Let's go deep OSCE by Michael

You have 3 minutes reading time. This OSCE will run for a maximum of 7 minutes.


You are the consultant on call in the ED of a metro hospital with hyperbaric facilities. Your receive a call from a country GP with concerns about an abalone diver who has presented with pain after a dive.

The attachment is for examiner use, please do not open.

View attached:  Attachment 1

Instructions for the candidate

You are to take a brief history, provide advice on initial management and assist in formulating a management plan for this patient.

Domains being examined

  • Medical Expertise
  • Communication
The candidate has 3 minutes reading time. This OSCE is expected to run for a maximum of 7 minutes.

For the actor

You are a country GP based in a seaside town with a fishing industry. You are 700km from the major centre you are calling. There is an airstrip in your town that is used by the RFDS. You have basic resources and facilities in your local hospital emergency, including 2 nurses. You have access to basic point-of-care testing (CBE, EUC, gas analysis). You are able to intubate and ventilate if required. You have no radiology on site.

Your patient is 39-year-old Roger, a professional abalone diver. He has no other past history, medications or allergies.

He surfaced from a routine dive, and soon after (within 10 minutes) began developing joint pains. He soon developed abdominal pain that became severe during the 1 hour boat ride in. He presented immediately after to your hospital.

On examination, he was distressed with pain, which has improved with IV morphine. His initial obs were:
GCS 15
HR 134
BP 130/60
SaO2 98% RA

His abdomen was soft, but with ongoing pain. You have commenced IV rehydration with normal saline.

You should be asked by the candidate for the following findings:
1. Physical examination
There is no neurology, lung sounds are clear with good air entry throughout. He has a macular/reticular rash, blanching, itchy that is darkening in colour (see attachment for example - the candidate should suggest this is cutis marmorata, a marker of significant decompression illness).

2. Other features of decompression illness
Gradual onset, headache, fatigue, vertigo, urinary retention, hypothermia

3. Dive details
Professional diver, this dive no different to others. Using standard air tanks. 2nd dive for the day. First was down to 30 metres, total time of 85 minutes, with appropriate decompression stops on ascent. The second was down to 27 metres, with slow ascent along bottom towards shore, total time 100 minutes. This was his 5th day diving. His dive tables were calculated as being in the safe range. He has not flown recently.

4. Investigations
Hb 210
WCC 16 (neut 14)
Plt 340

EUC largely normal

Gas analysis not done - could ask what looking for if prompted.

No CXR available.

ECG - sinus tachycardia

5. Exploration of arterial gas embolism
History features - rapid ascent, risk factors (lung disease, PFO)
Features - CNS involvement, headache, loss of consciousness, seizure, cardiac dysrythmias

6. Exclusion of other medical and diving related illness
Medical - other causes of abdo pain
Diving - barotrauma (ears, pneumothorax, GI barotrauma)

The following treatment should be suggested:
1. Copious IV rehydration titrated to urine output
2. High flow O2
3. Analgesia
4. Retrieval to hyperbaric centre - special transport considerations should be discussed. Air retrieval is indicated given distance and timeframe, with explicit use of sea-level pressurisation on transfer. You could ask "It typically takes 6 hours for our patients to reach [your city] - is it still worth doing this if he is improving?"
5. Recompression as the definitive treatment. May require multiple dives.
6. Longer term - may have recurrent symptoms (especially if not recompressed), has to avoid flying for 6 weeks post.

For the examiner

No specific instruction

Domains Assessment Objectives

Medical Expertise
Assessment, differentiation and management of decompression illness

Clear and concise phone-based communication

Other Assessment Notes

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Couple of quick points, though: supine position best; trendelenberg may increase risk of coronary artery bubbles, evidence for aspirin is scant and is not routinely recommended.

Michael at 19:31 11 May 2017  

high flow O2 anaglesia pressurised cabin or helicopter at 300m consider aspirin flat or consider trendenleburg need to dive in monitored hyperbaric chamber at 2-3 ATM

Luke Jeremijenko at 10:15 11 May 2017  

crap - disregard above - my notes (again misfiled)

Luke Jeremijenko at 10:16 11 May 2017