1 Center of Sleep Disorders, National Taiwan University

Hospital, Taiwan2 Department of Otolaryngology, National Taiwan Uni-

versity Hospital, Taiwan3 Department of Family Medicine, National Taiwan

University Hospital, Taiwan4 Division of Pulmonary and Critical Care Medicine,

National Taiwan University Hospital, Taiwan

Objectives: This study was to prove our hypothesis thatthe effect of continuous positive airway pressure (CPAP)in patients with obstructive sleep apnea (OSA) withoutdaytime sleepiness is as good as in OSA patients withdaytime sleepiness.Study design: Prospective observational study.Study population: From October 2003 to October2006, 465 patients were referred consecutively to sleeplab for sleep apnea and 302 were diagnosed with sus-pected obstructive sleep apnea (OSA). From 302patients, we recruited 28 patients with daytime sleep-iness (ESS 6 11) into this study. These two-grouppatients were matched in age, sex, body-mass index(BMI) and AHI.Material and methods: Patients: All 40 patients weretreated with CPAP and received regular out-patientfollow-up one month after CPAP use. All 40 patientsused CPAP for more than 5 h/night. The symptomsrelated to snore, ESS score, fatigue score, SF-36, 24hr ambulatory blood pressure, serum levels of epi-nephrine, norepinephrine, IL-6, IL-8 and TNF-a wereevaluated before and 1 month after CPAP treatment.The baseline and changes of these parameters werecompared in these two-group patients. The categoryparameters were analyzed and continuous variableswere analyzed with v2 test and Student’s test,respectively.Results: OSA patients with daytime sleepiness haslower minimal SpO2 (p = 0.022) than patients with-out. However, the baseline levels of serum epineph-rine (p = 0.707), norepinephrine (p = 0.618), CRP(p = 0.489), IL-6 (p = 0.216), IL-8 (p = 0.56), andTNF-a (p = 0.588) were similar in two groups. InOSA patients without daytime sleepiness, levels ofCRP (p = 0.012) and IL-8 (p = 0.049), systolic anddiastolic pressure were lower after 1-month CPAPtreatment. However, the BMI did not change(p = 0.314). In OSA patients with daytime sleepiness,IL-8 (p = 0.043), epinephrine (p = 0.003), norepineph-rine (p = 0.004), CRP (p = 0.001), systolic and dia-stolic pressure and BMI (p = 0.038) were lower afterone-month CPAP treatment. The changes of symp-toms, hypersomnolence, fatigue, quality of life, bloodpressure and serum levels of epinephrine, norepineph-rine, IL-6, IL-8 and TNF-a were similar in thesetwo-groups.

Conclusion: The CPAP treatment of OSA patients with-out daytime sleepiness is as effective as that of patientswith daytime sleepiness.

doi:10.1016/j.sleep.2006.07.041

138 Determining risk factors for cardiovascular diseases

Terry Young *

University of Wisconsin-Madison, Department of Health

Sciences, WI, USA

doi:10.1016/j.sleep.2006.07.042

139 Blood pressure as an endpoint

Anreas Jerrentrup *, Heinrich F. Becker

Philipps-University, Department of Respiratory Medi-

cine, Marburg, Germany

There is compelling epidemiological and experimentalevidence that obstructive sleep apnoea (OSA) is an inde-pendent risk factor for arterial hypertension. However,only two out of eight controlled studies published so fardemonstrated a significant reduction of mean blood pres-sure. How can these discrepant results be explained?Presence of hypertension: The most important problemin the negative studies is the low percentage of hyperten-sives included. In the study that showed the largesteffect, 66% of patients were hypertensive.Severity of OSA: The subgroup analysis in two studiesdemonstrated a reduction in blood pressure in patientswith more than 33 desaturations per hour or >20 desat-urations/h of at least 4%, whereas this was not the casein less severe OSA.Compliance, duration and effectivity of treatment: Insome studies, CPAP compliance was low and in onethe treatment period was only 1 week. In the only twopapers that reported the effect of treatment on AHIthere was a substantial decrease in AHI in the ‘‘sham’’group. Therefore, in the sham group of other studiesthere may well have been a treatment effect, leading toblood pressure reduction in the control group.

Number of patients treated/statistical power: All nega-tive studies did not perform a statistical power analysis,whereas both studies that included a power analysis showeda significant blood pressure reduction with treatment.

Is there an effect of CPAP on arterial hypertensionand what is the effect size?

Actually, most studies did not show an effect ofCPAP on blood pressure. However, all of the negativestudies had the limitations that patients were mainlyor exclusively normotensive and that treatment durationwas too short or compliance inadequate.

Abstracts / Sleep Medicine 7 (2006) S1–S127 S17