The effects of hypoxemia on cardiac output. A dose-response curve.

B. A. Phillips, J. W. McConnell, M. D. Smith

Research output: Contribution to journalArticlepeer-review

43 Scopus citations


To establish a dose-response curve for the effects of isocapnic hypoxemia on cardiac output (CO), we studied 20 healthy men, aged 20 to 34 years, using a tight-fitting face mask and an isocapnic partial rebreathing system (a modified anesthesia machine). We blended oxygen and hypoxic gas to achieve arterial oxygen saturations (SaO2) of 80, 85, and 90 percent; subjects also breathed 100 percent oxygen and room air (RA). Target SaO2 and end-tidal carbon dioxide were continuously monitored using an ear oximeter and CO2 gas analyzer. Subjects experienced the five SaO2 measurements in random order. CO was measured noninvasively at approximately two-minute intervals, using continuous-wave Doppler echocardiography. Mean cardiac output increased with increasing hypoxemia from 6.84 L/min at FIo2 1.0 to 8.44 L/min at SaO2 80 percent (p less than 0.0005); the increase was entirely due to increased heart rate. We concluded that cardiac output increases significantly in a dose-response manner in response to acute isocapnic hypoxemia in normal persons.

Original languageEnglish
Pages (from-to)471-475
Number of pages5
Issue number3
StatePublished - Mar 1988

Bibliographical note

Funding Information:
Supported by a grant from the American Lung Association of Kentucky.

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine
  • Cardiology and Cardiovascular Medicine


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