c. Administer External Chest Compressions. Proceed in this way:
(1) Lock your elbows with your arms straight. This makes chest
compressions more efficient and saves the rescuer's energy.
(2) Position your shoulders directly over your hands so that the thrust for
each chest compression is straight down. The casualty's torso may roll if you push
other than straight down. If the casualty rolls, the thrust of the chest compression will
be much weaker and less effective. Also, the rolling motion of the casualty can make
the rescuer very tired and cause additional injury to the casualty. Possible injuries
include fractured ribs, fractured xyphoid process, and lacerations (rips or punctures) of
internal organs caused by sharp pieces of broken bone.
(3) Push straight down on the sternum so that it goes down 1 1/2 to 2
inches for the normal sized adult. Use your weight when pushing down. Instead of
pushing down using your arm and shoulder muscles only, let the weight of your body
move forward and use that force to help depress the sternum. Remember to keep your
arms straight and your elbows locked during the push. (See figure 1-10.)
Figure 1-10. Rescuer administering external chest compressions.
(4) Give 15 compressions (10-12 seconds). A compression cycle consists
of a thrust which compresses the heart and a release which allows the heart to refill with
blood. These compressions are delivered at a rate of 80 cycles per minute (about 11
seconds for each 15 compressions). Delivering chest compressions at this rate will
allow the rescuer to administer a total of 60 compressions per minute since some time
will be required to administer two breaths after every 15 compressions.