Supplementary figures and methods
Supplementary figures and methods
Files in this Data Supplement:
- Supplementary figures and methods -
Online E1. Phantom airway consisting of ten sequential tubes constructed by drilling holes of known diameter (2.6-50.0 mm) through a solid plastic block. A catheter containing the fibre-optic probe is passed longitudinally through the centre of the phantom. Upon rotation of the probe, a cross-sectional image of the tube is displayed on a monitor. As the probe is mechanically retracted along the phantom, each of the tubes is imaged in turn. Three sites along each of the 10 tubes were selected for measurement of diameter and cross-sectional area.
Online E2. aOCT probe (A) passed through a bronchoscope and inserted into a resuscitation mannequin. The bronchoscope tip (B) is seen at the bottom of the mannequin, with the probe further advanced through the airway phantom (C; see online E1 for internal phantom characterisation). Sites of maximal probe curvature are indicated (D).
Online E3. Use of impedance plethysmography to equilibrate lung volume between awake and anaesthetised states in a human subject. Baseline awake FRC was determined after a period of quiet tidal breathing (left-most panel, indicated by dashed purple lines). Following anaesthetic induction, FRC falls to a new anaesthetised baseline. The anaesthetised baseline is then increased, returning it back to the awake baseline FRC using positive end-expiratory pressure (PEEP) and pressure support (PS).
Online E4. Distribution of analysed airway generations during the computed tomography (CT) - anatomical optical coherence tomography (aOCT) comparison.
Online E5. Linear correlation of computed tomography (CT) and anatomical optical coherence tomography (aOCT) measurements of A internal lumen area (Ai) and B short axis diameter in human airways from the trachea to subsegmental airways.
Online E6. Theoretical internal area (Ai) measurement error resulting when a hollow tube is scanned at oblique angles (A). Experimental measurement errors obtained from scanning a hollow cylinder (length 50 mm x diameter 20 mm) with anatomical optical coherence tomography (aOCT) with the probe oriented at increasingly oblique angles from the tube axis (B).
Online E7. Effect of probe axial position on internal area (Ai) measurements in a hollow cylinder (length 50 mm x diameter 30 mm; calculated Ai 706.4 mm2). Axial slices were scanned using anatomical optical coherence tomography (aOCT) with the probe parallel to the cylinder but positioned at increasing distances from the centre axis.
Methods
- Anatomical optical coherence tomography
- Phantom airway construction
- In-vivo human airways