Abstract 18: Difficulty of Cardiac Arrest Rhythm Identification does not Correlate with Length of Chest Compression Pauses before Defibrillation
Background: Recent data suggest that the success of defibrillation during cardiac arrest depends on CPR performance immediately before shock delivery. Specifically, long pauses in chest compressions (CC) before defibrillation (pre-shock pauses) are associated with reduced shock efficacy. The underlying reasons for long pre-shock pauses are unclear.
Objectives: We sought to determine whether pre-shock pause length during in-hospital resuscitations correlated with difficulty of rhythm identification or team performance factors independent of rhythm identification.
Methods: Consecutive in-hospital cardiac arrest transcripts collected via an investigational CPR-sensing defibrillator from 12/2002–12/2005 were analyzed for pre-shock pause durations. The ECG rhythms during these pauses were evaluated independently by 12 ACLS-trained reviewers (six physicians and six nurses) blinded to pre-shock pause and other resuscitation data. Reviewers determined each rhythm and scored the difficulty of rhythm identification, from 1 (most difficult to identify) to 5 (easiest to identify). The resuscitation cohort was grouped into pause duration quartiles for analysis. Senior resident physicians were then surveyed regarding pre-shock pause factors.
Results: From 164 arrest transcripts, 50 cases contained a total of 117 defibrillation attempts with a mean pre-shock pause in CC of 17.8+/−13.4 sec. When the 117 pauses were evaluated for ease of rhythm identification by 12 reviewers, longer pre-shock pauses were not associated with more difficult to identify rhythms, in fact the opposite was the case (longest pre-shock pause quartile, 23.5–60.0 sec, vs shortest quartile, 0.8–7.8 sec, rhythm difficulty scores, 3.2 vs 2.8, p=0.02). When 29 senior residents were surveyed regarding pre-shock pauses, 21.7% attributed long pauses to lack of time sense during arrest and 19.3% felt that room crowding hampered defibrillation.
Conclusions: While it might be assumed that longer pre-shock pauses occur in cases when the rhythm is difficult to determine, our results suggest that other human factors may play an important role. As successful resuscitation may depend on short pre-shock pauses, research into human factors surrounding defibrillation is required.