Autonomic Nervous System Regulation Research Articles

On the spatial phase distribution of cutaneous low-frequency perfusion oscillations

Distributed cutaneous tissue blood volume oscillations contain information on autonomic nervous system (ANS) regulation of cardiorespiratory activity as well as dominating thermoregulation. ANS associated with low-frequency oscillations can be quantified in terms of frequencies, amplitudes, and phase shifts. The relative order between these faculties may be disturbed by conditions colloquially termed ‘stress’. Photoplethysmography imaging, an optical non-invasive diagnostic technique provides information on cutaneous tissue perfusion in the temporal and spatial domains. Using the cold pressure test (CPT) in thirteen healthy volunteers as a well-studied experimental intervention, we present a method for evaluating phase shifts in low- and intermediate frequency bands in forehead cutaneous perfusion mapping. Phase shift changes were analysed in low- and intermediate frequency ranges from 0.05 Hz to 0.18 Hz. We observed that time waveforms increasingly desynchronised in various areas of the scanned area throughout measurements. An increase of IM band phase desynchronization observed throughout measurements was comparable in experimental and control group, suggesting a time effect possibly due to overshooting the optimal relaxation duration. CPT triggered an increase in the number of points phase-shifted to the reference that was specific to the low frequency range for phase-shift thresholds defined as π/4, 3π/8, and π/2 rad, respectively. Phase shifts in forehead blood oscillations may infer changes of vascular tone due to activity of various neural systems. We present an innovative method for the phase shift analysis of cutaneous tissue perfusion that appears promising to assess ANS change processes related to physical or psychological stress. More comprehensive studies are needed to further investigate the reliability and physiological significance of findings.

IDF21-0409 Hypoglycemia and heart rate variability: synchronous detection by Holter and continuous glucose monitors

Background: Hypoglycemia is a notorious diabetic side effect leading to unwanted major vascular events and sudden cardiac death due to change in autonomic cardiac function. Previous studies have reported electrocardiographic (ECG) abnormalities such as QT interval prolongation in patients with hypoglycemia, so did heart rate variability (HRV). Aim: To document ECG and HRV changes during hypoglycemia and expect to establish a portable device to early detect hypoglycemia in the future. Method: Seventeen participants including ten poor controlled type 2 diabetes, six type 1 diabetes and one Latent autoimmune diabetes in adults (LADA) were enrolled in this study. There were six males and eleven females, aged from 37 to 77 (mean 50.3 ± 12.0) years old, with self-reported duration of diabetes from 6 to 33 (mean 20.8 ± 8.7) years. The mean HbA1c was 8.3 ± 1.4 % on the time of the examination. We used Holter- electrocardiogram (VitalSigns) and continuous glucose monitor (Medtronic) to record ECG waveform, heart rate variability and glucose level with synchronization of time for a duration of seven days. Results: Two of the seventeen participants did not experience hypoglycemia (≦70 mg/dL). The other participants who experienced hypoglycemia revealed, as a whole, a trend of correlation between blood glucose, corrected QT Interval (QTc), and HRV. When the participants experienced hypoglycemia were sub-divided into response and non-response groups according to the appearance of QTc prolongation, significant difference of age was found between two groups, most of them were type 1 diabetic patients. Among 90 events of hypoglycemia, 56 events (62%) presented with increased heart rate and/or Low Frequency/ High Frequency (LF/HF) ratio and /or decreased Root Mean Square of the Successive Differences (RMSSD). Besides, there were a trend of difference of glucose nadir, HRV include heart rate, RMSSD and LF/HF ratio between two groups. Discussion: In this study, Type 1 DM patient and younger age were easier to have QT interval prolongation during hypoglycemia. Besides, increased LF/HF ratio may represent that these group of patients have better regulation of autonomic nervous system. Heart rate variability can be seen during hypoglycemic events in both type 1 and type 2 diabetic patients especially in the response group.

Validation of a smart shirt for heart rate variability measurements at rest and during exercise.

Heart rate variability (HRV) monitoring is a promising option to estimate the autonomic nervous system regulation responding to exercise. Textiles with embedded sensors recording heartbeat intervals are a simple tool for data collection. The so-called smart shirts offer comfort fordaily use and are managed easily. Their measurement accuracy for HRV calculation at rest is promising, but remains questionable during exercise. Therefore, the present study validated the Ambiotex smart shirt using HRV indices (root mean square of successive differences, rel. HF power [high-frequency power percentage of total power] and rel. LF [low-frequency power percentage of total power] power) during exercise. Eighty-three healthy participants (31 ± 6 years; 39 females, 44 males) completed an incremental exercise test on a bicycle ergometer wearing the smart shirt and an electrocardiogram simultaneously. We compared HRV indices of segments at rest (5 min), at warm-up (3 min) and twice at the exercise test (each 5 min). At rest and at warm-up, we observed excellent linear relationship (r > 0.96; R2 ​​​​​ > 0.94), excellent relative reliability (intraclass correlation coefficient ≥ 0.98; α ≥ 0.98) and acceptable agreement (bias < 10%). During the exercise test, measurement accuracy declined with increasing intensity but remained high (>0.8), although results for partial HRV indices were insufficient. In addition, percentage bias was unacceptable during an exercise test. However, the findings support the validity of the smart shirt for measuring HRV, especially at rest and at warm-up. We suggest using the smart shirt for monitoring HRV indices on a daily basis, but caution should be taken in the interpretation of HRV indices obtained during moderate to vigorous exercise intensities.

Effects of Supplemental Oxygen on Cardiovascular and Respiratory Interactions by Extended Partial Directed Coherence in Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic and restrictive disease characterized by fibrosis and inflammatory changes in lung tissue producing a reduction in diffusion capacity and leading to exertional chronic arterial hypoxemia and dyspnea. Furthermore, clinically, supplemental oxygen (SupplO2) has been prescribed to IPF patients to improve symptoms. However, the evidence about the benefits or disadvantages of oxygen supplementation is not conclusive. In addition, the impact of SupplO2 on the autonomic nervous system (ANS) regulation in respiratory diseases needs to be evaluated. In this study the interactions between cardiovascular and respiratory systems in IPF patients, during ambient air (AA) and SupplO2 breathing, are compared to those from a matched healthy group. Interactions were estimated by time series of successive beat-to-beat intervals (BBI), respiratory amplitude (RESP) at BBI onset, arterial systolic (SYS) and diastolic (DIA) blood pressures. The paper explores the Granger causality (GC) between systems in the frequency domain by the extended partial directed coherence (ePDC), considering instantaneous effects. Also, traditional linear and nonlinear markers as power in low (LF) and high frequency (HF) bands, symbolic dynamic indices as well as arterial baroreflex, were calculated. The results showed that for IPF during AA phase: 1) mean BBI and power of BBI-HF band, as well as mean respiratory frequency were significantly lower (p < 0.05) and higher (p < 0.001), respectively, indicating a strong sympathetic influence, and 2) the RESP SYS interaction was characterized by Mayer waves and diminished RESP BBI, i.e., decreased respiratory sinus arrhythmia. In contrast, during short-term SupplO2 phase: 1) oxygen might produce a negative influence on the systolic blood pressure variability, 2) the arterial baroreflex reduced significantly (p < 0.01) and 3) reduction of RSA reflected by RESP BBI with simultaneous increase of Traube-Hering waves in RESP SYS (p < 0.001), reflected increased sympathetic modulation to the vessels. The results gathered in this study may be helpful in the management of the administration of SupplO2.

The Effects of Heart Rate Variability (HRV) Biofeedback on HRV Reactivity and Recovery During and After Anger Recall Task for Patients with Coronary Artery Disease.

Patients with coronary artery disease (CAD) often experience anger events before cardiovascular events. Anger is a psychological risk factor and causes underlying psychophysiological mechanisms to lose balance of the autonomic nervous system (ANS). The heart rate variability (HRV) was the common index for ANS regulation. It has been confirmed that heart rate variability biofeedback (HRV-BF) restored ANS balance in patients with CAD during the resting state. However, the effects of HRV-BF during and after the anger event remain unknown. This study aimed to examine the effects of HRV-BF on ANS reactivity and recovery during the anger recall task in patients with CAD. This study was a randomized control trial with a wait-list control group design, with forty patients in the HRV-BF group (for six sessions) and 44 patients in the control group. All patients received five stages of an anger recall task, including baseline, neutral recall task, neutral recovery, anger recall task, and anger recovery. HRV reactivity in the HRV-BF group at the post-test was lower than that in the control group. HRV recovery at the post-test in the HRV-BF group was higher than that in the control group. The HRV-BF reduced ANS reactivity during anger events and increased ANS recovery after anger events for CAD patients. The possible mechanisms of HRV-BF may increase total HRV, ANS regulation, and baroreflex activation at anger events for patients with CAD, and may be a suitable program for cardiac rehabilitation.

The Indices of Instantaneous Pulse Rate Variability Are Indicators for Daily Life Quality Assessment in Patients with COPD.

Chronic obstructive pulmonary disease (COPD) is a progressive respiratory illness. Questionnaires such as modified Medical Research Council (mMRC) dyspnea scale and COPD assessment test (CAT) are useful for COPD condition and life quality assessment. These questionnaires reflect how respiratory disorder affects daily life. Breathing and autonomic nervous system (ANS) usually regulate each other. Few studies discussed the ANS activity and daily life quality in patients with COPD. Therefore, this study aimed to find the relationship between daily life quality assessed by mMRC or CAT and ANS assessed by a novel method, instantaneous pulse rate variability (iPRV), a method indicating not only the ANS activity but also the peripheral response. The result showed that the change in mMRC and the change in low frequency power to high frequency power ratio, which usually represents the sympathetic activity in conventional heart rate variability analysis, had significant correlation (r = 0.63; p < 0.05). The change in CAT and the change in high frequency power (regulated by vagal nervous and respiratory system) or very high frequency power (new frequency band can be indicated in iPRV spectrum) had significant negative correlation (r = −0.64 and −0.55, respectively; p < 0.05 for both). This study showed the change in iPRV indices when the condition of COPD was improvement or exacerbation. This study presents a possible way to show how cardiovascular activity affects daily life quality in patients with COPD. Increase in LF or decrease in HF and VHF would cause poorer quality of daily life in patients with COPD. The result can also be a reference for patients with COPD to choose the breathing type to adjust rehabilitation and therapy program for ANS regulation to indicate or improve their daily life quality.

Focal atrial tachycardia originating from the pulmonary vein with onset later than 3 years of age might have a better prognosis, possibly converting in adolescence

Two cases of focal atrial tachycardia probably originating from the pulmonary vein with onset later than 3 years of age are presented. Both cases had associated variable atrioventricular conduction and showed no signs of heart failure, and they converted to sinus rhythm at the time of puberty. In cases of focal atrial tachycardia originating from the pulmonary vein with onset later than 3 years of age, drug therapy may be effective. Even if drug therapy is not effective, changes in the autonomic nervous system are reflected strongly in the pulmonary veins, so that changes in autonomic nervous system regulation with growth might terminate focal atrial tachycardia. Therefore, focal atrial tachycardia originating from the pulmonary vein with onset later than 3 years of age might have a better prognosis.

Heart rate variability dynamics in women with urinary incontinence: a systematic review.

Sympathetic and parasympathetic pathways of the autonomic nervous system (ANS) regulate the lower urinary tract. The aim of the present study was to synthesize the evidence regarding ANS regulation in women with urinary incontinence (UI) evaluated through heart rate variability (HRV). This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA) guideline. Five databases were researched in April 2021 (PubMed, CINHAL, Scopus, Web of Science and Cochrane Library) and included cross-sectional studies in full-length publications in the English language. Studies assessed the HRV during bladder filling (group A) and after voiding (group B). The Joanna Briggs Institute (JBI) checklist was applied for methodological quality assessment purposes. A total of 920 articles were identified and 5 studies were included. Most studies analyzed the HRV by linear indexes. Studies from group A (n = 2) presented fair methodological quality; one study from group B (n = 3) showed fair methodological quality (Im et al. Korean J Urol. 51:183, 2010) whereas the others presented high methodological quality. One study from group A found an increase in both modulations between women with overactive bladder (OAB) versus women with stress UI, whereas a decrease was reported between incontinent and continent women. Studies from group B showed a decreased sympathetic and parasympathetic modulation in AOB with detrusor overactivity (DO), whereas one study found an increase in both modulations in women with OAB compared with stress UI. Parasympathetic and sympathetic modulationincreased during bladder filling and rest in UI with OAB associated or not with DO. Both modulations decreased during bladder filling in incontinent women and during rest in OAB.

Chronic stress, autonomic dysregulation and prospective drug use among African American emerging adults.

Chronic stress is associated with increased vulnerability to drug use and may contribute to drug-related health disparities in the African American community. The underlying physiological mechanisms by which chronic stress confers this increased risk remain unclear. The present study aimed to characterize the impact of chronic and race-related stress exposure on regulatory mechanisms of the autonomic nervous system (ANS) in response to acute stress, to examine John Henryism as potential moderator of this relationship, and to investigate the association between ANS reactivity and subsequent drug use among a sample of African American emerging adults (18-25 years old) in the Southern United States (U.S.). Participants (N = 276) completed self-report measures of chronic and race-related stress and John Henryism and underwent a laboratory-based stressor. ANS reactivity was assessed via heart rate variability (HRV) and skin conductance levels (SCL). At 90-day follow-up, retrospective reports of drug use were provided. Race-related stress was associated with greater SCL reactivity. John Henryism moderated the relationship between chronic stress exposure and HRV reactivity. SCL reactivity was associated with higher rates of alcohol and marijuana use at 90-day follow-up. HRV reactivity was associated with tobacco use at 90-day follow-up. Chronic stress exposure and active coping may interact to affect regulatory mechanisms of the ANS. ANS (dys)regulation may be an important endophenotype for increasing drug use vulnerability among African American emerging adults. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Blood–brain communication Essential for regulation of autonomic nervous system and optimal health?

Blood–brain communication Essential for regulation of autonomic nervous system and optimal health?

Temporal Clustering of Skin Sympathetic Nerve Activity Bursts in Acute Myocardial Infarction Patients.

Backgrounds: Acute myocardial infarction (AMI) affects the autonomic nervous system (ANS) function. The aim of our study is to detect the particular patterns of ANS regulation in AMI. We hypothesize that altered ANS regulation in AMI patients causes synchronized neural discharge (clustering phenomenon) detected by non-invasive skin sympathetic nerve activity (SKNA).Methods: Forty subjects, including 20 AMI patients and 20 non-AMI controls, participated in the study. The wide-band bioelectrical signals (neuECG) were continuously recorded on the body surface for 5 min. SKNA was signal processed to depict the envelope of SKNA (eSKNA). By labeling the clusters, the AMI subjects were separated into non-AMI, non-cluster appearing (AMINCA), and cluster appearing (AMICA) groups.Results: The average eSKNA was significantly correlated with HRV low-frequency (LF) power (rho = −0.336) and high-frequency power (rho = −0.372). The cross-comparison results demonstrated that eSKNA is a valid surrogate marker to assess ANS in AMI patients. The frequency of cluster occurrence was 0.01–0.03 Hz and the amplitude was about 3 μV. The LF/HF ratio of AMICA (median: 1.877; Q1–Q3: 1.483–2.413) revealed significantly lower than AMINCA (median: 3.959; Q1–Q3: 1.840–6.562). The results suggest that the SKNA clustering is a unique temporal pattern of ANS synchronized discharge, which could indicate the lower sympathetic status (by HRV) in AMI patients.Conclusion: This is the first study to identify SKNA clustering phenomenon in AMI patients. Such a synchronized nerve discharge pattern could be detected with non-invasive SKNA signals. SKNA temporal clustering could be a novel biomarker to classify ANS regulation ability in AMI patients.Clinical and Translational Significance: SKNA is higher in AMI patients than in control and negatively correlates with parasympathetic parameters. SKNA clustering is associated with a lower LF/HF ratio that has been shown to correlate with sudden cardiac death in AMI. The lack of SKNA temporal clustering could indicate poor ANS regulation in AMI patients.

Relationship Between Deceleration Morphology and Phase Rectified Signal Averaging-Based Parameters During Labor.

During labor, uterine contractions trigger the response of the autonomic nervous system (ANS) of the fetus, producing sawtooth-like decelerations in the fetal heart rate (FHR) series. Under chronic hypoxia, ANS is known to regulate FHR differently with respect to healthy fetuses. In this study, we hypothesized that such different ANS regulation might also lead to a change in the FHR deceleration morphology. The hypothesis was tested in an animal model comprising nine normoxic and five chronically hypoxic fetuses that underwent a protocol of umbilical cord occlusions (UCOs). Deceleration morphologies in the fetal inter-beat time interval (FRR) series were modeled using a trapezoid with four parameters, i.e., baseline b, deceleration depth a, UCO response time τu and recovery time τr. Comparing normoxic and hypoxic sheep, we found a clear difference for τu (24.8±9.4 vs. 39.8±9.7 s; p < 0.05), a (268.1±109.5 vs. 373.0±46.0 ms; p < 0.1) and Δτ = τu − τr (13.2±6.9 vs. 23.9±7.5 s; p < 0.05). Therefore, the animal model supported the hypothesis that hypoxic fetuses have a longer response time τu and larger asymmetry Δτ as a response to UCOs. Assessing these morphological parameters during labor is challenging due to non-stationarity, phase desynchronization and noise. For this reason, in the second part of the study, we quantified whether acceleration capacity (AC), deceleration capacity (DC), and deceleration reserve (DR), computed through Phase-Rectified Signal Averaging (PRSA, known to be robust to noise), were correlated with the morphological parameters. DC, AC and DR were correlated with τu, τr and Δτ for a wide range of the PRSA parameter T (Pearson's correlation ρ > 0.8, p < 0.05). In conclusion, deceleration morphologies have been found to differ between normoxic and hypoxic sheep fetuses during UCOs. The same difference can be assessed through PRSA based parameters, further motivating future investigations on the translational potential of this methodology on human data.

Correlation of heart rate recovery and heart rate variability with atrial fibrillation progression.

ObjectiveTo examine the combination of heart rate recovery (HRR) and heart rate variability (HRV) in predicting atrial fibrillation (AF) progression.MethodsData from patients with a first detected episode of AF who underwent treadmill exercise testing and 24-h Holter electrocardiography were retrospectively analysed. Autonomic dysfunction was verified using HRR values. Sympathetic and parasympathetic modulation was analysed by HRV. AF progression was defined as transition from the first detected paroxysmal episode to persistent/permanent AF.ResultsOf 306 patients, mean LF/HF ratio and HRR did not differ significantly by AF progression regardless of age (< or ≥65 years). However, when the LF/HF ratio was divided into tertiles, in patients aged <65 years, the mid LF/HF (1.60–2.40) ratio was significantly associated with lower AF progression rates and longer maintenance of normal sinus rhythm. For patients aged <65 years, less metabolic equivalents were related to higher AF progression rates. For patients aged ≥65 years, a low HRR was associated with high AF progression rates.ConclusionIn relatively younger age, high physical capacity and balanced autonomic nervous system regulation are important predictors of AF progression. Evaluation of autonomic function assessed by age could predict AF progression.

Association between severity of pain, perceived stress and vagally-mediated heart rate variability in women with endometriosis

ABSTRACT Chronic pelvic pain is the main symptom in women with endometriosis. Evidence suggests that psychological stress and autonomic regulation contribute to symptoms and pathophysiological modulation. We investigated the relationship between endometriosis-related pain severity, perceived stress, and autonomic balance in a sample of 81 women suffering chronic pelvic pain with deep endometriosis. Perceived stress and pelvic pain symptoms were assessed using the 10-item version of the Perceived Stress Scale (PSS-10) and the Numeric Pain Rating Scale (NPRS), respectively. Autonomic nervous system regulation was evaluated using vagally mediated components of the heart rate variability (vmHRV). Our results showed that pain unpleasantness and perceived stress were positively correlated, and women with mood disorders had higher perceived stress. The women with low resting vmHRV experience more intense pelvic pain, pain unpleasantness, and a higher number of severe endometriosis-related pain descriptors. The positive association between perceived stress, mood disorder, and pain unpleasantness demonstrates the additive effect between these aversive experiences. The inverse association between parasympathetic tone and pain suggests contributions of the Descending Inhibitory Pain pathway efficiency to symptom severity in women with endometriosis.

Cardiac Autonomic Modulation Response Before, During, and After Submaximal Exercise in Older Adults With Intellectual Disability.

The analysis of the heart rate variability (HRV) consists of changes in the time intervals between consecutive R waves. It provides information on the autonomic nervous system regulation and it is a predictor of adverse cardiovascular events. Several studies analyzed this parameter in youth and adults with Intellectual Disability (ID). Nevertheless, there is a lack of information regarding the HRV before, during, and after exercise in older adults with ID. Therefore, we aimed to describe and compare the cardiac autonomic modulation before, during, and after the six-minute walk test (6MWT) in older adults with and without ID. Twenty-four volunteers with ID and 24 without ID (non-ID) participated in this study. HRV was assessed by R-R intervals at rest, during and after the 6MWT. At rest and recovery periods, the participants remained sited. The symbolic analysis was used to evaluate non-linear HRV components. The recovery HR kinetics was assessed by the mean response time, which is equivalent to time constant (τ)+time delay (TD). Between groups differences in HRV variables were not significant. During the recovery period, HR kinetics time variables showed significant better results in non-ID participants (TD: 6±5s vs. 15±11s; τ: 19±10s vs. 35±17s; and MRT: 25±9s vs. 50±11s, all p<0.050). In conclusion, our results suggest that the HRV in older adults with and without ID is similar during rest, exercise, and recovery. Recovery HR kinetics after the 6MWT was slower in older adults with ID. The reason for these results may be a reduced post-exercise vagal rebound in older adults with ID.

Heart rate variability modifications in response to different types of exercise training in athletes.

Spectral analysis of heart rate variability (HRV) is a long-standing technique to indirectly assess neural cardiac regulation. This article specifically addressed how spectral analysis of HRV could help to understand neural cardiovascular adaptations to long-term exercise training; and inform us on training status in athletes. We reviewed literature searching for articles investigating resting cardiovascular adaptations to long-term exercise training through spectral analysis of HRV in athletes, from amateur to world class categories, practicing different sport disciplines, and focusing, in particular, on a series of work performed over time in our laboratory, which may highlight how different types of exercise training differently affect neural cardiac regulation. Spectral analysis of HRV has been shown its capability of detecting different adaptational changes in cardiac autonomic nervous system (ANS) regulation attending physical training in athletes of different sport disciplines. Studies showed that spectral analysis of HRV provide results that are sport-dependent and differ at individual level. ANS adaptations to exercise training are presented and discussed. Reported studies indicate that spectral analysis of HRV is an effective tool to monitor and optimize the training process and to predict athletic achievements in competitions. Cardiac ANS adaptations are strongly dependant on the type of training being performed. The individual nature of cardiac ANS adaptations should be considered to properly interpret the observed findings.

Insomnia in Emotional Labor: Its Role in Autonomic Nervous System Regulation.

ObjectiveThe relation between female emotional laborers’ sleep quality and autonomic nervous system activity was investigated. MethodsThirty-three subjects’ heart rate variability (HRV) data and results of self-reported scale on sleep, depression, anxiety and suicidality, were collected. Subjects were classified into good sleeper (GS) and poor sleeper (PS) groups relying on sleep quality. Changes of HRV between working time and resting time in each group were compared. ResultsThe PS group showed significantly lower difference in root mean square of successive differences (RMSSD), percentage of successive normal-to-normal intervals that differ by more than 50 ms (pNN50), and natural logarithm high-frequency (LnHF) when they were working as compared to when they were resting, which means decreased function of the parasympathetic nervous system (PNS). Repeated measures analysis of covariance showed that the group effect was significant only for LnHF, with score of depression scale as a covariate. ConclusionFemale emotional laborers who complain of sleep difficulty may have decreased function of the PNS. Therefore, good sleep quality is essential for maintaining and promoting mental and physical health of women engage in emotional labor.

1

1

The Worsening of Positional Mild Obstructive Sleep Apnea over Time Is Associated with an Increase in Body Weight: Impact on Blood Pressure and Autonomic Nervous System

Background: Most patients with mild obstructive sleep apnea (OSA) are positional dependent. Although mild OSA worsens over time, no study has assessed the natural course of positional mild OSA. Objectives: The aim of this study was to evaluate the natural course of positional mild OSA, its most valuable progression predictor, and its impact on blood pressure (BP) and the autonomic nervous system (ANS). Methods: This retrospective observational cohort study enrolled 86 patients with positional mild OSA and 26 patients with nonpositional mild OSA, with a follow-up duration of 32.0 ± 27.6 months and 37.6 ± 27.8 months, respectively. Polysomnographic variables, BP, and ANS functions were compared between groups at baseline and after follow-up. Results: In patients with positional mild OSA after follow-up, the apnea/hypopnea index (AHI) increased (9.1 ± 3.3/h vs. 22.0 ± 13.2/h, p = 0.000), as did the morning systolic BP (126.4 ± 13.3 mm Hg vs. 130.4 ± 15.9 mm Hg, p = 0.011), and the sympathetic activity (49.4 ± 12.3% vs. 55.3 ± 13.1%, p = 0.000), while the parasympathetic activity decreased (50.6 ± 12.3% vs. 44.7 ± 13.1%, p = 0.000). The body mass index changes were the most important factor associated with AHI changes among patients with positional mild OSA (Beta = 0.259, adjust R² = 0.056, p = 0.016, 95% confidence interval 0.425 and 3.990). The positional dependency disappeared over time in 66.3% of patients with positional mild OSA while 69.2% of patients with nonpositional mild OSA retained nonpositional. Conclusions: In patients with positional mild OSA, disease severity, BP, and ANS regulation worse over time. Increased weight was the best predictor for its progression and the loss of positional dependency. Better treatments addressing weight control and consistent follow-up are needed for positional mild OSA.

Changes in autonomic tone during delirium in acute stroke patients assessed by pupillometry and skin conductance

Delirium is a common complication in acute ischemic stroke, possibly caused by alterations in the regulation of the sympathetic autonomic nervous system. We investigated whether such an association could be demonstrated with two easy-to-use measurement techniques: Measurement of palmar skin conductance level (SCL) and pupillometry measuring the dilation velocity in the pupillary light reflex (PLRdil.vel.).The cohort study included 64 patients admitted with acute ischemic stroke. During the study period (median 4.1 days, interquartile range 2.1 days) patients were assessed for delirium once daily as well as with measurements of SCL and PLRdil.vel up to twice daily. SCL and PLRdil.vel. during delirium were lower than without delirium present. For SCL the unadjusted difference was −40.8% (95% CI (−55.1 to −22.0), P value <.001) and for PLRdil.vel the unadjusted difference was −0.22 mm/s (95% CI (−0.42 to −0.01), P value = .041). The results demonstrate changes in sympathetic autonomic nervous system regulation during delirium in acute stroke patients.