title: Breath-by-breath measurement of the volume displaced by diaphragm motion.
abstract: To develop an accurate method to measure the volume displaced by diaphragm motion (DeltaVdi) breath by breath, we compared DeltaVdi measured by a previously evaluated biplanar radiographic method (Singh B, Eastwood PR, and Finucane KE. J Appl Physiol 91: 1913-1923, 2001) at several lung volumes during vital capacity inspirations in 10 healthy and nine hyperinflated subjects with 1) DeltaVdi measured from the same chest X-rays by two previously described uniplanar methods (Petroll WM, Knight H, and Rochester DF. J Appl Physiol 69: 2175-2182, 1990; Verschakelen JA, Deschepper K, and Demendts M. J Appl Physiol 72: 1536-1540, 1992) and a proposed method that considered actual cross-sectional shape of the rib cage and spinal volume (DeltaVdi(S)); and 2) DeltaVdi(S) measured by lateral fluoroscopy in the same 10 healthy subjects. Relative to biplanar DeltaVdi, DeltaVdi(S) values from lateral chest X-rays and fluoroscopy were not different, whereas DeltaVdi values of Petroll et al. and Verschakelen et al. were increased by (means +/- SD) 1.98 +/- 1.59 and 1.16 +/- 0.82 liters, respectively (both P < 0.001). During quiet breathing, DeltaVdi(S) by lateral fluoroscopy was 66 +/- 16% of tidal volume and similar to that between functional residual capacity and one-half inspiratory capacity by the biplanar radiographic method. We conclude that accurate breath-by-breath measurements of DeltaVdi can be made by using lateral fluoroscopy.
authors.affiliation: Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands, Western Australia 6009, Australia. Bhajan.Singh@health.wa.gov.au
authors.forename: Bhajan
authors.initials: B
authors.lastname: Singh
authors.forename: Janine A
authors.initials: JA
authors.lastname: Panizza
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Finucane
mesh_terms: D000328:Adult; D000465:Algorithms; D002855:Chromatography, Thin Layer; D003964:Diaphragm / Q000033:anatomy & histology* / Q000000981:diagnostic imaging / Q000502:physiology*; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D013902:Radiography, Thoracic; D012016:Reference Values; D012119:Respiration; D015656:Respiratory Mechanics / Q000502:physiology; D013116:Spinal Cord / Q000033:anatomy & histology / Q000502:physiology; D013990:Tidal Volume / Q000502:physiology