Figures
- Figure 1
Schematic illustration of a generic inert gas washout system. Hardware required for washout is relatively simple: a flow meter, a fast-responding inert gas analyser, a gas delivery system, and a patient interface. The equipment-related deadspace volume (VD) can be divided into pre- and post-gas sampling points. Post-gas sampling point VD effectively introduces a small rebreathing chamber. Pre-gas sampling point VD is an extension of anatomical VD. Reproduced from [10] with permission.
- Figure 2
Example of a washout curve. From top to bottom, the breath-by-breath tracings show the volume/flow (red/black), nitrogen (N2) concentration (red), oxygen (O2) concentration (blue), and carbon dioxide (CO2) concentration (green). In this example there are multiple instances of gas leaks, apparent as increases or spikes in nitrogen concentration, where external nitrogen has been entrained and measured by the system. As the test measures the washout of nitrogen from the lungs, nitrogen contained in room air that enters the system will increase the measured gas concentration and over-estimate the LCI [26].
- Figure 3
Bland–Altman plot of the difference in repeated LCI measurements. The difference between LCI measurements is greater at higher LCI values. CF: cystic fibrosis. Reproduced from [31] with permission.
Tables
- Table 1
Summary of potential utility across disease groups
Disease group Use Healthy Assess airway function in individuals too young to perform spirometry Asthma Assess ventilation inhomogeneity Assess asthma control CF Detect early lung damage Tracking longitudinal changes in lung function Assessing response to treatment Bronchiectasis Detect early peripheral airway involvement COPD Detect early peripheral airway involvement BOS Detection of early post-transplant BOS
