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

• Conditions: Pulmonary Disease; Respiratory System Abnormalities; OSA; Respiratory Failure
• Interventions: Other: Position change

• Registration Number: NCT05462600
• Lead Sponsor: University of California, San Diego

Brief Summary

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.

Detailed Description

Not available

Study Timeline

• Study First Submitted: 2022-06-30
• Study First Submitted QC: 2022-07-15
• Study First Posted: 2022-07-18
• Study Start: 2022-07-19
• Status Verified: 2024-06
• Last Update Submitted: 2025-04-08
• Last Update Posted: 2025-04-11
• Primary Completion: 2026-12-30
• Study Completion: 2026-12-30

Recruitment & Eligibility

• Status: ENROLLING_BY_INVITATION
• Sex: All
• Target Recruitment: 40

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

Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
BMI>24.9 kg/m2	Position change	-
BMI 18-24.9 kg/m2	Position change	-

Primary Outcome Measures

Name	Time	Method
Distribution of ventilation	3 hours	Change in regional ventilation distribution (ventral/dorsal) measured through electrical impedance tomography (EIT)
Respiratory drive	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 Outcome Measures

Name	Time	Method
Pulmonary mechanics	3 hours	Pulmonary mechanics will be measured by transpulmonary pressure (cmH2O)obtained from esophageal manometry (transpulmonary pressure= airway pressure- esophageal pressure)
Dead space fraction	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
Ventilatory ratio	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

Trial Locations

Locations (1)

University of California San Diego Health; 🇺🇸 La Jolla, California, United States