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Critical Care Edition

Maintain vigilance in the ICU

How do work hours and sleep affect patient care?

Balas, Michele C. APRN, BC, CCRN, PhD; Casey, Colleen M. RN, CCRN, BS; Scott, Linda D. RN, PhD; Rogers, Ann E. RN, PhD, FAAN

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doi: 10.1097/01.NUMA.0000316057.20070.68
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Vigilance exists as an often intangible, but always essential, component of critical care nursing practice. Researchers define professional nursing vigilance as “a state of scientifically, intellectually, and experientially grounded attention to and identification of clinically significant observations, signals, and cues; calculation of risk inherent in nursing practice situations; and readiness to act appropriately and efficiently to minimize risks and to respond to threats.”1

Increasing evidence suggests professional nursing vigilance not only contributes to improvements in patients' health and outcomes, but also protects patients against errors.2 Because the ability to detect subtle changes in a patient's condition and to intervene appropriately can be adversely affected by the time of day (circadian factors), work schedules, and sleep, it's important to review what's known about these factors and provide practical suggestions for helping critical care nurses (CCNs) remain vigilant during their work shifts.


Circadian factors

Human circadian rhythms strongly favor sleeping during the nighttime hours. Overall capacity for physical work is reduced at night.3,4 Reaction times, visual search, perceptual motor tracking, and short-term memory are worse at night than during the daytime.5,6

Nurses are not exempt from difficulties remaining alert on duty at night. Approximately one-third of the nurses who worked straight night shifts or rotated to nights reported falling asleep on duty at least once a week when working nights.7 Most of the CCNs who participated in the Staff Nurse Fatigue and Patient Safety Study reported struggling to stay awake on duty at least once during the 28-day data gathering period, and 20% reported falling asleep on duty.8 Unlike prior studies of shift working nurses, not all of the episodes of drowsiness (40%) or falling asleep on duty (23%) occurred between midnight and 6 a.m.

Work schedules

Shift duration, the number of hours worked per week, as well as the duration of off-duty periods between shifts can have a significant impact on patient safety. Although the majority of nurses show a preference for 12-hour shifts because they allow more time for family and leisure activities, reduce commuting time, and involve fewer shifts per week, recent studies suggest that the hazards associated with these extended shifts outweigh the advantages.9-12 Nurses working shifts of 12½ hours or more are significantly more likely to make errors and to catch themselves making an error than nurses who worked shorter hours.8,13 Not only were CCNs more likely to report making more errors when working extended shifts (shifts 12½ hours or more) than CCNs working shorter shifts, but they were also more likely to report struggling to stay awake on duty or falling asleep on duty than nurses who worked fewer hours per day.8 Twelve-hour night shifts are particularly hazardous because the final 4 hours of the shift, when workers are most likely to be fatigued from extra hours of work, coincide with the circadian low point in arousal. As a result, workers are less efficient and report high levels of sleepiness.14 Researchers have also shown that older subjects (those over 40 years of age) are less tolerant of 12-hour night shifts, an important consideration for the nursing profession because half of the nurses in this country are 45 years of age or older.15,16

Very short off-duty periods (8 hours or less) don't allow for commuting time, recovery sleep, or time to take care of domestic responsibilities.3,14,17 Although off-duty intervals ranging from 10 to 16 hours are either suggested or mandated for many transportation workers, there are no regulations mandating specific off-duty periods between nursing shifts.17-18 Nor are there any regulations limiting the number of consecutive shifts worked in a 7-day period, or even the number of hours worked during a week.

Number of hours awake

Healthcare professionals often fail to appreciate the hazards associated with remaining awake for long periods of time. Studies have shown that remaining awake for 19 consecutive hours can result in performance impairments equivalent to or greater than levels of intoxication deemed unacceptable for driving, working, or operating dangerous equipment, which, in many countries, is a blood alcohol level (BAL) of between 0.05% and 0.08%.19-20 More prolonged periods of wakefulness (20 to 25 hours without sleep) can produce performance decrements equivalent to a BAL of 0.10%.19

Sleep duration

Most adults require approximately 7 to 8 hours sleep every 24 hours to function adequately at work. Unfortunately, adults in the United States obtain on average only 6.8 hours of sleep on weeknights.21 Although hospital staff nurses might be expected to be more aware of the benefits of obtaining adequate amounts of sleep, they obtain, on average, no more sleep than members of the general public.22 In fact, the majority of nurses (80%) regularly reported to work with 6 hours of sleep or less on at least one occasion, and 38 nurses (4.2%) reported obtaining no sleep in the 24-hour period preceding their work shift at least once during the 28-day data gathering period.23 Research has shown that the loss of even 1½ to 2 hours of sleep adversely affects waking performance and alertness the next day.24,25 Nurses who obtained less sleep were more likely to report difficulties remaining awake on duty and were more likely to report making an error.

Older age, longer shift durations, high caffeine intakes, and longer commutes were associated with shorter sleep durations among CCNs on workdays.26 Critical care nurses who had children under the age of 18 obtained the same amount of sleep on workdays as nurses who had no dependent care responsibilities.26 Those with dependent care responsibilities obtained on average 7 to 10 minutes less sleep on their days off than CCNs without dependent care responsibilities.

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Improve alertness

There are numerous strategies that nurses and their employers can use to improve alertness in critical care settings. (See “Improving alertness in critical care nurses.”) Many of these are adapted from the Fatigue Countermeasures Education and Training Program, developed by the National Aeronautics and Space Administration's Ames Research Center.27 Although the program was originally developed to improve flight crew and pilot alertness, the program has been adopted by many industries, including healthcare.

Strategies for employers

Hospitals can improve the alertness of their CCNs by carefully designing and monitoring work schedules. Shift rotation should be minimized whenever possible. If it isn't possible to eliminate rotating shifts, then shift schedules should rotate forward (days to evenings to nights or night shift to day shift) rather than backward (days to nights to evenings). At least 2 (preferably 3) days off should be planned when nurses rotate between night and day shifts.27

Because of the dangers of cumulative sleep loss when nurses work 12-hour shifts, nurses should be scheduled for no more than four consecutive 12-hour day shifts and no more than three consecutive 12-hour night shifts. Shift patterns, particularly the continued use of 12-hour shifts, also need to be reevaluated. Few CCNs leave work on time at the end of their scheduled shift, and regular breaks from patient care responsibilities are rare.8,28 Staffing should be adjusted to allow nurses to take a break from patient care responsibilities at least every 2 hours and to eliminate the necessity for nurses staying on average 45 minutes extra every day they work in order to complete their charting and other tasks. Because a short nap (15 to 30 minutes) is one of the most effective ways of increasing alertness during the night shift, policies that forbid napping during break and meal periods should be eliminated.23,29 Charge nurses should consider checking in with staff members about their levels of alertness during the early morning hours and encourage those that are tired to take an extra break or short nap. Finally, overtime, whether occurring at the end of a scheduled shift or on a different day, and on-call periods, should be monitored and their use minimized whenever possible.

Strategies for employees

There are several things that CCNs can do to improve their alertness on the job. First, it's important to become educated about the hazards associated with fatigue and inadequate sleep, then make the necessary changes to obtain sufficient sleep. Admittedly, making these changes may be difficult, but it's unsafe for nurses to continue working extended shifts without obtaining sufficient sleep. Unfortunately, no amount of training, motivation, or professionalism can overcome the performance deficits associated with inadequate sleep and the sleepiness associated with circadian variations in alertness.

Critical care nurses who work at night should be particularly careful about obtaining sufficient sleep. If working consecutive night shifts, it's best if CCNs try to fall asleep as early as possible after their shift ends, then nap again in the afternoon or early evening before the beginning of their next shift. When switching back to day shift after working night shift, CCNs should try to sleep only a couple of hours right after night shift, then remain awake until their regular bedtime.27

Even if a nurse obtains sufficient sleep, he or she should remember that human beings are physiologically programmed to be sleepiest between the hours of 2 to 5 a.m. and 1 to 5 p.m.27 It's at this time a CCN may be most at risk for making a mistake, falling asleep, encountering difficulties while concentrating, and being less vigilant. Unfortunately, most individuals can't accurately and reliably estimate the effect sleepiness has on their alertness and performance levels.27

Breaks, particularly if naps are allowed, and the therapeutic intake of caffeine can help mitigate the effects of circadian dips in alertness. Caffeine should be consumed judiciously and not on a regular basis or when alert.27 Instead, caffeine consumption should occur only at the beginning of a shift or about an hour before an anticipated decrease in alertness; for example, between 3 and 5 a.m. To reduce the possibility of insomnia, caffeine consumption should stop at least 3 hours before a planned bedtime.30

Because the effects of sleep loss are insidious until severe, and aren't usually recognized by the sleep-deprived individual, CCNs who notice that their colleagues are struggling to stay awake or are falling asleep on duty need to intervene, encouraging them to consume some caffeine or to take a brief break or nap.17,31 A colleague who regularly has difficulty remaining awake should be encouraged to seek help from a sleep specialist who can assess her sleep patterns, treat any sleep disorders that she might have, and suggest ways to help her obtain sufficient sleep.

Finally, CCNs should carefully consider how many hours they have worked in the current week, how much sleep they have obtained, and how many hours they will be awake before agreeing to work a double shift or coming into work on their day off. Working more than 40 hours/week, and working overtime whether at the end of a regularly scheduled shift or day off, significantly increases the risk of making an error.8,13 When long hours are coupled with insufficient sleep, the risk of an error is even greater. To protect their patients' safety, nurses must acknowledge that few adults can perform at high levels for more than 12 consecutive hours or function adequately with less than 6 hours of sleep.

Stay vigilant

Individual and system-level strategies outlined here serve as a starting point for discussing the various ways CCNs can increase their alertness and ultimately protect their patients from harm.


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