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NCT Number: NCT01751971

Estimating Apnea Phenotypes From Polysomnography: Oxygen

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.

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Key information

Conditions

Sleep Apnea Apnea Dyssomnias Nervous System Diseases Respiration Disorders Respiratory Tract Diseases Sleep Apnea Syndromes Sleep Disorders, Intrinsic Sleep Wake Disorders

Age range

20 year–79 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Brigham and Women's Hospital

Boston, Massachusetts, 02115, United States

About this study

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 whether a strong response (reduction in apnea severity) can be predicted by a higher loop gain (in the sham arm) using our method. We also assessed whether assessing upper airway anatomy/collapsibility, dilator muscle responsiveness, and the arousal threshold helped to predict responses to treatment.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Apnea/hypopnea index >20 events per hour
  • Age 20-79 years

Exclusion criteria

  • COPD with desaturation (resting SpO2<96%)
  • Use of respiratory stimulants or depressants
  • Pregnancy

Treatment and study plan

Inspired oxygen (40%)

Drug

Supplemental oxygen at 40% inspired via venturi mask (15 L/min). Equivalent to 5 L/min via nasal cannula.

Other names: Supplemental oxygen

SHAM

Other

Medical air with 21% oxygen via venturi mask (15 L/min).

Other names: Medical air

Primary outcomes

  1. Apnea-hypopnea Index

    Time frame: 1 night

    Apnea-hypopnea index (AHI) will be compared between oxygen and sham nights. Hypopneas are based on 30% reduction in airflow (no desaturation or arousal criteria). AHI data are exclusive to non-REM supine sleep.

    The results presented here are for the AHI at each intervention ("per intervention") regardless of the sequence (preferred clinicaltrials.gov format).

    Please note, however, that the a priori outcome measure was the reduction in AHI with oxygen as a percent of sham values, i.e. (AHI on sham - AHI on oxygen)/(AHI on sham) % (a comparison with greater statistical power), compared between patient subgroups (see Statistical Analysis section).

    Subgroups were defined a priori as higher (>=0.7) versus lower loop gain (<0.7), but tests were also performed in subgroups defined by "favorable" versus "unfavorable" pathophysiology.

Secondary outcomes

  1. Frequency of EEG Arousals (Events Per Hour)

    Time frame: 1 night

    Frequency of scored EEG arousals per hour of non-REM sleep. Note: Our objective was to describe changes in secondary outcomes within phenotypic subgroups. Overall effects (unselected patients / ignoring phenotypic subgroups) are first presented below, followed by effects in favorable vs. unfavorable subgroups.

  2. Overnight Change in Systolic Blood Pressure

    Time frame: 1 night

    The change in systolic blood pressure overnight. Two supine oscillometric measurements of blood pressure are made: just prior to lights out (evening), and after lights on (morning).

  3. Overnight Change in Diastolic Blood Pressure

    Time frame: 1 night

    The change in diastolic blood pressure overnight. Two supine oscillometric measurements of blood pressure are made: just prior to lights out (evening), and after lights on (morning).

  4. Subjective Sleep Quality (Oxygen vs Sham)

    Time frame: 1 night

    Better(+1)/Same(0)/Worse(-1) on oxygen vs sham, i.e. "a relative comparison between arms". When subjects had completed the entire study, they were asked to compare subjectively their sleep quality on the first versus second study.

  5. Subjective Sleepiness/Alertness (Stanford Sleepiness Scale)

    Time frame: 1 night

    Assessed in the morning after the single night of treatment. Minimum score: 1 (alert), maximum score: 7 (not alert).

Sponsors and collaborators

Lead sponsor

Brigham and Women's Hospital

Other

Collaborators

  • American Heart Association
  • National Heart, Lung, and Blood Institute (NHLBI)

Registry information

Official study title

Estimating Apnea Phenotypes From Routine Polysomnography: Application to Oxygen Therapy

Acronym: PSGtraits-O2

Important dates

Study start
2012
Primary completion
2016
Study completion
2016
First posted
Dec 18, 2012
Registry last updated
Mar 20, 2018

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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