clinical update publication

Center Offers Sleep Apnea Diagnostics

Since 1986, the Sleep Diagnostics Laboratory at Deborah Heart and Lung Center has been documenting sleep apnea syndrome (SAS) and providing effective treatments for hundreds of patients with this dangerous disorder, which has a strong relationship to cardiovascular disease.

"The estimated population affected by SAS can be as great as 40 million adults and, for this reason, it has recently captured the attention of the news media," said Alan Backman, RPSGT, Technical Director of Deborah's Department of Pulmonary Diagnostics, who manages its Sleep Lab. "This exposure, combined with other factors such as sleepiness while driving, snoring and lifestyle disruption, has raised awareness of the disorder in the general population. Today," Backman continued, "it is not uncommon for patients to tell their physician that they might have the syndrome."

"The typical patient is a middle-aged male, moderately overweight, who has a significant snoring history," notes Marivi Ora-Cajulis, M.D., Attending, Pulmonary Medicine and Medical Director of Deborah's Sleep Lab. "These patients usually look t ired, complain of daytime hypersomnolence and lack of energy. Age, alcohol consumption, obesity and family history are significant risk factors. Hypertension is not uncommon and is a frequent co-morbid condition in moderate stages of the disorder. Congestive heart changes can be seen in severe disease," continued Dr. Ora-Cajulis, "and may be secondary to hypoxemia that occurs during the apneas each night. A strong relationship has been noted between sleep apnea, cerebrovascular disease and coronary artery disease."

The effect of the syndrome in relation to quality of life issues is profound, according to Backman, and all activities of daily living can be impacted. Divorce, loss of job, motor vehicle accidents and cognitive impairments are statistically greater in this population. Backman also notes that three percent of women present with SAS and that post-menopausal patients are at greater risk. "A disturbing statistic is that at least three percent of all individuals driving during rush hour suffer from sleep apnea and have severe hypersomnolence behind the wheel," said Backman.

The primary care physician can effectively diagnose SAS by history. Both the patient and their bed partner can be interviewed to assess snoring, body movements and other common syndrome behaviors. A diet history can prove valuable; patients with the disorder crave carbohydrates.

To fully diagnose SAS, or any of the sleep disorders, a polysomnography is indicated. This evaluation requires an overnight stay in the Sleep Lab, where multiple bio-physical parameters are measured. Sleep is staged, respiration is measured and saturation is documented over the course of the night. In addition, other parameters such as leg movements, esophageal Ph and airway resistance are measured and assessed if needed. The study begins about 8 p.m. and ends at 6 a.m.

"Deborah's Sleep Lab has state-of-the-art computerized and analog equipment which provides flexibility in the various testing procedures," noted Backman. "The rooms are furnished to represent a bedroom in the home, including a full bathroom and showering capabilities, and are attached to the main monitoring room."

An apnea is clinically significant if it exceeds 10 seconds in duration, and it is not uncommon for apneas to range from 30 to 70 seconds or longer with severe hypoxia and hypercarbia. The apnea leads to a "micro-arousal," where the patient enters the waking state in order to effectively breathe, and then immediately returns to sleep where another apneic episode occurs. According to Dr. Ora-Cajulis, this results in sleep fragmentation, disruption of REM sleep and the corresponding waking problems in daily activity.

At the end of the study, the information is analyzed to provide an in-depth assessment of the patient's sleep profile. The assessment includes percentages of sleep stages, a sleep latency index, a sleep apnea index (representing the number of apneas per sleeping hour), a hypopnea index and a breakdown as to type of apnea, including obstructive, central or combined.

Obstructive apneas and hypopneas occur when the tongue occludes the airway, while central apneas and hypopneas occur when the respiratory drive is inactivated or blunted. Combined disorders are a mix of both obstructive and central components.

Patients with primary alveolar hypoventilation, as seen in morbid obesity, will usually present with a central apnea profile. Patients with a bull neck, a neck size greater than 17 inches, will usually present with the obstructive profile. Once diagnosed, Deborah develops a treatment plan for each patient. If the patient has a mild to moderate disorder, a full night diagnostic study will be performed. If the disorder is moderate to severe and meets the criteria for apneas, the lab will split the night, performing four hours of diagnostic study and four hours of therapy.
The first line of therapy consists of Continuous Positive Airway Pressure (CPAP) delivered through the nose. The pressure is adjusted to ensure a remission of the apneas, resumption of "normal" sleep staging and adequate oxygenation. The pressure is then set at optimum and is recommended for home use. If the patient cannot tolerate CPAP, they will be given a trial of Bi-Phasic Airway Pressure (Bi-PAP), which modifies the pressure during inspiration versus expiration. CPAP has also shown to have a therapeutic affect on central apneas and in those situations where CPAP does not work, respiratory stimulants such as Diamox, hormone therapy or others have been effective. Hypopnea will usually respond to multiple therapies, or just weight loss. In the case of pure nocturnal desaturation secondary to COPD, without concurrent sleep apnea or disturbances, patients are treated with low flow oxygen.

"It is important for the primary care physician to follow up on compliance with therapy by instituting nutritional counseling and by ensuring dietary change," said Backman. "A loss of as little as ten pounds can have a significant impact on the disorder. "A restudy is advised after weight loss as the CPAP setting will change, or even be unnecessary, in some cases. In cases where sleep disruption has been documented secondary to gastric reflux, it will be necessary to document resumption of a normal sleep profile after initiation of therapy.

For physicians who routinely review Holter monitors, Backman notes that there is a diagnostic gem hidden in that data. If, during the analysis of the nocturnal rate, a pattern of tachycardia followed by bradycardia is noted, an apneic episode may have occurred. In addition, if a patient complains of sub-sternal pain or burning and the cardiac work-up is negative, gastric reflux disorder is likely. "Some studies suggest that 25 percent of all non-cardiac chest pain may be reflux, and that reflux has also been implicated in sleep disruption," said Backman. "Both conditions warrant further investigation and possibly a polysomnography."

Alan Backman, RPSGT, Department of Pulmonary Diagnostics

Marivi Ora-Cajulis, M.D., Attending, Department of Pulmonary Medicine, Medical Director, Sleep Lab

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