Sudden Cardiac Arrest: Do You Need a
Home Defibrillator?
According to the
American Heart Association, sudden cardiac arrest kills more than
450,000 people in the United States each year. More than stroke,
lung cancer, breast cancer and HIV/AIDS combined. Because the
majority of sudden cardiac arrests occur within the home, a
significant number of individuals die before ever reaching the
hospital.
Sudden cardiac
arrest, or SCA, is not a heart attack (myocardial infarction). An MI
is caused when a blockage in a blood vessel interrupts the flow of
oxygen-rich blood to the heart, causing heart muscle to die. A
previous heart attack is, however, a predictor of future risk for
sudden cardiac arrest, as is coronary artery disease.
Sudden cardiac
arrest is caused by an electrical malfunction of the heart that
triggers one of two abnormal heart rhythms - ventricular tachycardia
or ventricular fibrillation - both of which are commonly fatal. In
v-tach the electrical pulse of the heart goes out of control,
causing it to beat very fast. In v-fib the heart's electrical
activity becomes disordered, causing the heart to stop pumping. The
ventricles begin to "flutter" rather than beat.
The only effective
emergency treatment for sudden cardiac death is the delivery of an
electric pulse (shock) to the heart from a device known as a
defibrillator. It uses an electrical shock to reset the electrical
state of the heart so that it may convert to a rhythm controlled by
its own natural pacemaker cells. CPR (cardiopulmonary resuscitation)
is often promoted as a therapeutic treatment for cardiac arrest
victims, but it does not stop VF. It only extends the time window
for a few small minutes until a successful shock can be delivered.
In 1967, when a
physician in Belfast plopped an AC defibrillator powered by two 12
volt car batteries into a hospital ambulance and went on the road,
he created the first successful resuscitation team to operate
outside of a hospital environment. Since that time one imperative
has remained steadfast: The single most significant factor in
determining the saving of a life is the time it takes from the onset
of cardiac arrest to an electrical intervention by defibrillation.
Recent studies
indicate survival rates from VF can exceed 90 percent if
defibrillation occurs in the first 1-2 minutes, however every minute
thereafter rates decline by 7 to 10 percent per minute. The average
response time to 911 calls by fire departments in urban areas is 4-5
minutes; longer in larger cities. The national average for emergency
medical technicians to respond is over nine minutes. Consequently in
many big cities the survival rate from SCA is less than 2 percent.
In response to a
challenge by the American Heart Association in 1992, the medical
device industry has developed a number of automated external
defibrillators (AED) designed to be used by minimally trained
individuals. They are targeted for use by lay persons, providing the
rescuer with voice commands and visual cues for action. One study
proved that even very young (sixth grade), untrained children can
successfully perform automated external defibrillation.
These portable AED's
are quite safe (97% sensitive and 100% specific, according to the
literature) and incorporate safeguards that prevent them jolting the
patient's heart if it is not in ventricular fibrillation. If the
defibrillator advises a shock is needed, it charges up and an alarm
sounds when the machine is ready. Depending on the model it will
automatically shock the victim, or it may instruct you to do so
manually. Most units shock up to 3 times, the third shock being the
strongest. AED units generally weigh from 4.5 pounds to 8 pounds.
Many automatically perform daily and monthly self tests, and some
even provide continuous monitoring during and after an arrest.
Defibrillators of
this ilk are already being used in public areas with a high
incidence of SCAs. In order, they are: airports, golf courses,
health clubs, industrial corporations, recreational events, shopping
malls, and other public areas such as casinos, cruise ships and
passenger trains. Since 2001, all 50 states have enacted Good
Samaritan Laws that provide civil immunity for AED users who have
completed training. People who are often first on the scene when
sudden cardiac arrest occurs -- police officers, firefighters,
security officers, athletic trainers, flight attendants, lifeguards
-- have already saved thousands of lives with a minimal amount of
training.
Until recently AEDs
for home use could only be purchased with a prescription.
Legislation has now passed which allows the public to purchase
automated external defibrillators for the home or office, making the
only constraint toward buying one for your first aid kit possibly a
financial one. Presently over twelve companies offer automated
cardiac defibrillators for roughly the cost of a personal computer,
and soon they'll be sold at your local discounter. Your home
defibrillator should be situated in a highly visible location within
three minutes of the remotest part of the area it is protecting, and
preferably next to a phone that can be used to dial 911.
The collapse of a
friend or relative at home can be a frightening event. Helping them
means keeping a cool head. Here are some tips that may help you save
a life: Gently shake the victim and shout "Are you OK?" If
the person answers, do not begin CPR. If the person is unresponsive
or shows signs of a heart attack, call 911. If a defibrillator is
nearby, follow its instructions. Otherwise, start CPR.
For more information or for training
on how to use a home defibrillator, contact the American Red Cross
or the American Heart Association.
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