I’m afraid this is a bit of a less cheery post than usual and it goes against the FOAMed grain of resuscitating everything regardless of likely outcome. But hey, my post on breaking bad news seems to have become a late hit so perhaps cheery is not in this season.
So, it is late February, the temperature outside is 39 degrees Celsius, (for our northern colleagues, that is summertime down here and hot) and your ED is full of bruised cricketers, boozy barbequers, overheated grandmothers and sunburnt teenagers when the ambulance deliver you an 18 month old baby girl in cardiac arrest. She was not seen by anyone for perhaps an hour until a family member spotted her in the family swimming pool.
On arrival in ED the patient is in PEA arrest with no spontaneous respiratory activity and an initial temperature of 25.7 degrees.
Because of the tender age of the victim you continue to cycle through your arrest protocol for 60 minutes at the end of which the child is asystolic.
You are about to call it a day when someone pipes up with the old chestnut “you’re not dead until you’re warm and dead”.
How does this catchy line apply to the child on your resus trolley?
In short, not at all.
Accidental hypothermia with secondary cardiac arrest must be differentiated from cardiac arrest due to asphyxiation (e.g. in cases of submersion injury) followed by equilibration with the surrounding temperature. The former has a very good prognosis, the latter, a universally poor one.
But there are all those stories of kids with prolonged submersion who do fine after resuscitation!
Yes there are. The common feature of all these cases is icy water (<5 degrees Celcius). All the medical case reports of this occurring are from arctic countries or high mountain regions like Colorado.
In fact, even in Finland1, which is pretty cold by our standards even when it is warm, people recovered from non-icy rivers in cardiac arrest have a universally poor outcome (that is to say, dead).
But why do resucitationists all teach rewarming techniques?
Hypothermia due to misadventure is a real problem and does definitely cause cardiac arrest and outcome is often good with rewarming. Examples are the skier who gets lost between the nightclub and the lodge and spends a night in the snow, the homeless New Yorker whose cardboard box gets snowed in or the patient incapacitated by sepsis, trauma or toxicology in a cold environment.
And it can happen in a warm place as demonstrated by this salient case report from sunny Queensland where medical incapacitation in an airconditioned room lead to severe hypothermia. 2
These people do indeed need urgent rewarming.
But perhaps the cooling might actually do some good to drowned kids, even if they water is not icy? Surely it must be a good thing to slow down cerebral and myocardial oxygen requirements? They have such a large surface area to weight ratio after all.
In fact, hypothermia has been shown to be a predictor of poor outcome in paediatric drowning victims from non-icy water. This is probably because it is a marker of length time submersed. Other predictors of poor outcome are prolonged submersion (the biggest rise in mortality occurring when the duration is longer than 5 minutes but with mortality continuing to increase steadily until it reaches 100% at around 25 minutes) and prolonged cardiac arrest (again, if more than 25 minutes of CPR is required death or catastrophic neurological outcome seems inevitable).3,4
So what temperature is a backyard pool in summer?
Most people in Victoria maintain their pools at around 25-27 degrees over summer with the use of heaters and pool covers. Without these the temperature depends on where you are but in temperate southern Australia you could probably expect a pool temperature of around 18-20 degrees.
Back to our unfortunate patient… When can you stop?
Timing of termination of unsuccessful paediatric resuscitation efforts generally has more to do with emotion than science. In general, children experiencing cardiac arrest have a dismal outcome as the arrest is the end result of a long progression of shock or hypoxia rather than a sudden electrical mishap due to myocardial ischaemia. The data quoted above would suggest that if there is no sign of life after 25 minutes of resuscitation there is not going to be any however it is unlikely that many paediatric resuscitations from out of hospital arrest (in Australia in any case) would be terminated at 25 minutes. At 25 minutes the child is usually just arriving in the ED and it would be usual to continue for another 30 minutes while history is gathered and reversible causes are considered, a fluid bolus and some adrenaline are give and a secure airway is confirmed. In all patients with cardiac arrest a rational approach to cessation of CPR is to do so once all reversible causes have been excluded rather than at a specific time.
- Silfvast T, Pettilä V. Outcome from severe accidental hypothermia in Southern Finland–a 10-year review. Resuscitation. 2003;59(3):285-90.
- Udy AA, Ziegenfuss MD, Fraser JF. Deep accidental hypothermia during the Queensland summer. Critical Care And Resuscitation: Journal Of The Australasian Academy Of Critical Care Medicine. 2007;9(4):341-3.
- Quan L, Wentz K, Gore E, Copass MK. Outcome and Predictors of Outcome in Pediatric Submersion Victims Receiving Prehospital Care in King County, Washington. Pediatrics. 1990;86(4):586-93.
- Kyriacou DN, Acinue EL, Peek C, Kraus J. Effect of Immediate Resuscitation on Children With Submersion Injury. Pediatrics. 1994;94(2):137-42.
Thanks to Dr Hamed Akhlagi who helped with the original lit review.
More (not quite) FOAMed on this topic
EMRAP did a good podcast on this topic a while back. It looks more generally at the question of severe hypothermia and death but does touch on some of this stuff.