Chest Compression Only CPR Can Succeed, But Not Without
Some Oxygen from Somewhere
‘For the first few minutes, it’s probably right
just to push on the chest. But at some point you probably need to add
oxygen, however you can’
Nov. 30, 2009 – A study released today adds to the
efforts to find a cardiopulmonary resuscitation method that is effective
and easy to use. The favored CPR method had been a combination of chest
compressions and blowing of air into the victim’s lungs. Recently,
however, the American Heart Association has been reviewing chest
compressions alone as an acceptable alternative. This new report says,
however, that the victim is going to need some oxygen during this
process to survive.
Mouth-to-mouth no longer recommended for bystanders
trying to save lives
March 31, 2008 - Chest compressions alone, or
Hands-Only Cardiopulmonary Resuscitation (CPR), can save lives and can
be used to help an adult who suddenly collapses, according to a new
American Heart Association scientific statement posted on the Web site
today. Read more...
MICR emphasizes minimal interruption of chest
compressions
March 11, 2008 – Those experiencing a cardiac
arrest outside of a hospital have a scant chance of survival, despite
massive efforts in cardiopulmonary resuscitation (CPR) training and
efforts to place more automated external defibrillators in public
places. A new study, however, finds hope in minimally interrupted
cardiac resuscitation (MICR), which emphasizes minimal interruption of
chest compressions during a rescue attempt.
Read more...
“People can survive cardiac arrest if they receive
only chest compressions during attempts to revive them – as advised by
the current
American Heart Association guidelines. But they cannot survive
without access to oxygen sometime during the resuscitation effort,
research suggests,” according to the news release on the study.
Scientists tested different scenarios in an animal
study of cardiac arrest. Rats received either 100 percent oxygen, 21
percent oxygen – the equivalent of room air – or no oxygen (100 percent
nitrogen) at the same time they received
cardiopulmonary resuscitation (CPR).
About 80 percent of the rats survived regardless of
the percentage of oxygen they received along with chest compressions.
However, in the group receiving no oxygen, only one animal could be
resuscitated.
Though these animals received the oxygen via
ventilation, people who suffer cardiac arrest in a public setting would
more likely obtain some oxygen by gasping during CPR or by receiving
some air from a vacuum effect resulting from chest compressions,
researchers say.
“The study showed that there is a need for oxygen.
How much oxygen is needed remains unknown. There is probably a sweet
spot in there somewhere,” said
Mark Angelos, professor of
emergency medicine at Ohio State University and senior author of the
study.
“For the first few minutes, it’s probably right
just to push on the chest. But at some point you probably need to add
oxygen, however you can – maybe mouth-to-mouth or with supplemental
oxygen. Where that sweet spot is is not yet clear.”
The research is published in a recent issue of the
journal
Resuscitation.
According to the American Heart Association, almost
80 percent of cardiac arrests that take place outside a hospital occur
at home and are witnessed by a family member. Yet only 6.4 percent of
sudden cardiac arrest victims survive because most witnesses do not know
how to perform CPR.
The association is in the midst of a new campaign
touting
“hands-only” CPR, urging people to call 911 and push “hard and fast”
in the center of the chest of a person in cardiac arrest.
“In a public setting, presumably we don’t
have any options. We see that ventilating with room air is just
as good as supplemental oxygen,” he said. “However, we also know
now that too little or the absence of any ventilation might be
harmful, at least over time, due to the lack of oxygen.”
Angelos said his research is not intended to
counter the current guidelines. Instead, scientists continue to study
the intricacies of the resuscitation process in the pursuit of ways to
improve the potential for survival after cardiac arrest.
Approximately 30 percent of cardiac arrest patients
will survive long enough to be hospitalized. But far fewer are ever
discharged from the hospital; most typically die of heart failure or
brain damage resulting from an extended loss of oxygen to the brain,
said Angelos, also an investigator in
Ohio State’s Davis Heart and Lung Research Institute.
In the study, Angelos and colleagues imposed six
minutes of cardiac arrest on 33 rats before CPR was started. During CPR,
animals were ventilated with either 100 percent oxygen or 21 percent
oxygen.
A control group of rats received nitrogen, which
eliminated oxygen from their lungs. This scenario allowed for lab
comparisons, but was not intended to mimic normal conditions because
people would likely have some residual oxygen in their lungs and blood
even during cardiac arrest.
CPR was continued until the surviving animals
experienced what is called the “return of spontaneous circulation,” when
the heart pumped blood on its own. All animals receiving oxygen returned
to spontaneous circulation at approximately the same time, between about
90 seconds and two minutes after CPR began.
All surviving animals continued to receive the same
levels of oxygen that they had received during CPR for two minutes after
their hearts started working, and then they were all transferred to 100
percent oxygen for an hour.
“That’s pretty typical for a hospitalized cardiac
arrest victim, to get a high concentration of oxygen early on,” Angelos
said.
The American Heart Association 2005 Guidelines for
Cardiopulmonary Resuscitation and Emergency Cardiovascular Care were
released in November 2005.
One rat unexpectedly survived CPR without any
oxygen, but died within 72 hours. Among the rats receiving oxygen during
CPR, nine of 11 (82 percent) of the rats in the 21-percent oxygen group
survived CPR, and 10 of 12 (83 percent) of the rats receiving 100
percent oxygen survived. At the 72-hour mark, those figures had dropped:
77 percent of the room-air rats were still alive, and 80 percent of
100-percent oxygen rats were still living.
Neurological tests showed that five of seven (71
percent) of the room-air rats and three of eight (38 percent) of the
rats on 100-percent oxygen during CPR returned to normal brain function
at 72 hours. The researchers considered these findings secondary to the
initial finding that oxygen was required for success during the initial
resuscitation process, Angelos noted.
“In a public setting, presumably we don’t have any
options. We see that ventilating with room air is just as good as
supplemental oxygen,” he said. “However, we also know now that too
little or the absence of any ventilation might be harmful, at least over
time, due to the lack of oxygen.”
Generally, Angelos noted, the concern has been too
much ventilation, which lessens the effectiveness of CPR.
Angelos conducted the research with Steven Yeh,
Rebekah Cawley and Sverre Aune of Ohio State’s Department of Emergency
Medicine; Yeh and Aune also are researchers in the Davis Heart and Lung
Research Institute and
Ohio State’s Biophysics Graduate Program.
Keep up with the latest news for senior citizens, baby
boomers
Nov. 30, 2009 – A study released today adds to the
efforts to find a cardiopulmonary resuscitation method that is effective
and easy to use. The favored CPR method had been a combination of chest
compressions and blowing of air into the victim’s lungs. Recently,
however, the American Heart Association has been reviewing chest
compressions alone as an acceptable alternative. This new report says,
however, that the victim is going to need some oxygen during this
process to survive.