A comparison of 2 types of chest compressions in a porcine model of cardiac arrest.

OBJECTIVE: Chest compressions performed by some medical workers are of poor quality, which are too few and shallow with incomplete release. This study was designed to compare the effects of these clinical quality chest compressions with standard manual chest compressions in a porcine model of cardiac arrest.
METHODS: Ventricular fibrillation was induced in 18 pigs by programed electrical stimulation. Then, 40 mg methylene blue was injected into right atrium after 4 minutes of untreated ventricular fibrillation (VF), followed by cardiopulmonary resuscitation for 9 minutes. Defibrillation was attempted at 13 minutes of cardiac arrest. Animals of no restoration of spontaneous circulation after 4 times of defibrillations were announced dead and dissected immediately to observe the cerebral perfusion with methylene blue coloration. Resuscitated animals were executed to remove the tissues of pallium, cardiac muscle, kidney, and liver for histopathology after evaluating a porcine Cerebral Performance Category score at 24 hours after cardiac arrest. All animals were randomized to the following 2 groups: (1) standard manual chest compressions group (n = 9)-chest compression rates were kept at 100 +/- 5 cpm and compression depth at 50 +/- 1 mm with complete release by Heartstart MRx Monitor; (2) clinical quality chest compressions group (n = 9)-chest compression rates were kept at 80 +/- 5 cpm and compression depth at 37 +/- 1 mm with incomplete release.
RESULTS: Compared with clinical quality chest compressions, standard manual chest compressions produced greater restoration of spontaneous circulation, neurologically normal 24-hour survival, and histopathologic findings.
CONCLUSIONS: High-quality chest compressions improve outcomes of resuscitation, especially postresuscitation brain damage.