Impact of post-dispatch advice on bystander cardiopulmonary resuscitation in out-of-hospital cardiac arrest in Hong Kong

Background: In Hong Kong, the post-dispatch advice on cardiopulmonary resuscitation has been implemented since October 2018. Our study aimed to (1) evaluate the impact of post-dispatch advice on the bystander cardiopulmonary resuscitation rate and out-of-hospital cardiac arrest survival and (2) characterise the reasons for not providing dispatch-assisted cardiopulmonary resuscitation, which have important implications in public cardiopulmonary resuscitation education. Method: We retrospectively analysed the records of 749 adult patients with out-of-hospital cardiac arrest between 1 September 2021 and 31 October 2021. The primary outcome was survival to hospital discharge. The secondary outcomes included return of spontaneous circulation and survival to hospital admission. Results: The overall dispatch-assisted cardiopulmonary resuscitation rate was 49.6%. Patients who received dispatch-assisted cardiopulmonary resuscitation had a higher proportion of witnessed cardiac arrest (37.7% vs 24.7%, p < 0.001) and a shorter time interval from recognition of cardiac arrest to chest compression (median 3.0 min vs 13.0 min, p < 0.001) compared with patients without dispatch-assisted cardiopulmonary resuscitation. 16.8% of out-of-hospital cardiac arrest victims had return of spontaneous circulation before or upon arrival at the hospital. Patients who received dispatch-assisted cardiopulmonary resuscitation had a higher return of spontaneous circulation (18.3% vs 15.4%), survival to hospital admission (15.9% vs 13.3%) and survival to hospital discharge (2.7% vs 1.3%) rates compared with those who did not. However, the differences did not reach statistical significance. Conclusion: Post-dispatch advice improved the overall bystander cardiopulmonary resuscitation rate in out-of-hospital cardiac arrest and shortened the time from out-of-hospital cardiac arrest recognition to chest compression, but the improvement in survival did not reach statistical significance. Further public education on cardiac arrest recognition and dispatch-assisted cardiopulmonary resuscitation is necessary.