3D Evaluation to Quantify Regional Volume Change Between FRC and TLC (MATH3D)

The aim of this study is first to validate an IC measurement using analysis of two 3D acquisitions, and to appreciate the inter-observer variability of this IC measurement between a trained technician of respiratory function analysis and a trained pulmonologist.

Study Overview

• Status: Active, not recruiting
• Conditions: Diaphragmatic Dysfunction

Detailed Description

3D visualization of the chest and abdomen surface in static condition is a simple and inexpensive solution to measure regional volume changes between two static respiratory volume positions. Five seconds of apnea is necessary for visualizing the thoraco-abdominal surface. If the two positions visualized correspond to the functional residual capacity (FRC) and the total lung capacity (TLC) the volume difference is inspiratory capacity (IC) which depends to the inspiratory muscles activation. This IC can be split in different thoraco-abdominal compartments and in supine position the abdominal contribution of this IC volume appreciates non-invasively diaphragmatic function. In addition asymmetry between right and left sides can appreciate unilateral diaphragmatic.

The aim of this study is first to validate an IC measurement using analysis of two 3D acquisitions, and to appreciate the inter-observer variability of this IC measurement between a trained technician of respiratory function analysis and a trained pulmonologist.

Accordingly, patients addressed for suspicion of diaphragmatic dysfunction, and able to maintain 5 sec of apnea in supine position will be proposed, by using the informed consent process, to participate to this study which consisted to beneficiate to a 3D trunk visualization at FRC and TLC during a spirometric IC measurement in supine position. Thoraco-abdominal volume difference between the two positions (FRC and TLC) will be calculated to obtain a 3D-IC volume. Then a Bland-Altman comparison will be done between the 3D-IC volumes measured and calculated by the two different observers (technician and pulmonologist), and the spirometric-IC volume considered as the reference. The Bland-Altman average discrepancies (the bias) and to the wide of the limits of agreement obtained will allow to select the best observer between the technician and the pulmonologist.

After the validation of the 3D-IC measurement against spirometry (difference > 10%), and after having confirmed that this analysis can be performed in routine by a pulmonary function technician, the next step will be to validate that the decrease of abdominal contribution of 3D-IC is an non-invasive index of diaphragmatic dysfunction. Accordingly, a linear regression analysis will be used in this study between the abdominal contribution to 3D-IC and the other parameters issued from exams prescribed by the clinician to confirm and evaluate diaphragmatic dysfunction. These other parameters are usually the fall of CV in supine position and/or a decrease of transdiaphragmatic pressure (Pdi) measurement by estimating the difference between oesophageal pressure (Peso) (intrathoracic pressure) and gastric pressure (Pga) (intra-abdominal pressure), [Pdi=Pga-Peso]. Pdi can be obtained during maximal voluntary efforts (the most frequent being the sniff test (Sniff Pdi)) or by using non-volitional test such as magnetic stimulation of the phrenic nerves (Twitch Pdi).

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

Study Locations

• France
  • Garches, France, 92380
    • Physiological/Respiratory functional exploration Department, Raymond Poincaré Hospital, APHP

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 90 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients addressed to the respiratory function laboratory for suspicion of diaphragmatic dysfunction

Description

Inclusion Criteria:

• Patients 18 - 90 years of age;
• Patients addressed for suspicion of diaphragmatic dysfunction, and able to maintain 5 sec of apnea in supine position.

Exclusion Criteria:

• Decubitus impossible;
• Apnea of 5 seconds impossible;
• Pregnant or Breastfeeding;
• Patient under juridic protection.

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Inspiratory capacity using a 3D technique	Thoraco-abdominal volume difference between the two respiratory positions will be calculated to obtain a difference in respiratory volume between these two positions.	at baseline

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Abdominal contribution to inspiratory capacity	Abdominal contribution to trunck volume change	at baseline

Collaborators and Investigators

• Sponsor: Assistance Publique - Hôpitaux de Paris
• Investigators: Study Director: Frédéric LOFASO, MD, PhD, Physiological/Respiratory functional exploration Department, Raymond Poincaré Hospital, APHP; Principal Investigator: Caroline HELIE, Physiological/Respiratory functional exploration Department, Raymond Poincaré Hospital, APHP

Study record dates

Study Major Dates

• Study Start (Actual): September 2, 2022
• Primary Completion (Estimated): September 1, 2026
• Study Completion (Estimated): September 1, 2026

Study Registration Dates

• First Submitted: April 15, 2022
• First Submitted That Met QC Criteria: April 15, 2022
• First Posted (Actual): April 21, 2022

Study Record Updates

• Last Update Posted (Estimated): November 19, 2025
• Last Update Submitted That Met QC Criteria: November 18, 2025
• Last Verified: November 1, 2025

More Information

Terms related to this study

• Keywords: Diaphragm; Neuromuscular; 3D analysis; Non invasive
• Other Study ID Numbers: APHP220330; 2021-A02798-33 (Registry Identifier: IDRCB)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No