Units of the Miami and Dade County Rescue Squads utilized the technique in a mid-point cross-over design. One of the three shifts at each of the study rescue stations had been thoroughly instructed in the SC-V CPR protocol. A second crew was given an intensive review of conventional CPR methodology. The third shift initially received the conventional CPR review and continued to perform conventional CPR. After six months, the third shift was trained in SC-V CPR and utilized the technique for one year. At the cross-over point, the crew trained in SC-V CPR received the same intensive review of conventional CPR as did the other crew. The conventional CPR crews, in turn, were trained in SC-V CPR. Total sample size was 994 patients, 494 in the treatment group and 500 in the control group.