HARVARD GAZETTE ARCHIVES

After working a typical shift of 20 or more consecutive hours, hospital interns are at a high risk of sticking themselves with needles containing disease organisms such as the AIDS virus. (Staff photos Justin Ide/Harvard News Office)

Overly tired interns working in hospitals make mistakes that endanger themselves as well as patients. A new Harvard study has found that doctors in their first year of training stick themselves with needles and cut themselves with scalpels and broken glass at an increased rate during night shifts and after working 20 or more consecutive hours.

A previous Harvard investigation showed that interns double their odds of getting into an automobile crash on their commute home after a 24-hour shift or during a typical 80-hour week. Such hours are not uncommon among the estimated 100,000 doctor-trainees in the United States.

"Exposures to contaminated fluids from needle sticks and skin lacerations are serious hazards associated with medical training," notes Charles Czeisler, Baldino Professor of Sleep Medicine at Harvard Medical School and Brigham and Women's Hospital in Boston. "These injuries may result in transmission of blood-borne disease organisms including hepatitis and AIDS viruses. Our research indicates that the odds of a percutaneous [skin] injury in interns working an average of 29 consecutive hours were 61 percent higher than those working an average of about six consecutive hours. This higher rate of injury is likely due to the adverse effects of sleep deprivation."

Czeisler and his colleagues tracked the hours worked and skin injuries sustained by 2,737 interns at various hospitals around the country from July 2002 through May 2003. During that time, 498 such injuries were recorded. Lapses in concentration and fatigue were the most commonly reported contributing factors.

As you might expect, skin sticks and tears occurred more frequently during days following overnight shifts compared with days preceded by a night off. Injuries were also more frequent during nighttime than daytime.

Many interns worked more than 24 hours every other shift, and put in a marathon 80 hours of work in a week. On nights when interns were on call, they got an average of about two and a half hours of sleep. On some nights they got no sleep at all, according to Czeisler.

Interns working an average of 29 consecutive hours were 61 percent more likely to injure themselves with contaminated needles or with scalpels and broken glass, according to a national study by researchers at Harvard Medical School and Brigham and Women's Hospital.

Long hours, little sleep

New work standards for interns and residents (those who are in the later years of training) were adopted in July 2003, but they still permit 80-hour workweeks and shifts of 30 consecutive hours twice a week.

The Harvard researchers document the long hours and painful skin sticks and cuts in the Sept. 6 issue of the Journal of the American Medical Association. The same issue carries a second article reporting that 84 percent of 1,278 interns surveyed worked more than the standard hours during one or more months in the year after the new rules were introduced.

In the skin injury report, Czeisler and his colleagues note that factors contributing to fatigue include out-of-sync daily rhythms, sleep deprivation, and sleep inertia. "During the latter half of the night and early morning, cumulative sleep deprivation converges with misalignment of [daily rhythms] to create a critical zone of vulnerability during extended durations of wakefulness," says Czeisler.

Adding to that may be sleep inertia, the familiar grogginess that occurs immediately on awakening. Interns typically attempt to sleep during their overnight work shifts, but are often awakened when patients need to be treated, the researchers point out. Drawing blood and assisting in surgery or childbirth when sleep deprived is not an ideal situation for either the patient or the intern.

The researchers end their report with a plea to their medical colleagues to reduce intern and resident working hours and to implement safety measures to combat fatigue and reduce risks to all involved.

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Interns crash more after long shifts