Cardiopulmonary resuscitation (CPR) quality is worse during in-hospital cardiac arrests occurring overnight than those that happen during the day, a new University of Pennsylvania School of Medicine study has indicated.
The researchers found that chest compression rates varied more at night - often dipping well below the rate per minute that's necessary to properly circulate blood - than during resuscitation efforts during the day, and rescuers paused for longer when switching between chest compressions and defibrillator shocks at night.
"Our study reveals an important factor to explain why, as previous studies have shown, patients who have cardiac arrests in hospitals during daytime hours are more likely to survive," said senior author Benjamin Abella, an assistant professor of Emergency Medicine and clinical research director in Penn's Center for Resuscitation Science.
"These findings suggest that more attention to clinical emergency training and staffing at night may be an important way to improve hospital safety and patient outcomes."
The authors studied 173 cardiac arrests that occurred in non-intensive care settings over the course of two years at three urban teaching hospitals.
The results showed that mean chest compression rate was lower during resuscitations that took place at night, between 11 p.m. and 7 a.m., compared to those during the day - 102 compressions per minute, with rates varying between 86 and 118, compared to 107, with variance between 100 and 114.
One hundred chest compressions per minute is the recommended rate, and previous research shows that when compressions are performed at lower rates, patients are more likely to die or suffer permanent brain damage from prolonged oxygen deprivation.
In addition, the researchers observed that staff members appeared to move slower when alternating between chest compressions and defibrillation during night resuscitations - they stopped compressions for a mean of 15.8 seconds before shocking patients at night, vs. 11.9 seconds during the day, and for 4.6 vs. 2.8 seconds after shocking patients.
Among factors that the authors say may influence the variability in CPR quality between night and day: fatigue, lower staffing levels, and lack of supervision from supervising physicians, who are less likely to be present during overnight resuscitations.
The study has been presented at the American Heart Association's annual Scientific Sessions.