Estimation of Arterial CO₂ Tension by Rebreathing Technique

¹ From the Department of Internal Medicine, College of Medical Evangelists, the Chest Disease Service of Los Angeles County Hospital, and White Memorial Hospital, Los Angeles, California

It has been shown that the mixed venous CO₂ tension can be determined by a rebreathing technique, using rapid infrared CO₂ analysis. Theoretical analysis by Suskind and Rahn indicates that the arteriovenous CO₂ tension difference is reasonably constant regardless of the cardiac output. Therefore it should be possible to estimate the arterial CO₂ tension once the mixed venous tension is determined. This hypothesis was investigated in a group of 60 consecutive patients with heart or lung disease. Many of the patients had severe pulmonary emphysema with CO₂ retention. The end-tidal and mixed venous CO₂ tensions were determined. A constant arteriovenous CO₂ tension difference of 6 mm Hg was assumed in all cases and the arterial Pco₂ calculated. The deviation by this method, from directly measured arterial CO₂ tension averaged +0.2 mm Hg with a standard deviation of 2.9 mm Hg (maximum errors observed ±5.3 mm Hg).

This article has been cited by other articles:

				G. Laszlo Respiratory measurements of cardiac output: from elegant idea to useful test J Appl Physiol, February 1, 2004; 96(2): 428 - 437. [Abstract] [Full Text] [PDF]

				A. Baydur, E. Layne, H. Aral, N. Krishnareddy, R. Topacio, G. Frederick, and W. Bodden Long term non-invasive ventilation in the community for patients with musculoskeletal disorders: 46 year experience and review Thorax, January 1, 2000; 55(1): 4 - 11. [Abstract] [Full Text]