Clinical and hemodynamic comparison of 15:2 and 30:2 compression-to-ventilation ratios for cardiopulmonary resuscitation*

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Abstract
To compare cardiopulmonary resuscitation (CPR) with a compression to ventilation (C:V) ratio of 15:2 vs. 30:2, with and without use of an impedance threshold device (ITD). Prospective randomized animal and manikin study. Animal laboratory and emergency medical technician training facilities. Twenty female pigs and 20 Basic Life Support (BLS)-certified rescuers. Acid-base status, cerebral, and cardiovascular hemodynamics were evaluated in 18 pigs in cardiac arrest randomized to a C:V ratio of 15:2 or 30:2. After 6 mins of cardiac arrest and 6 mins of CPR, an ITD was added. Compared to 15:2, 30:2 significantly increased diastolic blood pressure (20 +/- 1 to 26 +/- 1; p < .01); coronary perfusion pressure (18 +/- 1 to 25 +/- 2; p = .04); cerebral perfusion pressure (16 +/- 3 to 18 +/- 3; p = .07); common carotid blood flow (48 +/- 5 to 82 +/- 5 mL/min; p < .001); end-tidal CO2 (7.7 +/- 0.9 to 15.7 +/- 2.4; p < .0001); and mixed venous oxygen saturation (26 +/- 5 to 36 +/- 5, p < .05). Hemodynamics improved further with the ITD. Oxygenation and arterial pH were similar. Only one of nine pigs had return of spontaneous circulation with 15:2, vs. six of nine with 30:2 (p < 0.03). HUMANS: Fatigue and quality of CPR performance were evaluated in 20 BLS-certified rescuers randomized to perform CPR for 5 mins at 15:2 or 30:2 on a recording CPR manikin. There were no significant differences in the quality of CPR performance or measurement of fatigue. Significantly more compressions per minute were delivered with 30:2 in both the animal and human studies. These data strongly support the contention that a ratio of 30:2 is superior to 15:2 during manual CPR and that the ITD further enhances circulation with both C:V ratios.