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

Objective: 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). Design: Prospective randomized animal and manikin study. Setting: Animal laboratory and emergency medical technician training facilities. Subjects: Twenty female pigs and 20 Basic Life Support (BLS)-certified rescuers. Interventions, Measurements, and Main Results: Animals: 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. Conclusions: 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.