PT  - JOURNAL ARTICLE
AU  - R. V. Milani
AU  - M. R. Mehra
AU  - T. K. Reddy
AU  - C. J. Lavie
AU  - H. O. Ventura
TI  - Ventilation/carbon dioxide production ratio in early exercise predicts poor functional capacity in congestive heart failure.
AID  - 10.1136/hrt.76.5.393
DP  - 1996 Nov 01
TA  - Heart
PG  - 393--396
VI  - 76
IP  - 5
4099  - http://heart.bmj.com/content/76/5/393.short
4100  - http://heart.bmj.com/content/76/5/393.full
SO  - Heart1996 Nov 01; 76
AB  - OBJECTIVES: To evaluate whether changes in the ventilation/carbon dioxide production ratio during early exercise could reliably serve as a surrogate marker for maximal oxygen consumption in heart failure patients. Maximal oxygen consumption is an important determinant of the severity of congestive heart failure with values > 14 ml/kg/min conferring a good 2-year survival. However, many patients undergoing cardiopulmonary exercise testing cannot exercise maximally because of other functional limitations. METHODS: Ventilation/carbon dioxide production ratio was assessed at rest, anaerobic threshold, and peak exercise in 75 patients with chronic heart failure and in 12 healthy controls. Patients were divided into two groups on the basis of heart failure severity as judged by maximal oxygen consumption. RESULTS: Patients with mild-moderate heart failure had a 20% reduction in the ventilation/carbon dioxide production ratio at anaerobic threshold similar to that in healthy controls. Patients with severe heart failure failed to reduce this ratio at anaerobic threshold. Furthermore, a reduction in the ventilation/carbon dioxide production ratio in early exercise of less than 10% predicted a maximal oxygen consumption of < 14 ml/kg/min with a positive predictive value of 96% and a negative predictive value of 88%. CONCLUSIONS: A reduction of the ventilation/carbon dioxide production ratio of less then 10% with early exercise reliably predicts poor functional capacity in congestive heart failure. Changes in this ratio during early exercise may be used as a surrogate for maximal oxygen consumption in patients who cannot exercise maximally.