Seattle Fire Department Engine 2. The rescuer on the left has just placed a metronome on the ground.
I will eventually get around to composing a more thoughtful blog post about my experiences at the Resuscitation Academy but in the interim I wanted to share something about the ventilation strategy in King County, Washington.
There isn’t much controversy in the fact that ventilations are probably unnecessary in the first 4 minutes of sudden cardiac arrest. The idea is that the arterial system is full of fresh, oxygenated blood at the time of collapse. However, after that time period has elapsed things get a bit murky and this is where there are differences of opinion.
There is a high rate of bystander CPR in King County (about 1/2 the time dispatcher-directed) so bystanders are performing continuous chest compressions for 4-6 minutes prior to the arrival of EMS. I think we can all agree this is a good thing. However, you can also argue (and Peter Kudenchuk, M.D. does) that ventilations are not so easily omitted when 4-6 minutes of continuous chest compressions have already taken place.
Once EMS arrives at the scene, expertly performed chest compressions (rate, depth, and recoil) are initiated. They train with instrumented manikins in King County, and one thing we discovered is that every single one of us “leaned”. The smallest amount of leaning on the chest destroys recoil, preventing the negative pressure gradient responsible for blood return to the heart.
As a side note (not to stray too far off topic) the communication is excellent in the Medic One system, so problems with rate, depth, and recoil are corrected quickly because a fellow rescuer will point out the problem. It’s a part of their culture and professionalism that everyone observes what is happening.
There are slight differences between King County EMS and Seattle Fire but they are not too caught up in whether or not you shock as soon as possible or at the 2-minute mark once you have reached the patient’s side. However, the emphasis is on chest compressions and defibrillation. For example, if there were only 2 rescuers on scene, chest compressions and the first shock would take priority over using the BVM.
Once more help arrives, or assuming there is a third person, a BVM is deployed. As we have previously discussed, King County EMS uses a 30:2 strategy initially, while Seattle fire performs “BLS Continuous” where they ventilate at a 10:1 ratio without interrupting chest compressions.
This is where I want to point something out that is critical to understand. They are only bagging with 300-400 ml of volume! That is a very small bag squeeze. Without the instrumented manikin I wouldn’t have believed it was adequate. In the absence of chest compressions it causes a noticeable chest rise, and that’s all they interested in — just enough for air exchange and to prevent atelectasis.
There is no doubt that we have been over-bagging in my system, and I can see whyÂ cardiocerebral resuscitationÂ confers a benefit in systems that bag overzealously with 30:2 or delay for too long to deliver the breaths.
In the Medic One system, when 30:2 is used, the rescuer on chest compressions is “divorced” from the person on airway. They deliver 30 perfect chest compressions, pause for 2 seconds, and then deliver another 30 chest compressions. They don’t “wait” for the person on the airway.
As you can imagine it takes training, and re-training, to achieve this level of performance. But that’s sort of the point. They have been perfecting their craft since the Apollo program and each iterative change has been made thoughtfully and using the best available evidence (mostly derived from their own measurements).
Still, they readily concede that resuscitation is, and perhaps will always be, an unsolved puzzle. So whatever you do, don’t just be good at it; be absolutely phenomenal at it. If you are successful in cultivating a culture of excellence and continuous quality improvement your EMS system will get where it needs to go.
Nichol G, Leroux B, Wang H et al. Trial of Continuous or Interrupted Chest Compressions during CPR. New England Journal of Medicine. 2015;373(23):2203-2214. doi:10.1056/nejmoa1509139.
Kleinman M, Brennan E, Goldberger Z et al. Part 5: Adult Basic Life Support and Cardiopulmonary Resuscitation Quality. Circulation. 2015;132(18 suppl 2):S414-S435. doi:10.1161/cir.0000000000000259.
Ewy G. Cardiocerebral Resuscitation: The New Cardiopulmonary Resuscitation. Circulation. 2005;111(16):2134-2142. doi:10.1161/01.cir.0000162503.57657.fa.
How to Master BVM Ventilation at ACLS Medical Training