Studies on the physiology of the cardiovascular system suggested that the generation of the heart rate signal is governed by nonlinear chaotic dynamics. No study investigated the nonlinear dynamics of heart rate in hyperthyroidism. We examined whether the heart rate dynamics of hyperthyroid patients is different from normal controls by the nonlinear analysis of heart rate variability (HRV) with correlation dimension (CD). Thirty-three hyperthyroid Graves' disease patients (30 females and 3 males; age 31 +/- 1 years, means +/- SE) and 33 sex-, age-, and body mass index-matched normal controls were recruited to receive one-channel electrocardiogram recording for 30 min. The CD, an index of complexity, was computed from the sequence of normal R-R intervals by the Grassberger and Procaccia algorithm. Compared to the normal controls, the hyperthyroid patients showed significant reductions (P < 0.001) in the mean R-R interval (hyperthyroid 616 +/- 15 versus control 868 +/- 16 ms), the standard deviation of R-R intervals (25 +/- 2 versus 54 +/- 4 ms) and CD (5.02 +/- 0.11 versus 6.42 +/- 0.16). Our study demonstrated for the first time that hyperthyroid patients and normal controls could be distinguished by CD analysis of HRV. In addition, the decreased CD in hyperthyroid patients implies reduced complexity and impaired tolerance to cardiovascular stresses in hyperthyroidism. This finding helps to explain exercise intolerance and irritability manifested by the hyperthyroid patients.
The aim of this study was to establish a scoring system, Neonatal Facial Image Scoring System (NFISS), for investigating the pain responses in neonates during routine venipuncture. We collected 1998 facial images from 19 infants during the first phase of this study and identified twelve features of the facial image: normalized scale for NFISS (scale from 0-15), including brow bulge (0-2), vertical brow furrowing (0-1) and short distance (0-1), brow lowering (0-1), eyes close (0-1), bulging eyes (0-2), eye-eye furrowing (0-1), cheek bulge (0-1), nasal-labial furrowing (0-2), mouth open and stretch (0-1), lip purse (0-1) and taut tongue (0-1). During the second evaluation phase, with 2770 images from 31 newborn infants (average age: 2.85°”.027 days), the pain responses were graded on the NFISS scale. Two peak score values during a time course of baseline-venipuncture-recovery (3-3-10 min) were found with needle piercing and needle withdrawal. The reliability of the score analysis was evaluated using 492 randomly selected images out of the 2770 images. The results for intra-scorer (author, one week interval) and inter-scorer (author and one experienced nurse) has correlation coefficients of 0.916 and 0.826, respectively.
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