title: Evaluation by ventilation and perfusion scintigraphy in patients who developed postural hypoxemia in the supine position.
abstract: Ventilation and pulmonary perfusion scintigraphy were performed in 7 patients in whom postural change from the sitting position to the supine position decreased partial oxygen pressure in arteries (PaO2) by 15 mmHg or more. Six of these 7 patients were obese. Five patients had organic pulmonary disease or space occupying lesions of the liver. On lateral supine-position images taken by using the continuous inhalation method for 81mKr ventilation scintigraphy, ventilation was reduced in the dorsal area corresponding to a gravity-dependent area, but on pulmonary perfusion scintigrams, there were no marked changes compared to normal adults. The mismatch of ventilation to perfusion may have caused hypoxemia. Reduced ventilation was correlated with reduced PaO2. The distribution of 81mKr bolus gas inhalation suggested closure of the airway in the dorsal area at functional residual capacity (FRC), which means the resting expiratory level, in the supine position.
authors.affiliation: Department of Internal Medicine, Juntendo University Urayasu Hospital, Chiba, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tominaga
authors.forename: Y
authors.initials: Y
authors.lastname: Fukuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Mori
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D007727:Krypton Radioisotopes; D008168:Lung / Q000000981:diagnostic imaging*; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D016683:Supine Position; D013668:Technetium Tc 99m Aggregated Albumin; D014057:Tomography, X-Ray Computed
chemical_list: D007727:Krypton Radioisotopes; D019275:Radiopharmaceuticals; D013668:Technetium Tc 99m Aggregated Albumin; D010100:Oxygen