Markers in Exhaled Breath Condensate in Obstructive Sleep Apnoea (OSA) Patients
Condition: Obstructive Sleep Apnea
MeSH terms: Apnea; Sleep Apnea Syndromes; Sleep Apnea, Obstructive
Study type: Interventional

Summary: 
      Patients with obstructive sleep apnoea (OSA) have repetitive episodes of partial or complete
      upper airway obstruction during sleep. This leads to sleep fragmentation and symptoms like
      excessive daytime sleepiness and impaired psychosocial well-being. More evidence now
      suggested OSA is associated with cardiovascular diseases like hypertension, myocardial
      infarction, pulmonary hypertension and stroke.

      The upper airway structure and function are altered in OSA. Some studies suggested that an
      increase in the levels of systemic biomarkers of inflammation and oxidative stress in
      patients with OSA. So far, there is only very limited data on non-invasive monitoring of
      inflammation involved in the upper airway of OSA patients. The inflammatory mechanisms
      involved in the upper airway may give some insights to the systemic effect, like
      cardiovascular complications, of OSA.

      Measurement of the constituents of exhaled breath and exhaled breath condensate (EBC) is a
      non-invasive method to assess the degree of inflammation of the airway. Exhaled nitric oxide
      (eNO) can be measured with the subject exhaling to a mouthpiece connected to a machine
      measuring real-time eNO level. With the subject exhaling to a cooling unit, EBC can be
      collected as liquid is formed as a result of condensation.

      This study will assess the eNO in exhaled breath, oxidative stress marker (8-isoprostane) and
      cellular inflammatory markers (eotaxin, monocyted derived chemokine, growth related oncogene-
      alpha, monocyte chemoattractant protein-1) in the EBC and blood of OSA patients before and
      after 1 night and 3 months of continuous positive airway pressure treatment.
    

Detailed description: 
      Measurement of exhaled Nitric Oxide and collection of exhaled breath condensate and
      peripheral blood. This will be done 2 to 4 times(on admission,the morning after sleep
      study,immediately after CPAP titration, after CPAP use for 3 months). Each time eNO will be
      measured first, followed by EBC collection.

      For the tests in the morning, patients will be asked to postpone his/her breakfast until
      after the test which will take less than half an hour.

      OSA is defined as patients having a respiratory disturbance index of ≥5/hr.

      Measurement of Exhaled Nitric Oxide:

      eNO will be measured using a Sievers 280i chemiluminescence analyser (Sievers Instruments,
      Boulder, CO, USA) sensitive to NO from 1 ppb to 200 ppm and with a resolution of 1 ppb and
      accuracy of 1 ppb designed for online recording. The eNO measurement will be performed
      according to ATS standards. Briefly, subjects should remain seated without nose clip during
      the procedure, with 2-minute rest between eNO measurements. The eNO will be measured online
      at an expiratory flow rate of 50 ml/sec, a dead space of 10 ml and 2-second plateau duration.
      Repeated exhalations are performed until three NO plateau values agree at the 10% level or
      two agree at the 5% level. The mean NO value will then be recorded.

      Collection of Exhaled Breath Condensate:

      EBC will be collected using the ECoscreen (Jaeger, Germany) according to manufacturer
      instructions. After rinsing their mouth, the recruited subjects will breathe tidally through
      a mouthpiece that is connected through a unique one-way valve into a cooled collection tube
      where vapours, aerosols and moisture in the breath condense along the walls of the tube. The
      one-way valve is then used as a plunger that collects droplets stuck to the inside wall and
      holds the sample near the top of the tube. The device inherently prevents salivary
      contamination as shown by the absence of salivary amylase in EBC. On average, this device
      will be able to collect 300 microL per minute of EBC for an adult. Each subject will be asked
      to breathe through the collection kit for 5 minutes, which should be sufficiently long to
      yield 1 ml of condensate for inflammatory marker analysis. EBC will be stored immediately at
      -70oC until analysis for inflammatory markers.

      Measurement of 8 isoprostane, GRO alpha, MCP1, eotaxin and MDC levels in exhaled breath
      condensate:

      EBC stored at -70oC will be analysed for 8-isoprostane, GROalpha, MCP1, eotaxin and MDC
      levels concentrations in batches. We will use 96-well polystyrene microplates coated with
      murine monoclonal antibodies against human 8 isoprostane, GRO alpha, MCP1, eotaxin and MDC
      levels. The levels of these markers in EBC will be measured in duplicates by sandwich enzyme
      immunoassay (R & D Systems, Minneapolis, MN, USA) according to instructions provided by the
      manufacturer.
    

Intervention name(s): CPAP; placebo
Intervention type(s): Device; Device
Intervention description(s): Continuous positive pressure device with a time clock; no CPAP
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Obstructive sleep apnea