The simplification of CPR

Published: October, 2010

In most situations, mouth-to-mouth breaths aren't needed.

While everything else in this world seems to be getting more complicated, cardiopulmonary resuscitation (CPR) keeps on getting simpler. Remember old-fashioned CPR? You were supposed to clear the airway (scooping out the mouth if need be), give those mouth-to-mouth breaths, push on the chest, and check for a pulse every once in a while. But the American Heart Association has eliminated the airway clearing and pulse checks from its guidelines, and in 2008 the association endorsed "hands only" CPR in many cases, eliminating the mouth-to-mouth breaths.

Even if you've never taken a CPR class in your life, the heart association guidelines say to call 911 (easier to do right away now that most of us carry cell phones) and then start pushing hard and fast — 100 times a minute — on the person's breastbone until the emergency medical technicians (EMTs) or paramedics arrive. It's also important to have someone go get an automated external defibrillator (AED) if one is nearby so you can attempt to shock the heart back into a normal rhythm.

So we're all set: keep-it-simple, hands-only CPR is the way to go. Still, two studies published in The New England Journal of Medicine (NEJM) in July 2010 are a reminder not to oversimplify the situation. Over all, the results jibe perfectly with previous reports and further the case for taking a hands-only approach to cardiac arrest. The studies showed that people who received only chest compressions before EMTs arrived were just as likely to survive as those who received traditional CPR of compressions and breaths. But a finer analysis of the results of one of the studies showed that a small, but not insignificant, number of people did benefit from traditional CPR. They included people with "noncardiac" arrest, which usually means they had breathing problems before their hearts went haywire, as can happen with drug overdoses, asthma attacks, or near-drownings.

This is not an unanticipated finding. When the heart association gave its blessing to hands-only CPR, it came with a proviso that conventional CPR techniques might still benefit some people. Children and victims of drowning, trauma, airway obstruction, and acute respiratory disease are specifically mentioned.

Cardiac arrest vs. heart attack

Cardiac arrest is a term that throws some people. It's sometimes used interchangeably with heart attack, but they are not the same thing. Heart attacks usually occur when the blood supply to the heart is cut off because an artery has been blocked. The classic symptoms are gripping, heavy chest pain that may also spread to the jaw, back, or either arm; shortness of breath; nausea; or fatigue.

Cardiac arrest is the interruption of the normal heartbeat. The ventricles, the powerful lower chambers of the heart, race (ventricular tachycardia) or quiver chaotically (ventricular fibrillation) or may stop moving altogether. Without a pumping heart, blood stops circulating. When people suffer cardiac arrest, they collapse suddenly and lose consciousness because now the brain is not getting the blood it needs. Other systems, including breathing, also shut down quickly.

Part of the reason for the confusion about the difference between cardiac arrest and heart attack is that a heart attack is the most frequent trigger of cardiac arrest. On the other hand, people with perfectly "clean" coronary arteries suffer cardiac arrest for various reasons, including defects in the systems that drive the heartbeat.

About 300,000 Americans each year suffer cardiac arrest outside of a hospital. Cardiac arrest is often dramatized as taking place in public, but 80% of the time people are at home or in a residential setting. But some stereotypes ring a little more true: the typical victim is a man in his mid-to-late 60s.

Hold the breaths

There are two main reasons CPR has been simplified. First, the simpler it is, the more likely people will do it. Realistically, only a tiny minority of us are going to take CPR classes. We need CPR to be as uncomplicated as possible because we're going to be fighting some strong emotions if someone collapses in front of us. And the mouth-to-mouth breaths make people hesitant. They worry about doing them correctly and are squeamish about coming into contact with the stricken person's mouth.

Currently, about 30% of people who suffer cardiac arrest outside of the hospital receive "bystander" CPR, which, all things considered, doesn't seem too bad. It's a fair assumption, though, that simplifying CPR would increase the percentage and with it, the number of people who survive cardiac arrest.

The other reason is evidence that the mouth-to-mouth breaths may not accomplish very much — and may even do more harm than good. The chest compressions of CPR circulate the blood. They must be fast — faster than the usual heartbeat — because they don't push the blood along with the same force as a working heart.

When people administer the breaths, that interrupts the compressions, so blood flow slackens. Maybe that wouldn't be a problem, but most people take longer than just a few seconds — up to 16 seconds in one study — to deliver the breaths. Moreover, added pressure in the chest from breathing into the airways may impede the flow of blood making a return trip to the heart.

But isn't the oxygen delivered by those resuscitation breaths important? As the results published in NEJM show, perhaps it is when respiratory distress precedes cardiac arrest.

But otherwise, findings from animal experiments and various studies in people comparing the two versions of CPR indicate that there's enough oxygen in the blood for a person to survive several minutes — time enough for the EMTs to arrive in most urban areas or for somebody to get an AED to shock the heart back into a normal rhythm.

Calling 911

Even in the best circumstances, the odds of surviving cardiac arrest that occurs outside the hospital are long. In both of the NEJM studies, the rescuers were instructed by dispatchers. In one of the studies, conducted in Sweden, just 100 of the 1,276 people (7.8%) who received CPR, either compression-only or the conventional kind, were alive 30 days later. Results in the other study were a bit better: 227 of 1,941 (11.7%) people who received CPR survived to hospital discharge.

The long odds get even longer if the arrival of EMTs is delayed. But people are sometimes reluctant to call 911. What if it's not cardiac arrest and the person just fainted?

Dr. J. Toby Nagurney, a member of the Health Letter's editorial board and a physician in the emergency department at Massachusetts General Hospital, says err on the side of 911, because the consequences of not calling if it's cardiac arrest are disastrous. Getting help quickly for someone who has suddenly collapsed is one of the reasons the 911 system was created, notes Dr. Nagurney.

Naturally, circumstance and a person's age can be factored in. If an older person who is overweight and has other heart disease risk factors suddenly collapses, the chances of it being cardiac arrest are higher than if the person is in their 20s and healthy.

As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.