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How to do 2 a.m. research
How to Do 2 AM Research Michael A.E. Ramsay
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rgan transplantation programs are often required to operate at any time of the day or night. Indications for this include reduction of graft ischemia time, a failing recipient, scheduling pressures, and physician preferences. Taking care of high-acuity patients undergoing major organ transplantation can be very testing at the best of times, but many would agree that between 2 and 4 AM this is especially strenuous. If, in addition to this, a complex set of data collection is undertaken as part of an extensive research project, is accuracy affected? Despite the existence of an extensive volume of research data in the area of sleep deprivation and performance, information relating directly to physicians is inconsistent. However, when these data are combined with those obtained from aviation and industry, valid conclusions can be made. The human being is a complicated physiological machine that is prone to err. The incidence of human error is increased by fatigue, sleep deprivation, and stress.1 As performance deteriorates, errors of omission occur with increasing frequency. In the research arena this might be exhibited by not recording data points at a specific time. These errors may weaken the statistical analysis of the results but rarely destroy the project. As performance further deteriorates, errors of commission occur—‘‘mistakes’’ that may be technical or judgmental errors such as aborting a data collection computer file before it has been ‘‘backed up.’’ These mistakes may make the research project unsalvageable. Fatigue is the inability or unwillingness to continue effective performance and is caused by excessive workload, stress, sleep loss, and circadian disruption.2 Fatigue and sleep deprivation are different entities. Fatigue is more responsible for performance changes than are circadian rhythm disruptions, and it can be affected by environmen-
From the Baylor University Medical Center, the University of Texas Southwestern Medical School, and the Department of Periodontics, Baylor College of Dentistry, Dallas, Texas. Address reprint requests to Michael A.E. Ramsay, MD, Baylor University Medical Center, 3500 Gaston Ave, Dallas, TX 75246. Copyright r 1997 by the American Association for the Study of Liver Diseases 1074-3022/97/0304-0025$3.00/0
462
tal conditions.3 Cognitive function deteriorates more than physical performance, and fatigued individuals demonstrate impaired learning and thought processes, memory defaults, and interpersonal dysfunction. Sleep deprivation may be seen if less than 5 hours of sleep occur in 24 hours. It can cause measurable deficits in cognitive function, but motivation can compensate for decreased performance by increasing effort and arousal.2 The overall effects of sleep deprivation are decreased efficiency, instability, recent memory deficit, difficulty in thinking, depersonalization, and inappropriate humor. Continuous working adversely affects cognitive function and mood to the detriment of the person. Mental performance increases between 8 AM and 2 PM and then gradually decreases reaching a low point between 2 AM and 5 AM. This performance is limited by the body’s circadian rhythm, which governs body temperature, hormonal processes, and general performance. Body temperature is at its lowest between 2 AM and 5 AM and is associated with sleep, decreased performance, and worsened mood. Alertness closely follows the body temperature rhythm pattern.4 Sleep loss affects performance of new skills more than automated skills. There is tremendous individual variation in the physiological responses to sleep loss. In a controlled trial on Boeing 747 air crews, one group on long-haul flights took 40minute brief naps and the other group took no rest. In the group that did not rest, decrements in reaction time and psychomotor vigilance were noted as well as twice as many microevents (brief sleep events) as in the group that rested. It was concluded that brief naps act as an acute safety valve.4 In anesthesiologists, it has been demonstrated that 2 to 3 hours of sleep per 24 hours is better than none at all. However, after being up for 24 hours, a 30-min to 2-hour nap is followed by a period of sleep inertia. This is a period of impaired vigilance. At least a 4-hour nap is required to avoid this phenomenon.5 Under conditions of sleep deprivation, cognitively exciting tasks appear to be least affected. Performance of cognitive tasks is also enhanced when vigorous exercise is performed during rest periods, but this effect diminishes as sleep deprivation increases.
Liver Transplantation and Surgery, Vol 3, No 4 ( July), 1997: pp 462-464
463
How to Do 2 AM Research
A stressful environment impairs vigilance and adversely affects complex monitoring tasks. Complex performance as measured by the Multiple Task Performance Battery Test, which includes monitoring of warning lights and meters, mental arithmetic, problem solving, target identification, and tracking, decreases with sleep deprivation. Short bursts of exercise lead to better performance scores.6 The number of targets monitored has an effect on performance; decrements occur when 16 targets are monitored compared with 8.7 Vigilance requires a state of maximal physiological and psychological readiness to react. It requires a cognitive skill level that can rapidly and reliably assess a large volume of information. Vigilance, alertness, complex memory, decision making, attention, selection of information, and conscious effort all are vulnerable to compromise with sleep deprivation. Complex monitoring tasks, stress, and fatigue are all affected by environmental conditions. As task complexity increases in anesthesia management, record keeping deteriorates and carelessness and lapses in vigilance occur. The performance of experienced airline pilots is less affected by increasing workload than that of new graduates. Presumably, this would also apply to anesthesiologists. Noise may cause distraction during critical periods; it negatively affects information processing, interferes with effective verbal communication, and may mask task related cues. It also is detrimental to short-term memory.8 However, it may act as an ‘‘activator,’’ and appropriate background music may prevent performance decrements over time.9 Ambient temperature also may affect performance; over-heated, dry rooms cause performance deterioration, and extremely cold temperatures cause distraction and reduce manual dexterity. A temperature range of 17 to 18°C with moderate humidity (50%) is recommended for best work.10 Physical condition and personal habits can have a significant influence on vigilance and monitoring performance. Preventable human errors are a major contributor to poor outcomes. If one is feeling fatigued, it is likely that one is experiencing a vigilance decrement.11 Small doses of caffeine can have a positive effect on performance but may increase tremor and anxiety. Alcohol in small amounts (20 to 35 mg/dL) significantly impairs performance as does the effects of a ‘‘hangover.’’ In New York, in a landmark case, the grand jury
found that long working hours of residents had contributed to the death of patient Libby Zion. The state legislature reacted by prohibiting physicians from working more than 24 consecutive hours without an 8-hour rest period or working more than a total of 80 hours per week.12 Toward the end of a prolonged work period, the phenomenon of ‘‘end-spurt’’ may be seen. This occurs when a task is considered 90% complete and causes increased vigilance, but ‘‘let down’’ will occur if the procedure is prolonged beyond the expected finish time.13 The recommendation of industrial psychologists is that 4 hours be a maximum duration of work without a break. In conclusion, the following guidelines are suggested based on the data available. If possible, research activities should be avoided between 2 AM and 4 AM. If this is not possible, as much of the data collection as possible should be automated, the number of data points should be limited, and a clear protocol should be designed so that mistakes are reduced and errors are limited to those of omission only. Only research topics in which the data collector has an intense interest should be selected, so that motivation is high. Teach us to live that we may dread So few hours spent in bed. Let us sleep and we may save Our patients from an early grave. Asher14
References 1. Miller DP, Swain AD. Human error and human reliability. In: Salvendy G (ed). Handbook of human factors. New York: Wiley, 1986: 219-250. 2. Parker JBR. The effects of fatigue on physician performance: An underestimated cause of physician impairment and increased patient risk. Can J Anaesth 34:489495, 1987. 3. Dodge R. Circadian rhythms and fatigue: A discrimination of their effects on performance. Aviation Space Environ Med 1982;53:1131-1136. 4. Rosekind MR, Gander PH, Miller DL, Gregory KB, Smith RM, Weldon KJ, et al. Fatigue in operational settings: Examples from the aviation environment. Hum Factors 1994;36:327-338. 5. Weinger MG, Englund CE. Ergonomic and human factors affecting anesthesia vigilance and monitoring performance in the operating room environment. Anesthesiology 1990;73:995-1021. 6. Higgins EA, Mertens HW, McKenzie JM, Funkhouser GE, White MA, Milburn NJ. The effects of physical fatigue and altitude on physiological, biochemical and performance responses. US Department of Transporta-
464
7.
8. 9. 10.
Michael A.E. Ramsay
tion, Federal Aviation Administration, Office of Aviation Medicine, report FAA-AM-82-10, May 1982, pp 1-22. Thackray RI, Touchstone RM. The effect of visual taskload on critical flicker frequency (CFF) change during performance of a complex monitoring task. US Department of Transportation, Federal Aviation Administration, Office of Aviation Medicine, report FAA-AM-8513, Oct 1985, pp 1-18. Poulson E. A new look at the effects of noise: A rejoicer. Psychol Bull 1978;85:1068-1079. Hartley LR, Williams T. Steady state noise and music and vigilance. Ergonomics 1977;20:277-285. Ramsey JD, Burford CL, Beshir MY, Jensen RL. Effects
11. 12.
13.
14.
of workplace thermal conditions on safe work behavior. J Safety Res 1983;14:105-114. Cooper JB. Do short breaks increase or decrease anesthetic risk? J Clin Anesth 1989;1:228-231. Asch DA, Parker RM. The Libby Zion case: One step forward or two steps backward? N Engl J Med 1988;318: 771-775. Paget NS, Lambert TF, Sridhar K. Factors affecting an anaesthetist’s work: Some findings on vigilance and performance. Anaesth Intensive Care 1981;9:359-365. Asher RAJ. The danger of going to bed. Br Med J 1947;2:967-968.
O
rgan transplantation programs are often required to operate at any time of the day or night. Indications for this include reduction of graft ischemia time, a failing recipient, scheduling pressures, and physician preferences. Taking care of high-acuity patients undergoing major organ transplantation can be very testing at the best of times, but many would agree that between 2 and 4 AM this is especially strenuous. If, in addition to this, a complex set of data collection is undertaken as part of an extensive research project, is accuracy affected? Despite the existence of an extensive volume of research data in the area of sleep deprivation and performance, information relating directly to physicians is inconsistent. However, when these data are combined with those obtained from aviation and industry, valid conclusions can be made. The human being is a complicated physiological machine that is prone to err. The incidence of human error is increased by fatigue, sleep deprivation, and stress.1 As performance deteriorates, errors of omission occur with increasing frequency. In the research arena this might be exhibited by not recording data points at a specific time. These errors may weaken the statistical analysis of the results but rarely destroy the project. As performance further deteriorates, errors of commission occur—‘‘mistakes’’ that may be technical or judgmental errors such as aborting a data collection computer file before it has been ‘‘backed up.’’ These mistakes may make the research project unsalvageable. Fatigue is the inability or unwillingness to continue effective performance and is caused by excessive workload, stress, sleep loss, and circadian disruption.2 Fatigue and sleep deprivation are different entities. Fatigue is more responsible for performance changes than are circadian rhythm disruptions, and it can be affected by environmen-
From the Baylor University Medical Center, the University of Texas Southwestern Medical School, and the Department of Periodontics, Baylor College of Dentistry, Dallas, Texas. Address reprint requests to Michael A.E. Ramsay, MD, Baylor University Medical Center, 3500 Gaston Ave, Dallas, TX 75246. Copyright r 1997 by the American Association for the Study of Liver Diseases 1074-3022/97/0304-0025$3.00/0
462
tal conditions.3 Cognitive function deteriorates more than physical performance, and fatigued individuals demonstrate impaired learning and thought processes, memory defaults, and interpersonal dysfunction. Sleep deprivation may be seen if less than 5 hours of sleep occur in 24 hours. It can cause measurable deficits in cognitive function, but motivation can compensate for decreased performance by increasing effort and arousal.2 The overall effects of sleep deprivation are decreased efficiency, instability, recent memory deficit, difficulty in thinking, depersonalization, and inappropriate humor. Continuous working adversely affects cognitive function and mood to the detriment of the person. Mental performance increases between 8 AM and 2 PM and then gradually decreases reaching a low point between 2 AM and 5 AM. This performance is limited by the body’s circadian rhythm, which governs body temperature, hormonal processes, and general performance. Body temperature is at its lowest between 2 AM and 5 AM and is associated with sleep, decreased performance, and worsened mood. Alertness closely follows the body temperature rhythm pattern.4 Sleep loss affects performance of new skills more than automated skills. There is tremendous individual variation in the physiological responses to sleep loss. In a controlled trial on Boeing 747 air crews, one group on long-haul flights took 40minute brief naps and the other group took no rest. In the group that did not rest, decrements in reaction time and psychomotor vigilance were noted as well as twice as many microevents (brief sleep events) as in the group that rested. It was concluded that brief naps act as an acute safety valve.4 In anesthesiologists, it has been demonstrated that 2 to 3 hours of sleep per 24 hours is better than none at all. However, after being up for 24 hours, a 30-min to 2-hour nap is followed by a period of sleep inertia. This is a period of impaired vigilance. At least a 4-hour nap is required to avoid this phenomenon.5 Under conditions of sleep deprivation, cognitively exciting tasks appear to be least affected. Performance of cognitive tasks is also enhanced when vigorous exercise is performed during rest periods, but this effect diminishes as sleep deprivation increases.
Liver Transplantation and Surgery, Vol 3, No 4 ( July), 1997: pp 462-464
463
How to Do 2 AM Research
A stressful environment impairs vigilance and adversely affects complex monitoring tasks. Complex performance as measured by the Multiple Task Performance Battery Test, which includes monitoring of warning lights and meters, mental arithmetic, problem solving, target identification, and tracking, decreases with sleep deprivation. Short bursts of exercise lead to better performance scores.6 The number of targets monitored has an effect on performance; decrements occur when 16 targets are monitored compared with 8.7 Vigilance requires a state of maximal physiological and psychological readiness to react. It requires a cognitive skill level that can rapidly and reliably assess a large volume of information. Vigilance, alertness, complex memory, decision making, attention, selection of information, and conscious effort all are vulnerable to compromise with sleep deprivation. Complex monitoring tasks, stress, and fatigue are all affected by environmental conditions. As task complexity increases in anesthesia management, record keeping deteriorates and carelessness and lapses in vigilance occur. The performance of experienced airline pilots is less affected by increasing workload than that of new graduates. Presumably, this would also apply to anesthesiologists. Noise may cause distraction during critical periods; it negatively affects information processing, interferes with effective verbal communication, and may mask task related cues. It also is detrimental to short-term memory.8 However, it may act as an ‘‘activator,’’ and appropriate background music may prevent performance decrements over time.9 Ambient temperature also may affect performance; over-heated, dry rooms cause performance deterioration, and extremely cold temperatures cause distraction and reduce manual dexterity. A temperature range of 17 to 18°C with moderate humidity (50%) is recommended for best work.10 Physical condition and personal habits can have a significant influence on vigilance and monitoring performance. Preventable human errors are a major contributor to poor outcomes. If one is feeling fatigued, it is likely that one is experiencing a vigilance decrement.11 Small doses of caffeine can have a positive effect on performance but may increase tremor and anxiety. Alcohol in small amounts (20 to 35 mg/dL) significantly impairs performance as does the effects of a ‘‘hangover.’’ In New York, in a landmark case, the grand jury
found that long working hours of residents had contributed to the death of patient Libby Zion. The state legislature reacted by prohibiting physicians from working more than 24 consecutive hours without an 8-hour rest period or working more than a total of 80 hours per week.12 Toward the end of a prolonged work period, the phenomenon of ‘‘end-spurt’’ may be seen. This occurs when a task is considered 90% complete and causes increased vigilance, but ‘‘let down’’ will occur if the procedure is prolonged beyond the expected finish time.13 The recommendation of industrial psychologists is that 4 hours be a maximum duration of work without a break. In conclusion, the following guidelines are suggested based on the data available. If possible, research activities should be avoided between 2 AM and 4 AM. If this is not possible, as much of the data collection as possible should be automated, the number of data points should be limited, and a clear protocol should be designed so that mistakes are reduced and errors are limited to those of omission only. Only research topics in which the data collector has an intense interest should be selected, so that motivation is high. Teach us to live that we may dread So few hours spent in bed. Let us sleep and we may save Our patients from an early grave. Asher14
References 1. Miller DP, Swain AD. Human error and human reliability. In: Salvendy G (ed). Handbook of human factors. New York: Wiley, 1986: 219-250. 2. Parker JBR. The effects of fatigue on physician performance: An underestimated cause of physician impairment and increased patient risk. Can J Anaesth 34:489495, 1987. 3. Dodge R. Circadian rhythms and fatigue: A discrimination of their effects on performance. Aviation Space Environ Med 1982;53:1131-1136. 4. Rosekind MR, Gander PH, Miller DL, Gregory KB, Smith RM, Weldon KJ, et al. Fatigue in operational settings: Examples from the aviation environment. Hum Factors 1994;36:327-338. 5. Weinger MG, Englund CE. Ergonomic and human factors affecting anesthesia vigilance and monitoring performance in the operating room environment. Anesthesiology 1990;73:995-1021. 6. Higgins EA, Mertens HW, McKenzie JM, Funkhouser GE, White MA, Milburn NJ. The effects of physical fatigue and altitude on physiological, biochemical and performance responses. US Department of Transporta-
464
7.
8. 9. 10.
Michael A.E. Ramsay
tion, Federal Aviation Administration, Office of Aviation Medicine, report FAA-AM-82-10, May 1982, pp 1-22. Thackray RI, Touchstone RM. The effect of visual taskload on critical flicker frequency (CFF) change during performance of a complex monitoring task. US Department of Transportation, Federal Aviation Administration, Office of Aviation Medicine, report FAA-AM-8513, Oct 1985, pp 1-18. Poulson E. A new look at the effects of noise: A rejoicer. Psychol Bull 1978;85:1068-1079. Hartley LR, Williams T. Steady state noise and music and vigilance. Ergonomics 1977;20:277-285. Ramsey JD, Burford CL, Beshir MY, Jensen RL. Effects
11. 12.
13.
14.
of workplace thermal conditions on safe work behavior. J Safety Res 1983;14:105-114. Cooper JB. Do short breaks increase or decrease anesthetic risk? J Clin Anesth 1989;1:228-231. Asch DA, Parker RM. The Libby Zion case: One step forward or two steps backward? N Engl J Med 1988;318: 771-775. Paget NS, Lambert TF, Sridhar K. Factors affecting an anaesthetist’s work: Some findings on vigilance and performance. Anaesth Intensive Care 1981;9:359-365. Asher RAJ. The danger of going to bed. Br Med J 1947;2:967-968.