Environmental

Hypothermia following prolonged cold water immersion

Intermediate

Adult · 35yr · male

Patient Information

Dispatch	You are called to a patient (Rhys Connolly, 35YO male) at the Fremantle Triathlon Festival FAP. Bystanders report he exited the open water swim leg and collapsed near transition. He is conscious but confused and shivering violently.
Patient	Rhys Connolly — 35yr (80kg)
Incident History	Pt completed the 1.5km open water swim in the Swan River on a cold winter morning. Water temperature estimated 14°C. He exited the water approximately 10 minutes ago, did not change out of his wetsuit, and has been standing in the wind before collapsing at the transition zone. Event volunteers removed his wetsuit and wrapped him in a foil blanket.
Emergency Contact	Kate Connolly (Wife) — 0412 874 503

Initial Rapid Assessment

Response	Voice
Airway	Patent. Nil airway obstruction. Nil stridor or vomitus.
Breathing	Breathing present. Shallow with decreased rate. No wheeze or crackles. Shivering noted.
Circulation	Weak radial pulse. Skin pale, cold and moist. Peripheral cyanosis to fingertips. CRT 4 seconds.
Disability	GCS 12 (E3V4M5). Confused and disoriented to time and place. Slurred speech. Ataxia noted — unable to stand without support.
Exposure	Wet swimming attire only. Skin pale and mottled peripherally. No visible traumatic injury. Core area feels cool to touch despite foil blanket applied.

Vitals

Time	SpO2	Resp Dist	RR	Pulse	BP	CRT	GCS	PERL	Temp	BGL	Pain
Initial	91% (RA)	Mild	10	52	94/60	4s	12	4 4 SL	33.1	3.6 mmol/L	2
10 mins	96% (O2 NRB 15L)	Nil	13	60	102/66	3s	14	4 4 ++	33.5	4.2 mmol/L	1

History Taking

Treatment Response

Diagnosis

This patient is suffering from mild-to-moderate hypothermia (core temperature 33.1°C) following prolonged cold water immersion during the swim leg of a triathlon, complicated by wind exposure post-exit and delayed passive warming.

Facilitator Triggers — if trainees miss a critical step

! (If wet clothing is not removed promptly and the patient is not actively covered with blankets, tympanic temperature drops to 32.4°C at 10 minutes and patient becomes increasingly bradycardic at 46 bpm — inform trainees the patient is deteriorating.)
! (If patient is allowed to stand or is assisted to walk — e.g. to move to the FAP — trigger a sudden collapse. Remind trainees that sudden motion can trigger ventricular arrhythmia in moderate hypothermia.)
! (If BGL of 3.6 mmol/L is not actioned: at 10 minutes, patient develops increased confusion and GCS drops to 10 — prompt trainees to reassess BGL and consider Glucose Oral Gel.)
! (If oxygen is not applied within 5 minutes, SpO2 drops to 88% on RA and respiratory rate slows to 8 — prompt trainees to consider assisted ventilation.)

Treatment Objectives

1. Ensure scene safety — assess environment for cold wind exposure and move patient to a sheltered area or inside FAP.
2. Don appropriate PPE — gloves at minimum, given wet environment.
3. Perform Primary Survey — confirm patent airway, assess breathing rate and adequacy, assess circulation including central pulse.
4. Position patient recumbent — do not allow patient to stand or walk due to risk of triggering ventricular arrhythmia.
5. Remove remaining wet clothing — cut or assist removal of wet swimwear promptly.
6. Apply oxygen via Non-Rebreather Mask (NRB) at 10–15 L/min — titrate SpO2 to 94–98%.
7. Passively re-warm — wrap patient in blankets and activate Ready-Heat blanket if available. Place sticker-side down toward body, cover with standard blanket. Do NOT place directly on bare skin.
8. Perform Vital Signs Survey — GCS, SpO2, RR, BP, pulse, CRT, tympanic temperature, BGL.
9. BGL is 3.6 mmol/L — patient is symptomatic (confused, GCS 12) and BGL is below 4.0 mmol/L. GCS is NOT 15/15 therefore oral glucose drink is NOT indicated at this time. Monitor BGL closely and reassess GCS every 5 minutes.
10. (If GCS improves to 15 and BGL remains below 4.0 mmol/L: Administer Glucose Oral Gel 15g orally — entire contents of tube — as per Hypoglycaemia CPG. Reassess BGL after 10 minutes. Encourage complex carbohydrate once recovered.)
11. Reassure patient continuously — explain all procedures calmly.
12. Record full vital signs observations every 10 minutes — monitor temperature trend, GCS, and BGL.
13. Avoid sudden patient movement — handle gently to minimise risk of precipitating arrhythmia.
14. Request ambulance response — this patient is time critical given altered GCS, bradycardia, and tympanic temperature below 34°C.
15. Scenario ends on arrival of ambulance and IMISTAMBO handover.
16. Attention to hand hygiene will be given throughout the scenario.

Clinical references: Hypothermia · Hypoglycaemia · Oxygen Delivery · Blood Glucose Monitor · Ready Heat Blanket · Primary Survey · Glucose Oral Gel

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Signs/Symptoms	Confusion, slurred speech, shivering, weakness, ataxia. Peripheral cyanosis. Feeling very cold.
Allergies	Nil known
Medications	Nil regular medications
Pertinent History	Fit and healthy. Regular triathlete. No known cardiac or neurological history. Trained in pool swimming but less experienced with open water cold exposure. No prior episodes of hypothermia.
Last Oral Intake	Banana and water approximately 1 hour prior to swim start.
Events Leading	Completed the open water swim leg of the triathlon in the Swan River. Water was notably cold. Exited the water, felt immediately weak and confused, stood at the transition area for several minutes in the wind before collapsing.
Treatment Prior	Wetsuit removed by event volunteers. Foil emergency blanket applied. No medications administered.

Onset	Symptoms began approximately 5–10 minutes after exiting the water. Progressively worsening confusion noted by fellow competitors.
Pain	Mild generalised muscle aching. No chest pain. No head pain.
Quality	Diffuse muscular discomfort from sustained shivering.
Radiates	Nil
Severity	2/10