24-hour shifts negatively affect residents’ performance, study finds

Night float surgical residents averaged 5.5 hours of sleep in 24 hours, whereas those on 24-hour call had 1.3 hours of sleep.

Residents working night float or day shifts performed similarly and overall better than those on 24-hour shifts in tests of cognitive performance and reaction time, according to research that included a sleep questionnaire and test.

Investigators conducting the study sought to directly compare residents’ performance after 24-hour and night float shifts. To do so, they administered the Conner’s Continuous Performance Test (CPT) to surgical residents after their work shift and then compared the results with a control group of residents on day shift.

Candice O. McDaniel

“Residents on a night float shift performed at the level of residents on days in almost all parameters on the cognitive test,” Candice O. McDaniel, MD, said at the American Academy of Orthopaedic Surgeons annual meeting. “The 24-hour call group performed significantly worse than residents on days in five of the areas of attention and vigilance and performed significantly worse than the night float group on three areas and approached significance on two others.”

Attention, accuracy tested

Because it has been theorized that restricting residents’ work hours might help reduce patient morbidity and mortality, researchers wanted to observe how night float residents performed vs. residents after a 24-hour shift, Dr. McDaniel said.

Investigators studied 37 residents on night float, 31 residents on 24-hour call and 15 residents on days and asked how much they slept in the past 24 hours, with those on days serving as controls. They then had residents complete the 14-minute Conner’s CPT exam, which looks at attention, vigilance and impulsivity.

The test requires the individual to click a mouse button each time a letter other than “X” displays on a computer screen and checks the accuracy and speed of the responses.

Sleepless on 24-hour shift

The control group averaged significantly more sleep than the other groups, 6.5 hours in the previous 24 hours vs. about 5.5 hours in the night float group. The 24-hour group averaged 1.3 hours of sleep.

“Within every group, there was a trend that women performed better than men, but it did not reach significance,” Dr. McDaniel said. She noted that these findings correlated to a study into anesthesiologists’ performance that indicated that women did not suffer the same deterioration in function after sustained wakefulness on neuropsychology tests as their male counterparts.

The 24-hour group’s hit reaction time was worse (P < .05). Hit time is the time between when the letter is displayed and the resident clicks the mouse. The group’s scores were also among the worst for other standard error measurements of attentiveness.

“The 24-hour call group performed significantly worse than the residents on days in the analysis of smaller sub-blocks of the CPT,” Dr. McDaniel said. “The night float group performed close to the level of residents on days, which was consistent with another prior study.”

She said because such tests can only serve as a proxy measure of fatigue, attention and vigilance, it will have to be decided whether increasing sleep among residents translates into improved performance while on hospital duty.

This article originally appeared in Orthopedics Today, a SLACK Incorporated publication.

For more information:

Candice O. McDaniel, MD, can be reached at Medical College of Virginia, Box 980153, W. Hospital, 9th Floor, East Wing, Department of Orthopaedics, Richmond, VA 23298-0153; 804-827-1204; e-mail: cmcdaniel2@mcvh-vcu.edu. Dr. McDaniel has no direct financial interest in the products discussed in this article, nor is she a paid consultant for any companies mentioned.

Reference:

McDaniel CO, Potocki JJ, Zuelzer WA. Attention and vigilance in surgical residents following night float versus a 24-hour call. Paper presented at: American Academy of Orthopaedic Surgeons annual meeting; March 5-9, 2008; San Francisco.

Susan M. Rapp is an OSN Correspondent who writes primarily for Orthopedics Today.