CPR is a Life Skill Everyone should Know
Learning how to do CPR - Cardiopulmonary Resuscitaion - is a life skill everyone should acquire. One never knows when someone at work, at home or on the street may go into cardiac arrest. Also, it's not uncommon for someone to go into a cardiac arrest while hiking, backpacking, mountain biking, or training for a running, cycling, swimming or triathlon event or race. Many athletic event related cardiac arrests are related to electrolyte imbalance or severe dehydration or heat exhaustion (stroke). For tips on maintaining good hydration and electrolytes balance see:
Perhaps you haven’t yet been called upon to apply CPR, but it happens often enough that one day you might!
A Mini-Course on Cardiac Arrest
The term cardiac arrest refers to cessation of circulation and the most common cause is a heart rhythm call ventricular fibrillation (VF). If you could look at a heart muscle at the moment of cardiac arrest the heart in VF would look like a quivering and uncoordinated blob of muscle.
With the onset of VF the heart stops beating and there is no pulse or blood pressure—the person loses consciousness in a matter of seconds and is clinically dead. Clinical death will turn to biologic (and irreversible) death in a matter of 5-10 minutes. But if CPR can be started quickly, and if a defibrillatory shock (the type provided by firefighters, paramedics, doctors, nurses and increasingly by lay persons using automated devices) can be provided in 10-12 minutes, the person has a pretty good chance of surviving the event. The electric shock stops the VF and allows a normal rhythm to begin. It is like rebooting the heart.
How do I Recognize Cardiac Arrest?
If there is any doubt you should shout at the person and vigorously tap them. If there is no response begin chest compression. Remember, however, that there may be agonal respirations that may continue for a few minutes. These abnormal death-associated respirations sound like snoring or gasping. They often fool bystanders into thinking the person is still breathing but in fact the agonal breaths are ineffective and almost no oxygen is getting into the lungs. CPR instructions no longer include a pulse check. This was dropped because it was too difficult to determine the presence of a pulse especially in possible shock conditions.
How Does CPR Work?
CPR works by circulating blood to vital organs such as the heart and brain, and buys a few critical minutes of time until a defibrillator can shock the heart. When CPR is provided within four minutes, a shock can be successful up to 16 minutes into the arrest. But if there is no CPR then the window of opportunity for the shock to be successful is only eight minutes. Blood is moved forward with chest compression in two ways: one is from direct squeezing of the heart against the vertebrae on the back and the other, more important, is by increasing and decreasing pressure within the chest with the down-and-up motion.
Valves in the large veins prevent backward flow of blood. With every downward compression the brain is receiving blood and with every upward decompression the coronary arteries are receiving blood. The up and down circulates blood to the brain and heart. Of these two ways (squeezing the heart CPR—cardiopulmonary resuscitation and pressure changes) the latter is the most important and studies have demonstrated that chest compression can achieve about 30 percent of a normal cardiac output.
In the past few years the American Heart Association has stressed chest-compression only CPR, especially for untrained or tentative rescuers. This means if you encounter someone in cardiac arrest, it is acceptable to do only chest compression. This makes good sense since mouth-to-mouth ventilation is difficult to do well. And unless it is done well, it only wastes time when chest compression could be circulating blood. Professional responders are still being taught chest compression and mouth-to-mouth ventilation but for lay rescuers it is acceptable to only do chest compression.
Does CPR Make a Difference?
Yes. The bottom line is that it buys valuable time. And in so doing, doubles the likelihood of survival following cardiac arrest.
CPR in the Off-Trail, in the Countryside or in the Wild
Although success rates off-trail, in the countryside, in the wilderness or other remote areas aren’t always high, knowing CPR is essential and can be critical in saving a life. Whenever anyone asks me whether CPR should be done in the wilderness, I tell them to try it for 10-15 minutes and see if there is a response. Sometimes the cardiac arrest may be due to a very slow rhythm or a respiratory cause, both of which may respond to a short period of CPR. And if it doesn’t work, at least you tried to help.
Mickey Eisenberg is a Professor at the University of Washington Medical School, earned his MD at Case Western Reserve University Medical School, performed his Internship and Residency in Internal Medicine at the University of Washington School of Medicine, and is the author of Resuscitate. See Mickey's comprehensive CPR site Learn CPR. More about Ralph Teller. See Ralph's 1Vigor Log Calendar.<-- back to top
CPR, First Aid Articles
CPR—cardiopulmonary resuscitation, by Mickey Eisenberg, MD, PhD, Mountaineers Magazine
Learn CPR - You Can Do It! Contains two free mobile training apps for the iPhone and Android Phones
Cold Water Immersion: The Gold Standard for Exertional Heatstroke Treatment, Douglas J. Casa, Exerc Sport Sci Rev. 2007, Medscape