SVT at a city marathon event

Patient Information

Dispatch: A 47YO male has walked into the FAP complaining of a racing heart and feeling dizzy. (Marcus Holt)
Patient: Marcus Holt — 47yr (80kg)
Incident History: Pt was cheering on runners at the Perth City Marathon when he suddenly felt his heart 'take off'. States onset was abrupt approximately 8 minutes ago. Denies chest pain. Feels light-headed and clammy.
Emergency Contact: Sarah Holt (Wife) — 0412 774 338

Initial Rapid Assessment

Response: Alert
Airway: Patent. Nil airway obstructions. Speaking in short sentences.
Breathing: Slightly increased rate. Nil audible wheeze or crackles. Mild dyspnoea.
Circulation: Rapid, regular, weak radial pulse. Skin pale and diaphoretic. Nil visible bleeding.
Disability: GCS 15 (E4V5M6). Orientated to time, place and person. Anxious.
Exposure: Nil rashes or visible injuries. Wearing civilian clothing — spectator at event.

Vitals

Time	SpO2	Resp Dist	RR	Pulse	BP	CRT	GCS	PERL	Temp	BGL	Pain
Initial	97% (RA)	Mild	20	178	96/68	<2s	15	4 4 ++	37.1	5.4 mmol/L	2
10 mins	99% (O2 simple mask 6L)	Nil	16	168	108/72	<2s	15	4 4 ++	37.1	5.4 mmol/L	1

History Taking

Treatment Response

Diagnosis

This patient is suffering from Supraventricular Tachycardia (SVT) with haemodynamic compromise indicated by borderline hypotension, diaphoresis, and symptoms of reduced cardiac output.

Facilitator Triggers — if trainees miss a critical step

! (If the trainee does not limit patient exertion — e.g., allows patient to stand or walk — patient reports worsening dizziness and nearly faints; HR remains at 178 bpm)
! (If oxygen is not applied within 3 minutes, patient's respiratory rate increases to 24 and reports feeling more short of breath)
! (If the trainee does not take a blood pressure before any other intervention, facilitator prompts: 'The patient asks if everything is okay — what are you checking first?')
! (If the trainee asks about GTN for the chest discomfort without first checking BP, facilitator prompts: 'What does the BP need to be before you consider GTN?')
! (If the trainee attempts to administer GTN — note: GTN is not an authorised EHS treatment for cardiac dysrhythmia; facilitator prompts: 'Check the CPG — what indication does GTN have here?')
! (If no reassessment vitals are taken at 10 minutes, facilitator states: 'Five minutes have passed — the patient asks if the ambulance is coming; what are you doing right now?')

Treatment Objectives

1 Ensure scene safety and don appropriate PPE
2 Perform Primary Survey — confirm patent airway, assess breathing and circulation
3 Seat patient — limit all exertion; do not allow patient to stand or walk
4 Perform Vital Sign Survey — HR, BP, RR, SpO2, BGL, GCS, pain score, temperature
5 Apply oxygen via simple face mask at 6–8 L/min — titrate to SpO2 target 94–98%
6 Perform history taking using IMISTAMBO / SAMPLE framework
7 Reassure patient continuously — explain all actions calmly
8 Do NOT administer GTN — GTN is not indicated for cardiac dysrhythmia at EHS scope; chest discomfort is secondary to the rapid rate, not ischaemic in origin
9 Recognise SVT: HR ~178 bpm, sudden onset, regular, rapid, with signs of reduced cardiac output (borderline BP, diaphoresis, dizziness)
10 Recognise this patient is time critical — haemodynamically compromised SVT requires urgent ambulance via CSP
11 Request ambulance upgrade / urgent ambulance support via CSP — IMISTAMBO handover to CSP
12 Monitor patient persistently — record full observations every 10 minutes (or 5 minutes given time critical status)
13 Position patient seated and at rest; do not allow mobilisation
14 Document pre- and post-intervention pain scores
15 Consider Methoxyflurane (Penthrox) 3 mL inhaled via Penthrox inhaler — ONLY if chest pain escalates above 3/10 AND it can be safely self-administered; monitor for dizziness or over-sedation
16 Prepare resuscitation equipment at bedside — defibrillator, BVM, suction — given peri-arrest risk
17 Scenario ends on arrival of ambulance and IMISTAMBO handover
18 Attention to hand hygiene will be given throughout the scenario.

Clinical references: Cardiac Dysrhythmia · Chest Pain / Acute Coronary Syndrome · Oxygen · Methoxyflurane · Glyceryl Trinitrate · Primary Survey · Pulse Oximetry · Blood Pressure · Pain Assessment

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