Obstruction and Trauma of the Upper Respiratory Airway
OBSTRUCTION DURING SLEEP
A variety of respiratory disorders are associated with sleep, the most common being sleep apnea syndrome. Sleep apnea syn-drome is defined as cessation of breathing (apnea) during sleep.
Sleep apnea is classified into three types:
· Obstructive—lack of air flow due to pharyngeal occlusion
· Central—simultaneous cessation of both air flow and res-piratory movements
· Mixed—a combination of central and obstructive apnea within one apneic episode
The most common type of sleep apnea syndrome, obstructive sleep apnea, will be presented here.
It is estimated that 12 million Americans have sleep apnea (Na-tional Institute of Health, 2000). It is more prevalent in men, es-pecially those who are older and overweight. Cigarette smoking is a risk factor. Obstructive sleep apnea is defined as frequent and loud snoring and breathing cessation for 10 seconds or more for five episodes per hour or more, followed by awakening abruptly with a loud snort as the blood oxygen level drops. Patients with sleep apnea may experience anywhere from five apneic episodes per hour to several hundred per night. Other symptoms include excessive daytime sleepiness, morning headache, sore throat, in-tellectual deterioration, personality changes, behavioral disorders, enuresis, impotence, obesity, and complaints by the partner that the patient snores loudly or is unusually restless during sleep (Chart 22-3).
The obstruction may be caused by mechanical factors such as a reduced diameter of the upper airway or dynamic changes in the upper airway during sleep. The activity of the tonic dilator mus-cles of the upper airway is reduced during sleep. These sleep-related changes may predispose the patient to increased upper airway collapse with the small amounts of negative pressure generated during inspiration. Obstructive sleep apnea may be associated with obesity and with other conditions that reduce pharyngeal muscle tone (eg, neuromuscular disease, sedative/ hypnotic medications, acute ingestion of alcohol). The diagnosis of sleep apnea is made based on clinical features plus polysomno-graphic findings (sleep test), in which the cardiopulmonary sta-tus of the patient is monitored during an episode of sleep.
The effects of obstructive sleep apnea can seriously tax the heart and lungs. Repetitive apneic events result in hypoxia and hypercapnia, which triggers a sympathetic response. As a conse-quence, patients have a high prevalence of hypertension and an increased risk of myocardial infarction and stroke. In patients with underlying cardiovascular disease, the nocturnal hypoxemia may predispose to dysrhythmias.
Patients usually seek medical treatment because their partners ex-press concern or because they experience excessive sleeplessness at inappropriate times or settings (eg, while driving a car). A variety of treatments are used. In mild cases, the patient is advised to avoid alcohol and medications that depress the upper airway and to lose weight. In more severe cases involving hypoxemia with se-vere CO2 retention (hypercapnia), the treatment includes con-tinuous positive airway pressure or bilevel positive airway pressure therapy with supplemental oxygen via nasal cannula.
Surgical procedures (eg, uvulopalatopharyngoplasty) may be performed to correct the obstruction. As a last resort, a trache-ostomy is performed to bypass the obstruction if the potential for respiratory failure or life-threatening dysrhythmias exists. The tra-cheostomy is unplugged only during sleep. Although this is an ef-fective treatment, it is used in a limited number of patients because of its associated physical disfigurement (Murray & Nadel, 2001).
Treatment of central sleep apnea also includes medication. Pro-triptyline (Triptil) given at bedtime is thought to increase the respiratory drive and improve upper airway muscle tone. Med-roxyprogesterone acetate (Provera) and acetazolamide (Diamox) have been recommended for sleep apnea associated with chronic alveolar hypoventilation, but their benefits have not been well es-tablished. Administration of low-flow nasal oxygen at night can help relieve hypoxemia in some patients but has little effect on the frequency or severity of apnea.
The patient with obstructive sleep apnea may not recognize the potential consequences of the disorder. Therefore, the nurse ex-plains the disorder in language that is understandable to the patient and relates symptoms (daytime sleepiness) to the under-lying disorder. The nurse also instructs the patient and family about treatments, including the correct and safe use of oxygen, if prescribed.