Comparison of open-chest cardiac massage techniques in dogs

Manual compression of the heart during open-chest cardiac massage (OCPR) has been shown to be superior to closed-chest compression. Our study sought to determine, in a canine model, the optimal hand position for manual compression of the heart. Twelve dogs were anesthetized with ketamine, an orotracheal tube was placed, and anesthesia was maintained with halothane and nitrous oxide. Cannulae were placed to monitor diastolic (DBP) and systolic (SBP) blood pressures, intracranial pressure (ICP), and common carotid blood flow (CCBF). Control values were obtained under light general anesthesia, and ventricular fibrillation was induced. External CPR (ECPR) was performed with a mechanical compressor before opening the chest and pericardium through the left fifth interspace. The following sequence of three hand positions was used for OCPR: technique A, one-handed technique with thumb on left ventricle, fingers over the right ventricle, and apex in palm; technique B, two-handed technique with right ventricle cupped in left hand and fingers of right hand over left ventricle; and technique C, one-handed technique with fingers of right hand over left ventricle and heart against sternum. Each was done at a rate of 60 compressions per minute with the operator blind to results during performance. All three techniques produced significantly (P < .05) greater DBPs and CCBFs when compared with ECPR. All three also produced significantly lower (P < .05) ICPs when compared with ECPR. DBPs, SBPs, CCBFs, and cerebral perfusion pressures were similar for techniques B and C, and all were significantly greater (P < .05) than those achieved with technique A. These data suggest that techniques B and C (with several fingers pressing on the left ventricle) produce greater cardiac and cerebral blood flow during OCPR.