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The Link Between Sleep Apnea & Hypertension
 

Standfirst: Obstructive sleep apnea is a significant medical problem affecting middle-aged adults. The most common symptoms of sleep apnea are loud snoring, disrupted sleep and excessive daytime sleepiness. In addition, several studies have shown that patients with sleep apnea have often been linked with problems with hypertension and cardiovascular abnormalities. It is therefore important to treat the problem, as this has shown to lower these associated risks.

Daytime fatigue and sleepiness are the most significant complaints of patients with obstructive sleep apnea. Frequently, sleep apnea sufferers fall asleep during sedentary activities, such as watching television or sitting in a movie theater. Near-miss automobile crashes also commonly occur in these patients as they tend to doze off behind the wheel.

As daytime sleepiness becomes more excessive, patients may report falling asleep in embarrassing situations, such as during meals or when sitting in a car stopped at a traffic light. They may also complain of being tired on awakening in the morning.1 They often have to nap during the day but typically wake up unrefreshed.

Characteristic Features
Upon physical examination by a doctor, most sleep apnea patients reveal a crowded posterior airway. These patients may have an enlarged floppy uvula or tonsillar hypertrophy or an elongated soft palate that rests on the base of the tongue that cause airway obstruction 2

Studies have shown that most patients with obstructive sleep apnea are overweight and typically have a short, thick neck. Some may be of normal weight but tend to have lower-face abnormalities, which may include a small chin, maxilla and mandible, as well as a large tongue.2 These findings may not be obvious in some patients, but a receding jaw with 2 mm or more of overbite resulting in a prominent mental cleft or curling of the lower lip tends to be common upon examination.

The Link With Hypertension
Hypertension is the best documented cardiovascular condition associated obstructive sleep apnea. Several studies have shown this link.3 In one 8-year study that was published in the New England Journal of Medicine and that involved more than 700 people, researchers at the UW Medical School in the US established that sleep apnea is likely to be an important cause of hypertension. The UW researchers found that people with mild to moderate sleep apnea were twice as likely to become hypertensive and people with moderate to severe sleep apnea were almost three times as likely to become hypertensive.

In another study that was published in the Journal of the American Medical Association (JAMA), and was the largest of its kind, the Sleep Heart Health Study analyzed sleep study results and blood pressure measurements, along with other factors, of over 6,000 individuals 40 years old and older. Again, data revealed that rising rates of breathing disruptions during sleep were associated with higher blood pressure measurements. This relationship persisted even after adjustments for other factors that can affect blood pressure, such as obesity, age, and race.

Treatment of Sleep Apnea
Treatments for sleep apnea include non-invasive procedures like weight loss, nasal continuous positive airway pressure and dental devices that modify the position of the tongue or jaw. Invasive upper airway and jaw surgical procedures may benefit some.4

 However, many cases of obstructive sleep apnea can be relieved by a treatment called nasal continuous positive airway pressure (nasal CPAP). Nasal CPAP uses a mask-like device and pump that work together to keep the airway open with air pressure during each breathe when a patient is sleeping. The patient wears a snugly fitting nasal mask attached to a fan that blows air into the nostrils to keep the airway open during sleep. Eliminating the obstruction usually reverses the hypertension and cardiac problems associated with the problem.

Obstructive apnea is fairly common, but it often remains undiagnosed. As the disorder is associated with significant morbidity and even some mortality,5 it is important for family physicians to be familiar with its clinical presentation and treatment.

References:
1. Wittig R. Clinical evaluation of excessive daytime sleepiness. In: Victor LD, ed. Clinical pulmonary medicine. Boston: Little, Brown, 1992:439-60.

2. Victor LD. Obstructive sleep apnea in primary care. Dearborn, Mich.: Oakwood Hospital, 1997.

3. Shepard JW Jr. Cardiopulmonary consequences of obstructive sleep apnea. Mayo Clin Proc 1990;65: 1250-

4. Am Fam Physician 1999;60:2279-86.

5. Gould GA, Whyte KF, Rhind GB, Airlie MA, Catterall JR, Shapiro CM, et al. The sleep hypopnea syndrome. Am Rev Respir Dis 1988;137:895-8.

Addendum
I would like to add the following facts on the association between Obstructive Sleep Apnea (OSA) and Hypertension:

  • 50-90% of patients with OSA have daytime hypertension.

  • OSA patients have higher blood pressure during sleep – an average of 9 mmHg increase in blood pressure compared to healthy individuals without OSA, in whom blood pressure should be lower during sleep.

  • Nasal CPAP has been shown to unequivocally and dependably correct these sleeping blood pressure disturbances in OSA.

In view of the strong association between these 2 conditions, it has been recommended that doctors look out for symptoms of OSA such as loud habitual snoring, excessive daytime sleepiness/fatigue and restless or unrefreshing sleep with frequent awakenings in all patients with hypertension without any known secondary causes. Many cases of “essential hypertension” may have concomitant OSA that can easily be missed especially if questions related to patients’ quality of sleep are not part of routine history taking in the clinic.

 

 
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