Comparison of inspiratory and expiratory lung and lobe volumes among supine, standing, and sitting positions using conventional and upright CT

Abstract

Currently, no clinical studies have compared the inspiratory and expiratory volumes of unilateral lung or of each lobe among supine, standing, and sitting positions. In this prospective study, 100 asymptomatic volunteers underwent both low-radiation-dose conventional (supine position, with arms raised) and upright computed tomography (CT) (standing and sitting positions, with arms down) during inspiration and expiration breath-holds and pulmonary function test (PFT) on the same day. We compared the inspiratory/expiratory lung/lobe volumes on CT in the three positions. The inspiratory and expiratory bilateral upper and lower lobe and lung volumes were significantly higher in the standing/sitting positions than in the supine position (5.3–14.7% increases, all P < 0.001). However, the inspiratory right middle lobe volume remained similar in the three positions (all P > 0.15); the expiratory right middle lobe volume was significantly lower in the standing/sitting positions (16.3/14.1% decrease) than in the supine position (both P < 0.0001). The Pearson’s correlation coefficients (r) used to compare the total lung volumes on inspiratory CT in the supine/standing/sitting positions and the total lung capacity on PFT were 0.83/0.93/0.95, respectively. The r values comparing the total lung volumes on expiratory CT in the supine/standing/sitting positions and the functional residual capacity on PFT were 0.83/0.85/0.82, respectively. The r values comparing the total lung volume changes from expiration to inspiration on CT in the supine/standing/sitting positions and the inspiratory capacity on PFT were 0.53/0.62/0.65, respectively. The study results could impact preoperative CT volumetry of the lung in lung cancer patients (before lobectomy) for the prediction of postoperative residual pulmonary function, and could be used as the basis for elucidating undetermined pathological mechanisms. Furthermore, in addition to morphological evaluation of the chest, inspiratory and expiratory upright CT may be used as an alternative tool to predict lung volumes such as total lung capacity, functional residual capacity, and inspiratory capacity in situation in which PFT cannot be performed such as during an infectious disease pandemic, with relatively more accurate predictability compared with conventional supine CT.

Effect of gravity on brain structure as indicated on upright computed tomography

“…An upright computed tomography (CT) scanner, whose physical characteristics are comparable to those of a conventional CT machine, has recently been developed 6 . The usefulness of upright CT has been already shown in other studies 6 – 8 . This CT scanner can acquire 0.5-mm iso-voxel data 6 , which are much thinner slice thicknesses than the 4.0–5.0-mm slice thicknesses obtained in previous MRI studies 1 , 2 .…”

Effects of Body Position on the Outcome of Pulmonary Function Tests in Non-Mechanically Ventilated Adults: A Brief Review

“…Upright posture is associated with higher lung volumes due to descent of diaphragm which causes greater elastic recoil of lung and chest wall. 8 Upright sitting elicits a stronger contraction of abdominal muscles which leads to an increase in intrathoracic pressure causing a forceful expiration. The excursions of the inspiratory muscles occur unhindered in sitting compared to lying position.…”

Three-dimensional evaluation of the coccyx movement between supine and standing positions using conventional and upright computed tomography imaging

“…Among the 16 women, nine had given birth (all vaginal deliveries) and seven had not. The 32 enrolled volunteers had been analyzed for different purposes in previous studies that evaluated the vena cava, aorta, and pelvic floor 19 as well as the brain 20 and lung volume 21 , 22 but did not evaluate movement of the coccyx. All volunteers prospectively underwent conventional 320-detector row CT imaging (supine CT) (Aquilion ONE, Canon Medical Systems Corporation, Japan) in the supine position, as well as upright CT imaging (prototype TSX-401R, Canon Medical Systems Corporation, Japan) 18 – 22 in the standing position on the same day.…”