The content you’re about to read or listen to is at least two years old, which means evidence and guidelines may have changed since it was originally published. This content item won’t be edited but there will be a newer version published if warranted. Check the new publications and curriculum map for updates

Author: Mehrad Ramazany / Editor: Nikki Abela / Codes: EnvC1, EnvC3, EnvC4, EnvC5, EnvC9, RP3, RP8, SLO1, SLO2 / Published: 15/07/2020

You move to your second base as some divers have surfaced and are getting ready to pack up. You notice one of them is swaying left and right and stops due to complaints of pain in his back. He has started to feel out of breath. As it is a small village, his buddy recognises you from the hospital and asks you to have a look at him. You take some observations.

He feels out of breath, has pleuritic chest pain, has a bit of cough. He complains of pins and needles in his fingers. You suspect Decompression illness:

  • Small bubbles: decompression sickness (a.k.a “the bends”) – nitrogen coming out of solution causing inflammatory response and mass effect (evolved gas)
  • Big bubbles: arterial gas embolus ( AGE) – this is simply alveolar rupture leading to the gas entering the circulation (escaped gas)

These features normally happen within 6 hours of the dive. There are two types of Decompression Sickness:

Type I mainly being related to pain and general symptoms
Type II more severe, involving neuro, cardiopulmonary system
You perform a good examination mainly to looking at :

  • Chest – you want to make sure there is no pneumothorax, no surgical emphysema
  • Neuro – you do full medical school neurological exam
  • Joints – (pain being the main feature)
  • Skin – looking for a rash like this

You are worried about his symptoms and want him to go to the ED for O2, CXR (? does he have pneumothorax) and IV fluid.

You tell your junior “under no circumstance are we giving him Entonox for pain management and NSAIDs are best avoided”. Oxygen is your best analgesic.

You give your ED a courtesy call to get the hyperbaric chamber ready because recompression therapy is what this diver needs.

You also make a mental note to brush up on your diving medicine, now you live by the sea! Your colleague suggests the RCEMLearning module and reference – if you get some down time today, maybe worth a look at!

As you have spent some time near the sea today, you fuel up with a quick ice-cream and move on to the next base. There is a marathon on today and in spite of the near freezing temperatures at the start of your shift, the weather is now sweltering and you are getting ready for some opposite illness.


Illnesses include: heat oedema, syncope, cramps, exhaustion and stroke.

Heat exhaustion: where temperature is below 40C and the patient has nausea and vomiting, hypovolaemia develops and there is excessive sweating.

Heat stroke: This is the bad one where there is systemic inflammatory response to temperature above 40.6C with encephalopathy being the main feature.

Treat by cooling down to a temperature of 38.5C. Do not go lower as you can cause hypothermia. You can use tepid water spray, fan/AC, ice-packs, cold IV fluids, or a combination of these.

Have your IV fluid ready – you want a decent amount but beware of causing pulmonary oedema from the leaky vascular system.

If you’re needing sedation, or to treat seizures, the patient must be transferred to hospital. Have some benzo ready for seizures and do not forget about CK, rhabdo and renal failure with hyperkalaemia. Don’t forget paracetamol and antipyretics do not work to lower the temperature.
You take a deep breath, the marathon is over and it was a lucky day, no casualties. BUT there is a mountain climb this afternoon, you grab some lunch and get ready to ascend.

Acute Mountain Sickness (AMS):

Simply put, AMS is a combination of headache, nausea and sleep problems in people who ascend above 2500 metres rapidly. It can happen in people with cardiac problems in lower altitudes.

It can become more severe into the famous forms of:

High altitude cerebral oedema (HACE/O) which is basically progression of symptoms 2-4 days later on high grounds or high altitude pulmonary oedema (HAPE/O).

This is similar to COVID in a way, as patients come with saturations very low with minimal respiratory distress.

Some athletes take prophylactic Acetazolomide 125mg BD, or Dexamethasone 2mg QDS for HACE and have been advised to take Nifedipine 30mg SR BD for HAPE prevention as it reduces pulmonary artery pressure.

Risk factors for HACE include:

  • Previous AMS
  • A fast ascent (best prevention is slow ascent)
  • A recent history of strenuous exercise
  • Height over 4000m

Your first patient arrives, her sats are 82% on air.

You get an ECG as she is tachycardic which shows right heart strain.

You give her oxygen and a lot of it, pain relief with NSAIDs and organise an urgent descent.

Portable CPAP or a portable hyperbaric chamber would be ideal.
You clearly have portable X ray on the mountain :

Drug of choice for her pulmonary oedema remains Nifedipine, but be careful you don’t want to drop her blood pressure a lot and reduce her cerebral perfusion and cause ischaemic stroke, choose wisely.

You are in charge of her transfer to your local hospital and you end your event doctoring and you realise your colleague is still seeing patients at 4000m altitude.

While going back to pick her up you remind yourself of great days you had on this event:

You managed a drowning case very well , you will always remember drowning comes with aspiration and hypothermia.

Hypothermia has J waves ( Osborne wave) and it prolonges everything on your ECG.

Hypothermic arrest should be managed with no drugs below temperature of 30C and then double the interval till 35C.

Big bubbles and small bubbles happen in decompression illness, make sure these patients do not have pneumothorax, do not give them ENTONOX and get them some O2 and recompression therapy.

Heat Stroke is the bad form of heat illnesses with a multi organ involvement, cool them actively to 38.5C, give them fluid , check the salt and have some benzo ready.

And in altitude sickness never ascend quickly and take some Acetazolomide if you are going to climb fast. If headache is getting worse, descent is the only way forward.

References and Further Reading

  1. Decompression Sickness DAN , Divers Alert Network
  2. Clayton,S.Walklett C, Decompression illness 2019
  3. Shafer,S: Tox and Hound The Dirty on Dantrolene
  4. Baird,J: Heat Related Illness 2018
  5. Ryland Pace: Acute Mountain Sickness
  6. Andrew M Luks: Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Altitude Illness
  7. RCEMLearning Drug Induced Hyperthermia
  8. RCEMLearning Heat Stroke and Heat Exhaustion
  9. RCEMLearning Reference Heat Related Illness
  10. RCEMLearning SAQ Heatstroke