2009 Volume 129 Issue 1 Pages 1-7
Many reports show that dominant frequency of high frequency component(HF:0.15∼0.4Hz) of heart rate time series is synchronized with the respiratory frequency. In this paper, we proposed the method for estimating the condition of respiration continuously using dominant frequency and power of HF (HFP) of heart rate time series. Dominant frequency and HFP is calculated from the interval of the neighboring two extreme points and the subtraction of the neighboring two extremals.In the experimental results, high frequency components did not disappear completely during breath-holding. This fact is different from the previous study. Subjects were classified into two groups. In one group, dominant frequency of the HF is significant increased during breath-holding compared with normal breathing. In the other group, this phenomenon was not observed. On the other hand, HFP of total subjects significantly decreased during breath-holding compared with normal breathing. Correct rate during breath-holding and error rate during rest and recovery are calculated using HFP. In the results, average and S. D. of correct rate during breath-holding were 65.0±26.3%. Correct rate of 18 subjects was 80.0±14.1% and correct rate of other 8 subjects was 31.5±11.9%. Our method is expected to apply to the development of the respiratory monitor which can measure respiratory condition with non-restricted in continuously.