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The Influence of Posture on Airway Diameter, Resistance and Airflow Distribution in Healthy Subjects

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT01893697
Recruitment Status : Completed
First Posted : July 9, 2013
Last Update Posted : May 28, 2015
Information provided by (Responsible Party):
Wilfried De Backer, University Hospital, Antwerp

Tracking Information
First Submitted Date June 27, 2013
First Posted Date July 9, 2013
Last Update Posted Date May 28, 2015
Study Start Date April 2013
Actual Primary Completion Date September 2014   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures
 (submitted: July 2, 2013)
Functional Respiratory Imaging [ Time Frame: 1 study visit (1 day) ]
A low dose 3D spiral high resolution computed tomography (HRCT) scan will be taken on 2 volumes TLC and functional residual capacity (FRC) in both supine and lateral decubitus position. Image post processing is performed to look at local changes in airway or lobar volume [liter] and airway resistance [kiloPascal.seconds/liter] distribution in the lung
Original Primary Outcome Measures Same as current
Change History Complete list of historical versions of study NCT01893697 on Archive Site
Current Secondary Outcome Measures Not Provided
Original Secondary Outcome Measures Not Provided
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
Descriptive Information
Brief Title The Influence of Posture on Airway Diameter, Resistance and Airflow Distribution in Healthy Subjects
Official Title The Influence of Posture on Airway Diameter, Resistance and Airflow Distribution in Healthy Subjects
Brief Summary FRI could give the opportunity to investigate the possible effect of a lateral posture on airway diameter and airflow distributions. This physiological study in healthy subjects may help to identify the role of positioning as an aid in airway clearance techniques for patients with respiratory diseases.
Detailed Description

Many respiratory diseases require a physiotherapeutic treatment that focusses on clearance of excessive mucus from the airways.

The underlying physiological hypothesis why those mucus clearance techniques are effective is based on the development of an optimal expiratory airflow velocity that applies shearing forces on the mucus at the inner surface of the airway. These shearing forces eventually lead to displacement of mucus to the central airways were it could be evacuated.To accomplish optimal velocity with the same expiratory airflow, it is necessary to decrease the airway diameter and hence increase in the airflow velocity. In other words, the airway diameter and resistance are important factors to take into account in mucus clearance techniques.

In many mucus clearance techniques, postural position is used to facilitate this clearance. Clinical trials in patients with chronic obstructive pulmonary disease (COPD) and cystic fibrosis where they combined clearance techniques with different postural positions showed to be effective.

The influence of posture has been evaluated in the lateral decubitus position and resulted in a greater clearance of mucus in the depended lung. The authors suggested that this may be due to a better deflation of the depended lung that is favored by 3 forces: gravity, mediastinum weight and pressure of abdominal viscera on the infra lateral lung. Deflation of this lung leads not only to a decrease in lung volume, but also results in a decrease in airway diameter. Nevertheless, it is not known to what extend this decrease in diameter occurs in a lateral position. Furthermore, an optimal expiratory flow must be retained in the underlying lung at lower lung volumes. These regional changes in the underlying lung cannot be measured by for example classic lung function tests since these test are not sensitive enough. Indeed, Washko et. al. found no significant changes of overall residual volume (RV), total lung capacity (TLC) and vital capacity (VC) between the different positions in healthy subject.

However, Functional respiratory imaging (FRI) is able to assess the regional changes in healthy subjects. This 3D imaging technique in combination with computational fluid dynamics (CFD) is accurate in calculating regional changes such as airway diameter, volume and resistance. In addition, repetitive FRI measures are able to assess lobar expansion, which is an indirect measure of airflow distribution in a specific part of the lung.

Study Type Observational
Study Design Observational Model: Case-Crossover
Time Perspective: Prospective
Target Follow-Up Duration Not Provided
Biospecimen Not Provided
Sampling Method Non-Probability Sample
Study Population Healthy subjects
Condition Healthy Participants
Intervention Other: HRCT scan in a specific postural position
HRCT Scan taken in supine and lateral position
Study Groups/Cohorts Healthy Participants
HRCT scan in a specific postural position
Intervention: Other: HRCT scan in a specific postural position
Publications * Not Provided

*   Includes publications given by the data provider as well as publications identified by Identifier (NCT Number) in Medline.
Recruitment Information
Recruitment Status Completed
Actual Enrollment
 (submitted: May 27, 2015)
Original Estimated Enrollment
 (submitted: July 2, 2013)
Actual Study Completion Date September 2014
Actual Primary Completion Date September 2014   (Final data collection date for primary outcome measure)
Eligibility Criteria

Inclusion Criteria:

  1. Men or female patients age > 18
  2. No respiratory disease in the days prior to the enrollment
  3. Able to perform a lung function tests
  4. Motivated to participate.
  5. Written informed consent from the subject prior to the participation

Exclusion Criteria:

  1. Serious co-morbidity which would interfere with the examinations
  2. One or multiple CT scans of the chest during the last year.
  3. Deformities or complications preventing patients to maintain side lying position during the scanning procedure
Sexes Eligible for Study: All
Ages 18 Years to 40 Years   (Adult)
Accepts Healthy Volunteers Yes
Contacts Contact information is only displayed when the study is recruiting subjects
Listed Location Countries Belgium
Removed Location Countries  
Administrative Information
NCT Number NCT01893697
Other Study ID Numbers RESPT_2013_01
Has Data Monitoring Committee No
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement Not Provided
Responsible Party Wilfried De Backer, University Hospital, Antwerp
Study Sponsor University Hospital, Antwerp
Collaborators Not Provided
Principal Investigator: Wilfried De Backer, MD PhD University Hospital, Antwerp
PRS Account University Hospital, Antwerp
Verification Date May 2015