Dead Space Ventilation in Old Age

¹ From the Departments of Medicine and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, New York

Eighteen normal men between the ages of 68 and 89 years have been studied from the standpoint of respiratory function. In all instances basal oxygen consumption was low, but the mean minute volume of ventilation and respiratory frequency were high. Large anatomic dead space volumes were measured, but alveolar ventilation was normal since alveolar gas values did not vary significantly from young adult standards. All subjects showed an arterial oxygen saturation of about 90% with a wide alveolar-arterial oxygen tension difference, and a significant arterial-alveolar CO₂ tension difference was measured in some subjects. The shape of the expired CO₂ curve and marked fall in the respiratory exchange ratio throughout expiration provided evidence for a maldistribution of alveolar ventilation-blood flow ratios throughout the lung in some individuals. An explanation for the arterial-alveolar CO₂ gradient (alveolar dead space) has been sought in the distribution anomaly.

This article has been cited by other articles:

				N.G. Koulouris, P. Latsi, J. Dimitroulis, B. Jordanoglou, M. Gaga, and J. Jordanoglou Noninvasive measurement of mean alveolar carbon dioxide tension and Bohr's dead space during tidal breathing Eur. Respir. J., June 1, 2001; 17(6): 1167 - 1174. [Abstract] [Full Text] [PDF]

				D. S. DELOREY and T. G. BABB Progressive Mechanical Ventilatory Constraints with Aging Am. J. Respir. Crit. Care Med., July 1, 1999; 160(1): 169 - 177. [Abstract] [Full Text]

				J. S. Williams and T. G. Babb Differences between estimates and measured PaCO2 during rest and exercise in older subjects J Appl Physiol, July 1, 1997; 83(1): 312 - 316. [Abstract] [Full Text] [PDF]