Defibrillation is one of the cornerstones of effective resuscitation following cardiac arrest. The ability to reorganise a lethal arrhythmia into a perfusing rhythm with a simple electric shock is one of the most meaningful interventions we provide in the acute care setting.
While the act of defibrillation is straightforward, it isn’t without risk. Defibrillation works so well because the human body is a good conductor of electricity (allowing an impulse applied to the skin to be conducted through to the heart). This conductivity can introduce risk in the cardiac arrest setting where multiple people are engaged in interventions that involve touching the patient. If an electrical impulse is sent into the patient’s chest, there is the potential for that impulse to be conducted to any other perfectly conductive human in direct contact with the patient (i.e. the intern attempting to cannulate the patients foot). Rescuers in cardiac arrest must constantly balance the danger of electricity with the definitive benefit of defibrillation.
While the easiest way to ensure rescuer safety during an arrest is to lengthen the peri-shock pause and ensure all members of the team and well away from the patient prior to defibrillation, this may lead to poorer outcomes for patients. Studies have demonstrated a direct relationship between a longer pre-shock pause in compressions and a reduced efficacy of defibrillation (Cheskes et al, 2011). This is thought to be attributed to the sudden drop in myocardial perfusion immediately after chest compressions stop, making the regular conduction system less likely to heave back into action post shock. This serves to highlight the importance of balancing efficiency with safety when attempting defibrillation.
One of the best ways to balance these two important elements is to utilise a system like COACHED to synchronise the actions of the resus team members to achieve maximum safety while enabling a shock to be delivered quickly. COACHED is an acronym that outlines an order of events leading up to a defibrillation attempt:
COACHED allows for the defibrillator to be charged while chest compressions continue and all other rescuers move to safety. This means the defibrillator is armed and the team is safe when the rhythm check occurs, allowing defibrillation to be delivered very quickly when a lethal arrhythmia is identified.
COACHED is a great tool and is being taught in more and more ALS courses, but in practical terms it has a tendency to miss the mark if the team isn’t on the same page. Without good clear communication or adequate training, a well intentioned rhythm check can turn into a series of lengthy delays in compressions leading up to an eventual shock. In my experience the 2 most common causes of COACHED failure are:
- Half the team knowing (and expecting) COACHED while the other half are in the dark
- A team member attempting to ‘coach’ the COACHED algorithm but forgetting what the acronym stands for and getting hung up on the details
In a perfect world, it would be great if every member of the resus team was on the same page and had the same understanding of concepts like COACHED from the outset, however in reality this often isn’t the case. To ensure every team member has a sound understanding of the algorithm the team needs to invest a lot of time and resource into learning and practicing the process of safe and efficient defibrillation. And while this is a great goal to aim for, there is an easier way to get started.
Generally, when a rhythm check approaches there is one team member who takes the lead in communication (be it the team leader or the person operating the defib). In most cases this person is perfectly positioned to ‘coach’ the COACHED process. Essentially this means taking ownership of the process and using loud and clear communication to ensure each of the steps is followed. For example, if the defib operator takes the lead they would communicate to the chest compressor to continue while instructing the airway team and all other team members to move away. They would then charge the defibrillator, announcing this to the team as they go. When the defib is charged, they would instruct the chest compressor to step away allowing for clear visualisation of the underlying rhythm. If the rhythm is shockable, they would visually scan to ensure no one is touching the patient before delivering the shock – for a non shockable rhythm they would disarm the defib and request a pulse check / further compressions as required.
The three important points to remember for optimised defibrillation (whether using COACHED or not) are:
- Continue compressions while the defib charges (minimising the pre shock pause)
- The rhythm check ‘coach’ / leader should use loud, clear communication to the rest of the team (they should be the centre of attention during this process)
- It is the responsibility of the defib operator to ensure no one accidentally gets shocked (so perform that final visual sweep of the bed and shoo away any stragglers before shocking)
To ensure that mental blocks don’t get in the way of quick and safe defibrillation, it is extremely handy to have a cognitive aid for COACHED available during the resus. Advanced life support shouldn’t be a memory test, it’s ok to use supports to help you get the job done right.
In our ED we laminated ‘COACHED Cards’ and tied them to all our defibrillators with trache tape. These have COACHED on one side and a defib cheat sheet on the other. By having this card in hand during the resus, the defib operator is able to easily run through the steps of COACHED without mental hiccups, which in turn frees up some brain power to be distributed to other tasks (like assessing the rhythm). The COACHED card template can be found at the link below, feel free to print them out and use them in your place if you think they would make life easier. Otherwise just print the pneumonic and stick it on the wall, or write it on your arm or something – just avoid relying solely on peoples recall during crisis events like resuscitating an arrest.
So whether you use COACHED or not, take some time to think about the way you approach defibrillation and ensure you are keeping people safe and minimising the pre-shock pause. And remember, practice makes (closer to) perfect so don’t be afraid to drill this with your team when you have the chance – you may be able to teach someone something useful.
Cheskes, S. et al. (2011). Peri-shock pause: an independent predictor of survival from shockable out of hospital cardiac arrest. Circulation, 124(1): 58-66