Comparative Analysis of the Hemodynamic Effects of Remimazolam and Propofol During General Anesthesia: A Retrospective Study

PURPOSE

Hypotension is common during anesthesia induction. However, minimal hemodynamic effects of remimazolam anesthesia have been reported. We hypothesized that remimazolam would have weaker hemodynamic effects than would propofol. To test this, we simultaneously evaluated the hemodynamics using the estimated continuous cardiac output (esCCO) system and heart rate variability (HRV) during anesthesia induction.

METHODS

This was a single-center, observational, retrospective study of patients undergoing dental surgery under general anesthesia between 2020 and 2022. Seventy patients were divided into two groups: remimazolam (R group; n=34) and propofol (P group; n=36). The information obtained from the anesthesia records, patient information, esCCO system parameters, and HRV were integrated and analyzed. The percentages of various parameters were set to 100% for the pre-induction phase as the baseline.

RESULTS

The %MAP (noninvasive mean arterial blood pressure) decreased over a narrower range in the R compared to the P group (-17.8% (-26.3%, -11.9%) vs. -22.6% (-32.9%, -17.0%); P=0.039). The %HR (heart rate) increased significantly in the R group and decreased in the P group (+10.7% (+6.5%, +18.6%) vs. -6.5% (-14.5%, +8.4%); P<0.01). The %SVesCCO (stroke volume calculated using the esCCO system) decreased significantly in both groups, but the R group showed a smaller difference compared to the P group (- 5.1% (-7.7%, -2.1%) vs. -10.0% (-13.8%, -5.6%); P<0.01). The rates of change in %LF nu (normalized unit of low frequency) and %HF nu (normalized unit of high frequency) were lower for the R than for the P group, although the difference was not significant (+6.8% (-14.5%, 32.4%) vs. +9.2% (-7.2%, +59.7%), P=0.30; +7.9% (-51.0%, +66.9%) vs. +22.8% (-26.1%, +61.6%), P=0.57).

CONCLUSION

Remimazolam demonstrated a lower MAP reduction rate than propofol. A compensatory increase in HR occurred with a decrease in stroke volume. However, the HR increase was not attributable to the autonomic nervous system.

Cardiovascular Autonomic Nervous System in a Patient With Hereditary Angioedema Affected by COVID-19

Autonomic nervous system (ANS) regulation in hereditary angioedema (HAE) and coronavirus disease 2019 (COVID-19) is unknown. ANS alterations could be manifested during both the acute and post-acute phases of COVID-19. Implications of acute and chronic inflammation on ANS in HAE need to be addressed. In this case report, we monitored the systolic arterial blood pressure variability and baroreflex sensitivity in a female HAE patient both before experiencing COVID-19 symptoms and one month afterward. We also tracked the heart rate variability on the day preceding symptom onset, the day of symptom onset (SYM), the day following SYM, five days after SYM, the day of the first negative nasopharyngeal swab (i.e., 12 days after SYM), and one month after symptom onset. The results of this case report provide the characterization of vascular and cardiac autonomic profiles in an HAE patient until the resolution of an acute infection, a potential trigger for the acute HAE attack.

A Case Report of Chronic Epipharyngitis With Chronic Fatigue Treated With Epipharyngeal Abrasive Therapy (EAT)

A case of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) with chronic epipharyngitis was treated with epipharyngeal abrasive therapy (EAT). The symptoms of ME/CFS improved along with the improvement of chronic epipharyngitis. The patient was followed up with endocrine and autonomic function tests. Endocrine function tests included salivary cortisol and salivary α-amylase activity. Salivary α-amylase activity was stimulated by EAT. EAT improved the diurnal variability of salivary cortisol secretion. Autonomic function tests included heart rate variability analysis by orthostatic stress test. EAT normalized parasympathetic and sympathetic reflexes over time and regulated autonomic balance. Based on the improvement of symptoms and test results, EAT was considered effective for ME/CFS. A literature review was conducted on the mechanism of the therapeutic effect of EAT on ME/CFS.

The Effect of Epipharyngeal Abrasive Therapy (EAT) on the Baroreceptor Reflex (BR)

Introduction Epipharyngeal Abrasive Therapy (EAT) has been used as a treatment for chronic epipharyngitis, and although autonomic nerve stimulation has been pointed out as one of the mechanisms by which EAT produces therapeutic effects, there have been few reports examining this mechanism of action. This study investigated the effects of repeated EAT on autonomic nervous system activity in chronic epipharyngitis patients over time, using heart rate variability analysis. In addition, we conducted a loading test using the active standing test (AS test) to examine the effects of EAT on the baroreceptor reflex (BR). Subjects and methods A retrospective study was conducted on 39 patients who visited our clinic between July 2017 and November 2019 and underwent autonomic function tests with a diagnosis of chronic nasopharyngeal inflammation. The subjects were divided into two groups: the improvement group and the invariant group for comparison. Electrocardiographic recordings and blood pressure measurements were made under the stress of the AS test. Heart rate, high-frequency (HF) component, low-frequency (LF) component, and Coefficient of Variation on R-R interval were evaluated as indices of autonomic function. Component coefficient of variance high frequency was used as an index of parasympathetic function. ccvLF/ccvHF ratio was calculated by dividing the component coefficient of variance low frequency by ccvHF. The AS test was conducted in phase 1 in the initial resting sitting position, in phase 2 in the standing position, in phase 3 in the standing and holding the standing position, and in phase 4 in the seated and holding the sitting position. Systolic blood pressure, mean arterial pressure, and diastolic blood pressure were obtained in each phase. A paired t-test was used to compare the improved and invariant groups before and after treatment. The post-treatment comparison between the improved group and the invariant group was performed by unpaired t-test. Variation of the evaluation index over time was evaluated by repeated measures ANOVA. Multiple comparisons were corrected by the Bonferroni method. Results The EAT showed that parasympathetic activity was significantly suppressed in the improvement group, while the AS test showed significant fluctuations over time for the improvement and invariant groups. The interaction between the time course and the two factors in the improvement and invariant groups was not statistically evident. Although no significant difference was found, the improvement group showed a tendency to suppress parasympathetic activity and a tendency to stimulate sympathetic activity compared to the invariant group. Blood pressure in the improvement group showed a tendency to decrease. Conclusions EAT was found to suppress parasympathetic activity over time, and the AS test did not reveal an interaction effect of EAT on BR. However, there was a trend toward suppression of parasympathetic activity and stimulation of sympathetic activity in the improved group compared to the invariant group. Blood pressure in the improved group tended to decrease. It is possible that EAT may have a positive effect on autonomic neuropathy symptoms such as orthostatic dysregulation (OD), postural orthostatic tachycardia syndrome (POTS), etc. by stimulating the BRs. It is thought that the autonomic nervous system stimulating action and the immune system stimulating action act synergistically to express the therapeutic effect of EAT.

Heart Rate Variability Analysis on Electrocardiograms, Seismocardiograms and Gyrocardiograms of Healthy Volunteers and Patients with Valvular Heart Diseases

Heart rate variability (HRV) is the physiological variation in the intervals between consecutive heartbeats that reflects the activity of the autonomic nervous system. This parameter is traditionally evaluated based on electrocardiograms (ECG signals). Seismocardiography (SCG) and/or gyrocardiography (GCG) are used to monitor cardiac mechanical activity; therefore, they may be used in HRV analysis and the evaluation of valvular heart diseases (VHDs) simultaneously. The purpose of this study was to compare the time domain, frequency domain and nonlinear HRV indices obtained from electrocardiograms, seismocardiograms (SCG signals) and gyrocardiograms (GCG signals) in healthy volunteers and patients with valvular heart diseases. An analysis of the time domain, frequency domain and nonlinear heart rate variability was conducted on electrocardiograms and gyrocardiograms registered from 29 healthy male volunteers and 30 patients with valvular heart diseases admitted to the Columbia University Medical Center (New York City, NY, USA). The results of the HRV analysis show a strong linear correlation with the HRV indices calculated from the ECG, SCG and GCG signals and prove the feasibility and reliability of HRV analysis despite the influence of VHDs on the SCG and GCG waveforms.

Autonomic Nervous System Regulation Effects of Epipharyngeal Abrasive Therapy for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Associated With Chronic Epipharyngitis

OBJECTIVE

To evaluate the autonomic nerve stimulation effect of epipharyngeal abrasive therapy (EAT) on myalgic encephalomyelitis/chronic fatigue syndrome (CFS) associated with chronic epipharyngitis. Heart rate variability analysis was performed. The study was conducted by analyzing heart rate variability.

SUBJECTS AND METHODS

A total of 29 patients with chronic epipharyngitis who underwent EAT from July 2017 to April 2018 were classified into two groups: 11 patients in the CFS group and 18 patients in the control group without CFS. The patients were classified as phase 1 during bed rest, phase 2 during nasal endoscopy, phase 3 during nasal abrasion, and phase 4 during oral abrasion. Electrocardiographic recordings were made, and autonomic function was compared and evaluated by measuring heart rate, coefficient of variation on R-R interval (CVRR), coefficient of component variance high frequency (ccvHF), and low frequency/ccvHF ratio (L/H) for each of the four phases. The Shapiro-Wilk test was performed to confirm the normality of the two groups, and the parametric test was selected. A repeated measures analysis of variance was performed to assess changes over time between the four events in the two groups. Multiple comparisons were corrected by the Bonferroni method. Comparisons between resting data and three events within each group were performed by paired t-test.

RESULTS

The CFS group had an increased baseline heart rate compared to the control group, and the CFS group had a greater increase in parasympathetic activity and a decrease in heart rate with nasal abrasion. Oral abrasion elicited a pharyngeal reflex and increased heart rate and both sympathetic and parasympathetic activity.

CONCLUSION

The CFS group was in a state of dysautonomia due to autonomic overstimulation, with an elevated baseline heart rate. The CFS group was considered to be in a state of impaired autonomic homeostasis, with an increased likelihood that overstimulation would induce a pathological vagal reflex and the Reilly phenomenon would develop. The direct effects of EAT on the autonomic nervous system were considered to be vagus nerve stimulation and the regulation of autonomic function by opposing stimulation input to sympathetic and parasympathetic nerves. As an indirect effect, bleeding from the epipharyngeal mucosa due to abrasion was thought to restore the function of the cerebral venous and lymphatic excretory systems and the autonomic nerve center.

Frequent occurrence of postbreakfast syncope due to carotid sinus syndrome after surgery for hypopharyngeal cancer: A case report

RATIONALE

Syncope often occurs in patients with advanced head and neck cancers due to the stimulation of the autonomic nervous system by the tumor. Here, we describe a case of frequent syncopal episodes after laryngopharyngectomy for hypopharyngeal cancer. As all syncopal episodes were observed during the forenoon, we also evaluated the heart rate variability using ambulatory electrocardiography to determine why the syncopal episodes occurred during a specified period of the day.

PATIENT CONCERNS

A 73-year-old Japanese man who underwent laryngopharyngectomy for recurrent hypopharyngeal cancer started experiencing frequent episodes of loss of consciousness that occurred during the same time period (10:00-12:00). He had never experienced syncopal episodes before the operation. From 23 to 41 days postoperatively, he experienced 9 syncopal episodes that occurred regardless of his posture.

DIAGNOSES

Pharyngo-esophagoscopy revealed an anastomotic stricture between the free jejunum graft and the upper esophagus. Swallowing videofluoroscopy confirmed the dilatation of the jejunal autograft and a foreign body stuck on the oral side of the anastomosis. Contrast-enhanced computed tomography revealed that the carotid artery was slightly compressed by the edematous free jejunum. The patient was diagnosed with carotid sinus syndrome (CSS) as the free jejunum was dilated when consuming breakfast, which may have caused carotid sinus hypersensitivity and induced a medullary reflex.

INTERVENTIONS

Administration of disopyramide was effective in preventing syncope. Heart rate variability analysis using ambulatory electrocardiography showed that parasympathetic dominancy shifted to sympathetic dominancy during 10:00 to 12:00. The significant time regularity of the syncopal episodes may have been affected by modified diurnal variation in autonomic tone activity.

OUTCOMES

After the surgical release and re-anastomosis of the pharyngoesophageal stenosis via an open-neck approach, no recurrent episodes of syncope were reported.

LESSONS

We reported a case of frequent syncopal episodes limited to the forenoon due to CSS after surgery for hypopharyngeal carcinoma. The patient was treated with anticholinergics followed by the release and re-anastomosis of the pharyngoesophageal stenosis. When syncope occurs after surgery for head and neck lesions, CSS due to postoperative structural changes should be considered as a differential diagnosis of syncope.

Autoencoder-Based Extrasystole Detection and Modification of RRI Data for Precise Heart Rate Variability Analysis

Heart rate variability, which is the fluctuation of the R-R interval (RRI) in electrocardiograms (ECG), has been widely adopted for autonomous evaluation. Since the HRV features that are extracted from RRI data easily fluctuate when arrhythmia occurs, RRI data with arrhythmia need to be modified appropriately before HRV analysis. In this study, we consider two types of extrasystoles-premature ventricular contraction (PVC) and premature atrial contraction (PAC)-which are types of extrasystoles that occur every day, even in healthy persons who have no cardiovascular diseases. A unified framework for ectopic RRI detection and a modification algorithm that utilizes an autoencoder (AE) type of neural network is proposed. The proposed framework consists of extrasystole occurrence detection from the RRI data and modification, whose targets are PVC and PAC. The RRI data are monitored by means of the AE in real time in the detection phase, and a denoising autoencoder (DAE) modifies the ectopic RRI caused by the detected extrasystole. These are referred to as AE-based extrasystole detection (AED) and DAE-based extrasystole modification (DAEM), respectively. The proposed framework was applied to real RRI data with PVC and PAC. The result showed that AED achieved a sensitivity of 93% and a false positive rate of 0.08 times per hour. The root mean squared error of the modified RRI decreased to 31% in PVC and 73% in PAC from the original RRI data by DAEM. In addition, the proposed framework was validated through application to a clinical epileptic seizure problem, which showed that it correctly suppressed the false positives caused by PVC. Thus, the proposed framework can contribute to realizing accurate HRV-based health monitoring and medical sensing systems.

Classification of Sleep Apnea Severity by Electrocardiogram Monitoring Using a Novel Wearable Device

Sleep apnea (SA) is a prevalent disorder diagnosed by polysomnography (PSG) based on the number of apnea–hypopnea events per hour of sleep (apnea–hypopnea index, AHI). PSG is expensive and technically complex; therefore, its use is rather limited to the initial diagnostic phase and simpler devices are required for long-term follow-up. The validity of single-parameter wearable devices for the assessment of sleep apnea severity is still debated. In this context, a wearable electrocardiogram (ECG) acquisition system (ECG belt) was developed and its suitability for the classification of sleep apnea severity was investigated using heart rate variability analysis with or without data pre-filtering. Several classification algorithms were compared and support vector machine was preferred due to its simplicity and overall performance. Whole-night ECG signals from 241 patients with a suspicion of sleep apnea were recorded using both the ECG belt and patched ECG during PSG recordings. 65% of patients had an obstructive sleep apnea and the median AHI was 21 [IQR: 7–40] h−1. The classification accuracy obtained from the ECG belt (accuracy: 72%, sensitivity: 70%, specificity: 74%) was comparable to the patched ECG (accuracy: 74%, sensitivity: 88%, specificity: 61%). The highest classification accuracy was obtained for the discrimination between individuals with no or mild SA vs. moderate to severe SA. In conclusion, the ECG belt provided signals comparable to patched ECG and could be used for the assessment of sleep apnea severity, especially during follow-up.

Peak Detection Algorithm for Vital Sign Detection Using Doppler Radar Sensors

An accurate method for detecting vital signs obtained from a Doppler radar sensor is proposed. A Doppler radar sensor can remotely obtain vital signs such as heartbeat and respiration rate, but the vital signs obtained by using the sensor do not show clear peaks like in electrocardiography (ECG) because of the operating characteristics of the radar. The proposed peak detection algorithm extracts the vital signs from the raw data. The algorithm shows the mean accuracy of 96.78% compared to the peak count from the reference ECG sensor and a processing time approximately two times faster than the gradient-based algorithm. To verify whether heart rate variability (HRV) analysis similar to that with an ECG sensor is possible for a radar sensor when applying the proposed method, the continuous parameter variations of the HRV in the time domain are analyzed using data processed with the proposed peak detection algorithm. Experimental results with six subjects show that the proposed method can obtain the heart rate with high accuracy but cannot obtain the information for an HRV analysis because the proposed method cannot overcome the characteristics of the radar sensor itself.

Missing RRI Interpolation Algorithm based on Locally Weighted Partial Least Squares for Precise Heart Rate Variability Analysis

The R-R interval (RRI) fluctuation in electrocardiogram (ECG) is called heart rate variability (HRV), which reflects activities of the autonomic nervous system (ANS) and has been used for various health monitoring services. Accurate R wave detection is crucial for success in HRV-based health monitoring services; however, ECG artifacts often cause missing R waves and deteriorate the accuracy of HRV analysis. The present work proposes a new missing RRI interpolation technique based on Just-In-Time (JIT) modeling. In the JIT modeling framework, a local regression model is built by weighing samples stored in the database according to the distance from a query and output is estimated only when an estimate is requested. The proposed method builds a local model and estimates missing RRI only when an RRI detection error is detected. Locally weighted partial least squares (LWPLS) is adopted for local model construction. The proposed method is referred to as LWPLS-based RRI interpolation (LWPLS-RI). The performance of the proposed LWPLS-RI was evaluated through its application to RRI data with artificial missing RRIs. We used the MIT-BIH Normal Sinus Rhythm Database for nominal RRI dataset construction. Missing RRIs were artificially introduced and they were interpolated by the proposed LWPLS-RI. In addition, MEAN that replaces the missing RRI by a mean of the past RRI data was compared as a conventional method. The result showed that the proposed LWPLS-RI improved root mean squared error (RMSE) of RRI by about 70% in comparison with MEAN. In addition, the proposed method realized precise HRV analysis. The proposed method will contribute to the realization of precise HRV-based health monitoring services.

Psychophysiological evaluation of patients with transient consciousness loss of uncertain origin

BACKGROUND

Psychological profile (PsyP) of patients with transient loss of consciousness (TLoC) is evidence of high prevalence of anxiety and depression. However, the mechanistic link between abnormal PsyP and TLoC is still unclear.

AIM

This study aimed to evaluate: 1) prevalence of abnormal PsyP in TLoC patients; 2) cardiac autonomic response to head-up tilt test (HUTT) in patients with (PsyP+) or without abnormal PsyP (PsyP-), developing syncope (HUTT+) or not (HUTT-).

METHODS

Forty-one patients (66% female, mean age 36 ± 15 years), with history of TLoC, underwent PsyP before HUTT. Short-term heart rate variability analysis was carried out under baseline rest condition and at peak heart rate and/or onset of syncope induced by nitroglycerine (NTG), during HUTT.

RESULTS

HUTT+ occurred in 17/41 patients, more frequently in females, who had higher levels of anxiety (p < 0.0001). PsyP+ was prevalent in 70.5% of HUTT+ patients (p < 0.05). Among PsyP+ patients HUTT+ had dominant sympathetic modulation (DSM) at rest, which increased at the onset of syncope, whereas in HUTT patients vagal modulation was prevalent at rest. Among NTG-induced HUTT+ patients, fourfold higher increases of very low frequency (VLF) power were found in PsyP- compared with PsyP+.

CONCLUSIONS

58% of patients with history of TLoC were PsyP+. In PsyP+ patients, DSM at rest correlates with higher prob-ability of NTG-induced syncope, which occurs with 60% increment of low frequency and 530% increment of VLF power. Conversely, in patients with prevalent vagal modulation at rest and a decrease in VLF power after NTG, syncope did not occur. This supports interpretation of VLF power as an index of stress-induced sympathetic activity.

Assessment of autonomic nervous system function in nursing students using an autonomic reflex orthostatic test by heart rate spectral analysis

Nursing students experience academic demands, such as tests, theoretical and practical coursework, research activities, various aspects of professional practice, and contact with health professionals and patients. Consequently, nursing students face numerous types of stress, and increased stress levels contribute to physical and psychological distress in nursing students. The aim of the present study was to investigate the autonomic nervous system function of nursing students by assessing active standing load using the autonomic reflex orthostatic tolerance test, which enables quantitative analysis of dynamic autonomic nervous system function. The autonomic nervous system activity in the resting state was low in fourth-year students, they had parasympathetic hypotension, and there was a tendency towards higher sympathetic nervous system activity of fourth-year students compared with first-, second- and third-year students. In the standing state, there was a trend towards a higher autonomic nervous system activity response of fourth-year students compared with first-, second- and third-year students. These results suggest that stress may influence autonomic nervous activity in fourth-year nursing students. By correcting stress in fourth-year nursing students, it may be possible to prevent the development of health problems.

Electrocardiogram pattern recognition and analysis based on artificial neural networks and support vector machines: a review

Computer systems for Electrocardiogram (ECG) analysis support the clinician in tedious tasks (e.g., Holter ECG monitored in Intensive Care Units) or in prompt detection of dangerous events (e.g., ventricular fibrillation). Together with clinical applications (arrhythmia detection and heart rate variability analysis), ECG is currently being investigated in biometrics (human identification), an emerging area receiving increasing attention. Methodologies for clinical applications can have both differences and similarities with respect to biometrics. This paper reviews methods of ECG processing from a pattern recognition perspective. In particular, we focus on features commonly used for heartbeat classification. Considering the vast literature in the field and the limited space of this review, we dedicated a detailed discussion only to a few classifiers (Artificial Neural Networks and Support Vector Machines) because of their popularity; however, other techniques such as Hidden Markov Models and Kalman Filtering will be also mentioned.