Pregnancy induces important changes in the autonomic control. Measures of heart rate (HR) variability and systolic blood pressure (SP) variability are sensitive to those changes. The interactions between HR and SP are complex and strongly non-linear. Therefore they cannot be completely described by linear analysis techniques. A study of joint symbolic dynamics is presented as a new short-term non-linear analysis method to investigate the interactions between HR and SP. Continuous, non-invasive 30 min blood pressure recordings (Portapres) of 25 pregnant and 14 non-pregnant women were analysed. Time series of beat-to-beat HR and SP were extracted. Using the concept of joint symbolic dynamics, HR and SP changes were transformed into a bivariate symbol vector. Subsequently, this symbol vector was transformed into a word series (words consisting of three successive symbols), and the probability of occurrence of each word type was calculated and compared between both groups. Significant differences were found in five word types between pregnant and non-pregnant women: w0,4(0.021+/-0.011 against 0.008+/-0.006; p = 0.022), w4,6(0.020+/-0.010 against 0.007+/-0.003; p = 0.001), w3,2(0.004+/-0.003 against 0.007+/-0.003; p = 0.038), W6,5(0.009+/-0.007 against 0.023+/-0.008; p< 0.001) and w3,6(0.011+/-0.007 against 0.023+/-0.008; p = 0.001). Joint symbolic dynamics provides an efficient non-linear representation of HR and SP interactions that offers simple physiological interpretations.

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Resuscitated patients show a significantly reduced HRV before, during and after TH. Compared to survivors, the non-survivors show a further and significantly decrease of HRV immediately after hypothermia.

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We report on the comparison of simultaneous non-invasive measurements of finger blood pressure obtained at both hands with two Portapres systems. We investigated the impact of altering the measurement location on heart rate and blood pressure variability (HRV,BPV) parameters. Two 30 minutes recordings were done twice in 21 volunteers swapPing the systems. HRV and BPV parameters meanNN, sdNN, HF/P and Fw-Shannon were determined. Left and right side corresponding parameters were compared by U-test and correlations. Coincidence matrices were analysed by Mahalanobis distance. The minimal total divergence in HRV was 4.8%, in systolic BPV 6.7% and diastolic BPV 12.1%. These estimates recommend those parameters for multi-center studies that are insensitive to the measurement location.