Try our beta test site
IMPORTANT: Listing of a study on this site does not reflect endorsement by the National Institutes of Health. Talk with a trusted healthcare professional before volunteering for a study. Read more...

Effect of Continuous Positive Airway Pressure (CPAP) on Systemic Blood Pressure, Coagulability and Carotid Intima-media Thickness in Patients With Sleep Apnea

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified June 2011 by Chinese University of Hong Kong.
Recruitment status was:  Recruiting
Information provided by:
Chinese University of Hong Kong Identifier:
First received: March 8, 2006
Last updated: June 22, 2011
Last verified: June 2011

Sleep-disordered breathing (SDB) briefly means cessation of breathing during sleep at least 5 times per hour. Sleep-disordered breathing affects 9 to 24% of the middle-aged and overall 4% of the middle-aged males suffers from Obstructive sleep apnea syndrome (OSAS) i.e. SDB with associated daytime sleepiness. Several major epidemiological studies have shown that SDB is not only an independent risk factor for systemic hypertension but it is also associated with cardiovascular complications such as heart failure, stroke, and sudden death.

The mechanisms for the linkage between Sleep-disordered breathing and cardiovascular diseases are not fully determined but surges in sympathetic nerve activity are seen at the end of each apneic episode accompanied by large rises in systemic arterial blood pressure (BP). The increased levels of muscle sympathetic nerve activity are diminished by nasal continuous positive airway pressure (CPAP) therapy. Numerous studies have found a hypercoagulable state in terms of increased clotting factor and platelet activities, and impaired fibrinolysis in coronary artery disease, ischaemic stroke, and sleep-disordered breathing. Common carotid artery intima-media thickness (IMT) has been shown to correlate with traditional vascular risk factors and may predict the likelihood of acute coronary events and stroke. Recently, carotid artery intima-media thickness has been shown to have positive correlations with the severity of sleep disordered breathing.

Despite robust evidence showing improvement of symptoms, cognitive function and quality of life in patients with obstructive sleep apnea treated with nasal continuous positive airway pressure, there are conflicting short-term data whether continuous positive airway pressure can reduce blood pressure in patients with obstructive sleep apnea. This randomized controlled study aims to assess the long-term effects of nasal continuous positive airway pressure on 1) 24 hr systemic blood pressure; 2) Coagulation state; and 3) Carotid artery intimal media thickness.

Condition Intervention
Obstructive Sleep Apnoea
Device: Continuous Positive Airway pressure
Other: Placebo

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Open Label
Primary Purpose: Treatment
Official Title: A Randomized Controlled Study of the Long-term Effects of Nasal Continuous Positive Airway Pressure on Systemic Blood Pressure, Coagulability and Carotid Intima-media Thickness in Obstructive Sleep Apnea Syndrome

Resource links provided by NLM:

Further study details as provided by Chinese University of Hong Kong:

Primary Outcome Measures:
  • Blood Pressure measurement [ Time Frame: 6 and 12 months ]

Secondary Outcome Measures:
  • Changes in systolic and diastolic Blood pressure between the 2 groups at 6 & 12 months [ Time Frame: 6 and 12 months ]
  • serial changes of carotid intimal media thickness between the two treatment groups over 12 months [ Time Frame: 12 months ]
  • serial changes in haemostatic assays [ Time Frame: 6 and 12 months ]

Estimated Enrollment: 100
Study Start Date: January 2006
Estimated Study Completion Date: December 2013
Estimated Primary Completion Date: February 2013 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Active Comparator: A
Continue positive airway pressure
Device: Continuous Positive Airway pressure
Continuous positive pressure device with a time clock
Placebo Comparator: B
Other: Placebo

  Show Detailed Description


Ages Eligible for Study:   20 Years to 80 Years   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Age 20 to 80 yrs
  • Apnoea Hypopnea index ≥5/hr on Polysomnography with Epworth Sleepiness Scale ≥10

Exclusion Criteria:

  • Predominantly central sleep apnoea
  • Recent myocardial infarction 3 months before the study
  • Unstable angina
  • Underlying malignancy
  • Professional drivers and those handling dangerous machinery
  • Patients will be considered dropouts if anti-hypertensive medication is accidentally changed by the patients or their general practitioners
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT00300599

Contact: David S Hui, MD 852-26-323-134

Hong Kong
The Chinese University of Hong Kong Recruiting
Hong Kong, New Territories, Hong Kong
Contact: David S Hui, MD    852-26-323-135   
Sponsors and Collaborators
Chinese University of Hong Kong
Principal Investigator: David S Hui, MD Chinese University of Hong Kong
  More Information

Responsible Party: Dr. David SC Hui, The Chinese University of Hong Kong Identifier: NCT00300599     History of Changes
Other Study ID Numbers: Resp/hui/2006/001
Study First Received: March 8, 2006
Last Updated: June 22, 2011

Additional relevant MeSH terms:
Sleep Apnea Syndromes
Sleep Apnea, Obstructive
Respiration Disorders
Respiratory Tract Diseases
Signs and Symptoms, Respiratory
Signs and Symptoms
Sleep Disorders, Intrinsic
Sleep Wake Disorders
Nervous System Diseases processed this record on May 25, 2017