b. When the pressure is removed from the sternum, it rises to its normal position
and the heart resumes its normal shape (figure 2-1B). Since blood was forced out of
the ventricles during the compression, blood flows from the atria into the ventricles, as
the heart returns to its normal shape. As blood flows out from the atria into the
ventricles, blood also flows from the veins to refill the atria.
c. Each pressure-release cycle is roughly equal to one heartbeat.
ROLE OF THE RESCUER
In order to properly treat a casualty requiring CPR, the rescuer must take the
following actions. These actions are summarized in figure 2-2.
a. Early Access. The rescuer, whether trained or untrained, must activate the
emergency medical service (EMS) system early, even before beginning CPR.
tissues cannot tolerate long term hypoxia (low state of oxygen in the blood). Because of
this, CPR must be started as soon as possible to increase the chance of patient
survival. High-quality bystander CPR can double or triple survival rates from cardiac
arrest. Less than one-third of victims of sudden cardiac arrest (SCA) receive bystander
CPR, and even fewer receive "high-quality" CPR.
c. Early Defibrillation. Treatment of ventricular fibrillation (VF) in SCA requires
early CPR and shock delivery with a defibrillator. Lay rescuer and first responder CPR
and automated external defibrilator (AED) programs in airports and casinos and with
police officers have reported survival rates from witnessed VF SCA as high as 49 to 74
d. Early Advanced Care. Early Advanced Cardiac Life Support (ACLS)
procedures should be performed.
Figure 2-2. The CPR Chain of survival (adult).