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Chance of getting CPR in time
CPR is only likely to be effective if commenced within 6 minutes after the blood
flow stops, because permanent brain cell damage occurs when fresh blood infuses
the cells after that time, since the cells of the brain become dormant in as
little as 4-6 minutes in an oxygen deprived environment and the cells are unable
to survive the reintroduction of oxygen in a traditional resuscitation. Research
using cardioplegic blood infusion resulted in a 79.4% survival rate with cardiac
arrest intervals of 72±43 minutes, traditional methods achieve a 15% survival
rate in this scenario, by comparison. New research is currently needed to
determine what role CPR, electroshock, and new advanced gradual resuscitation
techniques will have with this new knowledge A notable exception is cardiac
arrest occurring in conjunction with exposure to very cold temperatures.
Hypothermia seems to protect the victim by slowing down metabolic and
physiologic processes, greatly decreasing the tissues' need for oxygen. There
are cases where CPR, defibrillation, and advanced warming techniques have
revived victims after substantial periods of hypothermia.
Chance of surviving
Used alone, CPR will result in few complete recoveries, and those that do
survive often develop serious complications. Estimates vary, but many
organizations stress that CPR does not "bring anyone back," it simply preserves
the body for defibrillation and advanced life support . However, in the case of
"non-shockable" rhythms such as Pulseless Electrical Activity (PEA),
defibrillation is not indicated, and the importance of CPR rises. On average,
only 5%-10% of people who receive CPR survive. The purpose of CPR is not to
"start" the heart, but rather to circulate oxygenated blood, and keep the brain
alive until advanced care (especially defibrillation) can be initiated. As many
of these patients may have a pulse that is impalpable by the layperson rescuer,
the current consensus is to perform CPR on a patient that is not breathing. A
pulse check is not required in basic CPR since it is so often missed when
present, or even felt when absent, even by health care professionals.
Studies have shown the importance of immediate CPR followed by defibrillation
within 3–5 minutes of sudden VF cardiac arrest improve survival. In cities such
as Seattle where CPR training is widespread and defibrillation by EMS personnel
follows quickly, the survival rate is about 30 percent. In cities such as New
York City, without those advantages, the survival rate is only 1-2 percent.
Type of Arrest ROSC Survival Source
Witnessed In-Hospital Cardiac Arrest 48% 22%
Unwitnessed In-Hospital Cardiac Arrest 21% 1%
Bystander Cardiocerebral Resuscitation 40% 6%
Bystander Cardiopulmonary Resuscitation 40% 4%
No Bystander CPR (Ambulance CPR) 15% 2%
Defibrillation within 3-5 minutes 74% 30%
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