Few medical interventions are as dramatic as cardiopulmonary resuscitation. There's the physicality of it – mouth to mouth, chest compressions, the need for urgency, the ‘stand clear' of defibrillation – and the high emotion of dealing with a pulseless person in an often public place. We saw just how public that can be on a football pitch last month. We GPs will expect to deal with this kind of emergency rarely, only once every few years, but we prepare for it – annual CPR training is meant to keep our skills honed.
But just how much of CPR is based on evidence? It seems ludicrous to question CPR – akin to asking for evidence for the use of parachutes. Yet the story of parachutes is one of testing, revising, animal experimentation and an expansion of ambition. Dr George Crile reported the first successful use of human external chest compressions in 1903.1 How much have we come on in our evidence – as CPR is now taught to us via the guidelines of the UK Resuscitation Council? A study from Sweden in 2007 compared the one-month survival rates between patients with out-of-hospital cardiac arrest who either received standard CPR or chest compressions only. There was no difference between the two.2 The exception is for children, where there is evidence that CPR including mouth to mouth is more effective.3 So for adults, mouth to mouth was not useful – worse, could it have been actively harmful?
It's known that CPR is performed in out-of-hospital arrests only a minority of times. Most collapsed people don't receive CPR. So could the instructions to perform mouth to mouth have discouraged citizens from getting involved at all? Some academics have argued that any interruption to chest compressions – for breaths – in patients with witnessed collapses may be, overall, harmful; arguing it's the compressions that are crucial. Have we made CPR instructions more complicated than necessary? A recent study from Japan randomised patients with out-of-hospital arrests to receive adrenaline or not from emergency services personnel.5 This found using adrenaline before reaching hospital decreased the chances of survival at one month as well as functional outcomes. It's fascinating – how much of what we do and think of as life saving is based on evidence? Not as much as we may wish.
Then again, I think back almost 20 years ago when, giving adrenaline in the heat of an arrest, a consultant cardiologist asked what I and my fellow juniors were doing. We were following guidelines; he replied he couldn't think of a worse thing to do.
We followed the CPR grid we had been taught. But were we really doing the right thing? Challenging authoritative protocols is not easy. Yet what is sold to us as definitive medical truth is not always as robust as it might appear. The problem when we don't test our hypotheses is not just in the direct harm we do, but also the unintended harms – chest compressions might have been successful many times before now had it been clear, sooner, that mouth to mouth for adults wasn't based on evidence. Having data on our side is what separates us from voodoo. We all need to challenge committee-think and demand that evidence.
Dr Margaret McCartney is a GP in Glasgow
1 American Heart Association. History of CPR. 2011. tinyurl.com/cf584ge
2 Bohn K, Rosenqvist M, Herlitz J et al. Arrhythmia/electrophysiology: survival is similar after standard treatment and chest compression only in out-of-hospital bystander cardiopulmonary resuscitation. Circulation 2007;116:2908-12. tinyurl.com/ctsqgtu
3 Kitamura T, Iwami T, Kawamura T et al. Conventional and chest-compression-only cardiopulmonary resuscitation by bystanders for children who have out-of-hospital cardiac arrests: a prospective, nationwide, population-based cohort study. Lancet 2010;375:9723:1346-54. tinyurl.com/cyle6xk
4 Ewy GA, Kellum MJ and Bobrow BJ. Cardiocerebral resuscitation. Emsworld, 2008. tinyurl.com/bukg6z5
5 Hagihara A, Hasegawa M, Abe T et al. Prehospital epinephrine use and survival among patients with out-of-hospital cardiac arrest. JAMA 2012;307:1161-8. tinyurl.com/cc2bbk6