Author: Mehrad Ramazany / Editor: Nikki Abela / Codes: HAP11, EnvC3, EnvC5, RP3, RP8, SLO1, SLO2 / Published: 14/07/2020
Big city medicine can sometimes be tricky to tick the box that says “Environmental Emergencies” in the RCEM curriculum. But a day in the life of a doctor living in more “outdoor” or seaside settings can help you get the mindset that is needed for these sort of pre-hospital jobs.
Your first job starts and you are car-sharing with a junior doctor on the way to work. The sun is shining, and you are fifteen minutes early. You pass a gelato van parked on the side of a busy beach and you stop to get an espresso. The beach is full of tourists who seem to have ignored the red flag indicating strong currents. As soon as you order your eye-opener for the day, you see a life-guard run out to a near drowning. You see from a distance that the patient isn’t moving.
As you walk (safety first, no running!) to the scene you remind your junior of a few drowning top tips:
- No CPR in the water (we are not that trained)
- Water is cold so cold water shock and hypothermia can happen
- and don’t do a Heimlich to force out the water.
You’ve got plenty of prep. time as you walked over, so decide to have a look at some definitions.
Near Drowning: This is a term that is no longer used (thank you for the reminder). It used to mean survival after immersion in liquid. So yes, we’re being optimistic that the patient will survive!
Cold Water Shock: Immersion in cold water can rapidly kill you as it causes involuntary reflexes, even in skilled swimmers. Those of you old enough to remember Sharron Davies and Duncan Goodhew, Olympic gold and silver medallists, will find this video interesting – it affects everyone. The cold water shock causes an involuntary gasp, and then a reduction in ability to breath hold, and sympathetic stimulation. Prevention of cold water shock is possible with gradual exposure. The involuntary gasp means laryngospasm is possible.
Diving Reflex: causes vagal stimulation.
Laryngospasm: OK, you know what laryngospasm is. But the key thing is, it doesn’t take a lot of water to trigger laryngospasm. We’re not talking half the Atlantic ocean – we’re talking tiny drops. The amount depends on whether it is fresh water or not – 22ml/kg of sea water, and 44ml/kg fresh water.
You get to the the patient who has been moved horizontally and good BLS with initial five rescue breaths (drowning modifications) is happening.
You have the Airway covered (of course you have intubated). You continue to provide excellent rescue breaths to cover breathing, and support he circulation with good chest compressions. You think about c-spine immobilisation, but as the patient didn’t dive into shallow water, a problem is unlikely.
You start to address the reversible causes for the arrest, thinking carefully about hypoxia and hypothermia. You start to passively warm the patient up by ensuring they are dry and then passively warming him with blankets. Passive rewarming is often difficult in a CPR situation when everyone wants access to different body parts and the blankets keep getting removed. If you’re outside, think carefully about sheltering the patient too – a windbreak will help.
The patient remains in PEA arrest and you continue your good CPR when the Pre-hospital Critical Care team arrives to take over. Just as the team take handover, he gets a ROSC and you happily and proudly move along to your base (who you have notified about your delay). The HEMS crew prepare to take him to the base and reassure you they will put NGtube in (to relieve all the stomach water).
The other doctor asks “What complications is he facing?”:
- aspiration pneumonitis
- negative pressure pulmonary oedema
- electrolyte imbalances
- spinal injuries (there was diving involved right?)
- hypoxic brain damage
You think prognosis could be good for him given :
- less than 5 minutes immersion/submersion
- good quality CPR
- short downtime and ROSC achieved quickly
- no apparent severe hypothermia
The most famous hypothermia case was a skier who had a long time of CPR – read about it here. Another hypothermia case was in the 1979 fastnet race – “Left for Dead” is a page turner.
“It seems like you know a lot about hypothermia , can you teach me a bit about it” the other doctor asks you over your well earned espresso.
Hypothermia is if the core temperature is below 35°C
- 32-35 : Mild
- 28-32: Moderate
- and <28 : Severe
It is difficult to measure core body temperature, so there is this Swiss staging system to help us estimate the severity of the hypothermia by looking at the clinical signs :
- Mild (Stage I) – conscious with shivering. 32 to 35°C.
- Moderate (Stage II) – Altered mental status without shivering. 28 to 32°C.
- Severe (Stage III) – Unconscious. 24 to 28°C
- Very Severe (Stage IV) – Apparent death. Core temperature 13.7 to 24°C (resuscitation may be possible). Remember cold delays the brain death.
- Death (Stage V) – Death due to irreversible hypothermia. Core temperature <9 to 13.7°C (resuscitation not possible).”
“What are the common ECG changes to find?” you ask.
“Bradycardia with many ECG changes of prolongation of all the intervals and the famous J wave due to slowed impulse through potassium channels.”
“Severe hypothermia can lead to: pulmonary oedema, oliguria, coma, hypotension.”
“A very cold heart is very sensitive and goes in to VF easily, handle the patient with care.”
“What about cardiac arrest?” The other doctor asks, testing your ALS.:
- Check for signs of life for one minute,
- Look at breathing, check a big artery for pulse, do you have ECG? look at that.
- Have a low reading thermometer, oesophageal is the best, rectal would do
- No adrenaline or other drugs until the patient is about 30 ̊C. 30 to 35 ̊C double the interval and follow normal protocol above 35̊C.
- If in VF, shock three times and stop after that if below 30̊C.
- Rewarm : Passive rewarming is only good for conscious patients, do active rewarming
Like us, you haven’t looked at the primary evidence for this, but suggest your colleague investigates – this twitter thread is a good start.
AND don’t forget to find the cause – was it just related to drowning or other things like sepsis, drug overdose, alcohol etc.
Rhabdo will happen – check CK and give fluid. You will need loads of fluid as vasodilation happens as you rewarm. Coagulopathy is common, electrolyte imbalance is common.
“Tell me more about rewarming” your colleague asks.
Well, heat is lost in several ways – radiation, evaporation, convection and conduction. The first step to rewarming is to stop heat loss as much as possible – you don’t want to warm someone up, only for it all to disappear again! This protection creates most of the “passive rewarming” techniques. Think about wind breaks. Cover above and below. Pop a hat on. Dry the patient (but only if they’re not going to get wet again!).
Then move on to active rewarming:
- Active rewarming : warmed oxygen and a bair hugger (tricky in arrest!).
Then consider invasive rewarming. This is obviously not going to be suitable for everyone:
- Invasive rewarming: Bladder irrigation, chest drain irrigation, peritoneal irrigation, ECMO.
“OK, OK. But why do you have to handle them carefully? Surely speed is key?” your enthusiastic colleague asks.
Well… in hypothermia your peripheries are shut down. Lots of blood is diverted to the core to keep the vital organs warm and perfused and working. This blood is healthy and oxygenated, but the peripheral blood isn’t so good. As people rewarm, this blood gradually mixes. If you move someone suddenly, you can cause the blood to speedily mix, which can cause sudden hyperkalaemia. The myocardium is likely already sensitive, so you need to treat it with care.
and that is enough of hypothermia – let’s keep warm.
References and further reading
RCEMLearning Hypothermia Module
RCEMLearning Cardiac Arrest in special circumstances
RCEMLearning Therapeutic Hypothermia
RCEMLearning Emergency Casebook
RCEMLearning SAQ – Feeling Blue
RCEMLearning SAQ – The Camel’s Hump
RCEMLearning SAQ – Canal No 5
RCEMLearning SAQ – Severe Hypothermia
RCEMLearning Podcast – Hypothermia in non shock rhythms