Abstract
By computing the ECG R-R intervals and using their coefficients of variation and the autoregressive model, we investigated the characteristics of respiratory-circulatory functions in elderly persons.
Especially for the purpose of analyzing the influences of being bedridden, a comparison was made between a group of those confined to bed and an ADL independent group in the house.
The obtained mean coefficient of variation of the R-R intervals was 1.63±0.62%, showing a tendency to decrease in those older than 60 as their age advanced. Also, of the above two groups, the CV was significantly lower for the group confined to bed than for the other group.
By applying a time series of R-R intervals to the autoregressive model, we found, in the group confined to bed, reductions of 0.2〜0.3 (beat)-1 rhythm, (which represents variation due to respiration); this was attributed to the decline of respiratory-circulatory functions caused by disuse.
