Automobile accidents in patients with sleep apnea syndrome. An epidemiological and mechanistic study

Continuous positive airway pressure for sleep apnoea/hypopnoea syndrome: usefulness of a 2 week trial to identify factors associated with long term use

BACKGROUND

The sleep apnoea/hypopnoea syndrome (SAHS) is common and treatment with continuous positive airway pressure (CPAP) is effective. However, not all patients can cope with the demands of using mask positive pressure. Compliance can be improved with an intensive educational programme and patient support, but this is not practical in most centres given the large numbers of patients coming forward for treatment. Several studies have evaluated correlations between various parameters at diagnosis in order to anticipate patients' behaviour and to avoid the social and health implications of undertreated SAHS. We have evaluated the use of additional data derived during a 2 week home CPAP trial to identify factors associated with longer term use of CPAP and compliance.

METHODS

Following a diagnostic study, 209 patients were offered a CPAP machine for a 2 week home trial. After completing the trial, patients were reassessed and scored their overall satisfaction with CPAP treatment on a five point scale ranging from “much worse” to “much better” and an Epworth score relating to the loan period. Machine run time was recorded from the integral clock. These data were added to those available at diagnosis to construct models indicative of continuing CPAP and average nightly use at 1 year.

RESULTS

209 patients were offered the 2 week loan at least a year before June 1999 (90.9% men, mean (SD) age 51.0 (10.6) years, body mass index (BMI) 34.6 (7.7) kg/m2, Epworth score 15 (IQR 11–18), apnoea/hypopnoea index (AHI) 38.1 (22.9) events/h). 153 patients (73.2%) opted to continue CPAP and 56 declined. One year later data were available for 187 patients; 128 (68.5% on an intention to treat analysis) continued to use the machine with a mean use of 5.0 (2.4) hours/night. A logistic regression model indicated that mean CPAP use during the loan period and the overall satisfaction score accurately defined continuing CPAP and “satisfactory” CPAP use at 1 year. For patients with low machine use and no symptomatic improvement during the loan period, the addition of baseline AHI, baseline Epworth score, and the Epworth score at the end of the loan to the equation identifying factors associated with “satisfactory” CPAP use (mean >2 hours/night) improved the value of the model.

CONCLUSION

Data derived from a 2 week CPAP trial are useful in identifying patients who will comply with CPAP treatment to 1 year. It can be used to identify patients with significant symptomatic disease who will struggle with CPAP and may benefit from additional education and support. High mean hourly use and a high degree of overall satisfaction during the loan period identified patients likely to use CPAP and be compliant with it at 1 year.

Screening of obstructive sleep apnoea: heart rate spectral analysis of nocturnal pulse oximetric recording

Using heart rate spectral analysis of nocturnal pulse oximetry, we prospectively evaluated the utility of this methodology in patients clinically suspected of having obstructive sleep apnoea (OSA). A hundred and ninety-seven outpatients referred with symptoms compatible with the diagnosis of OSA were studied. All participants had nocturnal pulse oximetry performed simultaneously with conventional polysomnography. Power density of heart rate obtained by nocturnal pulse oximetry was analysed using fast Fourier transformation of a Hamming-windowed signal. Recording test results were classified as abnormal (suspicion of OSA) in the presence of a peak in the periodogram between period boundaries 30-70 sec. A normal test result was defined as the absence of the 30-70 sec peak in the periodogram. The total area of the periodogram (S(TOT)), the area enclosed in the periodogram between the period boundaries 30-70 sec (S(30-70)), the area enclosed in the period boundaries 30-70 sec with respect to the total area of the periodogram (S) and the peak amplitude 30-70 sec (PA) were measured. The presence of a peak in the periodogram has a sensitivity of 81.3%, a specificity of 91.5% a positive predictive value of 89.1% and a negative predictive value of 85.1% for OSA diagnosis. The OSA patients were found to have higher values of S(TOT), S(30-70), S and PA than the non OSA patients. Receiver operating characteristics (ROC) curve was constructed at different thresholds of S(TOT), S(30-70) S and PA. For a PA threshold of 10(%)2, heart rate spectra analysis sensitivity for OSA was 58% and specificity was 92%. Furthermore, the positive and negative predictive values for diagnosis of OSA were 87 and 72% respectively. Apnoea hypopnea index (AHI) correlated significantly with S(TOT) (r=0.44; P<0.001), S(30-70) (r=0.59: P<0.001), S (r=0.58; P<0.001) and PA (r=0.58; P<0.001). According to our results, heart rate spectral analys s obtained by nocturnal pulse oximetry and identification of peak in the periodogram between period boundaries 30-70 sec could be useful as a diagnostic technique for OSA patients.

Reduction in motor vehicle collisions following treatment of sleep apnoea with nasal CPAP

BACKGROUND

Patients with untreated obstructive sleep apnoea (OSA) have increased motor vehicle collisions (MVCs). When successfully treated, they report improved driving and fewer mishaps, but there are few objective data to confirm this. A study was therefore undertaken to examine actual MVC data in a large group of patients with OSA before and after treatment with continuous positive airway pressure (CPAP) compared with a control group matched for age, sex, and type of driver's licence (commercial or non-commercial).

METHODS

Two hundred and ten patients of mean (SD) age 52 (11) years, body mass index (BMI) 35.5 (10) kg/m2, apnoea/hypopnoea index (AHI) 54 (29) events/h were treated with CPAP for at least 3 years. MVC records were obtained from the Ontario Ministry of Transportation (MTO) database for patients and an equal number of randomly selected control drivers. MVC rates were compared for 3 years before and after CPAP therapy for patients and for the corresponding time frames for controls.

RESULTS

Untreated patients with OSA had more MVCs than controls (mean (SD) MVCs/driver/year 0.18 (0.29) v 0.06 (0.17), p<0.001). Following CPAP treatment the number of MVCs/driver/year fell to normal (0.06 (0.17)) while, in controls, the MVC rate was unchanged over time (0.06 (0.17) v 0.07 (0.18), p=NS). Thus, the change in MVCs over time between the groups was very significant (change = –0.12 (95% CI –0.17 to –0.06), p<0.001)). The MVC rate in untreated patients (n=27) remained high over time. Driving exposure was not different following CPAP.

CONCLUSIONS

The risk of MVCs due to OSA is removed when patients are treated with CPAP. As such, any restrictions on driving because of OSA could be safely removed after treatment.

Reduction in motor vehicle collisions following treatment of sleep apnoea with nasal CPAP

BACKGROUND

Patients with untreated obstructive sleep apnoea (OSA) have increased motor vehicle collisions (MVCs). When successfully treated, they report improved driving and fewer mishaps, but there are few objective data to confirm this. A study was therefore undertaken to examine actual MVC data in a large group of patients with OSA before and after treatment with continuous positive airway pressure (CPAP) compared with a control group matched for age, sex, and type of driver's licence (commercial or non-commercial).

METHODS

Two hundred and ten patients of mean (SD) age 52 (11) years, body mass index (BMI) 35.5 (10) kg/m(2), apnoea/hypopnoea index (AHI) 54 (29) events/h were treated with CPAP for at least 3 years. MVC records were obtained from the Ontario Ministry of Transportation (MTO) database for patients and an equal number of randomly selected control drivers. MVC rates were compared for 3 years before and after CPAP therapy for patients and for the corresponding time frames for controls.

RESULTS

Untreated patients with OSA had more MVCs than controls (mean (SD) MVCs/driver/year 0.18 (0.29) v 0.06 (0.17), p<0.001). Following CPAP treatment the number of MVCs/driver/year fell to normal (0.06 (0.17)) while, in controls, the MVC rate was unchanged over time (0.06 (0.17) v 0.07 (0.18), p=NS). Thus, the change in MVCs over time between the groups was very significant (change = -0.12 (95% CI -0.17 to -0.06), p<0.001)). The MVC rate in untreated patients (n=27) remained high over time. Driving exposure was not different following CPAP.

CONCLUSIONS

The risk of MVCs due to OSA is removed when patients are treated with CPAP. As such, any restrictions on driving because of OSA could be safely removed after treatment.

Microsleep during a simplified maintenance of wakefulness test. A validation study of the OSLER test

Daytime somnolence is both a symptom in many patients and a prevalent complaint in the general population, but its objective assessment remains elusive. The current available tests are technically complex and thus inadequate for routine clinical use or epidemiological studies. A simplified behavioral maintenance of wakefulness test (OSLER test) has been recently described that could allow for widespread availability of objective measurements of this symptom. We verified the occurrence of (micro)sleep (episodes of sleep of > or = 3 s duration) during the performance of the OSLER test in 10 normal subjects after a non-sleep-deprived night and a sleep-deprived night in randomized order. Sleep was assessed electrophysiologically according to standard methods. The OSLER test (mean of four measurements) was significantly shorter after the sleep-deprived night (25 min versus 38 min). Single missed stimuli were frequent with or without (micro)sleep, but (micro)sleep was almost always present when four or more consecutive stimuli were missed. The sensitivity and specificity of the test in detecting sleep (of > or = 3 s duration) are 85% and 94%, respectively. The total number of missed stimuli per minute duration of the test could add valuable information to the simpler mean test result. Sensitivity and specificity are not altered when only three measurements are performed. We conclude that the OSLER test appears as a simple, easy, and reliable method to objectively assess daytime somnolence.

Outcome measurement in sleep medicine practice and research. Part 2: assessment of neurobehavioral performance and mood

Neurobehavioral performance and alterations in mood consequent to sleep disorders and their treatment has recently been the focus of clinical investigations. Primarily in patients with obstructive sleep apnea (OSA), there has been increased interest in the effects of sleep fragmentation and hypoxemia on the brain's ability to process information and to alter affect. The purpose of the second part of this two-part series is to describe measures that could be applied to document the impact of sleep disorders on neurobehavioral performance and mood, discuss factors affecting the selection of measures for research and practice, and to describe evidence generated by the use of these instruments in research. The neurobehavioral deficits that accompany sleep deprivation can be categorised as decrements in cognitive throughput, working memory and sustained attention. Usually evaluated using tasks of short duration, impairments associated with OSA have included impaired information processing and decline in the total number of completed and/or correct responses per unit time. Using assessments of working memory, including short recall maneuvers involving words or paragraphs, investigators have documented in sleep apnea patients the inability to consolidate and recall material producing deficits in the recollection and retention of new information. Evaluations of sustained attention appraise reaction time, the ability to remain on task, and the number of errors of omission and false responses. Evidence suggests that OSA patients display slowing of response time as well as increased errors, lapses and number of false responses. Similar deficits have been documented with sustained and divided attention tasks that present the respondent with challenges in tracking and reaction response, tasks required for driving. Although untreated sleep apnea patients were more impaired than normal controls, their performance on such tasks was greatly enhanced following CPAP treatment. In addition to substantial clinically meaningful improvements in many areas of neurobehavioral performance, changes in mood have also accompanied treatment for sleep apnea. 2001 Harcourt Publishers Ltd

Sonolência e acidentes automobilísticos

Objetivo: Este artigo tem por finalidade apresentar uma sucinta revisão sobre as repercussões da sonolência excessiva no desempenho dos motoristas no trânsito, enfatizando a necessidade da maior valorização do tema abordado. Métodos: Revisão bibliográfica da literatura nacional e internacional, abrangendo artigos originais e publicações oficiais da American Thoracic Society e da American Sleep Apnea Association. Resultados: As evidências de que a sonolência é um fator que pode contribuir de forma decisiva para a ocorrência de acidentes automobilísticos são crescentes. As dificuldades com relação à caracterização da sonolência precedendo o acidente são discutidas no texto. Muitas são as causas de sonolência excessiva; felizmente, sua maioria é passível de identificação e manejo adequado. Conclusões: É importante que haja maior entendimento do problema em nosso meio, para que possam ocorrer modificações na abordagem do paciente com sonolência excessiva e também discussões acerca das leis de trânsito vigentes e das obrigações legais do médico com relação a este problema.

Obstructive sleep apnea-hypopnea and related clinical features in a population-based sample of subjects aged 30 to 70 yr

The prevalence and related clinical features of obstructive sleep apnea-hypopnea (OSAH) in the general population were estimated in a two-phase cross-sectional study. The first phase, completed by 2,148 subjects (76.9%), included a home survey, blood pressure, and a portable respiratory recording, whereas in the second, subjects with suspected OSAH (n = 442) and a subgroup of those with normal results (n = 305) were invited to undergo polysomnography (555 accepted). Habitual snoring was found in 35% of the population and breathing pauses in 6%. Both features occurred more frequently in men, showed a trend to increase with age, and were significantly associated with OSAH. Daytime hypersomnolence occurred in 18% of the subjects and was not associated with OSAH. An apnea-hypopnea index (AHI) > or = 10 was found in 19% of men and 15% of women. The prevalence of OSAH (AHI > or = 5) increased with age in both sexes, with an odds ratio (OR) of 2.2 for each 10-yr increase. AHI was associated with hypertension after adjusting for age, sex, body mass index, neck circumference, alcohol use, and smoking habit. This study adds evidence for a link between OSAH and hypertension.

The role of driver sleepiness in car crashes: a systematic review of epidemiological studies

To assess the available evidence for a causal role of driver sleepiness in car crashes or car crash injury, and to quantify the effect, a systematic review of the international literature was conducted. The review included all studies with a fatigue-related exposure measure, a crash or crash injury outcome measure and a comparison group, regardless of publication status, language or date of the study. Eighteen cross-sectional studies and one case-control study fulfilled the inclusion criteria. The fatigue-related exposures investigated in these studies were sleep disorders (n = 14), shift work (n = 2), sleep deprivation/fragmentation (n = 1), and excessive daytime sleepiness (n = 2). Only one study used an injury outcome measure. Studies were limited in their ability to establish a causal relationship by their design, by biases, and in many cases, by small sample sizes. The better quality cross-sectional studies were suggestive of a positive relationship between fatigue and crash risk, but could not provide reliable estimates of the strength of the association. The case-control study provided moderately strong evidence for an association between sleep apnoea and risk of driver injury, with an adjusted odds ratio of 7.2 (95% confidence interval 2.4-21.8). We conclude that the direct epidemiological evidence for a causal role of fatigue in car crashes is weak, but suggestive of an effect. To estimate the burden of injury due to fatigue-related crashes in the population, information is required from well-designed observational epidemiological studies about the prevalence of fatigue in the car driving population and the size of the risk this confers.

Self-reported sleepiness while driving as a risk factor for traffic accidents in patients with obstructive sleep apnoea syndrome and in non-apnoeic snorers

The obstructive sleep apnoea syndrome (OSAS) is a condition causing daytime sleepiness and has been related to an increased risk for traffic accidents. However, the evidence linking severity of OSAS to a higher rate of automobile crashes is based on limited data. The aims of this study were to study the traffic accident rate in the last 5 years in patients referred to our sleep clinic because of clinical suspicion of OSAS and to analyse variables related to an increased risk for traffic accidents. A series of 189 consecutive patients with a driving license referred for a sleep study because of OSAS clinical suspicion and a control group (CG) of 40 hospital staff workers who denied snoring, matched for age and sex with the study population, were studied. Patients underwent a full-night polysomnography and both patients and the CG completed a self-answered questionnaire. One hundred and twenty-two patients were diagnosed as OSAS and 67 patients as non-apnoeic snorers (NAS). The self-reported number of accidents was significantly higher in OSAS patients compared with CG. The self-reported number of times off the road was significantly higher in OSAS patients compared with NAS and with CG. Variables associated with an increased risk for traffic accidents were self-reported sleepiness while driving (OR 5, 95%CI 2.3-10.9), having quit driving because of sleepiness (OR 3, 95%CI 1.1-8.6) and being currently working (OR 2.8, 95%CI 1.1-7.7). We conclude that self-reported sleepiness while driving is associated with an increased risk for traffic accidents in OSAS patients and in NAS. We suggest that this symptom can be used to alert patients and to give priority in the sleep clinic for study and treatment.

Habitually sleepy drivers have a high frequency of automobile crashes associated with respiratory disorders during sleep

Sleepiness is a common cause of traffic crashes with a cost of billions of dollars per year. A recent study has found that 2 to 3% of drivers are habitually sleepy while driving. However, there has not been a controlled study to define the characteristics, driving performance, or automobile crash rate of habitually sleepy drivers. The prevalence of respiratory disorders during sleep, and whether these respiratory disorders contribute to the increased automobile crash frequency, is unknown in habitually sleepy drivers. We interviewed 4,002 randomly selected drivers to define the prevalence of drivers who are habitually sleepy while driving. We studied the habitually sleepy drivers and an age- and sex-matched control group of drivers. These studies included reporting of daytime sleepiness, automobile crashes, driving performance and sleep studies. Of the 4, 002 drivers interviewed, 145 (3.6%, confidence interval [CI] = 3.1 to 4.3) were habitually sleepy while driving. The habitually sleepy drivers reported a significantly higher frequency of auto crashes than control subjects (the adjusted odds ratio [OR] was 13.3, CI = 4. 1 to 43). The habitually sleepy drivers had a significantly higher prevalence of respiratory sleep disorders than control subjects. For a total respiratory events index (apneas, hypopneas, and other respiratory effort-related arousals) >/= 15 the adjusted OR was 6.0, CI = 1.1 to 32. In the habitually sleepy drivers group, the frequency of sleep apnea (apnea-hypopnea index) between subjects with or without auto crashes was not statistically different. However, if we consider total respiratory events index, this frequency of respiratory sleep disorders was significantly higher in subjects with automobile crashes (the adjusted OR for a total respiratory event index >/= 15 was 8.5, CI = 1.2 to 59). Habitually sleepy drivers are a large group of drivers (1 of 30 drivers) who are involved in several fold more automobile crashes than control subjects. As these excess auto crashes can be explained in part by the presence of respiratory disorders during sleep, which are treatable, many automobile crashes in these sleepy drivers may be preventable. Our findings suggest that asking about excessive sleepiness while driving may better predict which subjects with breathing disorders during sleep have crashes than asking about overall sleepiness.

Reporting by physicians of impaired drivers and potentially impaired drivers. The Committee on Bioethical Issues of the Medical Society of the State of New York

Physicians routinely care for patients whose ability to operate a motor vehicle is compromised by a physical or cognitive condition. Physician management of this health information has ethical and legal implications. These concerns have been insufficiently addressed by professional organizations and public agencies. The legal status in the United States and Canada of reporting of impaired drivers is reviewed. The American Medical Association's position is detailed. Finally, the Bioethics Committee of the Medical Society of the State of New York proposes elements for an ethically defensible public response to this problem.

Hazardous materials events: an industrial comparison

Identifying industries at high risk for hazardous materials releases can facilitate prevention and preparation for such events. A retrospective review by Standard Industrial Classification (SIC) codes was conducted on non-petroleum hazardous materials emergency events from 1993 to 1995 and collected by the Washington State Department of Health in a program supported by the Agency for Toxic Substances and Disease Registry. Annual US Census data were used to determine the number of facilities and employees by SIC code in the state of Washington. SIC codes with the most total events and events per 10,000 employees were ranked and characterized by type of releases. In 3 years, 1269 events were recorded, with 294 involving human victims. Industries with the highest average annual number of events per 10,000 employees were agricultural chemical manufacturing (142); petroleum refining (122); industrial and miscellaneous chemical manufacturing (56); electric light and power (54); and pulp, paper, and paperboard mills (39). Industries with high rates of hazardous materials emergency events should continue to develop methods of preventing these releases.

Treatment with nasal CPAP decreases automobile accidents in patients with sleep apnea

We studied 50 consecutive patients to test the hypothesis that successful treatment of obstructive sleep apnea with nasal continuous positive airway pressure (nasal CPAP) will decrease automobile accidents in patients with sleep apnea. Thirty-six (72%) of the patients reported using nasal CPAP regularly during 2 yr. Fourteen patients reported they had not used CPAP during 2 yr. The patients with sleep apnea in this study had a higher automobile crash rate than all drivers in the state of Colorado (0.07 versus 0. 01 crash per driver per year, p < 0.02). Patients who were treated with nasal CPAP had a lower crash rate while being treated than before treatment (0.07 versus 0 crash per driver per year, p < 0.03). Untreated patients with sleep apnea continued to have a high crash rate (0.07 crash per driver before and after diagnosis). Drivers with sleep apnea were reluctant to report their automobile crashes, for the drivers in this study reported only one-third of the crashes in which they were involved. This is the first study to confirm with traffic records that patients with sleep apnea have fewer automobile crashes while being treated with nasal CPAP.

Sleep disorders and the dental patient: an overview

This article is intended to briefly describe common sleep disorders of interest to the dental profession and to render general management guidelines. Topics include sleep-related bruxism, xerostomia, hypersalivation, gastroesophageal reflux, apnea, and the effect of orofacial pain on sleep quality. The term sleep-related is used instead of the term nocturnal because some of the activities described can occur with daytime sleep.

Clinical presentations of obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common but still underrecognized disorder. It affects 2% to 4% of middle-aged adults, a significant proportion of whom are female. The spectrum of clinical presentations of OSAS and their severity is variable, ranging from neurocognitive complaints to cardiorespiratory failure. OSAS has a significant impact on quality of life, cardiovascular morbidity, and mortality. Its major sequelae include daytime somnolence and its consequences (motor vehicle accidents, poor work performance, disrupted social interactions), systemic and pulmonary hypertension, and ischemic heart disease. Treatment of OSAS results in improvement in symptoms, quality of life, and blood pressure control, and may improve mortality. An expansion of our understanding of this condition has resulted in increased awareness of its consequences, but the recognition of OSAS in clinical practice is still delayed. Identification of these patients in clinical practice requires attention to risk factors (history of snoring and witnessed apneas, obesity, increased neck circumference, hypertension, family history) and careful examination of the upper airway. Clinical impression alone, however, has poor (50% to 60%) sensitivity and specificity (63% to 70%) and the diagnosis is usually obtained on polysomnography. Physicians and other health care professionals need to be aware of the progress made in this area and recognize the necessity for prompt evaluation and treatment of these patients.

The behavioral morbidity of obstructive sleep apnea

The behavioral morbidity associated with obstructive sleep apnea (OSA) includes symptoms of excessive daytime sleepiness (EDS), neurocognitive deficits, psychological problems, and possibly an increased chance of accidents. EDS is among the most frequently reported symptoms in patients diagnosed with OSA. The available data suggest that the primary cause of EDS is sleep fragmentation. The subjective measures of sleepiness include the sleep wake activity inventory and the epworth sleepiness scale. Sleepiness can also be evaluated objectively in the sleep laboratory using the multiple sleep latency test or the maintenance of wakefulness test. The neurocognitive manifestations of OSA include impairments in vigilance, concentration, memory, and executive function. There is no agreed on consensus as to how to best quantify neurocognitive deficits in this population. Symptoms consistent with depression or personality changes have also been described, but are likely to be correlates of EDS and/or the chronicity of the disorder. Manifestations of the behavioral morbidity of OSA are reversible, but dependent on the degree of normalization in sleep-disordered breathing and the individual's sleep habits.