"To Those in the Field"

Cardio-Pulmonary Resuscitation

© 2004 Jeffrey E. Isaac, PA-C

Should You Learn CPR and AED?

             Absolutely, just be aware of its limitations. Cardio-Pulmonary Resuscitation is a simple technique for circulating oxygenated blood in the absence of effective cardiac activity – that is, pumping blood for someone whose heart has stopped. Brain death can be postponed for up to 20 minutes while emergency treatment is initiated.

             The technique itself can be learned in a lot less than 20 minutes, but most training courses are at least three hours in length and teach from a standardized curriculum. The programs teach a specific ratio of chest compressions to rescue breaths, and when to check for the return of a pulse. Most courses also now include instruction in the use of an Automatic External Defibrillator (AED’s). There is also basic instruction in clearing airway obstructions, and discussion of cardiac risk factors that can affect an individual’s chances of suffering a sudden cardiac death. It’s valuable information.

             A good reason to learn a standardized technique is so that the guy from San Francisco and the kid from Hong Kong can work to save the man from Boston who collapsed on the street in Seattle. Everybody will know what’s going on. If the patient is lucky enough to be in Seattle, he might even survive.

             Studies tell us that CPR can sustain some degree of perfusion and oxygenation for up to 20 minutes. But in the real world, survival after more than 5 minutes of CPR is rare. About 25 years ago, Seattle demonstrated that widespread community education in CPR, combined with a quick response by the emergency medical services (EMS), could improve survival rates in cardiac arrest. Recently, the proliferation of AED’s in airports, shopping malls, and police cars have doubled survival rates in some areas where the EMS response is a bit longer than 5 minutes.

             CPR buys you a little time pending the arrival of a defibrillator. The defibrillator is capable of temporarily restoring the heart to a functional rhythm as long as the cardio-vascular system is intact and the cause of the disrhythmia is reversible. In these lucky cases, survival then depends on stabilization with advanced life support and correction of the problem by a cardiologist. The best rates documented with this chain of care approach 28% survival to discharge. More typical is 6 – 16%.

             Unfortunately, the studies also show that CPR and defibrillation make no difference in survival rates outside the reach of urban EMS. Defibrillation after 20 minutes of cardiac arrest, even with advanced life support, is ineffective. Reports of survival after defibrillation without follow-up stabilization are notably absent from the literature.

             It is also important to know that CPR and defibrillation will not work if the cause of the cardiac arrest is trauma like brain injury or severe blood loss (aka “trauma arrest”). Even in a hospital trauma unit, survival of trauma arrest is less than 1%. Also, CPR and defibrillation will not work if the lungs cannot be ventilated due to fluid accumulation or airway obstruction.

             In spite of the absolute lack of scientific support for 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 medical care. Statements like “The more remote the setting, the more critical it is to have an AED” permeate the advertising copy and are appearing in EMS and rescue magazine articles. In my opinion, this is unethical and irresponsible. It is also very successful, they are selling lots of them.

             Why? The answer may lie in a study published by Diem, et al 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: 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% were trauma arrests. If you’re going to have a cardiac arrest, have it on television.

             These unrealistic depictions of success have driven CPR training for the masses, which is good. The same kind of unrealistic expectations are driving the sale of defibrillators to offshore sailors, which is bad. If you want to increase the chances of survival aboard your vessel, spend the money on survival suits, a better life raft, a new SSB, a storm sail, brighter running lights…almost any piece of safety equipment that you buy will have a better chance of saving your life at sea 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. Unless you live in the boonies, your local EMS will appreciate your efforts at home.

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

             Finally, the Coast Guard requires CPR training as a prerequisite to licensure. They are using the same unsupported assumptions that the retailers of AEDs are using, but they’re in charge. 

             CPR courses are available everywhere, for little or no money. CPR should not occupy training time in a compact and expensive marine medicine course. 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 Heartsaver, have stopped teaching rescue breathing in favor of just chest compressions and early defibrillation. You might want the longer Health Care Providers 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 the cessation of 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 trauma arrest, risk to rescuers, and severe hypothermia. You will probably be taught otherwise in urban context courses, but that’s fine for the city.

             For more information about CPR and Emergency Cardiac Care, see www.americanheart.org. If you actually hear about someone being successfully defibrillated offshore aboard a small vessel, and living to tell about it, please write. I’m anxiously awaiting that first case study.

             “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.”