Pre-surgical heart-rate variability strongly predicts less post-operative pain in patients with epilepsy

Exploring Heart Rate Variability Biofeedback as a Nonpharmacological Intervention for Enhancing Perioperative Care: A Narrative Review

Heart rate variability biofeedback (HRVBF) is a non-invasive therapeutic technique that aims to regulate variability in heart rate. This intervention has promise in mitigating perioperative stress, a critical factor for surgical patient outcomes. This comprehensive review aimed to explore the current evidence on the perioperative role of HRV biofeedback in improving patient outcomes, reducing perioperative stress, enhancing recovery, and optimizing anaesthesia management. A review of the PubMed and Google Scholar databases was conducted to identify articles focused on HRVBF in relation to the perioperative period. Studies were selected using appropriate keywords in English (MeSH). Ample potential applications of HRVBF in clinical anaesthesia have been identified and proven feasible. It is a non-invasive and an easy method an anaesthesiologists has at its disposal with potential utility in reducing perioperative stress, as a tool of optimization of comorbidities, analgesia supplementation and in predicting catastrophic complications. Although HRVBF has the potential to enhance anaesthesia management and improve patient outcomes, several limitations and challenges must be addressed to maximize its clinical utility. Overcoming these obstacles through research and technological advancements will be crucial for realizing the full benefits of HRVBF in perioperative care.

The brain-heart-immune axis: a vago-centric framework for predicting and enhancing resilient recovery in older surgery patients

Nearly all geriatric surgical complications are studied in the context of a single organ system, e.g., cardiac complications and the heart; delirium and the brain; infections and the immune system. Yet, we know that advanced age, physiological stress, and infection all increase sympathetic and decrease parasympathetic nervous system function. Parasympathetic function is mediated through the vagus nerve, which connects the heart, brain, and immune system to form, what we have termed, the brain-heart-immune axis. We hypothesize that this brain-heart-immune axis plays a critical role in surgical recovery among older adults. In particular, we hypothesize that the brain-heart-immune axis plays a critical role in the most common surgical complication among older adults: postoperative delirium. Further, we present heart rate variability as a measure that may eventually become a multi-system vital sign evaluating brain-heart-immune axis function. Finally, we suggest the brain-heart-immune axis as a potential interventional target for bio-electronic neuro-immune modulation to enhance resilient surgical recovery among older adults.

Prediction of pain using electrocardiographic-derived autonomic measures: A systematic review

BACKGROUND AND OBJECTIVE

Pain is a major clinical challenge, and understanding the pathophysiology is critical for optimal management. The autonomic nervous system reacts to pain stimuli, and autonomic dysfunction may predict pain sensation. The most used assessment of autonomic function is based on electrocardiographic measures, and the ability of such measures to predict pain was investigated.

DATABASES AND DATA TREATMENT

English articles indexed in PubMed and EMBASE were reviewed for eligibility and included when they reported electrocardiographic-derived measures' ability to predict pain response. The quality in prognostic studies (QUIPS) tool was used to assess the quality of the included articles.

RESULTS

The search revealed 15 publications, five on experimental pain, five on postoperative pain, and five on longitudinal clinical pain changes, investigating a total of 1069 patients. All studies used electrocardiographically derived parameters to predict pain assessed with pain thresholds using quantitative sensory testing or different scales. Across all study modalities, electrocardiographic measures were able to predict pain. Higher parasympathetic activity predicted decreased experimental, postoperative, and long-term pain in most cases while changes in sympathetic activity did not consistently predict pain.

CONCLUSIONS

Most studies demonstrated that parasympathetic activity could predict acute and chronic pain intensity. In the clinic, this may be used to identify which patients need more intensive care to prevent, for example postoperative pain and develop personalized chronic pain management.

SIGNIFICANCE

Pain is a debilitating problem, and the ability to predict occurrence and severity would be a useful clinical tool. Basal autonomic tone has been suggested to influence pain perception. This systematic review investigated electrocardiographic-derived autonomic tone and found that increased parasympathetic tone could predict pain reduction in different types of pain.

Higher Cardiovagal Baroreflex Sensitivity Predicts Increased Pain Outcomes After Cardiothoracic Surgery

Excessive postoperative pain can lead to extended hospitalization and increased expenses, but factors that predict its severity are still unclear. Baroreceptor function could influence postoperative pain by modulating nociceptive processing and vagal-mediated anti-inflammatory reflexes. To investigate this relationship, we conducted a study with 55 patients undergoing minimally invasive cardiothoracic surgery to evaluate whether cardiovagal baroreflex sensitivity (BRS) can predict postoperative pain. We assessed the spontaneous cardiovagal BRS under resting pain-free conditions before surgery. We estimated postoperative pain outcomes with the Pain, Enjoyment, and General Activity scale and pressure pain thresholds on the first (POD1) and second (POD2) postoperative days and persistent pain 3 and 6 months after hospital discharge. We also measured circulating levels of relevant inflammatory biomarkers (C-reactive protein, albumin, cytokines) at baseline, POD1, and POD2 to assess the contribution of inflammation to the relationship between BRS and postoperative pain. Our mixed-effects model analysis showed a significant main effect of preoperative BRS on postoperative pain (P = .013). Linear regression analysis revealed a significant positive association between preoperative BRS and postoperative pain on POD2, even after adjusting for demographic, surgical, analgesic treatment, and psychological factors. Moreover, preoperative BRS was linked to pain interfering with general activity and enjoyment but not with other pain parameters (pain intensity and pressure pain thresholds). Preoperative BRS had modest associations with postoperative C-reactive protein and IL-10 levels, but they did not mediate its relationship with postoperative pain. These findings indicate that preoperative BRS can independently predict postoperative pain, which could serve as a modifiable criterion for optimizing postoperative pain management. PERSPECTIVE: This article shows that preoperative BRS predicts postoperative pain outcomes independently of the inflammatory response and pain sensitivity to noxious pressure stimulation. These results provide valuable insights into the role of baroreceptors in pain and suggest a helpful tool for improving postoperative pain management.

Baseline heart rate variability predicts placebo hypoalgesia in men, but not women

Introduction

Placebo hypoalgesic effects vary greatly across individuals, making them challenging to control for in clinical trials and difficult to use in treatment. We investigated the potential of resting vagally-mediated heart rate variability (vmHRV) to help predict the magnitude of placebo responsiveness.

Methods

In two independent studies (total N = 77), we administered a placebo paradigm after measuring baseline HRV. In Study I, we delivered heat pain to the forearm, on skin patches treated with "real" and "control" cream (identical inactive creams). In Study II, electrical pulses to the forearm were modulated by sham transcutaneous electrical nerve stimulation. We combined data from both studies to evaluate the relationship between vagally-mediated HRV (vmHRV) parameters and the placebo response size, while also assessing sex differences in this relationship.

Results and Discussion

This revealed a positive association between vmHRV and the degree of pain relief, and this effect was driven by men. These results not only reveal new insights into the (sex-specific) mechanisms of placebo hypoalgesia, but also suggest that measuring vmHRV may be helpful in predicting placebo responsiveness. Given that placebo hypoalgesic effects contribute substantially to treatment outcomes, such a non-invasive and easily obtained predictor would be valuable in the context of personalized medicine.

Neuromodulation Applied to Diseases: The Case of HRV Biofeedback

The vagus or “wandering” nerve is the main branch of the parasympathetic nervous system (PNS), innervating most internal organs crucial for health. Activity of the vagus nerve can be non-invasively indexed by heart-rate variability parameters (HRV). Specific HRV parameters predict less all-cause mortality, lower risk of and better prognosis after myocardial infarctions, and better survival in cancer. A non-invasive manner for self-activating the vagus is achieved by performing a slow-paced breathing technique while receiving visual feedback of one’s HRV, called HRV-biofeedback (HRV-B). This article narratively reviews the biological mechanisms underlying the role of vagal activity and vagally mediated HRV in hypertension, diabetes, coronary heart disease (CHD), cancer, pain, and dementia. After searching the literature for HRV-B intervention studies in each condition, we report the effects of HRV-B on clinical outcomes in these health conditions, while evaluating the methodological quality of these studies. Generally, the levels of evidence for the benefits of HRV-B is high in CHD, pain, and hypertension, moderate in cancer, and poor in diabetes and dementia. Limitations and future research directions are discussed.

Prediction of pain responses to subsequent cold pressor test via baseline heart rate variability in healthy adults

BACKGROUND

Baseline heart rate variability (HRV) that reflects parasympathetic nervous system (PNS) activity may serve as an objective, physiological index of pain assessment, but more research is warranted to examine the link between HRV and laboratory pain responses. This study examined whether baseline HRV would predict pain responses to subsequent cold pressor test (CPT) in healthy adults.

METHODS

One hundred twenty-three participants completed resting HRV assessment and CPT consisting of immersing their right hand into a cold-water bath for a maximum of 2 minutes. Pain threshold and pain rating were assessed during CPT. Completion status of CPT, defined as completing CPT or terminating CPT before 2 minutes, was recorded as an additional laboratory pain measure. Pearson's correlation analysis was performed to examine the link between HRV and pain responses, whereas regression analysis was performed to test the prediction of pain responses via baseline HRV.

RESULTS

HF-HRV_log , which reflects PNS activity, was significantly associated with the CPT completion status (r = 0.23, p = 0.01), but not significantly associated with pain threshold (r = 0.17, p = 0.06) nor pain rating (r = -0.11, p = 0.24). HF- HRV_log was found to be a significant predictor of the CPT completion status (B = 0.53, p = 0.013).

CONCLUSIONS

Baseline HF- HRV_log may serve as an objective, physiological index to predict laboratory pain responses, and completion status of laboratory pain tests, such as CPT, may be used as a laboratory pain measure to capture important individual differences in pain processing.