RT Journal Article
SR Electronic
T1 Ventilation/carbon dioxide production ratio in early exercise predicts poor functional capacity in congestive heart failure.
JF Heart
JO Heart
FD BMJ Publishing Group Ltd and British Cardiovascular Society
SP 393
OP 396
DO 10.1136/hrt.76.5.393
VO 76
IS 5
A1 R. V. Milani
A1 M. R. Mehra
A1 T. K. Reddy
A1 C. J. Lavie
A1 H. O. Ventura
YR 1996
UL http://heart.bmj.com/content/76/5/393.abstract
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.