Daily Anesthesiology Research Analysis
Three impactful anesthesiology studies stood out today: a double-blind non-inferiority RCT shows PENG block provides analgesia comparable to intrathecal morphine after total hip arthroplasty without added motor impairment; a large cohort analysis links single-injection peripheral nerve blocks to increased in-hospital opioid use despite better immediate PACU outcomes, underscoring rebound pain; and a meta-analysis suggests inhaled nitric oxide during cardiopulmonary bypass may reduce AKI and myoc
Summary
Three impactful anesthesiology studies stood out today: a double-blind non-inferiority RCT shows PENG block provides analgesia comparable to intrathecal morphine after total hip arthroplasty without added motor impairment; a large cohort analysis links single-injection peripheral nerve blocks to increased in-hospital opioid use despite better immediate PACU outcomes, underscoring rebound pain; and a meta-analysis suggests inhaled nitric oxide during cardiopulmonary bypass may reduce AKI and myocardial injury, though effects on hard clinical endpoints remain inconsistent.
Research Themes
- Regional anesthesia optimization and opioid stewardship
- Perioperative analgesic strategies in orthopedic surgery
- Organ-protective adjuncts during cardiopulmonary bypass
Selected Articles
1. Pericapsular nerve group (PENG) block compared to intrathecal morphine for analgesic efficacy in total hip arthroplasty: A placebo-controlled randomized double-blind non-inferiority trial.
In a double-blind non-inferiority RCT (n=60), PENG block (levobupivacaine 0.5% 20 mL + dexamethasone 2 mg) provided pain control after THA that was non-inferior to intrathecal morphine 100 μg for both rest and active hip flexion over 48 hours, with similar rescue opioid use. Age-adjusted straight leg raise failure rates were comparable, indicating no added motor impairment.
Impact: Provides high-quality randomized evidence that a motor-sparing regional technique can replace intrathecal morphine for THA analgesia, supporting opioid-sparing ERAS pathways.
Clinical Implications: PENG block can be adopted as a primary analgesic strategy after THA under spinal anesthesia to avoid neuraxial opioid side effects while maintaining analgesic efficacy and motor function.
Key Findings
- PENG block was non-inferior to intrathecal morphine for maximum pain at rest and during active hip flexion over 48 hours.
- Cumulative 48-hour opioid consumption (MME) did not differ meaningfully between groups (difference −2.1 MME).
- Age-adjusted straight leg raise failure rates were similar (no additional motor impairment with PENG).
Methodological Strengths
- Double-blind, placebo-controlled randomized non-inferiority design with prespecified margins.
- Complete follow-up of all randomized patients with consistent multimodal analgesia.
Limitations
- Single-center study with a modest sample size (n=60), limiting generalizability.
- Not powered to detect rare adverse events or long-term functional outcomes.
Future Directions: Multicenter RCTs powered for functional recovery, opioid-related adverse events, and comparative effectiveness against other regional techniques (e.g., fascia iliaca, periarticular infiltration).
2. Association of peripheral nerve blocks with increased postoperative pain and opioid use in orthopaedic surgery: a single-centre retrospective cohort study.
In 22,956 orthopedic cases, single-injection peripheral nerve blocks reduced PACU pain and immediate opioid use but were associated with higher in-hospital opioid consumption (+22.7%) and higher maximum in-hospital pain. Opioid prescriptions increased at 30 days (not at 90/180 days), while chronic pain diagnoses decreased at 1 year, highlighting rebound pain as a key management target.
Impact: Challenges common assumptions about net opioid-sparing benefits of single-shot nerve blocks and emphasizes the need for structured rebound pain mitigation strategies.
Clinical Implications: Implement standardized protocols to mitigate rebound pain (e.g., longer-acting techniques or catheters, perineural/systemic adjuvants like dexamethasone, scheduled non-opioid multimodal regimens, and anticipatory discharge instructions) to reduce overall opioid exposure.
Key Findings
- Peripheral nerve blocks lowered PACU maximum pain and immediate opioid use.
- In-hospital opioid consumption increased by 22.7% and maximum pain was higher among block recipients.
- Opioid prescriptions increased at 30 days post-discharge but not at 90 or 180 days; chronic pain diagnoses were lower at 1 year.
Methodological Strengths
- Very large sample size with propensity score weighting to reduce confounding.
- Comprehensive outcome assessment spanning PACU, inpatient course, and post-discharge periods up to 1 year.
Limitations
- Single-center retrospective design with potential residual confounding and heterogeneity in block types and perioperative care.
- Opioid prescription data may not reflect actual consumption; causality cannot be inferred.
Future Directions: Prospective trials testing rebound pain mitigation bundles (e.g., continuous catheters vs. long-acting formulations, perineural adjuvants) and opioid stewardship pathways that integrate risk stratification.
3. The organ-protective effects of nitric oxide in adult patients undergoing cardiac surgery with cardiopulmonary bypass: a systematic review and meta-analysis.
Across 10 RCTs (n=838), inhaled NO during CPB reduced AKI risk (RR 0.78) and lowered cardiac troponin I, but benefits did not consistently translate into improved clinical outcomes; an initial signal for reduced ventilation duration disappeared after adjusting for publication bias. Evidence certainty is limited by small sample sizes and small-study effects.
Impact: Synthesizes randomized evidence on a widely available intraoperative adjunct with plausible mechanisms for organ protection, informing selective use and future trial design.
Clinical Implications: Consider inhaled NO selectively for high-risk CPB patients where renal protection is prioritized, while recognizing uncertain effects on broader outcomes; prioritize enrollment into adequately powered trials.
Key Findings
- Inhaled NO reduced the incidence of acute kidney injury after CPB (RR 0.78, 95% CI 0.64–0.94).
- cTnI levels were lower with NO, suggesting reduced myocardial injury.
- No consistent improvements in major clinical outcomes; the apparent decrease in ventilation duration was not robust after publication bias adjustment.
Methodological Strengths
- PRISMA-compliant systematic review with GRADE assessment and meta-regression.
- Sensitivity analyses and publication bias evaluation (funnel plots, trim-and-fill).
Limitations
- Small cumulative sample size and small-study effects limit certainty.
- Heterogeneity in NO dosing and timing; inconsistent reporting of clinical endpoints.
Future Directions: Large multicenter RCTs targeting high-risk CPB populations with standardized NO protocols, renal biomarkers, and patient-centered clinical endpoints (e.g., MAKE, KDIGO-defined AKI, ICU/hospital LOS, mortality).