypotension, reduced GCS, and absent shivering — consistent with his prolonged cold and wet exposure. His beta-blocker (metoprolol) blunts the normal compensatory tachycardia, and warfarin use is a relevant background factor requiring documentation for the receiving facility.

Facilitator Triggers — if trainees miss a critical step

! (If trainees do not remove wet clothing promptly — after 3 minutes the patient begins shivering violently then abruptly stops, and GCS drops to 9. Facilitator states: 'The patient is no longer responding to your voice.')
! (If oxygen is not applied within 3 minutes — SpO2 drops to 90% on room air and respiratory rate falls to 7. Facilitator states: 'The patient's breathing is becoming more shallow.')
! (If BGL is not checked — facilitator prompts at 5 minutes: 'The patient seems to be getting more confused — is there anything else you want to check?')
! (If trainees attempt to mobilise the patient rapidly or handle roughly — facilitator states: 'As you move him briskly the patient suddenly becomes unresponsive and pulseless.' Manage as cardiac arrest secondary to hypothermia. Emphasise that sudden motion can trigger ventricular arrhythmia in moderate-to-severe hypothermia.)
! (If warm oral fluids are offered without confirming GCS is 15 — facilitator states: 'The patient reaches for the cup but cannot grip it and his head slumps forward.' Remind trainees warm oral fluids are only appropriate if the patient is fully conscious.)

Treatment Objectives

1 Ensure scene safety and don appropriate PPE.
2 Perform Primary Survey — establish patient is responsive to voice, airway self-maintained, breathing shallow and slow, pulse weak and bradycardic.
3 Move patient to a sheltered environment (inside FAP or ambulance) — remove from wind and cold immediately.
4 Handle patient gently throughout — avoid sudden or rough movement to reduce risk of precipitating ventricular arrhythmia.
5 Remove all wet clothing carefully — dress shirt and trousers are wet and must be removed.
6 Apply oxygen via non-rebreather mask at 10–15 L/min targeting SpO2 94–98%.
7 Perform Vital Sign Survey — obtain GCS, SpO2, RR, BP, HR, CRT, BGL, and tympanic temperature.
8 Record tympanic temperature — note this may underestimate true core temperature in extreme cold environments; document and interpret in conjunction with clinical presentation.
9 Check BGL — result 3.6 mmol/L. Patient is at low threshold; monitor closely but does not meet criteria for glucose gel at this time (threshold <4 mmol/L with altered conscious state; BGL is borderline — reassess at 10 minutes).
10 Passively rewarm patient — wrap in Ready-Heat blanket (place sheet between blanket and skin first), then cover with standard blanket. Apply additional blankets as available.
11 Do NOT offer warm oral fluids — patient GCS is 11/15, therefore oral intake is unsafe.
12 Record full observations every 10 minutes.
13 Note medications: metoprolol (beta-blocker) will blunt compensatory tachycardia — low HR may underestimate severity; warfarin — relevant for receiving facility documentation.
14 Reassess GCS, SpO2, HR and temperature at 10 minutes — expect gradual improvement with passive rewarming and oxygen.
15 Arrange transport — urgent given GCS <15, bradycardia, hypotension, and moderate hypothermia. Pre-notify receiving ED.
16 Continue monitoring during transport — be alert for deterioration in GCS or cardiac rhythm changes (bradyarrhythmias are common in moderate hypothermia).
17 Prepare resuscitation equipment — defibrillator and BVM at hand in the event of cardiac arrest secondary to hypothermia.
18 Scenario ends on arrival of ambulance and IMISTAMBO handover.
19 Attention to hand hygiene will be given throughout the scenario.

Clinical references: Hypothermia · Oxygen Delivery · Blood Glucose Monitor · Tympanic Thermometer · Ready Heat Blanket · Primary Survey · Unconsciousness

How did you go?