Daily Anesthesiology Research Analysis
Three perioperative anesthesia studies stand out today: an RCT meta-analysis finds that withholding ACE inhibitors/angiotensin receptor blockers preoperatively reduces intraoperative hypotension (though with very low certainty for downstream outcomes); pediatric pharmacokinetic modeling refines safe ropivacaine dosing for continuous lumbar plexus blocks by highlighting late accumulation of the metabolite PPX; and a randomized trial shows perineural—versus intravenous—dexamethasone significantly
Summary
Three perioperative anesthesia studies stand out today: an RCT meta-analysis finds that withholding ACE inhibitors/angiotensin receptor blockers preoperatively reduces intraoperative hypotension (though with very low certainty for downstream outcomes); pediatric pharmacokinetic modeling refines safe ropivacaine dosing for continuous lumbar plexus blocks by highlighting late accumulation of the metabolite PPX; and a randomized trial shows perineural—versus intravenous—dexamethasone significantly prolongs and strengthens thoracic paravertebral block analgesia after lung cancer surgery.
Research Themes
- Perioperative management of cardiovascular medications
- Pediatric regional anesthesia pharmacokinetics and safety
- Optimization of regional anesthesia adjuvants for thoracic surgery
Selected Articles
1. Withholding vs. continuing angiotensin-converting enzyme inhibitors or angiotensin receptor blockers before surgery: a systematic review and meta-analysis of randomized controlled trials.
Across 14 RCTs (n=4,063), withholding ACEIs/ARBs before noncardiac surgery reduced intraoperative hypotension (36.4% vs 48.4%; RR 0.73, 95% CI 0.60–0.88). Effects on vasopressors and postoperative outcomes were uncertain, and overall certainty (GRADE) was very low, warranting cautious interpretation and further trials.
Impact: This synthesis addresses a ubiquitous perioperative decision with immediate bedside implications and aggregates the highest-level experimental data available.
Clinical Implications: Consider withholding ACEIs/ARBs on the day of noncardiac surgery to lower intraoperative hypotension risk, particularly in patients vulnerable to hemodynamic instability; balance against indications necessitating continuation and acknowledge very low certainty for downstream outcomes.
Key Findings
- Withholding ACEIs/ARBs reduced intraoperative hypotension (36.4% vs 48.4%; RR 0.73, 95% CI 0.60–0.88).
- Meta-analysis included 14 RCTs with 4,063 patients and used GRADE to rate evidence.
- Effects on vasopressor use and postoperative outcomes (AKI, MACE, LOS, 30-day mortality) remain uncertain with very low certainty.
Methodological Strengths
- Meta-analysis restricted to randomized controlled trials with predefined outcomes.
- Use of GRADE framework and PROSPERO registration (CRD42021253965).
Limitations
- Very low certainty across several outcomes due to heterogeneity and potential bias.
- Incomplete reporting of secondary endpoints in abstracts limits precision of effect estimates.
Future Directions: Large, pragmatic, pre-registered RCTs with standardized definitions should evaluate patient-centered outcomes (AKI, MACE, mortality) and stratify by heart failure, hypertension control, and surgical risk.
2. Revisiting Infusion Rate Limitations for Continuous Lumbar Plexus Blocks in Children and Adolescents with 0.2% Ropivacaine: A Pharmacokinetic Analysis.
In 20 children receiving 0.2% ropivacaine lumbar plexus blocks (2 mg/kg bolus + 0.4 mg·kg−1·h−1 infusion), unbound ropivacaine and PPX showed wide interpatient variability, and simulations indicated the 95th percentile of unbound ropivacaine + 1/12 PPX approached toxicity after prolonged infusion. Modeling supports standard dosing for the first 24 hours, then reducing/eliminating infusion in favor of timed boluses.
Impact: This provides rare pediatric human PK data on unbound ropivacaine and PPX during continuous regional anesthesia, directly informing safer dosing beyond 24 hours.
Clinical Implications: For continuous lumbar plexus blocks in children, maintain 0.4 mg·kg−1·h−1 for the first 24 hours with 0.2 mg/kg 6-hourly boluses; thereafter, consider discontinuing infusion and using timed boluses to mitigate PPX-driven late toxicity risk, especially in patients with altered clearance.
Key Findings
- Unbound ropivacaine plateau concentrations varied ~5-fold and PPX ~10-fold across patients.
- Standard infusion (0.4 mg·kg−1·h−1) plus regular boluses led the 95th percentile sum of unbound ropivacaine + 1/12 PPX toward the estimated toxic threshold after prolonged infusion.
- Switching after 24 hours to 6-hourly boluses lowered simulated ropivacaine and PPX concentrations while preserving analgesia strategy.
Methodological Strengths
- Prospective sampling of total and unbound ropivacaine and PPX with population PK modeling.
- Clinically anchored simulations against accepted toxicity thresholds to inform dosing.
Limitations
- Small single-center cohort of healthy children undergoing hip/femur surgery limits generalizability.
- Toxicity thresholds are estimated; clinical outcomes (toxicity events) were not primary endpoints.
Future Directions: Validate PK-guided dosing with multicenter trials including children with comorbidities and longer infusions, incorporating therapeutic drug monitoring and clinical toxicity endpoints.
3. Comparison of Postoperative Analgesic Effects of Intravenous versus Perineural Dexamethasone Injection Combined with Ropivacaine in Thoracoscopy-Guided Thoracic Paravertebral Block for Thoracoscopic Radical Lung Cancer Resection: A Prospective Randomized Controlled Trial.
In 150 patients undergoing thoracoscopic lung cancer resection with thoracoscopy-guided paravertebral block, perineural dexamethasone (with ropivacaine) prolonged time to first rescue analgesia, lowered VAS scores at all time points, reduced 48-hour sufentanil use, blunted postoperative hyperglycemia, and hastened ambulation and discharge compared with intravenous dexamethasone.
Impact: This RCT provides direct, practice-changing evidence on dexamethasone route for a widely used thoracic regional technique, with consistent benefits across pain, opioid use, glycemia, and recovery.
Clinical Implications: When using thoracic paravertebral blocks for thoracoscopic lung surgery, consider perineural dexamethasone as the preferred adjuvant to enhance and prolong analgesia and facilitate ERAS goals, while observing local regulations regarding off-label perineural steroid use.
Key Findings
- Perineural dexamethasone prolonged time to first rescue analgesia versus intravenous administration.
- VAS pain scores were lower at all postoperative time points with perineural dosing.
- Perineural dosing reduced 48-hour sufentanil consumption, attenuated postoperative glucose rise, and shortened time to ambulation and hospital stay.
Methodological Strengths
- Prospective randomized controlled design with adequate sample size (n=150).
- Multidomain outcomes (analgesia, opioid use, glycemia, recovery) increase external validity.
Limitations
- Blinding procedures and detailed effect sizes were not fully reported in the abstract.
- Single-center setting may limit generalizability; long-term outcomes not assessed.
Future Directions: Confirm efficacy and safety across centers, assess optimal dosing of perineural dexamethasone, and evaluate long-term outcomes (chronic pain, functional recovery); consider comparative cost-effectiveness within ERAS pathways.