Sixteen periods of conventional CPR followed by SC-V CPR and return to conventional CPR were studied in 11 cases of in-hospital cardiac arrest at Johns Hopkins University. The findings indicated that simultaneous compression and ventilation at high airway pressures (SC-V CPR) greatly increased carotid flow velocity and radial artery pressure over values achieved with conventional CPR. Maximum benefit was achieved in patients in whom standard or conventional cardiopulmonary resuscitation was least effective. The increases in flow index noted with simultaneous compression and ventilation were up to 274 percent of control.