Induced Relaxation Enhances the Cardiorespiratory Dynamics in COVID-19 Survivors.

Most COVID-19 survivors report experiencing at least one persistent symptom after recovery, including sympathovagal imbalance. Relaxation techniques based on slow-paced breathing have proven to be beneficial for cardiovascular and respiratory dynamics in healthy subjects and patients with various diseases. Therefore, the present study aimed to explore the cardiorespiratory dynamics by linear and nonlinear analysis of photoplethysmographic and respiratory time series on COVID-19 survivors under a psychophysiological assessment that includes slow-paced breathing. We analyzed photoplethysmographic and respiratory signals of 49 COVID-19 survivors to assess breathing rate variability (BRV), pulse rate variability (PRV), and pulse-respiration quotient (PRQ) during a psychophysiological assessment. Additionally, a comorbidity-based analysis was conducted to evaluate group changes. Our results indicate that all BRV indices significantly differed when performing slow-paced breathing. Nonlinear parameters of PRV were more appropriate for identifying changes in breathing patterns than linear indices. Furthermore, the mean and standard deviation of PRQ exhibited a significant increase while sample and fuzzy entropies decreased during diaphragmatic breathing. Thus, our findings suggest that slow-paced breathing may improve the cardiorespiratory dynamics of COVID-19 survivors in the short term by enhancing cardiorespiratory coupling via increased vagal activity.

Optimizing Fall Risk Diagnosis in Older Adults Using a Bayesian Classifier and Simulated Annealing.

The aim of this study was to improve the diagnostic ability of fall risk classifiers using a Bayesian approach and the Simulated Annealing (SA) algorithm. A total of 47 features from 181 records (40 Center of Pressure (CoP) indices and 7 patient descriptive variables) were analyzed. The wrapper method of feature selection using the SA algorithm was applied to optimize the cost function based on the difference of the mean minus the standard deviation of the Area Under the Curve (AUC) of the fall risk classifiers across multiple dimensions. A stratified 60-20-20% hold-out method was used for train, test, and validation sets, respectively. The results showed that although the highest performance was observed with 31 features (0.815 ± 0.110), lower variability and higher explainability were achieved with only 15 features (0.780 ± 0.055). These findings suggest that the SA algorithm is a valuable tool for feature selection for acceptable fall risk diagnosis. This method offers an alternative or complementary resource in situations where clinical tools are difficult to apply.

Analysis of fetal heart rate fluctuations in women diagnosed with preeclampsia during the latent phase of labor.

Introduction: Fetal heart rate variability (fHRV) is a tool used to investigate the functioning of the fetal autonomic nervous system. Despite the significance of preeclampsia, fHRV during the latent phase of labor has not been extensively studied. This study aimed to evaluate fetal cardiac autonomic activity by using linear and nonlinear indices of fHRV analysis in women diagnosed with preeclampsia without hypertensive treatment during gestation, compared to normotensive women during the latent phase of labor. Methods: A cross-sectional and exploratory study was conducted among pregnant women in the latent phase of labor, forming three study groups: normotensive or control (C, 38.8 ± 1.3 weeks of pregnancy, n = 22), preeclampsia with moderate features (P, 37.6 ± 1.4 weeks of pregnancy n = 10), and preeclampsia with severe features (SP, 36.9 ± 1.2 weeks of pregnancy, n = 12). None of the participants received anti-hypertensive treatment during their pregnancy. Linear and nonlinear features of beat-to-beat fHRV, including temporal, frequency, symbolic dynamics, and entropy measures, were analyzed to compare normotensive and preeclamptic groups. Results: Significantly lower values of multiscale entropy (MSE) and short-term complexity index (Ci) were observed in the preeclamptic groups compared to the C group (p < 0.05). Additionally, higher values of SDNN (standard deviation of R-R intervals) and higher values of low-frequency power (LF) were found in the P group compared to the C group. Conclusion: Our findings indicate that changes in the complexity of fetal heart rate fluctuations may indicate possible disruptions in the autonomic nervous system of fetuses in groups affected by undiagnosed preeclampsia during pregnancy. Reduced complexity and shifts in fetal autonomic cardiac activity could be associated with preeclampsia's pathophysiological mechanisms during the latent phase of labor.

Hemodynamic response to low-flow acute supplemental oxygen in idiopathic pulmonary fibrosis and elderly healthy subjects.

BACKGROUND: Hemodynamic response to supplemental oxygen in idiopathic pulmonary fibrosis (IPF) is still not well known. OBJECTIVE: To determine and compare the effect of low-flow acute supplemental oxygen on the hemodynamics of IPF patients and matched healthy subjects. METHODS: Descriptive and comparative study in 20 IPF-patients and 19 Control-subjects, (60-80 years old) breathing ambient air followed by acute nasal low-flow (3 L/min) supplemental oxygen. Non-invasive methods were used during the supine position to evaluate oxygen saturation, heart rate, stroke volume index, cardiac output index, total peripheral resistance and arterial blood pressure. RESULTS: Breathing ambient air, IPF (vs. Control) presented lower values in stroke volume index (38.7 [29.4-43.2] vs. 45.4 [38.4-50.9] mL•kg-1•m2; p=0.009) and cardiac output index (2.484 [2.268 - 2.946] vs. 2.857 [2.628 - 3.054] L•min-1•m-2; p=0.028), with higher total peripheral resistance (1644 [1559-2076] vs. 1505 [1366-1784] dyne•s•cm-5; p=0.017). During supplemental oxygen (vs. ambient air), both groups increased oxygen saturation above 94% (p<0.001) while heart rate decreased about 6 to 8% (p<0.001); stroke volume index increased around 7% in the Control-group (p=0.004) but only 1% in the IPF-group (p=0.017). In addition, IPF showed increments in total peripheral resistance (1644 [1559-2076] vs. 1706 [1554-2278] dyne•s•cm-5; p=0.017) with subsequent decrements in cardiac output index (2.484 [2.268 - 2.946] vs. 2.362 [2.139 - 2.664] L•min-1•m-2; p<0.001). CONCLUSION: Low-flow acute supplemental oxygen in IPF causes a meaningful decrement in cardiac output due to greater reduction in heart rate and increment in total peripheral resistance than matched healthy subjects. Knowing the hemodynamic profile of IPF patients may be helpful in determining their management with supplemental oxygen.