Aims: Incidences and outcomes of out-of-hospital cardiac arrest (OHCA) are known to show seasonal variations. This study aimed to investigate the seasonal variations of bystander- and EMS-performed prehospital defibrillation and the factors associated with the variations.
Methods: By combining and reconciling the nation-wide database for 504,561 OHCA cases with another emergency medical service (EMS) transportation database containing detailed information on locations, we created an extended database including detailed locations of 495,939 OHCA cases with any prehospital resuscitation effort during the period of 2016-2019. This database was subjected to prehospital defibrillation analyses (Defibrillation cohort). After excluding 542,284 cases without any prehospital defibrillation and 5,356 EMS-witnessed cases, we analyzed the incidence of bystander-performed first defibrillation (PAD) in 48,299 non-EMS-witnessed OHCA cases with prehospital defibrillation (PAD cohort). Multivariable logistic regression analyses including outdoor/indoor classification of OHCA location were applied to investigate the variations of prehospital defibrillation, PAD and neurologically favorable one-month survival rate.
Results: The incidences of any prehospital defibrillation in the defibrillation cohort (10.3% in the winter vs 11.1% in the other seasons), and PAD in the PAD cohort (14.4% vs 17.8%), and the rates of neurologically favorable survival in the defibrillation cohort (2.7% vs 3.5%) and PAD cohort (13.2% vs 18.3%) were lowered in the winter, which was associated with higher incidences of OHCA (P<0.01). These variations were enhanced when the etiology of OHCA was non-cardiac and when OHCA was not witnessed. Furthermore, the decreased incidence of PAD in the winter was more prominent in outdoor OHCA (16.2% in the winter vs 22.0% in the others), compared with indoor OHCA (13.1% vs 16.8%): P=0.02 by interaction test.
Conclusion: Automated external defibrillators (AEDs) are rarely placed in the outdoors. The secured placement of an AED in the outdoors under should be considered to improve the outcomes of OHCA in the winter.

Seasonal variations of bystander- and EMS-performed prehospital defibrillation

Implementation of the Guidelines - How do we put the new ERC Guidelines into practice?

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