A method to quantify autonomic nervous system function in healthy, able-bodied individuals

Abstract

Background The autonomic nervous system (ANS) maintains physiological homeostasis in various organ systems via parasympathetic and sympathetic branches. ANS function is altered in common diffuse and focal conditions and heralds the beginning of environmental and disease stresses. Reliable, sensitive, and quantitative biomarkers, first defined in healthy participants, could discriminate among clinically useful changes in ANS function. This framework combines controlled autonomic testing with feature extraction during physiological responses. Methods Twenty-one individuals were assessed in two morning and two afternoon sessions over two weeks. Each session included five standard clinical tests probing autonomic function: squat test, cold pressor test, diving reflex test, deep breathing, and Valsalva maneuver. Noninvasive sensors captured continuous electrocardiography, blood pressure, breathing, electrodermal activity, and pupil diameter. Heart rate, heart rate variability, mean arterial pressure, electrodermal activity, and pupil diameter responses to the perturbations were extracted, and averages across participants were computed. A template matching algorithm calculated scaling and stretching features that optimally fit the average to an individual response. These features were grouped based on test and modality to derive sympathetic and parasympathetic indices for this healthy population. Results A significant positive correlation (p = 0.000377) was found between sympathetic amplitude response and body mass index. Additionally, longer duration and larger amplitude sympathetic and longer duration parasympathetic responses occurred in afternoon testing sessions; larger amplitude parasympathetic responses occurred in morning sessions. Conclusions These results demonstrate the robustness and sensitivity of an algorithmic approach to extract multimodal responses from standard tests. This novel method of quantifying ANS function can be used for early diagnosis, measurement of disease progression, or treatment evaluation. Trial registration This study registered with Clinicaltrials.gov, identifier NCT04100486. Registered September 24, 2019, https://www.clinicaltrials.gov/ct2/show/NCT04100486.

Inconclusive evidence that breathing shapes pupil dynamics in humans: a systematic review

“…Additionally, a significant increase in pupillary unrest index, and a significant decrease in sample entropy, was found during the deep breathing condition [65]. However, in an investigation into the physiological responses to a series of autonomic function tests, which included a 7-min period of deep breathing at 6 bpm, no significant changes in pupil diameters were discovered [15].…”

“…Six studies included in this review reported results for measures of breathing depth, volume, or amplitude [15,21,36,50,59,65].…”

Closed-Loop Vagus Nerve Stimulation for the Treatment of Cardiovascular Diseases: State of the Art and Future Directions

“…Neural interfaces used for stimulation can also be used to record neural signals and monitor ANS activity in real-time ( 13 ). While innovative neural interfaces with multiple contacts are designed to improve the quality and information content of neural recordings ( 148 – 151 ), comparable efforts are being made to develop advanced signal processing and data analysis methods ( 152 , 153 ).…”

“…The development of BM was inspired by the growing comprehension of the autonomic nervous system (ANS), which plays a key role in the control of whole-body homeostasis. Dysfunctions of the ANS are consequently implicated in the development and progression of many diseases, including those affecting the cardiovascular system ( 4 , 7 – 13 ). BM utilizes this body of knowledge as a reference for the design of implantable devices ( 5 ) that modulate signals of the peripheral nervous system to visceral organs for therapeutic purposes ( 14 – 16 ).…”

Biochemical and Hematological Relationship with the Evaluation of Autonomic Dysfunction by Heart Rate Recovery in Patients with Asthma and Type 2 Diabetes

“…Most of them require specialized equipment and trained staff to perform the evaluation. Parasympathetic responses decrease with increasing body mass index (BMI) [ 5 ]. Recently, a considerable amount of attention has been paid to hematological parameters as an innovative tool to evaluate a variety of ASN alterations related to an acute coronary syndrome in the hospital setting.…”