The interposed abdominal compression CPR
method requires 2 rescuers, who alternately compress the chest
and the abdomen in a seesaw motion (Figure 8E), with the
possible mechanisms of augmenting diastolic aortic pressure as
well as forcing visceral venous blood into the chest between
thoracic compressions. Clinical trials have demonstrated improved
survival with interposed abdominal compression CPR
over conventional CPR after inpatient97 but not outpatient
cardiac arrest.98 A mechanical piston device can replicate manual
chest compressions, shows improvements in some physiological
parameters, and can be used as an approximately equivalent
alternative to traditional CPR.