Daily Anesthesiology Research Analysis
Three impactful studies in anesthesiology and perioperative care stand out today: a double-blind RCT shows gastrodin infusion halves postoperative delirium after CABG; a controlled crossover trial in Anesthesiology quantifies remimazolam–remifentanil PK/PD interactions to guide sedation targeting; and a large cohort in Neurology suggests long-term epilepsy risk may be higher after general versus neuraxial anesthesia, emerging years later.
Summary
Three impactful studies in anesthesiology and perioperative care stand out today: a double-blind RCT shows gastrodin infusion halves postoperative delirium after CABG; a controlled crossover trial in Anesthesiology quantifies remimazolam–remifentanil PK/PD interactions to guide sedation targeting; and a large cohort in Neurology suggests long-term epilepsy risk may be higher after general versus neuraxial anesthesia, emerging years later.
Research Themes
- Prevention of postoperative neurocognitive complications in cardiac anesthesia
- Precision dosing and drug–drug interactions in modern anesthetic regimens
- Long-term neurological outcomes associated with anesthesia modality
Selected Articles
1. Efficacy and safety of gastrodin in preventing postoperative delirium following cardiac surgery: a randomized placebo controlled clinical trial.
In a double-blind RCT of 155 CABG patients, gastrodin infusion (600 mg twice daily through POD6) reduced postoperative delirium incidence from 35.9% to 19.5% and increased odds of hospital discharge without drug-related adverse events. POCD incidence was low and similar between groups.
Impact: This is one of the first adequately blinded RCTs to show a pharmacological reduction in postoperative delirium after cardiac surgery, a high-impact outcome lacking effective prophylaxis.
Clinical Implications: Gastrodin infusion may be considered as a prophylactic adjunct for delirium in CABG patients pending replication, with monitoring protocols and inclusion in multimodal delirium prevention bundles.
Key Findings
- Postoperative delirium incidence reduced to 19.5% with gastrodin versus 35.9% with placebo (RR 0.54, 95% CI 0.32–0.93).
- No increase in adverse events; none were drug related (9.1% vs 14.1%).
- Greater odds of discharge in the gastrodin group (subhazard ratio 1.20, 95% CI 1.00–1.84).
Methodological Strengths
- Double-blind, randomized, placebo-controlled design with trial registration.
- Modified intention-to-treat analysis with prespecified co-primary outcomes.
Limitations
- Single-country, single drug regimen; generalizability beyond CABG ± valve surgery is uncertain.
- Sample size modest; POCD outcomes were rare, limiting power for cognitive endpoints.
Future Directions: Multicenter, larger RCTs across cardiac and non-cardiac surgeries, dose–response assessments, mechanistic studies (GABAergic/anti-inflammatory pathways), and health economic evaluations.
BACKGROUND: Delirium and postoperative cognitive dysfunction (POCD) are common complications post-cardiac surgery, yet no specific medical intervention is currently recommended for prevention. This study aimed to evaluate the efficacy of gastrodin infusion in preventing delirium and POCD in critically ill patients following cardiac surgery. MATERIAL AND METHODS: A double-blind, randomized, placebo-controlled trial was conducted on patients aged 18-75, scheduled for coronary artery bypass grafting (CABG) surgery, with or without valve replacement. Participants were randomized in a 1:1 ratio to receive gastrodin infusion 600 mg twice daily or placebo from the day of surgery until the postoperative day (POD) 6. The co-primary outcomes were the incidences of delirium and POCD, assessed from ICU admission until POD 7 and at 1 and 3 months postoperatively. This study was registered with the Chinese Clinical Trials Registry (ChiCTR1800020414). RESULTS: Of 160 randomized participants, 155 were analyzed (77 gastrodin, 78 placebo) according to a modified intention to treat principle. The incidence of postoperative delirium was 19.5% in the gastrodin group and 35.9% in the placebo group, with a significant relative risk of 0.54 (95% CI 0.32-0.93, p = 0.022). The incidence of in-hospital POCD was 2.9% and 4.0% in the placebo and gastrodin groups, respectively. The odds of hospital discharge were significantly greater in the gastrodin group (subhazard ratio, 1.20; 95% CI 1.00-1.84; p = 0.049). Adverse events occurred in 9.1% (7/77) of patients administered gastrodin and 14.1% (11/78) of patients administered the placebo, with none being drug-related. CONCLUSION: Gastrodin infusion significantly reduced postoperative delirium and improved discharge outcomes in patients undergoing CABG, but larger studies are needed to confirm its efficacy in preventing delirium.
2. Influence of Remifentanil on the Pharmacokinetics and Pharmacodynamics of Remimazolam in Healthy Volunteers.
In a 24-subject crossover trial, remifentanil altered remimazolam PK/PD, reducing CNS7054 clearance and synergistically deepening sedation across MOAAS and BIS endpoints. Modeling identified remimazolam targets of ~200–275 ng/mL with 0–0.5 ng/mL remifentanil to maximize moderate sedation (MOAAS 2–3) probabilities.
Impact: Provides quantitative PK/PD interaction data and actionable target concentrations for a widely adopted ultra–short-acting benzodiazepine–opioid combination, informing safer, precise titration.
Clinical Implications: Use lower remimazolam targets when co-administering remifentanil and anticipate deeper sedation and increased tolerance to stimulation; adjust TCI setpoints and monitoring (MOAAS/BIS) accordingly.
Key Findings
- Remifentanil decreased apparent clearance of remimazolam’s metabolite CNS7054 (half-max inhibition at 8.0 ng/mL).
- Pharmacodynamic interaction detected across MOAAS, BIS, TOL, and TOTS endpoints.
- Simulated optimal targets for moderate sedation: remimazolam 200–275 ng/mL with 0–0.5 ng/mL remifentanil (MOAAS 2–3 probability ~44–45%).
Methodological Strengths
- Three-period randomized crossover design with target-controlled infusions and dense PK/PD sampling.
- Nonlinear mixed-effects modeling enabling simulation of clinical target combinations.
Limitations
- Healthy volunteers; external validity to surgical patients limited.
- Exposure–response for TOL and TOTS not fully characterized by design constraints.
Future Directions: Validation in perioperative patients (including elderly and comorbid), effect on recovery profiles, respiratory safety, and integration into closed-loop sedation systems.
BACKGROUND: Synergistic effects between opioids and remimazolam on Bispectral Index (BIS) and Modified Observer's Assessment of Alertness and Sedation (MOAAS) score were previously described. This study aimed to characterize the influence of remifentanil on the sedative properties of remimazolam as measured by MOAAS, BIS, and tolerance to laryngoscopy or tetanic stimulation (TOL or TOTS) and to determine target concentrations that maximize MOAAS 2 or 3. METHODS: A three-period, crossover, dose-ranging clinical trial was performed in 24 healthy volunteers. In all periods, remimazolam was administered using a step-up and step-down target controlled infusion protocol (50 to 2,000 ng/ml). Stable remifentanil target concentrations of 0.5 ng/ml and 0.1 to 4.0 ng/ml were maintained in periods 2 and 3, respectively. Remifentanil, remimazolam, and CNS7054 (metabolite) concentrations and MOAAS, BIS, TOL, and TOTS were collected in each step of the target controlled infusion protocol. Data were analyzed using nonlinear mixed-effects models, where P ≤ 0.01 was considered significant. RESULTS: Remifentanil reduced the apparent clearance of CNS7054 with a half-maximum inhibition at 8.0 ng/ml (95% CI, 5.5 to 13.4 ng/ml). A pharmacodynamic interaction was detected on all endpoints. Simulations indicate that the probability of observing a MOAAS 2 or 3 is highest at remimazolam target concentration of 275, 250, or 200 ng/ml combined with 0, 0.1, or 0.5 ng/ml remifentanil resulting in probabilities of 45%, 45%, and 44%, respectively. Additionally, simulations indicate that the highest probability of observing TOTS and TOL was 93.3% and 85.5%, respectively, at the highest studied target concentrations. CONCLUSIONS: A pharmacokinetic and pharmacodynamic drug-drug interaction between remimazolam and remifentanil was quantified in this clinical trial. Appropriate target concentrations for MOAAS and BIS could be estimated, but for TOL and TOTS, the trial design did not allow to fully characterize the exposure-response relationship.
3. Epilepsy Risk Associated With the Receipt of General Anesthesia Relative to Neuraxial Anesthesia: A Retrospective Cohort Study.
In over 177,000 adults undergoing procedures amenable to either general or neuraxial anesthesia, weighted analyses showed a time-dependent increase in new-onset epilepsy risk with general anesthesia compared with neuraxial techniques, becoming significant after ~3 years of follow-up.
Impact: Addresses a critical, long-debated question of long-term neurological sequelae of anesthesia with a large, methodologically rigorous cohort, likely to stimulate guideline and research reconsiderations.
Clinical Implications: When feasible, neuraxial anesthesia may be preferred in patients concerned about long-term neurological risks; informed consent should acknowledge uncertainty and potential time-delayed risks after general anesthesia.
Key Findings
- Weighted epilepsy incidence: 48.8 vs 35.5 per 100,000 person-years (general vs neuraxial).
- Time-varying effect: HR at time 0 was 0.61, but risk increased over time (time interaction HR 1.36), becoming significantly higher after ~3 years for general anesthesia.
- Robust methodology: IPTW adjustment and Fine–Gray competing risk modeling.
Methodological Strengths
- Large population-based cohort with linkage of administrative databases.
- Advanced causal methods: inverse probability weighting and competing risk models.
Limitations
- Residual confounding and unmeasured differences (e.g., surgical indications) may remain.
- Onset of new epilepsy risk factors during follow-up could not be fully controlled.
Future Directions: Procedure-specific analyses, prospective registries capturing perioperative brain insults, and mechanistic studies to disentangle anesthesia effects from surgical/pathology contributors.
BACKGROUND AND OBJECTIVES: Evidence suggests that the receipt of general anesthesia may be associated with an increased risk of epilepsy compared with neuraxial (i.e., spinal or epidural) anesthesia. Our study objective was to estimate the risk of developing new-onset epilepsy associated with the receipt of general anesthesia relative to neuraxial anesthesia. METHODS: We conducted a population-based retrospective cohort study using linked health administrative databases in Ontario, Canada. Participants who underwent an eligible surgical procedure with general or neuraxial anesthesia between April 1, 2007, and March 31, 2015, were included and followed for up to 5 years. Eligible surgical procedures included gynecologic, lower extremity, peripheral vascular, and urologic procedures that could be performed using general or neuraxial anesthesia. Patients with epilepsy or epilepsy risk factors in the 10 years before their surgical procedure were excluded. We used inverse probability of treatment weighting to control for confounding and Fine-Gray subdistribution models to estimate the hazard ratio for epilepsy, accounting for the competing risk of death. RESULTS: The final sample included 100,547 patients who received general anesthesia and 76,644 patients who received neuraxial anesthesia. After weighting, the general and neuraxial anesthesia cohorts comprised 64.8% and 63.0% of women and the mean ages were 56.0 and 56.8 years, respectively. The estimated weighted event rates of epilepsy were 48.8 and 35.5 per 100,000 person-years for general and neuraxial anesthesia cohorts, respectively. The hazard ratio (HR) for epilepsy associated with general anesthesia was 0.61 at time zero (95% CI 0.34-1.07). However, there was evidence that risk changed over the five-year follow-up period (time interaction HR = 1.36, 95% CI 1.12-1.64). This led to a significantly increased risk of epilepsy associated with general anesthesia after approximately 3 years. DISCUSSION: The effects of general anesthesia may take multiple years to become significantly associated with an increased risk of epilepsy. However, our findings are likely affected by other factors, such as unmeasured differences between the anesthesia cohorts, types of surgical procedures, and the occurrence of epilepsy risk factors during follow-up. Future research should explore whether there is effect modification between specific surgical procedures and control for the onset of epilepsy risk factors after anesthesia receipt.