From a 1946 article in Popular Science.
Here’s the gist if the two methods:
Schafer: Pressure applied presses the abdominal contents (intestines, stomach, etc.) forward into the concave arch of the diaphragm. This bulges upward and compresses the lungs from the bottom upward. Air is expired. When the pressure is released, the ribs spring back into place, the abdominal content slides back, and the diaphragm resumes its natural position. A return flow of new air rushes downward into the lungs under normal pressure of about 15 pounds per square inch. Thus, the lungs are made to function artificially. Coats or blankets are recommended to apply external heat.
Eve: The rocking ventilates the lungs by alternately pushing and pulling the diaphragm up and down. At the same time, blood is forced through the oxygen-starved heart muscle, helping to start it or to restore a feeble beat. Further, the nerve cells of the brain and breathing center receive blood at normal pressure. When the feet-down tilt is made, blood from the extended arms fills the heart and encourages it to beat and pump. Dr. Eve goes beyond the blankets-for-warmth phase, when the equipment is available, in recommending application of hot bottles over the neck to revive the chilled nerve cells at the base of the brain.
Experiments have shown that the Eve method, with a 30-degree rock, produced an average intake of 150 cubic centimeters of air at each inhalation as against 55 c.c.â€™s under the Schafer method.
The most important thing to remember is that all systems of artificial respiration depend primarily on PROMPT ACTION. Any delay may be fatal. As one authority puts it:
â€œDonâ€™t waste time; start squeezing the chest even if you have to use your foot.â€