Estimating Apnea Phenotypes From Polysomnography: Oxygen (PSGtraits-O2)
This study seeks to employ advanced methods to estimate the individual factors contributing to sleep apnea from standard recordings made during routine clinical sleep studies. This study focuses on breathing control or "loop gain" as one of the factors contributing to sleep apnea. Increased levels of oxygen in the air is known to make breathing more stable by lowering "loop gain". Here, our goal is to use a new method capable of detecting a reduction in loop gain with oxygen. The investigators also aim to test whether a high loop gain measured at baseline/placebo predicts a greater improvement in sleep apnea with oxygen therapy.
|Study Design:||Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Crossover Assignment
Masking: Single Blind (Subject)
Primary Purpose: Treatment
|Official Title:||Estimating Apnea Phenotypes From Routine Polysomnography: Application to Oxygen Therapy|
- The reduction in severity of sleep apnea (Apnea-Hypopnea Index, Events/hour) [ Time Frame: 1 night ] [ Designated as safety issue: No ]Acute change in AHI is taken as the difference between values on the sham and oxygen nights, taken approximately 1 week apart.
- Overnight change in chemosensitivity [ Time Frame: 1 night ] [ Designated as safety issue: No ]The rise in chemosensitivity overnight will be compared between sham and oxygen treatment arms using dynamic CO2 stimulation.
- Subjective sleepiness/alertness (Stanford Sleepiness Scale) [ Time Frame: 1 night ] [ Designated as safety issue: No ]Assessed in the morning after the single night of oxygen/air, and compared between sham and oxygen studies.
- Overnight change in blood pressure [ Time Frame: 1 night ] [ Designated as safety issue: No ]The change in blood pressure overnight will be assessed in both studies, and compared between sham and oxygen studies approximately 1 week apart.
|Study Start Date:||November 2012|
|Estimated Study Completion Date:||August 2013|
|Estimated Primary Completion Date:||August 2013 (Final data collection date for primary outcome measure)|
Inspired oxygen at 40%
Drug: Inspired oxygen (40%)
Supplemental oxygen at approximately 40% e.g. via Pink venturi mask
Other Name: Supplemental oxygen
Placebo Comparator: Air
Placebo/Sham using air at the same flow rate
In a single-blinded randomized crossover study, inspired oxygen/air (40%/21%) is delivered on two separate nights. Loop gain is measured from routine polysomnography using a novel mathematical method. A value of loop gain >1 reflects unstable breathing, and a value less than but approaching 1 denotes a system more prone to oscillate. Loop gain is measured as the changes in ventilatory drive/effort that arises subsequent to changes in ventilation (e.g. due to obstructive apnea). A simple chemoreflex model (gain, time constant, delay) is fit to surrogate ventilation data (derived from airflow) during sleep. The best model is one that best matches the elevated ventilatory drive (measured as ventilation in the absence of airflow obstruction) based on the prior apneic/hypopneic fall in ventilation. Loop gain is calculated from this model. We aim to use loop gain measured on and off oxygen to determine (1) whether our method detects a reduction in loop gain, and whether a strong response (reduction in apnea severity) can be predicted by a higher loop gain (in the sham arm) using our method.
|Contact: SCOTT A SANDS, PhDfirstname.lastname@example.org|
|United States, Massachusetts|
|Brigham and Women's Hospital||Recruiting|
|Boston, Massachusetts, United States, 02115|
|Contact: Scott SANDS, PhD email@example.com|
|Sub-Investigator: Scott A Sands, PhD|
|Principal Investigator:||Andrew Wellman, MD||Brigham and Women's Hospital|