EFFECTS OF VARIOUS DEGREES OF COMPRESSION AND ACTIVE DECOMPRESSION ONHEMODYNAMICS, END-TIDAL CO2, AND VENTILATION DURING CARDIOPULMONARY-RESUSCITATION OF PIGS

The effects of various degrees of compression and active decompression during cardiopulmonary resuscitation were tested in a randomized cros s-over-design during ventricular fibrillation in eight pigs using an a utomatic hydraulic chest compression device. Compared with 4/0 (compre ssion/decompression in cm), mean carotid arterial blood flow rose by 6 0% with 5/0, by 90% with 4/2 and 4/3, and by 105% with 5/2. Two cm act ive decompression increased mean brain and myocardial blood flow by 53 % and 37%, respectively, as compared with 4/0, Increasing standard com pression from 4 to 5 cm caused no further increase in brain or heart t issue blood flow whether or not combined with active decompression, Ti ssue blood flow remained unchanged or decreased when active decompress ion (4/3) caused that 50% of the pigs were lifted from the table due t o the force required. Myocardial blood flow was reduced with 5/0 vs, 4 /0 despite no reduction in end decompression coronary perfusion pressu re ((aortic-right atrial pressure) (CPP), (7 +/- 8 mmHg with 4/0, 14 /- 11 mmHg with 5/0)(Ns)). End decompression CPP increased by 186% wit h 4/2 vs. 4/0, by 200% with 4/3, and by 300% with 5/2. Endo-tracheal p artial pressure of CO2 was significantly increased during the compress ion phase of active decompression CPR compared with standard CPR, Acti ve decompression CPR generated an significantly increased ventilation compared with standard CPR, Conclusion: Carotid and tissue blood flow, ventilation, and CPP increase with 2 cm of active decompression. An a ttempt to further increase the level of active decompression or increa sing the compression depth from 4 to 5 cm did not improve organ blood flow.