title: Regional lung ventilation in humans during hypergravity studied with quantitative SPECT.
abstract: Recently we challenged the view that arterial desaturation during hypergravity is caused by redistribution of blood flow to dependent lung regions by demonstrating a paradoxical redistribution of blood flow towards non-dependent regions. We have now quantified regional ventilation in 10 healthy supine volunteers at normal and three times normal gravity (1G and 3G). Regional ventilation was measured with Technegas ((99m)Tc) and quantitative single photon emission computed tomography (SPECT). Hypergravity caused arterial desaturation, mean decrease 8%, p<0.05 vs. 1G. The ratio for mean ventilation per voxel for non-dependent and dependent lung regions was 0.81±0.12 during 1G and 1.63±0.35 during 3G (mean±SD), p<0.0001. Thus, regional ventilation was shifted from dependent to non-dependent regions. We suggest that arterial desaturation during hypergravity is caused by quantitatively different redistributions of blood flow and ventilation. To our knowledge, this is the first study presenting high-resolution measurements of regional ventilation in humans breathing normally during hypergravity.
authors.affiliation: Department of Anesthesiology and Intensive Care, Karolinska University Hospital Solna, 171 76 Stockholm, Sweden; Department of Physiology and Pharmacology, Section of Anesthesiology and Intensive Care Medicine, Karolinska Institutet, 171 77 Stockholm, Sweden. Electronic address: malin.ax@karolinska.se.
authors.forename: M
authors.initials: M
authors.lastname: Ax
authors.forename: L L
authors.initials: LL
authors.lastname: Karlsson
authors.forename: A
authors.initials: A
authors.lastname: Sanchez-Crespo
authors.forename: S G E
authors.initials: SG
authors.lastname: Lindahl
authors.forename: D
authors.initials: D
authors.lastname: Linnarsson
authors.forename: M
authors.initials: M
authors.lastname: Mure
authors.forename: J
authors.initials: J
authors.lastname: Petersson
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D018471:Hypergravity; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D010477:Perfusion; D011601:Psychophysics; D012123:Pulmonary Ventilation; D015899:Tomography, Emission-Computed, Single-Photon; D055815:Young Adult
keywords: Human centrifuge; Technegas; Technetium; Ventilation-to-perfusion mismatch