Contrary to suggestions that sleepy surgeons might make more mistakes in the middle of the night, a large study finds no differences in patient deaths after trauma surgeries done at night or during the day.
Researchers who looked at U.S. death rates after so-called exploratory laparotomies, which are done in trauma victims to discover the extent of injuries, found similar mortality both day and night.
“Obviously, no one wants to get into an accident, but you can be reassured that whether it occurs during the day or at night, the outcomes in terms of mortality will be the same,” said study author Dr. Daniel Tran, assistant professor of surgery at Howard University College of Medicine.
“This is important because exploratory laparotomies are done in life and death situations when it’s not possible to wait for a better time of day to operate,” he told Reuters Health.
Tran and colleagues analyzed 2007-2010 data from the National Trauma Databank on 16,096 exploratory laparotomies started between midnight and 6 a.m. and 15,109 between 7 a.m. and 5 p.m.
The average patient age was 36, and close to 80 percent were men. Most injuries were caused by car crashes, gunshots and stabbings.
After daytime surgeries, 16.1 percent of patients died during their hospital stay. After middle-of-the-night surgeries, 11.5 percent died while in the hospital - but the difference wasn’t statistically significant after adjusting for other variables like patient age and severity of the injuries.
Patients treated during the day were typically older and had more severe injuries.
“People who are involved in a lot of traumas at night can tend to be younger, and it can involve drinking,” said Dr. Angela Gardner, associate professor in the department of emergency medicine at the University of Texas Southwestern in Dallas and past president of the American College of Emergency Physicians.
The study found the lowest mortality when the surgery began between 4 a.m. and noon.
“There is a common belief that if you scheduled surgery, you should try to schedule in the morning,” said Gardner, who wasn’t involved in the study. “This data would certainly support that.”
One limitation of the study, published in The American Journal of Surgery, is the lack of data on individual surgeons, such as how experienced they are or how many hours they had worked before starting the operation.
The findings also might not be relevant for more complex surgeries, said Dr. Carlos Pellegrini, chair of the surgery department at the University of Washington in Seattle and a past president of the American College of Surgeons.
“The exploratory laparotomy in general is a relatively straightforward procedure for which mortality or morbidity are very low,” said Pellegrini, who wasn’t involved in the study.
Pinpointing how sleep deprivation impacts surgical outcomes – and at what point a surgeon tips from fatigued, but functional, to exhausted and error-prone, is difficult. The idea that surgeons might make more mistakes at night is based on evidence linking disturbed sleep cycles and internal body clocks to impaired motor skills and diminished cognitive function in shift workers and night workers.
In a separate study in the same journal, Danish researchers monitored 30 surgeons for four days and found that working nights negatively affected circadian rhythm, the 24-hour cycle that tells the body when to sleep and regulates physiological functions.
The researchers tested for two hormones – melatonin, which rises with fatigue, and cortisol, which increases with stress – starting a day before surgeons worked a 17-hour overnight shift and continuing for two days after.
Melatonin fell during the night shifts, indicating an abnormal circadian rhythm.
“Being awake in artificial light disrupts the circadian rhythm,” lead study author Dr. Ilda Amirian, from the department of surgery at Herlev Hospital, University of Copenhagen.
Cortisol, a stress hormone which might increase during a complex surgical procedure, was lower during the night shift than on the other days.
Results might be different in the U.S., where many surgeons work longer hours than in Denmark, Amirian said.
Still, taken together, the studies suggest that surgeons can adapt to night shifts, Pellegrini noted
“It is extremely difficult in a single study to account for every variable that impacts performance,” Pellegrini said. “The studies here add to a growing body of evidence suggesting that surgeons, particularly experienced surgeons, can devise techniques to compensate for sleep disruption.”
(This version of the story revises paras 1, 2 and 7 to clarify that deaths occurred during the patient’s hospital stay, not necessarily during the surgery.)