title: Cardiac output determination during progressive exercise in cystic fibrosis.
abstract: Cardiac output (Q) determination using the equilibrium CO2-rebreathe indirect Fick technique (Equil) to estimate mixed venous PCO2 (Pv-CO2) has been validated during steady state (SS) exercise in subjects with lung disease. A modification of the exponential method using a low concentration of CO2 with an exponential rise in PEt-CO2 (Ex) during rebreathing to estimate Pv-CO2 has been validated during nonsteady state exercise. The purpose of the present study was to validate the Ex method in subjects with lung disease. Q was measured by Ex at every second work load during Prog. Q was measured after 5 min of SS exercise by both Ex and Equil. Arterial PCO2 was estimated from PEtCO2. There was no significant difference in the Q-VO2 relationship during Prog exercise between the combined control and mild (FEV1 > 70%) CF subjects or the moderate and severe CF subjects. Q can be determined in the nonsteady state using the exponential CO2-rebreathe indirect Fick technique in subjects with CF, allowing for noninvasive examination of cardiopulmonary interaction during exercise at a wide range of work loads.
authors.affiliation: Department of Pediatrics, Chedoke Hospital, McMaster University, Hamilton, Canada.
authors.forename: L C
authors.initials: LC
authors.lastname: Lands
authors.forename: G J
authors.initials: GJ
authors.lastname: Heigenhauser
authors.forename: N L
authors.initials: NL
authors.lastname: Jones
mesh_terms: D000328:Adult; D002245:Carbon Dioxide / Q000097:blood / Q000502:physiology; D002302:Cardiac Output; D003550:Cystic Fibrosis / Q000097:blood / Q000503:physiopathology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D011659:Pulmonary Gas Exchange; D012119:Respiration
chemical_list: D002245:Carbon Dioxide