Underappreciation of sleep disorders as a cause of motor vehicle crashes

Prediction of drowsiness events in night shift workers during morning driving

The morning commute home is an especially vulnerable time for workers engaged in night shift work due to the heightened risk of experiencing drowsy driving. One strategy to manage this risk is to monitor the driver's state in real time using an in vehicle monitoring system and to alert drivers when they are becoming sleepy. The primary objective of this study is to build and evaluate predictive models for drowsiness events occurring in morning drives using a variety of physiological and performance data gathered under a real driving scenario. We used data collected from 16 night shift workers who drove an instrumented vehicle for approximately two hours on a test track on two occasions: after a night shift and after a night of rest. Drowsiness was defined by two outcome events: performance degradation (Lane-Crossing models) and electroencephalogram (EEG) characterized sleep episodes (Microsleep Models). For each outcome, we assessed the accuracy of sets of predictors, including or not including a driver factor, eyelid measures, and driving performance measures. We also compared the predictions using different time intervals relative to the events (e.g., 1-min prior to the event through 10-min prior). By examining the Area Under the receiver operating characteristic Curve (AUC), accuracy, sensitivity, and specificity of the predictive models, the results showed that the inclusion of an individual driver factor improved AUC and prediction accuracy for both outcomes. Eyelid measures improved the prediction for the Lane-Crossing models, but not for Microsleep models. Prediction performance was not changed by adding driving performance predictors or by increasing the time to the event for either outcome. The best models for both measures of drowsiness were those considering driver individual differences and eyelid measures, suggesting that these indicators should be strongly considered when predicting drowsiness events. The results of this paper can benefit the development of real-time drowsiness detection and help to manage drowsiness to avoid related motor-vehicle crashes and loss.

Combined Uvulopalatopharyngoplasty and Radiofrequency Tongue Base Reduction for Treatment of Obstructive Sleep Apnea/Hypopnea Syndrome

OBJECTIVE

In this study, we compare the objective results of uvulopalatopharyngoplasty (UPPP) combined with tongue base radiofrequency reduction (TBRF) with standard UPPP treatment of obstructive sleep apnea/hypopnea syndrome (OSAHS).

STUDY DESIGN

We conducted a retrospective study of 277 patients who had stage I, II, or III OSAHS based on the Friedman staging system previously presented.

METHODS

One hundred thirty-four patients who had treatment with UPPP only were used as a control group. This included 31 patients with stage I, 29 patients with stage II, and 74 patients with stage III OSAHS. An additional 143 patients with Stage II (n = 52) and III (n = 91) OSAHS were treated with combined UPPP and TBRF, initially and followed by additional TBRF treatments (up to 9000 J) as necessary. Subjective results were collected based on questionnaires and the Epworth Sleepiness Scale score for the experimental group, but these subjective measures were not available for the control group. Objective results were compared based on the polysomnographic findings before and after surgery.

RESULTS

Subjectively, the study group did extremely well. Based on objective measures of successful treatment, UPPP plus TBRF resulted in a significantly higher percentage of patients who were "cured" of OSAHS compared with the control group.

CONCLUSIONS

Stage I patients were usually successfully treated with UPPP only. However, patients allocated to stage II or III will benefit from the addition of TBRF to standard UPPP. Many UPPP-plus-TBRF patients in this study aborted further recommended TBRF treatments after subjective improvement and therefore objective results for this group, although improved in comparison to stage II and III patients treated with UPPP only, may not represent maximal potential improvement.

Gunshot wound to the head: an unusual complication of sleep apnea and bilevel positive airway pressure

Obstructive sleep apnea syndrome (OSAS) has been associated with motor vehicle accidents and work-related injuries. Proposed mechanisms for this association have included excessive sleepiness, decreased vigilance, inattentiveness, and psychological impairment, all related to the abnormal sleep and nocturnal hypoxia seen in OSAS. This report describes a case of an accidental gunshot wound to the head in an individual with known OSAS who was experiencing progressive cognitive and psychological deterioration due to suboptimal treatment of his sleep-disordered breathing. The literature on the neuropsychological consequences of OSAS is briefly reviewed.

The physiologic impact of sleep apnea on wakefulness

The physiologic impact of sleep apnea on wakefulness is believed to be mediated by sleep fragmentation secondary to airway obstruction. Although there has been much study on the association between sleep apnea and daytime sleepiness, little is known about the effects of sleep apnea on non-sleepiness-related manifestations of impaired wakefulness, such as fatigue and depression. Present studies suggest that impaired wakefulness secondary to sleep apnea probably plays a contributory role in traffic and industrial accidents.