Peter W. Munt

How do prolonged wakefulness and alcohol compare in the decrements they produce on a simulated driving task

The effects of alcohol ingestion were compared with those of prolonged wakefulness on a simulated driving task. Eighteen healthy, male subjects aged between 19 and 35 years drove for 30 min on a simulated driving task at blood alcohol concentrations of 0.00, 0.05 and 0.08%. Subjective sleepiness was assessed before and after the driving task. Driving performance was measured in terms of the mean and standard deviation (S.D.) of lane position (tracking); the mean and S.D. of speed deviation (the difference between the actual speed and the posted speed limit); and the number of off-road occurrences. Ratings of sleepiness increased with increasing blood alcohol concentration, and were higher following the driving task. With increasing blood alcohol concentration, tracking variability, speed variability, and off-road events increased, while speed deviation decreased, the result of subjects driving faster. The results were compared with a previous study examining simulated driving performance during one night of prolonged wakefulness [Arnedt, J.T., MacLean A.W., 1996. Effects of sleep loss on urban and motorway driving stimulation performance. Presented at the Drive Alert... Arrive Alive International Forum, Washington DC], using an approach adopted by Dawson and Reid [Dawson, D., Reid, K., 1997. Fatigue, alcohol and performance impairment. Nature 388, 23]. For mean tracking, tracking variability, and speed variability 18.5 and 21 h of wakefulness produced changes of the same magnitude as 0.05 and 0.08% blood alcohol concentration, respectively. Alcohol consumption produced changes in speed deviation and off-road occurrences of greater magnitude than the corresponding levels of prolonged wakefulness. While limited to situations in which there is no other traffic present, the findings suggest that impairments in simulated driving are evident even at relatively modest blood alcohol levels, and that wakefulness prolonged by as little as 3 h can produce decrements in the ability to maintain speed and road position as serious as those found at the legal limits of alcohol consumption.

Validation of the MediByte ® type 3 portable monitor compared with polysomnography for screening of obstructive sleep apnea

BACKGROUND Portable monitors are increasingly being used as a diagnostic screening tool for obstructive sleep apnea (OSA), and in-laboratory validation of these devices with polysomnography (PSG) is required. OBJECTIVE To assess the reliability of the MediByte (Braebon Medical Corporation, Canada) type 3 screening device compared with overnight PSG. METHODS To cover a range of OSA severity, a consecutive series of patients wore the screening device while simultaneously undergoing PSG. Data acquired from the screener and PSG were blinded and scored separately. The number of apneas and hypopneas per hour were calculated using recording time (respiratory disturbance index [RDI]) for the MediByte device, and sleep time (apnea-hypopnea index [AHI]) for PSG. RESULTS Data from 73 patients with a mean age of 53 years and body mass index of 32.2 kg⁄m2 showed high measurement association between the RDI and AHI, with a Pearson correlation of 0.92, accounting for 85% of the variance. Based on Bland-Altman measurement agreement, the mean difference between the RDI and AHI (-5.9±11.2 events⁄h) indicated screener under-reporting. For an AHI of greater than 15 events⁄h, the sensitivity and specificity of the screener was 80% and 97%, respectively; for an AHI of greater than 30 events⁄h, the positive predictive value was 100%, while the negative predictive value was 88%. CONCLUSION The MediByte device accurately identified patients without OSA and had a high sensitivity for moderate-to-severe OSA.

Flock Worker's Lung Disease: Natural History of Cases and Exposed Workers in Kingston, Ontario

BACKGROUND The natural history of flock workers lung (FWL) and longitudinal lung function changes in nylon flock-exposed workers have not been well characterized. METHODS Symptoms, pulmonary function testing, and chest radiographs from five index cases, subsequent case referrals, and screened employees of a flocking plant in Kingston, Ontario, Canada, were compared and analyzed for changes over time (variable follow-up intervals between 1991 and 2011). RESULTS Nine cases and 30 flock-exposed workers without FWL were identified. Four cases had persistent interstitial lung disease despite three having left the workplace. Two developed hypoxemic respiratory failure and secondary pulmonary hypertension and died of complications 18 and 20 years after diagnosis, respectively. Five cases resolved after leaving the workplace. Compared with resolved cases, persistent cases had lower diffusing capacity of the lung for carbon monoxide at presentation (P < .05) and follow-up (P < .05). Among exposed workers employed for 14.5 ± 4.7 years, five had abnormal chest radiographs vs none at baseline (P = .001) over 14.8 ± 4.6 years of follow-up. The prevalence of wheeze increased (P = .001), and FEV₁/FVC decreased (P < .001). FEV₁% predicted was significantly lower at follow-up (P = .05). Average FEV₁ decline was 46 mL/year (range, -27 to 151 mL/y). Seventy-seven percent of exposed workers were current or former smokers. CONCLUSIONS The natural history of FWL includes the following patterns: complete resolution of symptoms; radiographic and pulmonary function abnormalities; permanent, but stable symptoms and restrictive pulmonary function deficits; and progressive decline in pulmonary function, causing death from respiratory failure and secondary pulmonary hypertension. A low baseline diffusing capacity of the lung for carbon monoxide is associated with the persistence and progression of FWL.

Simultaneous use of membrane oxygenation and high-frequency jet ventilation in acute pulmonary failure.

A 16-yr-old female suffering acute, rapidly progressive combined respiratory and cardiac failure that was unresponsive to conventional volume-cycled ventilation, was stabilized with the simultaneous short-term use of veno-venous membrane oxygenation and high-frequency jet ventilation. Percutaneousl) introduced cannulas afforded rapid vascular access for membrane oxygenation, minimal wound problems during the perfusion, and easy decannulation. This is the first reported combined use of high-frequency jet ventilation and extracorporeal membrane oxygenation, and the first reported percutaneous initiation of veno-venous bypass. The patient remained alive and well 4 months after therapy.