Understanding the mismatch between in-vivo and in-silico rhinomanometry

Area of Science:

• Biomedical Engineering
• Medical Device Design
• Respiratory Physiology

Background:

• Clinical measurements and numerical simulations of nasal resistance show significant quantitative disagreements, often exceeding 100%.
• Existing known sources of uncertainty do not adequately explain this large mismatch in nasal resistance data.

Purpose of the Study:

• To investigate a previously unconsidered source of bias in rhinomanometry: the design of the medical device itself.
• To evaluate the impact of the ambient pressure probe's location on the accuracy of rhinomanometer measurements.

Main Methods:

• Rhinomanometry was performed on a 3D silicone model of patient-specific nasal anatomy.
• A clinical rhinomanometer and dedicated sensors were used concurrently for validation.
• Numerical simulations of airflow were conducted using various fidelity levels on the same anatomical model.

Main Results:

• The intrinsic uncertainty of numerical simulations was found to be of minor importance.
• The location of the pressure tap for measuring external pressure critically influences the results.
• Probe placement can account for mismatches comparable to those seen between in-silico and in-vivo data.

Conclusions:

• A systematic bias may exist in current rhinomanometer designs.
• The assumption that external pressure measurements are unaffected by internal flow development may be flawed.
• Optimizing probe placement in rhinomanometers is crucial for improving measurement accuracy.