Cardiac output during exercise by the open circuit acetylene washin method: Comparison with direct Fick

Bruce David Johnson, K. C. Beck, D. N. Proctor, Jordan D Miller, N. M. Dietz, Michael Joseph Joyner

Research output: Contribution to journalArticle

108 Citations (Scopus)

Abstract

An open-circuit (OpCirc) acetylene uptake cardiac output (Q̇T) method was modified for use during exercise. Two computational techniques were used. OpCirc1 was based on the integrated uptake vs. end-tidal change in acetylene, and OpCirc2 was based on an iterative finite difference modeling method. Six subjects [28-44 yr, peak oxygen consumption (V̇O 2) = 120% predicted] performed cycle ergometry exercise to compare Q̇T using OpCirc and direct Fick methods. An incremental protocol was repeated twice, separated by a 10- min rest, and subsequently subjects exercised at 85-90% of their peak work rate. Coefficient of variation of the OpCirc methods and Fick were highest at rest (OpCirc1, 7%, OpCirc2, 12%, Fick, 10%) but were lower at moderate to high exercise intensities (OpCirc1, 3%, OpCirc2, 3%, Fick, 5%). OpCirc1 and OpCirc2 Q̇T correlated highly with Fick Q̇T (R 2 = 0.90 and 0.89, respectively). There were minimal differences between OpCirc1 and OpCirc2 compared with Fick up to moderate-intensity exercise (<70% peak V̇O 2); however, both techniques tended to underestimate Fick at >70% peak V̇O 2. These differences became significant for OpCirc1 only. Part of the differences between Fick and OpCirc methods at the higher exercise intensities are likely related to inhomogeneities in ventilation and perfusion matching (R 2 = 0.36 for Fick - OpCirc1 vs. alveolar-to-arterial oxygen tension difference). In conclusion, both OpCirc methods provided reproducible, reliable measurements of Q̇T during mild to moderate exercise. However, only OpCirc2 appeared to approximate Fick Q̇T at the higher work intensities.

Original languageEnglish (US)
Pages (from-to)1650-1658
Number of pages9
JournalJournal of Applied Physiology
Volume88
Issue number5
StatePublished - May 2000

Fingerprint

Acetylene
Cardiac Output
Ergometry
Oxygen Consumption
Ventilation
Arterial Pressure
Perfusion
Oxygen

Keywords

  • Dead space
  • Inhomogeneity
  • Pulmonary blood flow
  • Solubility

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Cardiac output during exercise by the open circuit acetylene washin method : Comparison with direct Fick. / Johnson, Bruce David; Beck, K. C.; Proctor, D. N.; Miller, Jordan D; Dietz, N. M.; Joyner, Michael Joseph.

In: Journal of Applied Physiology, Vol. 88, No. 5, 05.2000, p. 1650-1658.

Research output: Contribution to journalArticle

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abstract = "An open-circuit (OpCirc) acetylene uptake cardiac output (Q̇T) method was modified for use during exercise. Two computational techniques were used. OpCirc1 was based on the integrated uptake vs. end-tidal change in acetylene, and OpCirc2 was based on an iterative finite difference modeling method. Six subjects [28-44 yr, peak oxygen consumption (V̇O 2) = 120{\%} predicted] performed cycle ergometry exercise to compare Q̇T using OpCirc and direct Fick methods. An incremental protocol was repeated twice, separated by a 10- min rest, and subsequently subjects exercised at 85-90{\%} of their peak work rate. Coefficient of variation of the OpCirc methods and Fick were highest at rest (OpCirc1, 7{\%}, OpCirc2, 12{\%}, Fick, 10{\%}) but were lower at moderate to high exercise intensities (OpCirc1, 3{\%}, OpCirc2, 3{\%}, Fick, 5{\%}). OpCirc1 and OpCirc2 Q̇T correlated highly with Fick Q̇T (R 2 = 0.90 and 0.89, respectively). There were minimal differences between OpCirc1 and OpCirc2 compared with Fick up to moderate-intensity exercise (<70{\%} peak V̇O 2); however, both techniques tended to underestimate Fick at >70{\%} peak V̇O 2. These differences became significant for OpCirc1 only. Part of the differences between Fick and OpCirc methods at the higher exercise intensities are likely related to inhomogeneities in ventilation and perfusion matching (R 2 = 0.36 for Fick - OpCirc1 vs. alveolar-to-arterial oxygen tension difference). In conclusion, both OpCirc methods provided reproducible, reliable measurements of Q̇T during mild to moderate exercise. However, only OpCirc2 appeared to approximate Fick Q̇T at the higher work intensities.",
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