Purpose: Hands-only cardiopulmonary resuscitation (HO-CPR) is one of the most debated topic. However, if high-quality CPR is a key factor to improve survival after an out-of-hospital cardiac arrest (OHCA), it is very difficult to perform a high-quality CPR until the arrival of EMS with HO-CPR. Our aim was to verify whether the inclusion of intentional interruptions of different frequency and duration during the CPR could increase laypeople CPR quality compared with HO-CPR.
Methods: we randomised 572 laypeople who passed a basic life support course in 8 training centers to one of four CPR protocols in an 8 minutes simulated cardiac arrest scenario on a manikin: 30 compressions and 2 seconds pause (30c2s), 50 compressions and 5 seconds pause (50c5s), 100 compressions and 10 seconds pause (100c10s) and hands-only (HO-CPR). The primary endpoint was the percentage of chest compressions performed with correct depth evaluated by a computerised feedback system. The secondary endpoints were percentage compressions with correct release, with correct hand position, with adequate rate and the number of interruptions lasting more than 10 seconds (10s-pause). 
Results: 68.5% of the study population were males, mean age was 32.2±11.6 years, mean height was 174.5±8.3 cm and mean weight 73.7±13.6 kg. There were no difference among the anthropometric characteristics of the 4 protocol groups. Regarding primary outcome, there was a statistical significant difference among the 4 groups (p=0.006). Comparing each protocol to the standard (HO-CPR) through a post-hoc analysis, 30c2s (96%, p=0.007) and 50c5s (96%, p=0.001) were significantly better than HO-CPR (79%), whilst 100c10s did not reach significance (92%). Among secondary endpoint only the 10s-pause was significantly different among the groups (p<0.001), with more 10s-pause in 100c10s (4, IQR 2-6) respect to the others (0, IQR 0-0).
Conclusions: The inclusion of intentional interruptions during CPR increase laypeople CPR quality. The protocols consisting in alternating 30 compressions and 2 seconds of pause or 50 compressions and 5 seconds of pause seems to be the more promising to maintain HQ-CPR during an 8 minutes scenario.

3 - Hands-only CPR, are we doing the best? Results from Multicenter International Randomized Controlled Manikin Study on Different Protocols of Cardiopulmonary Resuscitation for laypeople (MANI-CPR Trial)