Physiological measurement
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Analysis of human eye pupil reactivity is a very valuable diagnostic method used mainly for evaluation of the condition of the autonomic nervous system and the visual system. The paper presents an experimental pupillometer built in the Institute of Physics of the Wroclaw University of Technology. ⋯ The detector system used in the pupillometer allows us to record the pupil diameter at a rate of 90 Hz with a linear accuracy of 0.008 mm. In this paper, the proposed detection method, the principle of operation and calibration of the apparatus and the possibilities of the measurement system are presented.
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Physiological measurement · Jan 2007
Correlations between frequency-domain HRV indices and lagged Poincaré plot width in healthy and diabetic subjects.
The conventional Poincaré plot for heart rate variability (HRV) analysis is a scatterplot of successive (lag 1) pairs of RR intervals (intervals between heartbeats), and its width (SD1) is considered a measure of short-term variability. It has been shown that SD1 correlates better with HF than with LF (high- and low-frequency bands of the spectrum, respectively). Our aim was to assess how these correlations were affected when SD1 was obtained for longer lags. 10 min ECGs were used to construct Poincaré plots with lags of 1-10 heartbeats in two groups of subjects, one with normal HRV and the other with impaired HRV (control and diabetic groups respectively, N = 15 each). ⋯ In the control group, SD1 for lags 1 and 2 was highly correlated with HF (r(s) > 0.9), while SD1 for lags 4 correlated better with LF (r(s) 0.9) than with HF (0.65