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Clinical InvestigationsSleep and BreathingEffect of Continuous Positive Airway Pressure and Placebo Treatment on Sympathetic Nervous Activity in Patients With Obstructive Sleep Apnea
Section snippets
Materials and Methods
We recruited patients for this study by advertisement and referral. All patients gave oral and written consent to this University of California at San Diego Human Subjects Committee-approved protocol. Patients were eligible if they had never received CPAP, if they were between 35 years and 65 years old, and if they were from 100 to 170% of ideal body weight. Patients underwent a blood count, chemistry panel, ECG, history, and physical examination. Patients with any major medical disorder other
Results
The 38 patients entered into this study had sleep apnea with an RDI > 15. The 11 hypertensive patients were studied when they were not receiving antihypertensive drugs. The randomized groups were of similar age, race, height, and BP status. However, those randomized to CPAP treatment were heavier and had higher urinary NE levels (Table 1).
Although all subjects had sleep apnea, the severity of their sleep disturbance and hypoxia correlated with their daytime urinary NE excretion (Table 2).
Discussion
When compared with placebo, CPAP treatment lowered RDI, plasma NE levels, daytime urine NE levels, and daytime heart rate, and increasedβ 2-adrenergic receptor sensitivity. Diseases exacerbated by sympathetic nervous activity, such as hypertension and angina pectoris, respond to placebo treatment. Wearing a mask attached to an operating machine might elicit a powerful placebo response. A trial14 of CPAP for sleep apnea used a pill as placebo and found no significant effect on BP. We recently
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Supported by National Institutes of Health grants HL 44915, HL 58120, and MO1-RR0827.