2001 Volume 68 Issue 3 Pages 246-252
Dyspnea is a major clinical symptom of various respiratory diseases. However, no objective assessment of dyspnea on exertion (DOE) in elderly subjects has been established yet. Furthermore, the factors which may influence DOE in healthy elderly subjects have not yet been precisely elucidated. An oxygen cost diagram (OCD), which was originally developed by McGavin (1978), is one of the methods of assessing dyspnea on exertion in a semi-quantitative way, although it is still uncertain which factor (s) might influence the changes in OCD values. The present study was, therefore, undertaken to study; 1) whether OCD values are useful for the assessment of DOE in elderly subjects, and 2) the possible factors (s) which might contribute to changes in OCD values in these patients.
The total number of subjects which were enrolled in the present study was 818, consisting of 355men and 463 women, whose mean age was 76.4 years old, was studied. Spirometry, arterial blood gases and OCD values were measured on the same day. The OCD value and FEV1.0 declined linearly with advanced aging. It was found that the factors which significantly reduce OCD values were as follows: aging, vital capacity, FEV1.0, and maximal voluntary ventilation (MVV). The odd ratio which contributes to changes in OCD values was calculated. It appeared that there was a gender difference: when the odd ratio of OCD values of less than 70 was taken as 1 in the men, the odd ratio in women was calculated as 1.42. The odd ratio increased with advancing age; when the value in the 65~69 year-old group was 1, the odd ratios in the 85~89 year-old and 90~94 year-old groups were in approximately 6 and 8, respectively. Similarly, the odd ratio increased parallel with reduction in MVV.
From these results, we conclude that the OCD value is reliable, simple and the best method of evaluating dyspnea in elderly subjects semi-quantitively, and both the minute ventilatory volume and age are closely related with changes in OCD values.
