Low-dose theophylline reduces symptoms of acute mountain sickness.

OBJECTIVE: Headache, nausea, and sleeplessness at altitude [acute mountain sickness (AMS)] are major health problems for several million mountain recreationists who ascend to high altitudes each year. We aimed to test the efficacy of low-dose, slow-release theophylline for the prevention of AMS in a placebo-controlled, double-blind, randomized trial. METHODS: Twenty healthy male volunteers (mean age 34.7 y) were randomized (random allocation) to receive either 300 mg theophylline daily or placebo 5 days prior, during ascent, and during a stay at 4,559 m altitude. AMS symptoms were collected using the Lake Louise Score on each day during ascent and at high altitude. A 12-channel sleep recorder recorded sleep and breathing parameters during the first night at 4,559 m. Theophylline serum levels were drawn prior to the sleep study. RESULTS: Seventeen completed the entire study. Theophylline (n = 9) compared to placebo (n = 8) significantly reduced AMS symptoms at 4,559 m (Lake Louise Score: 1.5 +/- 0.5 vs placebo 2.3 +/- 2.37; p < 0.001), events of periodic breathing (34.3/h vs placebo 74.2/h; p < 0.05), and oxygen desaturations (62.3/h vs placebo 121.6/h; p < 0.01). No significant differences in sleep efficiency or sleep structure were present in the two groups. No adverse drug effects were reported. CONCLUSIONS: Low-dose, slow-release theophylline reduces symptoms of AMS in association with alleviation of events of periodic breathing and oxygen desaturations.

Prevalence of symptoms and risk of sleep apnea in primary care.

BACKGROUND: To obtain prevalence estimates for key symptoms and features that can indicate the presence of obstructive sleep apnea (OSA) in a broad range of primary care settings. DESIGN: Cross-sectional survey. SETTING: Forty offices and clinics in the United States, Germany, and Spain. PARTICIPANTS: Consecutive patients who were > 15 years of age, regardless of the reason for the visit. MEASUREMENTS: We collected demographic information, prevalence of self-reported chronic snoring, sleepiness, obesity (body mass index [BMI] > 30), hypertension, and calculation of OSA risk, and we also compared results between the United States and Europe. RESULTS: There was a 78% return rate for 8,000 surveys (mean age, 51 years; age range, 15 to 98 years; 52% women). One third of participants (32%) had a high pretest probability for OSA, with a higher rate in the United States (35.8% of 3,915 participants) than in Europe (26.3% of 2,308 participants; p < 0.001; age-matched and sex-adjusted odds ratio [OR], 1.37; 95% confidence interval [CI], 1.16 to 1.61). Sleepiness (32.4% vs 11.8%, respectively; p < 0.001) followed by obesity and/or hypertension (44.8% vs 37.1%, respectively; p < 0.01) contributed to the OSA risk difference between participants in the United States and Europe, as frequent snoring and breathing pauses were similarly reported (44%). A high pretest probability for OSA was more often present in men than in women (37.9% vs 27.8%, respectively; p < 0.005; OR, 1.96; CI, 1.59 to 2.88) and in those that were obese (ie, BMI, > or = 30 kg/m(2)), a condition that is generally more common in the US population than in the European population (27.9% vs 17.2%, respectively; p < 0.01). CONCLUSIONS: Primary care physicians in the United States and Europe will encounter a high demand for services to confirm or manage sleep apnea, sleepiness, and obesity.