The research capabilities in sleep & wake include:
- Digital polysomnographic (PSG) recording of sleep
- PSG screening for sleep disorders
- Manual sleep scoring by experienced scorers according to standard criteria, using the AASM (American Academy of Sleep Medicine) or the R&K (Rechtscahffen and Kales) scoring systems
- Spectral analysis of the sleep and wakefulness EEG
- Multiple Sleep Latency and Maintenance of Wakefulness Tests
- Noise models of sleep disruption
- Circadian models of sleep disruption
- Actigraphic recording of sleep-wake cycles
Furthermore, we are one of only a handful of centres who are able to offer undisturbed 24 hour pharmacokinetic sampling via “hole in the wall” access to our sleep labs.
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Assessment of the Optimal Duration of Continuous Positive Airway Pressure (CPAP) Pre-Operatively in Patients with Newly-Diagnosed Obstructive Sleep Apnoea Syndrome Referred for Bariatric Surgery.
Obesity is increasing pandemically and is the greatest risk factor for Obstructive Sleep Apnoea/Hypopnoea Syndrome (OSAHS), which occurs in up to 70% of patients referred for Bariatric (weight-reduction) surgery.
OSAHS is caused by recurrent collapse of the upper airway during sleep leading to intermittent airway obstruction, despite respiratory effort. This resulting recurrent cycles of hypoxaemia (reduced blood oxygen levels) and repeated waking (“arousals”), cause fragmented sleep. Three mechanisms resulting from intermittent hypoxaemia/arousals relevant to cardiovascular consequences of OSAHS have been proposed: sympathetic activation, oxidative stress, and systemic inflammation. These are thought to be associated with an increased risk of hypertension, heart attacks, heart failure, strokes, and sudden death from heart rhythm disturbances.
Patients referred for bariatric surgery are screened for OSAHS; if present they are treated with Continuous Positive Airway Pressure (CPAP), a mechanism of delivering air at continuous pressure via a face-mask in order to “splint open” the patient’s airway and prevent repetitive airway closure. Previous studies have demonstrated a beneficial effect of CPAP in this group of patients on such variables as blood pressure, heart function, exercise capacity and blood levels of chemicals released in OSAHS (inflammatory markers). However, the question of how long this should be used before patients are considered optimised (fit) for surgery remains unanswered.
Our feasibility study aims to assess the effect of CPAP and duration of use in patients with newly-diagnosed OSAHS on several of these variables whilst they are undergoing routine assessment for bariatric surgery, a process that lasts approximately 12 to 24 months in our Trust (Ashford and St Peter’s Hospitals NHS Foundation Trust). Patients will be studied at baseline and at pre-determined time points before surgery, then once after surgery. The majority of the tests will be performed at the Surrey Human Performance Institute, in collaboration with Surrey University.
What is the principal research question/objective?
To determine the optimal duration of Continuous Positive Airway Pressure (CPAP) treatment of patients with newly-
diagnosed Obstructive Sleep Apnoea/Hypopnoea Syndrome (OSAHS) who are undergoing assessment for Bariatric weight-reduction) Surgery; in other words to determine the minimal duration of treatment to ensure clinically significant improvement in heart and lung function, using a variety of measures including Cardio-Pulmonary Exercise (cycle) testing, the 6-minute walk test and various markers of inflammation (blood tests). These will be measured serially over the course of the 6-month period following the participant starting CPAP treatment after the diagnosis of OSAHS has been made, and also on one occasion after weight-reduction surgery.
2015/16 Circadian Rhythm Protocol development project those with sleep disorders