The effect of compressive thyroid goitres on the airway
File(s)
Author(s)
McIntyre, Lottie
Type
Thesis
Abstract
This work comprises an assessment of the use of computational fluid dynamics (CFD) to
investigate the airflow through the tracheas of subjects with symptomatic, compressive,
retrosternal thyroid goitres. In order to do this, 3D volume meshes were created to accurately
represent patients’ airways from individual CT scans. CFD was used to assess airflow through
the tracheas of study subjects undergoing thyroid surgery in a prospective, observational study.
The CFD employed an SST (Menter) K-omega steady RANS turbulence model that was
validated using an experimental model; this RANS-based model was then used to estimate
pressure loss across the pathological tracheas.
Twenty-one subjects were included in the study, and they underwent pre-and post-operative lung function tests and quality of life questionnaires. A geometric analysis was performed on the subjects’ tracheas and the results were correlated with the pressure loss, as estimated by CFD. The results showed that both the minimum cross-sectional area of the trachea (Amin) and the hydraulic diameter of the trachea are very strongly correlated with the pressure loss across the trachea, as estimated using CFD, at flow rates of 15L/min and 30L/min (representing breathing at rest and light exercise respectively).
Using the Amin and a loss co-efficient equation, the pressure loss across the trachea can be
estimated and when comparing the results with the pressure loss estimations using СFD, there
is no significant difference. This presents an opportunity to estimate pressure loss across the trachea in a patient using the Amin, without the need to perform CFD. In a healthy trachea, the estimated pressure loss is thought to be around 5 Pa at 15L/min. Comparing the estimated pressure loss across the trachea in a patient with a compressive goitre with a normal pressure loss of 5 Pa, could add more useful information when deciding whether to operate.
investigate the airflow through the tracheas of subjects with symptomatic, compressive,
retrosternal thyroid goitres. In order to do this, 3D volume meshes were created to accurately
represent patients’ airways from individual CT scans. CFD was used to assess airflow through
the tracheas of study subjects undergoing thyroid surgery in a prospective, observational study.
The CFD employed an SST (Menter) K-omega steady RANS turbulence model that was
validated using an experimental model; this RANS-based model was then used to estimate
pressure loss across the pathological tracheas.
Twenty-one subjects were included in the study, and they underwent pre-and post-operative lung function tests and quality of life questionnaires. A geometric analysis was performed on the subjects’ tracheas and the results were correlated with the pressure loss, as estimated by CFD. The results showed that both the minimum cross-sectional area of the trachea (Amin) and the hydraulic diameter of the trachea are very strongly correlated with the pressure loss across the trachea, as estimated using CFD, at flow rates of 15L/min and 30L/min (representing breathing at rest and light exercise respectively).
Using the Amin and a loss co-efficient equation, the pressure loss across the trachea can be
estimated and when comparing the results with the pressure loss estimations using СFD, there
is no significant difference. This presents an opportunity to estimate pressure loss across the trachea in a patient using the Amin, without the need to perform CFD. In a healthy trachea, the estimated pressure loss is thought to be around 5 Pa at 15L/min. Comparing the estimated pressure loss across the trachea in a patient with a compressive goitre with a normal pressure loss of 5 Pa, could add more useful information when deciding whether to operate.
Version
Open Access
Date Issued
2022-10
Date Awarded
2024-02
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Tolley, Neil
Doorly, Denis
Sponsor
Royal College of Surgeons of England
Publisher Department
Department of Aeronautics and Department of Surgery and Cancer
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)