Interposed abdominal compressions and carotid blood flow during cardiopulmonary resuscitation. Support for a thoracoabdominal unit.

To determine if the timing of interposed abdominal compressions (IAC) affects the augmented blood flow during this form of cardiopulmonary resuscitation (CPR), we performed early-onset or late-onset abdominal compressions at three vascular volumes in nine dogs. Early-onset IAC began immediately following chest compression; we predicted that this would act primarily by emptying the aorta and sustaining the elevated intrathoracic pressure. Late-onset IAC began one-fourth to one-third of the time into diastole; this would have primarily increased venous return.