Continuous Monitoring Nocturnal Beat-to-beat Blood Pressure Fluctuation in OSA With or Without Hypertension
Condition: Blood Pressure Disorders
Study type: Interventional

Summary: 
      Emerging evidence suggests that there is a causal link between obstructive sleep apnea(OSA)
      and hypertension. Patient with this syndrome exhibit several characteristics: high
      prevalence, frequent non-dipper status, diastolic and nocturnal predominance, which are
      related to clinical and subclinical organ damage in heart and brain. However, the influence
      of OSA on nocturnal hypertension development has not yet been clarified. Blood pressure
      variability (BPV) plays a role in vascular damage, independent of blood pressure. Apnea
      overloads the autonomic cardiovascular control system and may influence BPV,which is
      classified by different time interval, including beat-to-beat, hour-to-hour day-to-night
      changes or long-term, for example days, weeks, months, seasons, and even years. All BPV
      abnormalities are associated with an increased incidence of cardiovascular events and
      mortality. The investigators pre-experiment estimate BPV by ambulatory blood pressure
      monitoring (ABPM), which unable to capture the BP fluctuation accurately during the apnea
      event. The small studies exam beat-to-beat BP and OSA，and the investigators can't couple the
      events with blood fluctuation, also incapable calculate the correlation of them. This study
      is aimed to use pulse transmit time(PTT) based blood pressure measurement which can be useful
      for continuous monitoring of blood pressure to monitor nocturnal beat-to-beat blood pressure
      fluctuation in OSA with or without hypertension, investigating the degree of relevance
      between hypoxia, AHI, nocturnal hypertension development and BPV. Besides that the
      investigators also evaluate the effect of continuous positive airway pressure(CPAP) on blood
      pressure and nocturnal beat-to-beat BPV.
    

Detailed description: 
      Methods:

      Between March 2016 and December 2016,the investigators initially recruited 450 individuals
      reporting severe habitual snoring. Primal evaluations including office blood pressure,
      Epworth Sleepiness Scale Score(ESS), antihypertensive medicine demographic and anthropometric
      data. Then overnight polysomnography were performed. Of them,100 were severe OSA (AHI>30
      episode/h) with hypertension, who were agreed to stop taking antihypertensive medicine. The
      investigators calculated the time to stop based on the half-life of patients taking oral
      drugs and last time administration time. The subject who withdrawal time was less than three
      days was enrolled in this study. These patients were hospitalized and close monitoring of
      blood pressure, for blood pressure three times greater than 180/110mmHg or appearing
      dizziness, headache and other clinical syndrome, the investigators will give a timely
      clinical intervention and get rid of this study. The control group consisted of 100 subjects
      just with severe OSA whose blood pressure is normal. The investigators recorded nocturnal
      blood pressure, oximetry, beat-to-beat BPV, AHI, BP event was calculated. Screening of 40
      newly diagnosed patients with hypertension and subjects with poor blood pressure control, the
      investigators would give one-night continuous positive airway pressure(CPAP) to compare the
      AHI, the mean nocturnal systolic blood pressure and diastolic blood pressure, the number of
      blood events before and after short-term CPAP therapy, to compare the AHI, the mean nocturnal
      systolic blood pressure and diastolic blood pressure, the number of blood events before and
      after short-term CPAP therapy.
    

Intervention name(s): CPAP
Intervention type(s): Other
Intervention description(s): OSA complicated with hypertension：In order to avoid the effects of drugs on this study, we calculated the time to stop based on the half-life of patients taking oral drugs and last time administration time. The subject who withdrawal time was less than three days was enrolled in our study. These patients were hospitalized and close monitoring of blood pressure, for blood pressure three times greater than 180/110mmHg or appearing dizziness, headache and other clinical syndrome, we give a timely clinical intervention and get rid of our study. Screening of 40 newly diagnosed patients with hypertension and subjects with poor blood control,the investigators would give one-night CPAP
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment