Scenario — Anaphylaxis following wasp sting at community festival

intermediate Medical · Adult · 35yr · female

Patient Information

Dispatch	A 35YO female has been brought to the FAP by friends after being stung by a wasp approximately 5 minutes ago. She is complaining of throat tightness and difficulty breathing. (Sarah Nguyen)
Patient	Sarah Nguyen — 35yr (65kg)
Incident History	Pt was walking through the market stalls at the Fremantle Community Festival when she was stung on the right forearm by a wasp. Within minutes she developed generalised itching, raised welts across her arms and chest, and now reports her throat feels like it is swelling. Friends brought her directly to the FAP.
Emergency Contact	David Nguyen (Husband) — 0412 883 541

Initial Rapid Assessment

Response	Alert
Airway	Patent but patient reports subjective throat tightness. Mild stridor audible on auscultation. No visible angioedema to tongue at this time.
Breathing	Increased work of breathing. Audible wheeze bilaterally. RR elevated. Patient speaking in short sentences.
Circulation	Rapid and weak radial pulse. Skin flushed with urticarial welts across bilateral forearms, anterior chest and neck. Diaphoretic.
Disability	GCS 15 (E4V5M6). Alert and orientated to time, place and person. Anxious.
Exposure	Visible wheal and flare reaction at right forearm sting site. Raised urticarial welts extending across bilateral forearms, chest and neck. No visible stinger remaining in skin.

Vitals

Time	SpO2	Resp Dist	RR	Pulse	BP	CRT	GCS	PERL	Temp	BGL	Pain
Initial	91% (RA)	Moderate	24	118	86/54	3s	15	4 4 ++	–	–	5
10 mins	97% (O2 NRB 15L)	Mild	18	98	102/66	2s	15	4 4 ++	–	–	3

History Taking

Scenario Progression and Treatment Objectives

Diagnosis

This patient is suffering from anaphylaxis secondary to a wasp sting, presenting with urticaria, bronchospasm, hypotension, and subjective upper airway involvement consistent with a multi-system allergic response.

Facilitator Triggers — if trainees miss a critical step

! (If trainees attempt to sit the patient upright in a chair or allow her to stand, inform them she becomes acutely dizzy and nearly collapses — reinforce supine positioning with legs outstretched.)
! (If EpiPen is not administered within 3 minutes of arrival, patient's wheeze worsens, SpO2 drops to 87% on RA and she becomes increasingly distressed — prompt: 'She is telling you her throat feels much tighter now.')
! (If oxygen is not applied after EpiPen administration, SpO2 remains at 91% at 5 minutes — prompt: 'Her breathing still looks laboured, what else can you do?')
! (If trainees do not check for a remaining stinger or attempt to remove the trigger, facilitator prompts: 'Is there anything at the sting site you should address?')
! (If trainees attempt to administer antihistamine instead of or before EpiPen, facilitator states: 'She tells you her throat is getting tighter — does antihistamine address that?' and redirect to Anaphylaxis CPG.)
! (If trainees allow the patient to mobilise after EpiPen administration within the first 60 minutes, patient suddenly reports dizziness and her BP drops again — reinforce no mobilisation for minimum 1 hour post single dose adrenaline.)

Treatment Objectives

1. Ensure scene safety and don appropriate PPE.
2. Perform primary survey — identify anaphylaxis: multi-system involvement (skin, respiratory, cardiovascular).
3. Position patient supine with legs outstretched — do NOT sit upright or allow standing.
4. Administer Adrenaline Auto-Injector (EpiPen) 300 MICROg IM to outer mid-thigh — anaphylaxis.
5. Inspect right forearm sting site and remove any remaining stinger if present.
6. Apply oxygen via non-rebreather mask at 10–15 L/min — target SpO2 94–98%.
7. Perform vital sign survey: BP, HR, RR, SpO2, GCS, CRT — document baseline.
8. Conduct IMISTAMBO-style history: allergies, medications, prior anaphylaxis, last oral intake.
9. Monitor patient persistently — reassess vitals every 5 minutes given time-critical presentation.
10. Anticipate need for repeat EpiPen 300 MICROg IM at 5-minute intervals if symptoms not improving.
11. Do NOT allow patient to mobilise — minimum 1 hour post single EpiPen dose before considering mobilisation.
12. Arrange Priority 1 ambulance transport — advise patient must be monitored at a medical facility for 4 hours after last adrenaline dose due to risk of biphasic reaction.
13. Provide continuous reassurance throughout.
14. Scenario ends on arrival of ambulance and IMISTAMBO handover.
15. Attention to hand hygiene will be given throughout the scenario.

Clinical references: Anaphylaxis · Adrenaline Auto-Injector (EpiPen) · Oxygen Delivery · Adrenaline Autoinjector 'EpiPen' · Primary Survey · Pulse Oximetry

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Signs/Symptoms	Throat tightness, difficulty breathing, wheeze, generalised itching, raised welts across forearms and chest, diaphoresis, dizziness.
Allergies	No known drug allergies. No previous allergic reactions. No prior history of anaphylaxis. No EpiPen prescribed.
Medications	Nil regular medications. Oral contraceptive pill. No antihistamines taken today.
Pertinent History	No known wasp or bee allergy. No asthma. No cardiac history. No current illness.
Last Oral Intake	Ate a meat pie and soft drink approximately 45 minutes ago.
Events Leading	Pt was browsing market stalls in the outdoor festival area when she felt a sharp sting on her right forearm. She initially ignored it but rapidly developed itching and welts before feeling her throat beginning to tighten.
Treatment Prior	Friend applied a cold pack to the sting site. No medications given prior to EHS arrival.

Onset	Approximately 5–8 minutes ago following wasp sting to right forearm.
Pain	Localised pain and burning at sting site right forearm. Throat discomfort described as pressure or squeezing sensation.
Quality	Throat tightness is progressive. Wheeze and shortness of breath began within 3–4 minutes of the sting.
Radiates	Itching and welts spreading from forearms toward chest and neck.
Severity	5/10 overall. Throat tightness reported as 6/10.