g. Perform 30 Chest Compressions. A compression 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 approximately 100 per minute. Figure
4-3 shows a rescuer delivering chest compressions. It is recommended to push hard
and fast to make sure adequate depth and rate of compressions are maintained.
Figure 4-3. Rescuer administering chest compressions.
(1) Thrust. When performing the thrust, keep your elbows locked and push
straight down. Do not push with all of your strength, but do use enough force to push
the casualty's sternum down 1 1/2 to 2 inches (4 to 5 centimeters). Instead of pushing
down using your muscles only, let the weight of your body move forward and use that
force to help depress the sternum.
(2) Release. Releasing the pressure allows the heart to refill with blood.
Release the pressure completely so that the sternum resumes its normal position, but
do not remove the heel of your hand from the compression site.
If you do lose the compression site, quickly repeat the procedures given in
paragraphs d and e.)
(3) Rhythm. You should establish a definite rhythm when performing
external chest compressions. The release part of the cycle should be equal in time to
the thrust part of the cycle. Both parts should be distinct--do not "bounce." Use a
system to keep the compressions regular, smooth, and uninterrupted. One system for
keeping track of the number of compressions administered is given below.