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 By Lisa Rapaport
(Reuters Health) - Cardiac arrest
patients who get cardiopulmonary resuscitation (CPR) from a
bystander at the scene may have better survival odds even when an
ambulance takes a long time to arrive, a Danish study suggests.
Researchers examined data on 7,623 cardiac arrest patients and found
when an ambulance arrived within five minutes of a 911 call,
patients were 2.3 times more likely to survive at least 30 days if
they received bystander CPR than if they didn't get this aid at the
scene.
When ambulances took up to 10 minutes to arrive, bystander CPR was
associated with tripled survival odds, the study also found. After
13 minutes, patients who got CPR at the scene continued to have
better survival odds but the difference was no longer statistically
meaningful.
"Early CPR saves lives, and the lack of CPR efforts from bystanders
could result in significantly decreased chances of survival," said
lead study author Dr. Shahzleen Rajan of Copenhagen University
Hospital in Denmark.
Cardiac arrest involves the abrupt loss of heart function, breathing
and consciousness. Unlike a heart attack, which happens when blood
flow to a portion of the heart is blocked, cardiac arrest occurs
when the heart's electrical system malfunctions, often due to
irregular heart rhythms. Cardiac arrest may occur with no warning
and is often fatal.
Chest compressions or CPR can help restore circulation, increasing
the odds of survival. Bystander CPR generally won't restore a normal
heart rhythm but it can buy time by maintaining blood flow to vital
organs.
"We know from previous research that 1 in 8 people survive after a
cardiac arrest if a bystander initiates CPR before the arrival of
the emergency medical services," Rajan said by email. "In contrast,
if CPR is not initiated before the arrival of the emergency medical
services, only 1 in 30 people survive a cardiac arrest."
For the current study, researchers looked at 30-day survival for
patients who had cardiac arrests outside of a hospital between 2005
and 2011.
When the ambulance arrived within five minutes, 14.5 percent of
patients in the bystander CPR group survived at least 30 days,
compared with 6.3 percent in the group that didn't get this help.
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For ambulance arrival times up to ten minutes, 6.7 percent in the
CPR group and 2.2 percent of the other patients survived. If the
ambulance took more than 13 minutes, the survival rate was 3.7
percent in the CPR group and 1.5 percent for the others - a
difference that wasn't statistically meaningful.
The study is observational and doesn't prove bystander CPR increases
survival odds, the authors note in Circulation. Researchers also
lacked data on how quickly bystanders intervened after the start of
cardiac arrest, which could influence outcomes, the authors note.
"Once a victim has sustained a cardiac arrest with little or no
blood supply going to the heart or brain, the time to reestablishing
blood flow with oxygenated blood is critical," said Dr. Lenworth
Jacobs, director of trauma and emergency medicine at Hartford
Hospital in Connecticut.
"It is generally thought that the sooner this is implemented the
better," Jacobs, who wasn't involved in the study, added by email.
The biggest obstacle to bystander CPR remains that too few people
know how to do it, said Dr. Peter Pons, an emergency physician in
Denver and professor emeritus at the University of Colorado School
of Medicine.
"Clearly, if someone has been motivated to learn and has been taught
CPR, they will often assist," Pons, who wasn't involved in the
study, said by email. "When someone does not have that knowledge,
they tend to be more reluctant to act and may fear making things
worse."
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