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Enrolling by Invitation

NCT Number: NCT05462600

Distribution of Ventilation, Respiratory Drive and Gas Exchange: Measurements and Monitoring

Respiratory physiology involves a complex interplay of elements including control of breathing, respiratory drive, pulmonary mechanics, distribution of ventilation and gas exchange. Body position may also play an important role in respiratory mechanics. While effective methods exist for measuring these variables, they are typically measured in isolation rather than in combination. In pulmonary disease, decreasing mechanical stress and strain and optimizing transpulmonary pressure or the distending pressure across the lung, minimizing overdistention and collapse are central to clinical management. Obesity has a significant impact on pulmonary mechanics and is a risk factor for obstructive sleep apnea (OSA). However, our understanding of these elements is limited even in the general population. The investigators plan to use various validated methods to assess control of breathing, respiratory drive, distribution of ventilation and gas exchange to obtain a better understanding of underlying physiologic signatures in patients with and without obesity and the role of posture/position, with a secondary analysis comparing participants with and without obstructive sleep apnea.

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Key information

Conditions

Pulmonary Disease Congenital Abnormalities Congenital, Hereditary, and Neonatal Diseases and Abnormalities Lung Diseases OSA Respiration Disorders Respiratory Failure Respiratory Insufficiency Respiratory System Abnormalities Respiratory Tract Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

University of California San Diego Health

La Jolla, California, 92037, United States

Who can participate

Healthy volunteers accepted: Yes

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

Inclusion criteria

  • 18 years or older
  • Non-smokers

Exclusion criteria

  • <18 years old
  • Significant history of pulmonary disease
  • Chest wall, anatomical, physical abnormalities, skin integrity issues precluding placement of electrode belt in direct contact with skin
  • Skin integrity issues precluding placement of nose clips, or transcutaneous carbon dioxide monitoring
  • Inability to form a seal around a mouthpiece
  • Known esophageal strictures, webs, or varices (if esophageal manometry to be included)
  • Known platelet count < 100,000 (if esophageal manometry to be included)
  • On therapeutic anticoagulation (if esophageal manometry to be included)
  • Known multidrug resistant (MDR) pulmonary infection
  • Non-English language speakers
  • Chronic hypoxemic respiratory failure
  • Confirmed or suspected intracranial bleed, stroke, edema
  • Active implants (i.e. implantable electronic devices such as pacemakers, cardioverter defibrillators or neurostimulators) or if device compatibility is in doubt
  • Pregnant or lactating patients as safety and efficacy for use of EIT in such cases has not been verified

Treatment and study plan

Position change

Other

Distribution of ventilation, respiratory drive, pulmonary mechanics and gas exchange will be measured in 3 unique positions: prone, head of bed (HOB) flat (i.e. 0 degrees) and HOB elevated (i.e. 30 degrees).

Primary outcomes

  1. Distribution of ventilation

    Time frame: 3 hours

    Change in regional ventilation distribution (ventral/dorsal) measured through electrical impedance tomography (EIT)

  2. Respiratory drive

    Time frame: 3 hours

    Respiratory drive differences will be measured by mean desaturation (change from baseline percent oxygen saturation) following breath-hold maneuvers

  3. Respiratory drive

    Time frame: 3 hours

    Respiratory drive differences will be assessed by the duration of maximal breath-hold (seconds)

  4. Respiratory drive

    Time frame: 3 hours

    Respiratory drive will also be assessed by measurement of occlusion pressure (cm H2O) at 100 ms (P0.1) after the initiation of an inspiratory effort against a closed circuit.

Secondary outcomes

  1. Pulmonary mechanics

    Time frame: 3 hours

    Pulmonary mechanics will be measured by transpulmonary pressure (cmH2O)obtained from esophageal manometry (transpulmonary pressure= airway pressure- esophageal pressure)

  2. Dead space fraction

    Time frame: 3 hours

    Dead space fraction will be calculated by partial pressure arterial/transcutaneous CO2 (PCO2) minus partial pressure of CO2 in mixed expired gas divided by the partial pressure of arterial/transcutaneous CO2

  3. Ventilatory ratio

    Time frame: 3 hours

    Ventilatory ratio will be calculated as measured minute ventilation multiplied by the measured partial pressure of PCO2 divided (transcutaneous) by the predicted minute ventilation based on ideal body weight multiplied by the ideal PaCO2

Sponsors and collaborators

Lead sponsor

University of California, San Diego

Other

Registry information

Important dates

Study start
2022
Primary completion
2026
Study completion
2026
First posted
Jul 18, 2022
Registry last updated
Apr 11, 2025

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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