Active compression-decompression cardiopulmonary resuscitation (CPR), with the help of a suction-cup device, augmented with negative intrathoracic pressure via an impedance device, improves blood flow to the brain and heart following cardiac arrest and should be considered as an alternative to standard CPR to increase long-term survival, according to a study published online Jan. 19 in the Lancet.
Study researchers noted that standard manual chest compressions with ventilation provides less than 25 percent of healthy blood flow to the heart and brain. In addition, chest compressions are often inadequately delivered, further compromising hemodynamics.
Previous research has shown that a decrease in intrathoracic pressure is linked to a simultaneous decrease in intracranial pressure, the mechanism by which blood flow is increased to the heart and brain.
In the current study, Tom P. Aufderheide, MD, from the department of emergency medicine at the Medical College of Wisconsin, Milwaukee, and colleagues evaluated 1,653 patients randomized to receive either standard CPR or active compression-decompression CPR with augmented negative intrathoracic pressure.
Rescuers did active compression-decompression CPR with a hand-held device consisting of a suction cup that was attached to the chest, a handle, an audible metronome set to 80 beats per minute and a force gauge to guide compression depth and chest wall recoil (ResQPump, Advanced Circulatory Systems).
The impedance threshold device lowered intrathoracic pressure during the decompression phase by impeding passive inspiratory gas exchange during the chest recoil phase, yet allowing periodic positive pressure ventilation (ResQPOD, Advanced Circulatory Systems).
Participating in the study were 46 emergency medical service agencies (serving 2.3 million people) in urban, suburban and rural areas of the U.S.
The primary endpoint was survival to hospital discharge with favorable neurological function.
Aufderheide and colleagues found that 6 percent of 813 controls survived to hospital discharge with favorable neurological function compared with 9 percent of 840 patients in the intervention group (odds ratio, 1.58).
In addition, 6 and 9 percent of the control and intervention group, respectively, survived to one year with equivalent cognitive skills, disability ratings and emotional-psychological statuses.
The overall major adverse event rate did not differ between groups, but more patients had pulmonary edema in the intervention group (11 percent) than did controls (7 percent).
"Our results show that treatment with active compression-decompression CPR with enhancement of negative intrathoracic pressure during the decompression phase significantly increases survival to hospital discharge with favorable neurological function compared with standard CPR after an out-of-hospital cardiac arrest of presumed cardiac cause," researchers concluded.
"Furthermore, overall survival increased by nearly 50 percent by one year in the intervention group compared with controls."
They noted that the benefit gained by the intervention group were independent of sex, age, date of enrollment and study site.
The researchers also suggested that this particular approach, which required training of EMS personnel, could be "expandable to any emergency medical service system that follows present European Resuscitation Council or American Heart Association guidelines."