Commercial drivers are required to undergo periodic medical evaluations to determine medical readiness to operate commercial motor vehicles.
The goal is to screen for any condition that could potentially lead to sudden incapacitation of the driver, to ensure that medical conditions are properly controlled and to ultimately reduce the risk on the roadway.
There are insidious health conditions, such as obstructive sleep apnea (OSA) that can be more difficult to diagnose because the symptoms start gradually, and ill effects of some conditions are not always obvious to the patient. OSA is a relatively prevalent condition that has numerous negative effects on health and performance.
Drivers who have untreated OSA have up to a seven-fold increase in risk of accidents than those without OSA. Drivers might be aware they are sleepy, but might not realize they are impaired.
OSA is a sleep-related breathing disorder that occurs when the upper airway muscles relax during sleep and pinch off the airway causing an individual to not get enough oxygen. These episodes result in a temporary pause in breathing (obstructive apneas) or a reduction in breathing (hypopneas).
These episodes occur repeatedly throughout sleep causing disrupted sleep patterns with resultant lack of appropriate oxygenation and lack of deep, nourishing sleep.
The prevalence of OSA among adults in the United States is up to 30% in males and 15% in females. However, sleep apnea rates increase significantly in postmenopausal women due to hormonal changes and to the tendency to gain weight in the abdominal region.
Untreated obstructive sleep apnea causes an increase in blood sugar, heart rate, blood pressure and stress hormones. People with untreated OSA are at increased risk for adverse health effects, including motor vehicle crashes, inattention, impaired executive function, irritability, depression, sexual dysfunction, hypertension, coronary artery disease, heart attack, abnormal heart rhythms, heart failure, stroke and Type 2 diabetes.
The true risk of untreated OSA is from damage done over time. Left untreated, it can lead to the aforementioned poor health effects.
Symptoms of OSA could include daytime sleepiness, loud snoring, nonrestorative sleep, interruptions in breathing while sleeping or awakening with choking or gasping during sleep. The bed partner of the individual with untreated OSA might notice these symptoms and have greater insight into the frequency and severity of the symptoms the individual is experiencing.
Less common symptoms include night time restlessness, morning headaches and sleep maintenance insomnia with repetitive awakenings.
There are numerous risk factors that increase the probability of developing OSA including older age, male gender, obesity and facial or upper airway abnormalities. Obesity is a major risk factor, and the greater the obesity, the greater the risk of developing OSA. The excess weight can narrow the opening of the throat and push against the lungs, adding to airway collapse during sleep.
It’s important to note that not all people who have OSA are obese, but sleep apnea occurs in about 3% of normal weight individuals, and affects more than 20% of individuals who are obese. Multiple factors, in addition to BMI, are taken into consideration when determining overall likelihood that an individual has undiagnosed OSA.
During Department of Transportation physicals, every driver is screened for OSA. In 2016, the Medical Review Board, a Federal Motor Carrier Safety Administration (FMCSA) advisory board, outlined recommendations regarding which commercial motor vehicle operators should be referred for OSA diagnostic testing:
• Any individual with a body mass index (BMI) greater than or equal to 40 mg/kg2.
• Individuals with BMI greater than or equal to 33 and less than 40, in addition to three or more of the following: Hypertension, Type 2 diabetes, history of stroke/coronary artery disease, arrhythmias, loud snoring, witnessed apneas, small airway, neck size greater than 17 inches (male) and greater than 15.5 inches (female), hypothyroidism, age 42 and older, male or post-menopausal female.
The gold standard diagnostic test for OSA is polysomnography (PSG). Another option is a home sleep apnea test. These monitor individuals during their typical sleep period and measures the number of times an individual has a pause in breathing or is not breathing effectively, while simultaneously measuring their breathing and oxygen levels in the blood.
The PSG and home sleep apnea test determine the apnea-hypopnea index (AHI). This determines the severity of OSA by calculating the number of breathing pauses per hour while the individual sleeps. An AHI of 5-15 events per hour is consistent with mild OSA. An AHI of 15-30 events per hour is consistent with moderate sleep apnea. An AHI of greater than 30 events per hour is consistent with severe OSA.
The FMCSA requires that all individuals with moderate or severe OSA have effective treatment prior to being certified to drive commercial vehicles. Whether or not an individual with mild sleep apnea requires treatment depends on whether the individual is symptomatic (awake time/daytime sleepiness) and whether the individual has other health risks that increase need for treatment of OSA.
The main option for treatment is a breathing device called a continuous positive airway pressure (CPAP) machine. The machine pipes air through the nose which creates air pressure to keep the throat tissues open while asleep, thereby preventing pauses in breathing, and helps maintain proper oxygen levels while sleeping.
Achieving normal levels of oxygenation while sleeping will prevent episodes of abnormal breathing, and the resultant repeated disruptions in sleep.
OSA testing is important to consider for all individuals deemed to be high risk for having undiagnosed OSA, especially individuals who are in safety sensitive positions, such as commercial motor vehicle drivers. Regardless of the career of an individual, screening, appropriate testing and treatment of OSA are imperative for achieving good health. The result of successful treatment of OSA is restful, nourishing sleep and improved quality of life.
References
• Federal Motor Carrier Safety Administration. (2017). Final MRB task 16-01 letter report from MCSAC and MRB. www.fmcsa.dot.gov/advisory-committees/mrb/final-mrb-task-16-01-letter-report-mcsac-and-mrb.
• Hartenbaum, N. (2020). The DOT medical examination (7th ed.). OEM Press.
• Johns Hopkins Medicine. (2021). Obstructive sleep apnea. www.hopkinsmedicine.org.
• Lewis, K. MD (2021). Clinical presentation and diagnosis of obstructive sleep apnea in adults. UpToDate. www.uptodate.com.