Daily Anesthesiology Research Analysis
Analyzed 101 papers and selected 3 impactful papers.
Summary
Analyzed 101 papers and selected 3 impactful articles.
Selected Articles
1. Auricular vagus nerve stimulation drives analgesia via an auricle-brain axis in a mouse model of neuropathic pain.
In mice, taVNS produced robust analgesia via a defined auricle-to-brain circuit: auricular fibers to JNG, engaging NTS pro-opiomelanocortinergic neurons and activating vlPAG glutamatergic neurons. Opto/chemogenetic manipulations validated circuit necessity and sufficiency, offering mechanistic targets to optimize clinical taVNS for pain.
Impact: This study provides first-principles, mechanistic mapping of taVNS-induced analgesia, bridging peripheral stimulation sites to central pain modulatory hubs. It establishes causal circuit elements that can inform parameter selection and patient stratification in neuromodulation trials.
Clinical Implications: Although preclinical, these data support rational optimization of taVNS (site, dose, frequency) for perioperative and chronic pain, and suggest biomarkers (e.g., targetable NTS–vlPAG activity) to guide translation and monitor response.
Key Findings
- taVNS produced analgesia in a mouse neuropathic pain model.
- Auricular vagal signals engage JNG, NTS pro-opiomelanocortinergic neurons, and activate vlPAG glutamatergic neurons.
- Optogenetic activation mimicked taVNS analgesia and chemogenetic silencing abolished it, confirming circuit necessity and sufficiency.
Methodological Strengths
- Multimodal mechanistic approach (viral tracing, calcium imaging, multi-electrode recordings, opto/chemogenetics).
- Causal testing of defined circuit nodes demonstrating necessity and sufficiency.
Limitations
- Findings are in mice and limited to neuropathic pain models; translational generalizability to postoperative pain remains to be shown.
- No direct assessment of stimulation parameter space relevant to human devices.
Future Directions: Translate circuit-informed taVNS parameters into human trials, evaluate biomarkers of NTS–vlPAG engagement, and test efficacy in postoperative and chronic pain populations.
Despite its long-recognized effects in relieving pain, the neural substrates of auricular stimulation remain elusive. Here, we show that trans-auricular vagus nerve stimulation (taVNS), i.e., electrical stimulation of the auricular concha, effectively induces analgesia in a mouse model of neuropathic pain. Viral tracing, microendoscopic calcium imaging, and multi-electrode recordings reveal that auricular vagal signals travel to the jugular-nodose ganglia (JNG), which in turn connect to pro-opiomelanocortinergic neurons in nucleus tractus solitarius (NTS), subsequently activating glutamatergic neurons in ventrolateral periaqueductal gray (vlPAG). Optogenetic stimulation of central vagus terminals, JNG-derived auricular peripheral fibers, or vlPAG-projecting NTS neurons mimics taVNS-induced analgesia, whereas chemogenetic silencing of central vagus terminals or NTS neurons abolishes this effect. This study identifies an auricle-to-brain circuit underlying taVNS-driven analgesia in mice, with potential for facilitating taVNS optimization for pain management and other neurological conditions.
2. Transcutaneous Auricular Vagus Nerve Stimulation and Pectoral-Intercostal Fascial Block for the Prevention of Chronic Postsurgical Pain in Elderly Patients Undergoing Off-Pump Coronary Artery Bypass Grafting: A 2×2 Factorial, Double-Blinded, Randomized Clinical Trial.
In a 2×2 factorial, double-blind RCT in elderly OPCABG patients (n=260), taVNS reduced 3‑month CPSP (28.6% vs 40.9% vs sham), without interaction with PIFB. Mediation analyses suggest benefits are partly driven by reduced acute pain and inflammation; single-shot PIFB offered limited CPSP prevention.
Impact: Provides randomized, double-blind evidence that perioperative taVNS prevents CPSP in cardiac surgery, advancing a scalable, nonpharmacologic strategy aligned with opioid-sparing perioperative care.
Clinical Implications: Consider integrating taVNS into enhanced recovery pathways for high-risk cardiac surgery patients to reduce CPSP, while recognizing that single-shot PIFB alone may be insufficient for prevention.
Key Findings
- Overall CPSP incidence was 34.6% at 3 months after OPCABG.
- taVNS reduced CPSP compared with sham (28.6% vs 40.9%), with no taVNS×PIFB interaction.
- Mediation analyses indicated partial mediation via reduced acute postoperative pain and inflammation; single-shot PIFB had limited preventive effect.
Methodological Strengths
- Double-blind, randomized 2×2 factorial design with sham control.
- Preplanned mediation analyses linking clinical effects to plausible biological pathways.
Limitations
- Single-center trial; generalizability to other surgical populations and settings needs confirmation.
- Details of taVNS dosing/parameters and adherence are essential for replication and were not fully elaborated in the abstract.
Future Directions: Multicenter trials to validate efficacy, optimize stimulation parameters and timing, and assess long-term functional outcomes and opioid-sparing effects across procedures.
BACKGROUND: Chronic postsurgical pain (CPSP) is common after off-pump coronary artery bypass grafting (OPCABG) in elderly patients. This trial investigated the efficacy of perioperative transcutaneous auricular vagus nerve stimulation (taVNS) and pectoral-intercostal fascial block (PIFB) for CPSP prevention. METHODS: In this 2×2 factorial trial, 260 elderly patients (≥60 years) undergoing OPCABG were randomized to taVNS + ropivacaine PIFB, taVNS + placebo PIFB, sham taVNS + ropivacaine PIFB, or sham taVNS + placebo PIFB groups. The primary outcome was CPSP incidence at 3 months postoperatively. Several secondary outcomes were evaluated. Logistic regression was employed to analyze risk factors associated with CPSP. Lastly, mediation analyses were performed to explore the mediating factors between interventions and CPSP. RESULTS: The overall incidence of CPSP was 34.6%. No interaction was found between taVNS and PIFB. Compared with sham taVNS, taVNS significantly reduced CPSP incidence (28.6% vs 40.9%, CONCLUSION: Perioperative taVNS significantly reduced CPSP incidence and enhanced postoperative recovery in elderly OPCABG patients, partly mediated by alleviating acute pain and inflammation. Single-shot PIFB showed limited preventive effect on overall CPSP.
3. A population-based cross-sectional analysis of extended-release opioid dispensing incidence, prognostic factors, and variation after total joint arthroplasty.
In 229,995 arthroplasties, 12.1% filled a new extended-release opioid within 7 days post-discharge. Neuraxial anesthesia, peripheral nerve blocks, and acute pain service involvement were associated with lower ERO dispensing, while institutional and surgeon-level practices drove most variation, highlighting targets for stewardship and standardized discharge protocols.
Impact: Identifies modifiable system-level drivers of inappropriate ERO exposure after arthroplasty and quantifies the protective association of neuraxial/regional techniques, informing quality improvement and policy.
Clinical Implications: Hospitals should implement opioid stewardship with standardized discharge prescribing, prioritize neuraxial and regional anesthesia, and engage acute pain services to reduce unnecessary ERO exposure.
Key Findings
- 12.1% of 229,995 arthroplasty patients filled a new extended-release opioid within 7 days of discharge.
- Neuraxial anesthesia (OR 0.79), peripheral nerve block (OR 0.84), and acute pain service involvement (OR 0.77) were protective.
- Variation was dominated by hospital (VPC 46%, MOR 9.3) and surgeon (VPC 26%, MOR 5.3) levels; anesthetist-level variation was minimal (VPC 1%).
Methodological Strengths
- Very large, population-based dataset with multilevel modeling quantifying variance at provider and institutional levels.
- Adjustment for patient, surgical, anesthetic, and hospital covariates with robust effect estimates (ORs, VPCs, MORs).
Limitations
- Observational design cannot establish causality; residual confounding possible.
- Prescription fill data do not capture actual consumption or clinical indications.
Future Directions: Test stewardship interventions (standardized discharge protocols, feedback dashboards) in pragmatic trials and evaluate patient-centered outcomes and opioid-related harms.
INTRODUCTION: Extended-release opioids (EROs) are not recommended for acute postoperative pain, yet their prescribing persists. This study examined the incidence, predictors, and variation in ERO dispensing after total hip and knee arthroplasty. METHODS: We conducted a population-based cross-sectional study of adults undergoing primary total hip or knee arthroplasty between 2013 and 2022 using linked administrative databases in Ontario, Canada. The primary outcome was fulfillment of an ERO prescription within seven days of discharge. Multilevel logistic regression estimated associations between patient, surgical, anesthetic, and hospital factors and filling an ERO prescription. Variation was quantified using variance partition coefficients (VPCs) and median odds ratios (MOR) with 95% confidence intervals (CI), based on random effects. RESULTS: Among 229,995 knee and hip arthroplasty procedures, 27,915 (12.1%) patients filled a new ERO prescription post-discharge. Male sex (OR 1.14, 95% CI 1.09-1.19), preoperative opioid exposure (Opioid Naïve-Exposed-Tolerant (ONET) Score 2 OR 1.21, 95% CI 1.15-1.27; ONET 3 OR 1.38, 95% CI 1.20-1.58), and ASA 3 status (OR 1.07, 95% CI 1.01-1.12) increased odds of filling a new ERO prescription. Neuraxial anesthesia (OR 0.79, 95% CI 0.74-0.84), peripheral nerve block (OR 0.84, 95% CI 0.79-0.89), and acute pain service involvement (OR 0.77, 95% CI 0.70-0.85) were protective against filling a new ERO prescription. Substantial variation was found across hospitals (VPC 46%, 95% CI 0.4-0.54; MOR 9.3, 95% CI 6.57-15.27) and surgeons (VPC 26%, 95% CI 0.24-0.26; MOR 5.3, 95% CI 4.63-6.11), with minimal anesthetist-level variation (VPC 1%, 95% CI 0.010-0.011; MOR 1.4, 95% CI 1.36-1.46). Patient-level factors explained a minority of variation. CONCLUSIONS: One in ten patients fills an ERO prescription after total hip or knee arthroplasty, a practice with high variation that is predominantly driven by institutional and surgical practice patterns rather than patient factors. Future research should explore institutional stewardship, standardized discharge protocols, and multidisciplinary engagement to reduce unnecessary postoperative exposure to EROs.