['Infant CPR guidelines recommend two-finger chest compression with a lone rescuer and two-thumb with two rescuers. Two-thumb provides better chest compression but is perceived to be associated with increased ventilation hands-off time. We hypothesized that lone rescuer two-thumb CPR is associated with increased ventilation cycle time, decreased ventilation quality and fewer chest compressions compared to two-finger CPR in an infant manikin model.', 'Crossover observational study randomizing 34 healthcare providers to perform 2 min CPR at a compression rate of 100 min(-1) using a 30:2 compression:ventilation ratio comparing two-thumb vs. two-finger techniques.', 'A Laerdal Baby ALS Trainer manikin was modified to digitally record compression rate, compression depth and compression pressure and ventilation cycle time (two mouth-to-mouth breaths). Manikin chest rise with breaths was video recorded and later reviewed by two blinded CPR instructors for percent effective breaths. Data (mean+/-SD) were analyzed using a two-tailed paired t-test. Significance was defined qualitatively as p< or =0.05.', 'Mean % effective breaths were 90+/-18.6% in two-thumb and 88.9+/-21.1% in two-finger, p=0.65. Mean time (s) to deliver two mouth-to-mouth breaths was 7.6+/-1.6 in two-thumb and 7.0+/-1.5 in two-finger, p<0.0001. Mean delivered compressions per minute were 87+/-11 in two-thumb and 92+/-12 in two-finger, p=0.0005. Two-thumb resulted in significantly higher compression depth and compression pressure compared to the two-finger technique.'] Is two-thumb technique superior to two-finger technique during lone rescuer infant manikin CPR?