Onset of dyspnea on exertion in elderly and young patients with congestive heart failure

Abstract

We previously reported that dyspnea on exertion in patients with congestive heart failure was not associated with pulmonary function at rest, but was associated with the appearance of the anaerobic threshold and with the respiratory compensation point during exercise. Here we described a study of the influence of aging on the onset of dyspnea on exertion on elderly and in young patients with congestive heart failure. A total of 53 patients were studied: 35 were less than 65-year-old (average age, 47-year-old; 19 men and 16 women) and 18 were more than 65-year-old (average, 70-year-old; 13 men and 5 women). All patients underwent maximal graded exercise testing on a bicycle ergometer. The workload increased according to a ramp protocol, and perceived exertion was evaluated with the Borg scale. The anaerobic threshold, the respiratory compensation point, and the peak V̇O2 were recorded. Values of 13 (somewhat hard) and 17 (very hard) on the Borg scale were considered to mark the start of dyspnea on exertion and an increase in dyspnea on exertion respectively. In the young patients, dyspnea on exertion began at about the time that the anaerobic threshold was reached, and it increased at about the time that the respiratory compensation point was reached. In contrast, elderly patient dyspnea on exertion began 70 seconds after the anaerobic threshold was reached, and it increased 30 seconds after respiratory compensation point was reached. The V̇O2 at the start of dyspnea on exertion and the V̇O2 at the anaerobic threshold correlated more closely in the young patients than in the old patients. The same was true of the V̇O2 at the time that dyspnea on exertion increased and the V̇O2 at the respiratory compensation point. These findings suggest that elderly patients with congestive heart failure are less sensitive to the stimuli that cause dyspnea than are young patients.