Circadian variation of in-hospital cardiac arrest

Out of hospital cardiac arrests, especially those due to ventricular tachyarrhythmias, have higher incidence in the morning. It is unknown whether in-hospital cardiac arrests follow a similar pattern. The purpose of this study was to analyze the circadian variation of in-hospital cardiac arrest incidence. This retrospective review of data from the multicenter Get With The Guidelines-Resuscitation registry between 2000 and 2014 used multivariable hierarchical logistic regression analysis to examine circadian rhythm of in-hospital cardiac arrest over a 24-h cycle, stratified by initial shockable versus non-shockable rhythm. Among 154,038 patients, initial rhythm was recorded as asystole or pulseless electrical activity (non-shockable) in 124,918 (81%), and ventricular fibrillation or ventricular tachycardia (shockable) in 29,120 (19%). Among non-shockable events, the highest relative proportion occurred during 0400−0759 (17.9%), followed by 0000−0359 (17.1%). For shockable rhythms the greatest relative proportion occurred between 2000−2359 (17.0%), followed by 1200−1559 (16.9%). Multivariable analysis showed that the relative risk of non-shockable compared to shockable arrest was slightly higher from midnight through 0359 (aOR 1.13; 95% CI 1.06–1.20, p