title: Nasal CPAP reduces systemic blood pressure in patients with obstructive sleep apnoea and mild sleepiness.
abstract: BACKGROUND
  A randomised controlled study was undertaken to examine the effect of nasal continuous positive airway pressure (CPAP) on 24 hour systemic blood pressure (BP) in patients with obstructive sleep apnoea (OSA).
  
  
  METHODS
  Patients were fitted with an ambulatory BP measuring device as outpatients during normal activities and recorded for 24 hours before starting therapeutic or subtherapeutic (4 cm H(2)O) CPAP treatment. BP monitoring was repeated before completion of 12 weeks of treatment. The primary end point was the change in 24 hour mean BP.
  
  
  RESULTS
  Twenty three of 28 participants in each treatment arm completed the study. There was no significant difference between the two groups in age, body mass index, Epworth Sleepiness Score, apnoea-hypopnoea index, arousal index, and minimum Sao(2). Twenty four patients were hypertensive. The pressure in the therapeutic CPAP group was 10.7 (0.4) cm H(2)O. CPAP usage was 5.1 (0.4) and 2.6 (0.4) hours/night for the therapeutic and subtherapeutic CPAP groups, respectively (p<0.001). After 12 weeks of treatment there were significant differences between the two CPAP groups in mean (SE) changes in 24 hour diastolic BP (-2.4 (1.2) v 1.1 (1.0) mm Hg (95% CI -6.6 to -0.5), p = 0.025); 24 hour mean BP (-2.5 (1.3) v 1.3 (1.1) mm Hg (95% CI -7.2 to -0.2), p = 0.037); sleep time systolic BP (-4.1 (2.1) v 2.2 (1.8) mm Hg (95% CI -11.8 to -0.7), p = 0.028); and sleep time mean BP (-3.6 (1.7) v 1.3 (1.4) mm Hg (95% CI -9.2 to -0.4), p = 0.033).
  
  
  CONCLUSIONS
  Compared with subtherapeutic CPAP, 12 weeks of treatment with therapeutic CPAP leads to reductions in 24 hour mean and diastolic BP by 3.8 mm Hg and 3.5 mm Hg, respectively, in mildly sleepy patients with OSA.
authors.affiliation: Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong. dschui@cuhk.edu.hk
authors.forename: D S
authors.initials: DS
authors.lastname: Hui
authors.forename: K W
authors.initials: KW
authors.lastname: To
authors.forename: F W
authors.initials: FW
authors.lastname: Ko
authors.forename: J P
authors.initials: JP
authors.lastname: Fok
authors.forename: M C
authors.initials: MC
authors.lastname: Chan
authors.forename: J C
authors.initials: JC
authors.lastname: Ngai
authors.forename: A H
authors.initials: AH
authors.lastname: Tung
authors.forename: C W
authors.initials: CW
authors.lastname: Ho
authors.forename: M W
authors.initials: MW
authors.lastname: Tong
authors.forename: C-C
authors.initials: CC
authors.lastname: Szeto
authors.forename: C-M
authors.initials: CM
authors.lastname: Yu
mesh_terms: D000959:Antihypertensive Agents / Q000627:therapeutic use; D001794:Blood Pressure / Q000502:physiology*; D002940:Circadian Rhythm; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D005260:Female; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D020181:Sleep Apnea, Obstructive / Q000150:complications / Q000503:physiopathology / Q000628:therapy*; D012893:Sleep Wake Disorders / Q000150:complications
chemical_list: D000959:Antihypertensive Agents