Cardiac output, coronary blood flow, and blood gases during open-chest standard and compression-active-decompression cardiopulmonary resuscitation.

OBJECTIVE

To determine whether open-chest compression-active-decompression (CAD) could improve cardiac output, coronary blood flow, blood gases, and resuscitation compared to open-chest manual compression in a porcine model of cardiac arrest.

DESIGN

Prospective, randomized laboratory investigation for measurement of cardiac output, coronary blood flow, arterial and mixed venous blood gases and potassium levels, and return of spontaneous circulation.

SUBJECTS

Ten pigs each weighing approximately 36.4 kg.

INTERVENTIONS

Following preparation of the model and opening of the chest, ultrasonic flow probes were placed on the ascending aorta and left anterior descending artery. Cardiac arrest was induced by epicardial pacing. Subjects received either open-chest CAD or open-chest manual compression. After 10 min of arrest, defibrillation was attempted.

MEASUREMENTS AND MAIN RESULTS

Cardiac output fell to 46+/-53% (95% CI: -20 to 112) and 41+/-14% (95% CI: 23-59) (P>0.05) of baseline with CAD and manual methods at 5 min after arrest, respectively. Similarly, coronary blood flow fell to 33+/-14% (95% CI: 16-50) and 42+/-16% (95% CI: 22-62) (P>0.05) of baseline at 5 min. Both groups developed similar levels of metabolic acidosis, mixed venous hypoxemia, and hyperkalemia, with potassium levels: 6.5+/-4.0 meq/l (95% CI: 1.6-11.4) at 5 min and 7.5+/-4.6 meq/l (95% CI: 1.8-13.2) at 10 min in the CAD group and 5.8+/-2.0 meq/l (95% CI: 3.4-8.3) at 5 min and 6.1+/-1.4 meq/l (95% CI: 4.4-7.9) at 10 min in the manual group. Levels of hyperkalemia were inversely proportional to the square of PvO(2). One pig in each group was resuscitated after defibrillation.

CONCLUSION

We found no benefit using CAD. Both low coronary blood flow and hyperkalemia may have limited resuscitation.