title: Rest and exercise cardiac output and diffusing capacity assessed by a single slow exhalation of methane, acetylene, and carbon monoxide.
abstract: To study rest and exercise pulmonary capillary blood flow (Qc) and diffusing capacity (DLexh) assessed by the rapid analysis of methane, acetylene, and carbon monoxide during a single, slow exhalation, we evaluated 36 subjects during first-pass radionuclide angiography (RNA). At rest (N = 36) and at exercise (N = 21) there was no difference in the respective measurements of cardiac output (Qc = 6.0 +/- 1.7 and CORNA = 6.9 +/- 2.5 at rest; Qc = 13.7 +/- 3.2 and CORNA = 14.5 +/- 4.1 at exercise, L/min, mean +/- SD, r = .80). Mild maldistribution of ventilation, as manifested by an increased phase 3 alveolar slope for methane (CH4 slope), did not significantly influence the results. CH4 slope and DLexh did increase significantly with exercise, while total lung capacity remained unchanged (CH4 slope: 6.2 +/- 5.0 vs 12.5 +/- 6.8% delta CH4/L, mean +/- SD, p less than 0.001; Dsb: 27.7 +/- 9.2 vs 42.0 +/- 17.9 ml/min/mm Hg, mean +/- SD, p less than 0.001; TLC: 5.47 +/- .20 vs 5.96 +/- 1.20 L, mean +/- SD). DLexh was related to CORNA (r = .68) and RNA stroke volume (r = .50). Qc was significantly less than CORNA in the subset of studies with valvular regurgitation (VHD) (N = 7). On the other hand, Qc was significantly greater than CORNA in the setting of coronary artery disease (CAD) and severe wall motion abnormalities (N = 7). These differences may be attributed to regurgitant fractions in VHD, and the influence of wall motion abnormalities on the estimation of left ventricular volume by the area-length method in CAD. These two noninvasive methods compare well at rest and exercise in clinical subjects and may provide complementary information in certain cardiopulmonary diseases.
authors.forename: J E
authors.initials: JE
authors.lastname: Ramage
authors.forename: R E
authors.initials: RE
authors.lastname: Coleman
authors.forename: N R
authors.initials: NR
authors.lastname: MacIntyre
mesh_terms: D000114:Acetylene / Q000032:analysis*; D000293:Adolescent; D000328:Adult; D002248:Carbon Monoxide / Q000032:analysis*; D002302:Cardiac Output; D002648:Child; D003327:Coronary Disease / Q000503:physiopathology; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging; D006349:Heart Valve Diseases / Q000503:physiopathology; D006801:Humans; D007201:Indicator Dilution Techniques; D008168:Lung / Q000378:metabolism / Q000502:physiology; D008176:Lung Volume Measurements; D008297:Male; D008697:Methane / Q000032:analysis*; D008875:Middle Aged; D005082:Physical Exertion; D011652:Pulmonary Circulation; D011653:Pulmonary Diffusing Capacity; D011877:Radionuclide Imaging; D012119:Respiration; D012146:Rest
chemical_list: D002248:Carbon Monoxide; D000114:Acetylene; D008697:Methane