Chest, Vol 105, 183-189, Copyright © 1994 by American College of Chest Physicians

ARTICLES

Dead space loading and exercise limitation in patients with interstitial lung disease

DD Marciniuk, RE Watts and CG Gallagher
Department of Medicine, University of Saskatchewan, Saskatoon, Canada.

STUDY DESIGN: We tested the hypothesis that maximal exercise performance in subjects with interstitial lung disease (ILD) is limited by respiratory factors. Assuming this is so, ventilatory stimulation by added dead space (VD) should impair exercise capacity. METHODS: Six subjects with ILD each underwent three maximal incremental exercise studies on a bicycle ergometer; control 1, added VD, and control 2. During the VD study, external VD (500 ml) was added to the circuit, and results obtained were compared with the mean results from the control studies. RESULTS: Exercise duration (TLIM) was significantly less in the VD study when compared to the control study (369 +/- 50 vs 439 +/- 55, p < 0.05), as was work rate (102 +/- 13 vs 125 +/- 14 W, p < 0.05) and peak oxygen uptake per minute (VO2) (1.08 +/- 0.09 vs 1.43 +/- 0.14 L/min, p < 0.05). At end-exercise, the Borg scale was higher in the VD study when compared to the control study (6 +/- 1 vs 5 +/- 1, p < 0.05), while no significant difference in minute ventilation (VI) or oxygen desaturation was noted. When compared to the control study at matched times during exercise, the addition of VD resulted in a significant increase in VI while no significant change was noted in VO2, carbon dioxide output (VcO2), or heart rate (HR). CONCLUSION: The decrease observed in TLIM, work rate, and peak VO2 with added VD, associated with a lack of change in VI or oxygen desaturation at end- exercise, suggests that exercise limitation in ILD is primarily due to respiratory factors.

This article has been cited by other articles:

				E. F. McKone, S. C. Barry, M. X. FitzGerald, and C. G. Gallagher Role of arterial hypoxemia and pulmonary mechanics in exercise limitation in adults with cystic fibrosis J Appl Physiol, September 1, 2005; 99(3): 1012 - 1018. [Abstract] [Full Text] [PDF]

				A. Chauhan, G. Sridhar, R. Clemens, B. Krishnan, D. D. Marciniuk, and C. G. Gallagher Role of Respiratory Function in Exercise Limitation in Chronic Heart Failure Chest, July 1, 2000; 118(1): 53 - 60. [Abstract] [Full Text] [PDF]

				D. E. O'Donnell, H. H. Hong, and K. A. Webb Respiratory sensation during chest wall restriction and dead space loading in exercising men J Appl Physiol, May 1, 2000; 88(5): 1859 - 1869. [Abstract] [Full Text] [PDF]

				B. D. Johnson, K. C. Beck, R. J. Zeballos, and I. M. Weisman Advances in Pulmonary Laboratory Testing Chest, November 1, 1999; 116(5): 1377 - 1387. [Abstract] [Full Text] [PDF]

				E. F. McKone, S. C. Barry, M. X. FitzGerald, and C. G. Gallagher Reproducibility of Maximal Exercise Ergometer Testing in Patients With Cystic Fibrosis Chest, August 1, 1999; 116(2): 363 - 368. [Abstract] [Full Text] [PDF]

				B. D. Johnson, I. M. Weisman, R. J. Zeballos, and K. C. Beck Emerging Concepts in the Evaluation of Ventilatory Limitation During Exercise: The Exercise Tidal Flow-Volume Loop Chest, August 1, 1999; 116(2): 488 - 503. [Abstract] [Full Text] [PDF]