IntroductionPatients who suffer in-hospital cardiac arrest (IHCA) are less likely to survive if the arrest occurs during nighttime versus daytime. Diastolic blood pressure (DBP) as a measure of chest compression quality was associated with survival from pediatric IHCA. We hypothesized that DBP during CPR for IHCA is lower during nighttime versus daytime. MethodsThis is a secondary analysis of data collected from the Pediatric Intensive Care Quality of Cardiopulmonary Resuscitation Study. Pediatric or Pediatric Cardiac Intensive Care Unit patients who received chest compressions for ≥1 min and who had invasive arterial BP monitoring were enrolled. Nighttime was defined as 11:00PM to 6:59AM and daytime as 7:00AM until 10:59PM. Primary outcome was attainment of DBP ≥ 25 mmHg in infants <1 year and ≥30 mmHg in older children. Secondary outcomes were mean DBP, ROSC, and survival to hospital discharge. Univariable and multivariate analyses evaluated the relationships between time (nighttime vs. daytime) and outcomes. ResultsBetween July 1, 2013 and June 30, 2016, 164 arrests met all inclusion/exclusion criteria: 45(27%) occurred at nighttime and 119(73%) during daytime. Average DBPs achieved were not different between groups (DBP: nighttime 28.3 mmHg[25.3, 36.5] vs. daytime 29.6 mmHg[21.8, 38.0], p = 0.64). Relative risk of DBP threshold met during nighttime vs. daytime was 1.27, 95%CI [0.80, 1.98], p = 0.30. There was no significant nighttime vs. daytime difference in ROSC (28/45[62%] vs. 84/119[71%] p = 0.35) or survival to hospital discharge (16/45[36%] vs. 61/119[51%], p = 0.08). ConclusionsIn this cohort of pediatric ICU patients with IHCA, there was no significant difference in DBP during CPR between nighttime and daytime.