Background: Rhythm analysis with current semi-automatic external defibrillators (AEDs) requires mandatory interruptions of chest compressions that may compromise the outcome after cardiopulmonary resuscitation (CPR). We hypothesised that interruptions would be shorter when the defibrillator was operated in manual mode by trained and certified ambulance personnel.
Materials and methods: Sixteen pairs of ambulance personnel operated the defibrillator (Lifepak((R))12) in both semi-automatic (AED) and manual (MED) mode in a randomised, cross-over manikin CPR study, following the ERC 2000 Guidelines.
Results: Median time from last chest compression to shock delivery (with interquartile range) was 17s (13, 18) versus 11s (6, 15) (mean difference (95% CI) 6s (2, 10), p=0.004). Similarly, median time from shock delivery to resumed chest compressions was 25s (22, 26) versus 8s (7, 12) (median difference 13s, p=0.001) in the AED and MED groups, respectively. While sensitivity for identifying ventricular fibrillation (VF) in both modes and specificity in the AED mode were 100%, specificity was 89% in manual mode. Thus, some unwarranted shocks resulting in hands-off time (time without chest compressions) were given in manual mode. However, mean hands-off-ratio (time without chest compressions divided by total resuscitation time) was still lower, 0.2s (0.1, 0.3) versus 0.3s (0.28, 0.32) in manual mode, mean difference 0.10s (0.05, 0.15), p=0.001.
Conclusion: Paramedics performed CPR with less hands-off time before and after shocks on a manikin with manual compared to semi-automatic defibrillation following the 2000 Guidelines. However, 12% of the shocks given manually were inappropriate.