Comparison of different methods of heart rate entropy analysis during acute anoxia superimposed on a chronic rat model of pulmonary hypertension

Multiscale Entropy Analysis of Short Signals: The Robustness of Fuzzy Entropy-Based Variants Compared to Full-Length Long Signals

Multiscale entropy (MSE) analysis is a fundamental approach to access the complexity of a time series by estimating its information creation over a range of temporal scales. However, MSE may not be accurate or valid for short time series. This is why previous studies applied different kinds of algorithm derivations to short-term time series. However, no study has systematically analyzed and compared their reliabilities. This study compares the MSE algorithm variations adapted to short time series on both human and rat heart rate variability (HRV) time series using long-term MSE as reference. The most used variations of MSE are studied: composite MSE (CMSE), refined composite MSE (RCMSE), modified MSE (MMSE), and their fuzzy versions. We also analyze the errors in MSE estimations for a range of incorporated fuzzy exponents. The results show that fuzzy MSE versions-as a function of time series length-present minimal errors compared to the non-fuzzy algorithms. The traditional multiscale entropy algorithm with fuzzy counting (MFE) has similar accuracy to alternative algorithms with better computing performance. For the best accuracy, the findings suggest different fuzzy exponents according to the time series length.

Altered sympathovagal balance and pain hypersensitivity in TNBS-induced colitis

INTRODUCTION

Pain hypersensitivity, abnormal motility and autonomic dysfunction contribute to functional symptoms of inflammatory bowel disease (IBD).

MATERIAL AND METHODS

The aim of this study was to assess: nociceptive thresholds for mechanical allodynia (MA) and thermal hyperalgesia (TH), intestinal motility (distal colonic transit and emptying), and cardiac autonomic neuropathy (indices of heart rate variability - HRV) in male Wistar rats with experimental trinitrobenzene sulfonic acid (TNBS) induced colitis. To identify a potential vagal contribution the bilateral subdiaphragmatic vagotomy (SDV) was performed.

RESULTS

Experimental colitis resulted in a significant decrease in pain threshold (MA 23.60 ±2.12, p < 0.001, TH 8.51 ±1.49, p < 0.001), reduced expulsion time (6.2 ±3.5, p < 0,01) and increase in the sympathetic autonomic activity (LFnu 32.54 ±21.16, p < 0.03). The animals with diminished vagal integrity presented with reduced gastrointestinal motility (39.8 ±25.1, p < 0.01) and a decrease in the parasympathetic high-frequency domain of HRV (HFnu 55.37 ±22.80, p < 0.002). The vagotomized rats with colitis showed the strongest nociceptive response (MA 22.46 ±3.02, p < 0.004; TH 7.99 ±1.12, p < 0.003) as well as significant changes in sympatho-vagal balance on HRV testing (LFnu 28.25 ±14.66, p < 0.04; HFnu 71.34 ±14.55, p < 0.04).

CONCLUSIONS

The relationship between the cardiovascular and gastrointestinal system is modulated by neural, hormonal and inflammatory factors. This leads to dysregulation of the brain-gut interactions in the course of IBD. Sensitization and visceral-somatic convergence trigger pain hypersensitivity and autonomic sympathovagal imbalance. While integral vagal innervation impacts analgesic mechanisms via modulation of the immune response, SDV raises sympathetic activity and induces excessive hyperalgesia.

Toward the improvement in fetal monitoring during labor with the inclusion of maternal heart rate analysis

Fetal heart rate (FHR) monitoring is used routinely in labor, but conventional methods have a limited capacity to detect fetal hypoxia/acidosis. An exploratory study was performed on the simultaneous assessment of maternal heart rate (MHR) and FHR variability, to evaluate their evolution during labor and their capacity to detect newborn acidemia. MHR and FHR were simultaneously recorded in 51 singleton term pregnancies during the last two hours of labor and compared with newborn umbilical artery blood (UAB) pH. Linear/nonlinear indices were computed separately for MHR and FHR. Interaction between MHR and FHR was quantified through the same indices on FHR-MHR and through their correlation and cross-entropy. Univariate and bivariate statistical analysis included nonparametric confidence intervals and statistical tests, receiver operating characteristic curves and linear discriminant analysis. Progression of labor was associated with a significant increase in most MHR and FHR linear indices, whereas entropy indices decreased. FHR alone and in combination with MHR as FHR-MHR evidenced the highest auROC values for prediction of fetal acidemia, with 0.76 and 0.88 for the UAB pH thresholds 7.20 and 7.15, respectively. The inclusion of MHR on bivariate analysis achieved sensitivity and specificity values of nearly 100 and 89.1%, respectively. These results suggest that simultaneous analysis of MHR and FHR may improve the identification of fetal acidemia compared with FHR alone, namely during the last hour of labor.

Gender-specific heart rate dynamics in severe intrauterine growth-restricted fetuses

BACKGROUND

Management of intrauterine growth restriction (IUGR) remains a major issue in perinatology.

AIMS

The objective of this paper was the assessment of gender-specific fetal heart rate (FHR) dynamics as a diagnostic tool in severe IUGR.

SUBJECTS

FHR was analyzed in the antepartum period in 15 severe IUGR fetuses and 18 controls, matched for gestational age, in relation to fetal gender.

OUTCOME MEASURES

Linear and entropy methods, such as mean FHR (mFHR), low (LF), high (HF) and movement frequency (MF), approximate, sample and multiscale entropy. Sensitivities and specificities were estimated using Fisher linear discriminant analysis and the leave-one-out method.

RESULTS

Overall, IUGR fetuses presented significantly lower mFHR and entropy compared with controls. However, gender-specific analysis showed that significantly lower mFHR was only evident in IUGR males and lower entropy in IUGR females. In addition, lower LF/(MF+HF) was patent in IUGR females compared with controls, but not in males. Rather high sensitivities and specificities were achieved in the detection of the FHR recordings related with IUGR male fetuses, when gender-specific analysis was performed at gestational ages less than 34 weeks.

CONCLUSIONS

Severe IUGR fetuses present gender-specific linear and entropy FHR changes, compared with controls, characterized by a significantly lower entropy and sympathetic-vagal balance in females than in males. These findings need to be considered in order to achieve better diagnostic results.