title: Revised one-step method for determination of cardiac output.
abstract: Cardiac output (Q) is a determinant of blood pressure and O(2) delivery and is critical in the maintenance of homeostasis, particularly during environmental stress and exercise. Cardiac output can be determined invasively in patients; however, indirect methods are required for other situations. Soluble gas techniques are widely used to determine (Q). Historically, measurements during a breathhold, prolonged expiration and rebreathing to CO(2) equilibrium have been used; however, with limitations, especially during stress. Farhi and co-workers developed a single-step CO(2) rebreathing method, which was subsequently revised by his group, and has been shown to be reliable and compared closely to direct, invasive measures. V(CO2), P(ACO2), and P(VCO2) are determined during a 12-25s rebreathing, using the appropriate tidal volume, and (Q) is calculated. This method can provide accurate data in laboratory and field experiments during exercise, increased or decreased gravity, water immersion, lower body pressure, head-down tilt, altered ambient pressure or changes in inspired gas composition.
authors.affiliation: Department of Physiology and Biophysics, Center for Research and Education in Special Environment, University at Buffalo, 3435 Main Street, Buffalo, NY 14214, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Olszowka
authors.forename: B E
authors.initials: BE
authors.lastname: Shykoff
authors.forename: D R
authors.initials: DR
authors.lastname: Pendergast
authors.forename: L E
authors.initials: LE
authors.lastname: Farhi
mesh_terms: D000465:Algorithms; D001944:Breath Tests / Q000379:methods; D002245:Carbon Dioxide; D002302:Cardiac Output / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D006334:Heart Function Tests / Q000379:methods*; D006801:Humans; D008955:Models, Cardiovascular; D008991:Monitoring, Physiologic / Q000379:methods; D012119:Respiration
chemical_list: D002245:Carbon Dioxide