CPR and Defibrillation

© 2024 Jeffrey Isaac, PA-C

Should you learn CPR and AED? Absolutely, just be aware of its limitations. Cardio-Pulmonary Resuscitation is a basic technique for circulating oxygenated blood in the absence of effective cardiac activity – that is, pumping blood for someone whose heart has stopped. The technique itself can be learned in about 20 minutes, but most training courses are at least three hours in length and teach from a standardized curriculum. All courses also now include instruction in the use of an Automatic External Defibrillator (AED). There is also  instruction in clearing airway obstructions, and discussion of cardiac risk factors that can affect an individual’s chances of suffering a sudden cardiac death. 

CPR buys you a little time pending the arrival of a defibrillator, and you really only have about 10 minutes. Recently, the proliferation of public use AED’s in airports, shopping malls, and police cars have reduced the time to defibrillation and doubled survival rates in areas where the ambulance response takes a bit longer.  The defibrillator actually stops the heart, ending the run of ventricular fibrilation or tachycardia that is preventing effective circulation. The heart can then restart itself in a functional rhythm as long as the cardio-vascular system is intact and the cause of the dysrhythmia is reversible. Survival then depends on stabilization in the ambulance and emergency department and correction of the underlying problem by a cardiologist. The best rates documented with this chain of care approach 28% survival to discharge. More typical is 6 – 16%.

Unfortunately, studies also show that CPR and defibrillation offers no improvement in survival rates outside of the reach of the ambulance and a hospital. The probability of successful defibrillation after more than 10 minutes of cardiac arrest is very low, but delayed defibrillation is only part of the problem. Reports of survival after successful defibrillation without early access to an amblance and hospital care are notably absent from the literature. CPR and defibrillation will not save a patient whose heart that has stopped as a result of traumatic brain injury or blood loss. 

Yet, in spite of the lack of scientific or anecdotal evidence to support the idea, the manufacturers and distributors of AED’s continue to push them on offshore sailors, expedition medics, and other people operating well out of reach of sophisticated medical care. Statements like “The more remote the setting, the more critical it is to have an AED” permeate non-medical forums and outdoor and marine advertising content.This is an unsubstianted extrapolation of urban success to the wilderness context.

Why? Beyond the obvious profit motive, the answer may lie in a study published by Diem, et al way back in 1996 in the New England Journal of Medicine. The researchers compared survival rates following CPR in a hospital coronary care unit with those on three popular television shows at that time: Chicago Hope, Rescue 911, and ER. The real hospital patients survived at a rate around 16%, none from a trauma arrest. On TV, however, the survival to discharge rate was 65%, even though 72% of these were trauma arrests. The message in this tongue-in-cheek article is clear: If you’re going to have a cardiac arrest, have it on television.

Fortunately, these unrealistic depictions of success have driven CPR and AED training for the masses, which is good. The same kind of unrealistic expectations are driving the sale of defibrillators to offshore sailors, which is questionable at best. If you really want to reduce the chances of dying at sea consider spending your money on survival suits, a better life raft, a sat phone, a storm sail, or brighter running lights. Almost any piece of safety equipment will have a better chance of saving your life than a defibrillator.

Having said all of that, why should the cruising sailor learn CPR and the use of an AED? Primarily because you’re not always sailing. You probably travel to your boat by commercial airliner which will have a defibrillator and the ability to land near a hospital within minutes. Once on board, you might spend most of your time in a slip at a large marina in the city with a defibrillator in a box next to the fire extinguisher at the head of the pier. 

Secondly, the techniques for rescue breathing and airway control taught as part of these courses are very important to marine rescue. Respiratory failure or arrest can be treated for hours with rescue breathing, as long as the heart is still beating. These cases may account for many of the dramatic saves attributed to CPR. The heart never stopped, but breathing did. The most likely examples include near-drowning, lightning strikes, and airway obstruction.

CPR courses are available everywhere for minimal tuition. The major providers are the American Heart Association and the Red Cross, but a number of other organizations have developed their own, very similar programs. Choose one that includes rescue breathing. Some of the very short programs, like the American Heart Association’s Hands Only CPR, have stopped teaching rescue breathing in favor of just chest compressions and early defibrillation. You might want the longer Health Care Provider or Professional Rescuer program.

Wilderness Medical Associates includes CPR in its Wilderness Advanced First Aid and Wilderness First Responder courses. The curriculum also includes wilderness protocols for CPR that call for stopping resucitation efforts after 30 minutes of pulselessness, or anytime the process puts the rescuers at risk. The protocols also outline the reasons not to start CPR in cases of a trauma arrest, risk to rescuers, and severe hypothermia. You will probably be taught to continue CPR until the ambulance arrives in urban context courses, but that’s fine for the city.

For more information about CPR and Emergency Cardiac Care, start with the American Heart Association. And, if you actually hear about someone being successfully defibrillated offshore aboard a small vessel and living to tell about it, please send us the details. As far as we know, it has not happened yet.


  “At sea as in the mountains, it is just as important to know when you don’t have a medical emergency as when you do.”