title: Falls in blood pressure in patients with obstructive sleep apnoea after long-term nasal continuous positive airway pressure treatment.
abstract: OBJECTIVE
  Effective treatment of obstructive sleep apnoea (OSA) with nasal continuous positive airway pressure (nCPAP) lowers blood pressure (BP). The long-term effects of nCPAP treatment on BP in OSA patients are not well known. The time period of such treatment sufficient to lower BP in OSA patients is also not known. We investigated compliance with long-term nCPAP therapy and its effects on BP.
  
  
  METHODS
  This observational study involved 66 OSA patients [59 men, seven women; mean age, 51 (48-54) years; body mass index (BMI), 28.7 (27.7-29.7) kg/m; apnoea and hypopnoea, 50.3 (45.6-55.0)/h; 95% confidence intervals]. BP and BMI were measured before the study and at two checkpoints after usage of nCPAP [620 (552-688) and 1071 (1000-1143) days].
  
  
  RESULTS
  The different times between the first and second checkpoints for detecting objective compliance were 17 (4-30) min (P = 0.003). Diastolic BP decreased by 5.9 (3.1-8.7) mmHg after 600 days nCPAP treatment and by 4.6 (2.0-7.2) mmHg after 1000 days (P = 0.0006). Systolic BP and BMI did not change significantly. Usage of nCPAP treatment for a daily average of 3 h was needed to achieve a significant decrease in diastolic BP [7.4 (4.3-10.6) mmHg, P < 0.0001]. Diastolic BP of normotensive OSA patients did not change significantly by nCPAP treatment, but that of hypertensive OSA patients decreased significantly within 1 month-3 years of nCPAP treatment whether or not medication was used.
  
  
  CONCLUSIONS
  In patients with severe OSA, the use of nCPAP for a daily average of 3 h would be sufficient to decrease the diastolic BP of hypertensive OSA patients.
authors.affiliation: Department of Physical Therapeutics, Kyoto University Hospital, Kyoto, Japan. chink@kuhp.kyoto-u.ac.jp
authors.forename: Kazuo
authors.initials: K
authors.lastname: Chin
authors.forename: Takaya
authors.initials: T
authors.lastname: Nakamura
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Takahashi
authors.forename: Kensuke
authors.initials: K
authors.lastname: Sumi
authors.forename: Hisako
authors.initials: H
authors.lastname: Matsumoto
authors.forename: Akio
authors.initials: A
authors.lastname: Niimi
authors.forename: Shunichi
authors.initials: S
authors.lastname: Fukuhara
authors.forename: Michiaki
authors.initials: M
authors.lastname: Mishima
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakamura
mesh_terms: D001794:Blood Pressure / Q000502:physiology*; D015992:Body Mass Index; D045422:Continuous Positive Airway Pressure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy*; D013997:Time Factors