Monday, March 3, 2008

Effects of Fatigue And Other Human Factors Upon Driving Performance

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The Effects of Fatigue And Other Human Factors Upon Driving Performance

Arnedt, Owens, Crouch, Stahl, Carskadon, Neurobehavioral Performance of Residents After Heavy Night Call vs. After Alcohol Ingestion 294(9) JAMA 1025-1033 (2005)

CONTEXT: Concern exists about the effect of extended resident work hours; however, no study has evaluated training-related performance impairments against an accepted standard of functional impairment.

OBJECTIVES: To compare post-call performance during a heavy call rotation (every fourth or fifth night) to performance with a blood alcohol concentration of 0.04 to 0.05 g% (per 100 mL of blood) during a light call rotation, and to evaluate the association between self-assessed and actual performance.

DESIGN, SETTING, AND PARTICIPANTS: A prospective 2-session within-subject study of 34 pediatric residents (18 women and 16 men; mean age, 28.7 years) in an academic medical center conducted between October 2001 and August 2003, who were tested under 4 conditions: light call, light call with alcohol, heavy call, and heavy call with placebo.

INTERVENTIONS: Residents attended a test session during the final week of a light call rotation (non-post-call) and during the final week of a heavy call rotation (post-call). At each session, they underwent a 60-minute test battery (light and heavy call conditions), ingested either alcohol (light call with alcohol condition) or placebo (heavy call with placebo condition), and repeated the test battery. Performance self-evaluations followed each test.

MAIN OUTCOME MEASURES: Sustained attention, vigilance, and simulated driving performance measures; and self-report sleepiness, performance, and effort measures.

RESULTS: Participants achieved the target blood alcohol concentration. Compared with light call, heavy call reaction times were 7% slower (242.5 vs 225.9 milliseconds, P<.001); commission errors were 40% higher (38.2% vs 27.2%, P<.001); and lane variability (7.0 vs 5.5 ft, P<.001) and speed variability (4.1 vs 2.4 mph, P<.001) on the driving simulator were 27% and 71% greater, respectively. Speed variability was 29% greater in heavy call with placebo than light call with alcohol (4.2 vs 3.2 mph, P = .01), and reaction time, lapses, omission errors, and off-roads were not different. Correlation between self-assessed and actual performance under heavy call was significant for commission errors (r = -0.45, P = .01), lane variability (r = -0.76, P<.001), and speed variability (r = -0.71, P<.001), but not for reaction time.

CONCLUSIONS: Post-call performance impairment during a heavy call rotation is comparable with impairment associated with a 0.04 to 0.05 g% blood alcohol concentration during a light call rotation, as measured by sustained attention, vigilance, and simulated driving tasks. Residents' ability to judge this impairment may be limited and task-specific.

Source: www.pubmed.org – A service of the National Library of Medicine and the National Institutes of Health