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Awake at the Wheel
by Jim Park
One of the first things you learn in driver ed class is that a vehicle will cover a distance of 88 ft in a single second while traveling at 100 km/h. A lot can happen in that second, and if your eyes are closed because you're experiencing a fatigue-induced micro-sleep, you won't be in a position to respond. Humans respond to acute fatigue by, well, sleeping. Lapsing into sleep is an automatic response triggered by a physiological need, the same way you'll pull your finger back if you touch something hot. Remaining awake while your brain is trying to sleep requires considerable conscious effort and sometimes, despite our best efforts, the onset of sleep can occur at the most inopportune moments - like while dining with your in-laws or driving along a highway. The most common cause of such fatigue is chronic short sleep, where you just don't get enough rest to meet your body's needs. Whether you choose to remain awake for more time than is good for you, or some external factor prevents you from resting properly matters not. The point is, if you're not getting adequate rest, you're going to be dangerously tired sooner or later. Obstructive sleep apnea (OSA) is one of those external factors. It's essentially a cessation of breathing during sleep, caused by an obstruction - in this case, it's often the soft tissues at the back of the throat relaxing during sleep and easing downward, closing off the airway. This condition is said to be very common among males with a collar size of 17 in. or larger. Dr. Allan Pack, MD, PhD, director of the sleep center at the University of Pennsylvania, says the inability to draw a breath is what wakes you up. "When the airway closes, the oxygen level in the blood declines. The brain senses this and wakes you to a lighter stage of sleep. As you wake, the brain sends a signal to these muscles to open up so you can breathe," says Pack. "When you go back to a deep sleep, the whole thing repeats. You have multiple episodes where your breathing actually stops or markedly declines during sleep." And the sleeper is often not aware this is occurring. The classic response when researchers ask subjects if they wake up during the night is to say they wake to go to the bathroom. Sometimes they'll wake up snoring or gasping for air, but usually they just wake to a lighter stage of sleep where they're not aware of waking. The result, Pack says, is very fragmented sleep. "We can test for this in the lab by disturbing a person's sleep throughout the night. You can make that perfectly normal person excessively sleepy during the day. And because of the fragmented nature of this kind of sleep, you don't get into the deeper stages of sleep that we believe are the most restorative," he notes. "Patients with severe sleep apnea are very, very sleepy people. They will fall asleep in all sorts of circumstances: talking to people, even eating, and of course while driving." That's why the U.S. Federal Motor Carrier Safety Administration (FMCSA) is now very interested in OSA. One of the consequences of excessive sleepiness is a higher propensity to fall asleep while driving. No studies have been done with commercial drivers who suffer from sleep apnea, Pack says, but multiple studies done on car drivers show those with significant sleep apnea have roughly twice the normal risk of a crash. Twice. The second reason to be concerned is that the disorder is very prevalent amongst truck drivers, who are thought to have a higher percentage of sleep apnea sufferers than the general population because as a group they tend to be more obese than normal - particularly at a young age. We're told there's a strong correlation between obesity and elevated OSA risk. What constitutes 'obese' here? Obesity is a condition where excess body fat has accumulated to such an extent that health could be compromised. It's determined using a statistical measurement that compares a person's weight and height, called a body mass index (BMI). Though it doesn't actually measure the percentage of body fat, it's a useful tool for estimating a healthy body weight based on how tall a person is. Persons with a BMI of 30 are considered obese, and due to its ease of measurement and calculation, officials with the U.S. DOT plan to use BMI as a screening tool for mandated sleep apnea testing for commercial drivers. The Carrot or the Stick Following the release of results from a Fatigue Management Program study that showed positive rates of therapy compliance with drivers taking part, FMCSA is expected to issue an notice of proposed rule-making (NPRM) that would mandate sleep apnea screening for drivers fitting the profile of a sleep apnea sufferer as part of the required DOT medical exam. "We expect, on the DOT physical, that all drivers who display OSA symptoms would be required to have an in-home or in-lab sleep study done," says Dr. Kirsty Kerin, director of strategic development for Sleep Health Centers in Brighton, Mass. "If drivers test positive, they would be steered toward nasal CPAP therapy." That treatment involves use of a Nasal Continued Positive Airway Pressure device. It's simple, and sleep apnea can be abolished on the first night. A mask is worn over the nose, or often the nose and mouth, and it's connected to a machine that uses a blower to create positive air pressure inside the mask. This forces air into the lungs through the nose and mouth, keeping the airway open. "The improvement is often very dramatic," claims Dr. Pack. "Patients who report not having had a good night's sleep in years put the mask on and get the first good sleep they can remember... It's almost like a religious experience. They feel terrific for the first time in memory." Dr. Pack, who was a member of the expert panel reporting to FMCSA on the OSA issue, says the panel recommended to the Agency a three-part process to screen, treat, and verify compliance. "We understand drivers may see this as a threat, but the goal here is not to have this sword of Damacles hanging over anyone's head. Our plan is to keep [drivers] driving for one month following the screening in order to get diagnosed. If they are shown to have obstructive sleep apnea, they would have three more months to get effectively treated and onto a therapy program. They'd also need to show that they are using the therapy," Pack explains "The goal is not to drive people off the road and to lose their jobs, the goal was to give them time to get diagnosed and begin a treatment program and to document the efficacy of the treatment." Dr. Kerin understands that drivers would be very nervous about this, but stresses that they really should prepare for it. While the proposed rulemaking hasn't even been written yet, it's expected that these new medical requirements would apply to Canadian drivers in much the same way current Drug and Alcohol testing rules do. We may even have a similar medical standard of our own before too long. Not surprisingly, there's concern amongst some drivers that OSA screening could cost them their jobs, and they've expressed concern about the confidentiality of medical records being shared across so many government agencies and with various carriers. To hear the complete Obstructive Sleep Apnea interview with Dr. Allan Pack, check out Truck Talk on www.todaystrucking.com.
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