Regional Anesthesia and Pain Medicine最新文献

Background: Regional anesthesia is widely used in pain management to reduce opioid requirements, enable early mobilization and improve postoperative outcomes. However, commonly used combinations of local anesthetics and adjuvants can crystallize under clinical conditions, which generates concerns regarding neurotoxicity and embolization complications.

Purpose: This study aimed to determine whether microporous filters can effectively eliminate crystals formed by mixing local anesthetics and adjuvant.

Method: Commonly used local anesthetics (lidocaine, mepivacaine and ropivacaine) and adjuvants (dexamethasone, dexmedetomidine and sodium bicarbonate) were combined and tested. The mixture was passed through 5 µm and 0.2 µm filters, and the presence of crystals before and after filtration at specific time points and volumes was assessed microscopically.

Results: Lidocaine mixtures showed no detectable crystallization under any condition. In contrast, crystallization occurred in most combinations containing mepivacaine or ropivacaine, with the highest grades observed in ropivacaine-bicarbonate mixtures (grade 5). Filtration reduced crystallization grades by 1-3 points depending on the mixtures, but did not eliminate crystals in most mixtures. Crystals also persisted after longer intervals and with larger filtration volumes. No meaningful difference was observed between the 5 µm and 0.2 µm filters.

Conclusion: Crystallization can occur in anesthetic-adjuvant mixtures that are commonly used for regional anesthesia. Although filtration reduces these crystals, it does not eliminate crystals, especially those with large volumes or unstable combinations.

Background: Thoracic paravertebral block (TPVB) can provide effective analgesia for patients undergoing video-assisted thoracoscopic surgery (VATS). However, the duration of analgesia achieved with conventional local anesthetics combined with dexamethasone remains limited. This study aimed to determine if liposomal bupivacaine (LB) is superior to bupivacaine combined with dexamethasone (BD) with respect to duration of postoperative analgesia in VATS patients.

Methods: Adults scheduled for VATS were randomized to treatment with LB or BD. The primary outcome was duration of analgesia. Secondary outcomes involved Numeric Rating Scale (NRS) pain scores, cumulative oxycodone consumption, total intraoperative sufentanil consumption, first times to ambulation and flatus, length of hospital stay, patient satisfaction level, and incidence of adverse reactions.

Results: Of 93 total subjects, 78 were randomized into two groups (n=39 each). The LB group demonstrated a significantly prolonged duration of analgesia compared with the BD group (1160.4±403.8 min vs 743.1±216.8 min, p<0.001), with a mean increase of 417 min (a 56% extension). LB was associated with lower resting and cough NRS pain scores on the first postoperative day. The 72-hour area under the curve values for scores for resting pain (67.5 vs 87.9) and pain during cough (213.9 vs 244.0) were lower for the LB group versus the BD group. In exploratory analyses, cumulative oxycodone consumption on the first postoperative day was numerically lower in the LB group. Subjects receiving treatment LB had lower cumulative oxycodone consumption on the first postoperative day, earlier times to first ambulation and first flatus, and higher satisfaction scores as compared with subjects receiving BD. There was no significant difference between the two groups in terms of total intraoperative sufentanil consumption, duration of hospital stay, or incidence of adverse events.

Conclusion: In VATS patients receiving TPVB, LB significantly prolonged the duration of postoperative analgesia compared with BD. Exploratory secondary outcomes suggested modest improvements in early pain profiles and potential opioid-sparing and early recovery benefits.

Trial registration number: ChiCTR2500095090.

Background: Chronic intrathecal opioid use via intrathecal drug delivery system (IDDS), while effective in some patients, can lead to serious complications and side effects. Complications related to IDDS include mechanical/device malfunction, intrathecal catheter problems, infections, and provider errors. These issues often require urgent surgical intervention, IDDS removal, and abrupt discontinuation of the analgesic infusion. In these scenarios, the safe and effective transition to alternative opioid delivery routes such as intravenous or oral administration is critical. However, an accurate calculation of equianalgesic doses to ensure adequate pain control while minimizing the risk of withdrawal is not well documented.

Case report: A patient in their 60s with a complex medical history, including chronic low back pain managed with IDDS for 30 years, presented with severe pain unresponsive to dose adjustments. Imaging revealed a catheter-related granuloma at thoracic 8 level, leading to intrathecal therapy discontinuation. A rapid weaning protocol reduced the intrathecal morphine dose by 10% daily, transitioning to systemic opioids based on pain severity and short-acting opioid needs. The final intrathecal-to-oral morphine conversion ratio by the time the pump was empty on day 10 was approximately 1:10.

Conclusion: Current guidelines for intrathecal-to-systemic opioid conversion vary widely, with outdated literature suggesting a 1:300 ratio, whereas real-world cases report ratios between 1:2.5 and 1:70. Given this variability, a conservative, patient-specific approach is essential. Clinicians should consider pharmacokinetics, tolerance, and comorbidities, starting with lower conversion ratios and titrating carefully.

Background: Despite clear evidence of treatment gaps for opioid use disorder (OUD) among the general population, diagnosis and treatment patterns among surgical patients remain poorly characterized. This study aimed to examine national trends in OUD diagnosis and exposure to treatment with medications for opioid use disorder (MOUD) among US surgical patients.

Methods: This population-based cohort study used the Merative MarketScan Commercial Database from July 1, 2016 to December 31, 2022. US adults aged 18-64 years undergoing inpatient or outpatient surgery were included. OUD was identified using International Classification of Disease, 10th Revision codes. MOUD receipt was defined as 1+pharmacy or medical claims for buprenorphine, methadone, or naltrexone within 180 days before surgery. Multivariate logistic regression assessed trends in OUD and MOUD receipt, adjusting for patient, surgical, and clinical variables.

Results: Among 5 341 768 surgical patients (62.5% female), 31 094 (0.58%) had an OUD diagnosis. The prevalence of OUD declined from 0.71% in 2016 to 0.50% in 2022. Among patients with OUD, the proportion receiving MOUD in the 6 months before surgery increased from 17.8% to 32.6% over the study period. The corresponding treatment gap in MOUD receipt decreased from 82.2% in 2016 to 67.4% in 2022.

Conclusions: In this national cohort of commercially insured surgical patients, most individuals diagnosed with OUD did not receive evidence-based treatment before surgery, despite modest improvements over time. These findings highlight a persistent treatment gap and suggest missed opportunities to improve perioperative care and outcomes for patients with OUD.

Background: Conditioned pain modulation (CPM) assesses the attenuation of pain when a concurrent noxious stimulus is applied and is linked to prognosis in pain syndromes. Clinical implementation remains constrained by response variability and equipment requirements. The objective of this study was to assess the feasibility, variability, and reliability of a novel, user-friendly transcutaneous electrical nerve stimulation (TENS)-pressure-cuff CPM paradigm and compare it to a conventional algometry-pressure-cuff paradigm.

Methods: Two cross-sectional experiments totaling 82 healthy participants were conducted. In Experiment 1, 50 healthy participants underwent both TENS-pressure-cuff and algometry-pressure-cuff CPM paradigms. An additional experiment (Experiment 2) was conducted in an independent cohort of 32 subjects to replicate findings from Experiment 1 while controlling potential bias sources.

Results: In Experiment 1, TENS-pressure-cuff paradigm showed a mean electrical pain threshold (ΔEPT) of 5.6 mA (17%; p<0.001) versus a non-significant pressure pain threshold (ΔPPT) of 0.14 kg (11%; p=0.53); with lower coefficient of variation (CV) and higher standardized response mean (SRM). In Experiment 2, ΔEPT remained significant (p=0.026) while ΔPPT did not (p=0.06), though paradigms exhibited comparable CVs and SRMs. Inter-rater reliability was higher for TENS (ICC = 0.84; 95% CI 0.69 to 0.92) than algometry (ICC=0.27; 95% CI -0.09 to 0.57), with no difference in inter-session reliability (TENS=0.57; 95% CI 0.26 to 0.76 vs algometry=0.11; 95% CI -0.50 to -0.29). Finally, 67.7% of participants were classified as CPM responders with TENS versus 16.4% with algometry (McNemar's χ² = 8.47, p=0.004).

Conclusions: A TENS-pressure-cuff paradigm is a suitable approach for assessing CPM. Its variability and inter-session reliability are comparable to a conventional algometry-pressure-cuff paradigm, while exhibiting higher inter-rater reliability and sensitivity to detect inhibitory CPM responses. Further research should evaluate the utility of this paradigm in pathological populations.

Background and objectives: The popliteal plexus block is a motor-sparing regional anesthetic technique used as an adjunct to multimodal analgesia after total knee arthroplasty. Clinical studies have used varying local anesthetic volumes for the block, reflecting uncertainty regarding the optimal volume. This randomized clinical trial aimed to determine whether using 20 mL of local anesthetic for the popliteal plexus block provides superior analgesic efficacy and early functional outcomes compared with 10 mL after total knee arthroplasty.

Methods: In this single-center, blinded, randomized controlled trial, 120 adults undergoing primary unilateral total knee arthroplasty under spinal anesthesia were randomized to receive a popliteal plexus block with either 10 mL or 20 mL of bupivacaine 5 mg/mL, in addition to a standardized multimodal analgesic regimen including a femoral triangle block. The primary outcome was 24-hour postoperative opioid consumption. Secondary outcomes included the proportion of patients achieving opioid-free analgesia, pain scores, early functional outcomes and patient-reported Quality of Recovery-15.

Results: No statistically significant or clinically relevant differences were observed between the two groups in 24-hour postoperative opioid consumption (median 15 (IQR 3.75-30) vs 15 mg (IQR 0-30) oral morphine milligram equivalents; median difference 0 mg, 95% CI -10 to 5; p=0.6), the proportion of patients achieving opioid-free analgesia, pain at rest or during ambulation, ability to ambulate with crutches, motor impairment, or patient-reported quality of recovery.

Conclusions: Use of 20 mL of local anesthetic for the popliteal plexus block as part of a multimodal analgesic regimen after total knee arthroplasty does not provide superior analgesic efficacy or improved functional outcomes compared with 10 mL. Consistent with the principle of using the lowest effective dose and minimizing cumulative local anesthetic exposure, these findings support the use of 10 mL of local anesthetic for popliteal plexus block in clinical practice and in future research.

Trial registration number: EUCT number: 2024-520204-26-00.

Background: Low back pain is a leading cause of disability. Up to 45% of lumbar spine pain may be facetogenic. Both standard radiofrequency ablation (SRFA) and cooled radiofrequency ablation (CRFA) have been deployed to treat facetogenic pain.

Methods: Patients with lumbar facetogenic back pain, identified by two positive medial branch blocks (MBBs), were randomized to treatment with CRFA or SRFA. The primary endpoint was the proportion of subjects whose back pain decreased by ≥50% on the Numeric Rating Scale (NRS (usual): patient's level of pain over the past 7 days) at 6 months, with subjects followed through 12 months. Secondary endpoints included changes in SF-36 (36-Item Short Form Health Survey) Physical Functioning (PF), Oswestry Disability Index (ODI), Global Perceived Effect scale (GPE), and EQ-5D-5L index (EuroQol's Health-Related Quality of Life Score using 5 levels over 5 dimensions).Enrollment (target 188) ended early after 18 months due to funding reallocation and strict Medicare criterion requiring ≥80% pain relief from dual MBBs.

Results: 74 patients (37 CRFA, 37 SRFA) were randomized, treated, and included in the intention-to-treat analysis. 61 patients (27 CRFA, 34 SRFA) completed the 6-month primary endpoint visit. Both CRFA and SRFA provided robust, statistically significant and clinically relevant reductions in NRS pain scores from baseline at every time point (p≤0.0001). CRFA met the predefined non-inferiority criterion relative to SRFA (p=0.0069), with a high proportion of both groups achieving ≥50% pain relief at the primary endpoint-74.1% with CRFA and 64.7% with SRFA. Although CRFA showed numerically greater reductions in NRS pain scores from baseline (-4.3 vs -3.4), both treatments exceeded the minimal clinically important difference threshold. No statistically significant differences in NRS scores were observed between groups at any time point, likely due to the premature termination of the study (only 52% enrolled). Both groups also showed significant and comparable improvements in NRS, EQ-5D-5L, ODI, SF-36 (PF), and GPE at 6 and 12 months.

Conclusion: Despite the smaller than intended sample size, due to early termination by the sponsor, this study demonstrated that with appropriate patient selection and proper procedural technique, both CRFA and SRFA can relieve chronic facetogenic low back pain, improve disability, function, and quality of life for 6-12 months.

Trial registration number: NCT04803149.

Background: This randomized trial compared ultrasound-guided interscalene block (ISB) and combined infraclavicular (ICB)-anterior suprascapular nerve block (SSNB) for arthroscopic shoulder surgery. We hypothesized that combined ICB-anterior SSNB provides equivalent analgesia to ISB 30 min after surgery.

Methods: Fifty subjects were randomized to ISB or combined ICB-anterior SSNB. Twenty mL of bupivacaine 0.5% with epinephrine 5 µg/mL was used for ISB. For ICB and anterior SSNB, we administered 20 mL and 3 mL of bupivacaine 0.5% with epinephrine 5 µg/mL, respectively. Subsequently, all patients underwent general anesthesia.The primary outcome was the pain score at 30 min in the post-anesthesia care unit. Secondary outcomes included the rate of complete sensorimotor blockade (assessed after the performance of the blocks using a 14-point composite scale), postoperative pain scores at 0.5, 1, 3, 6, 12, 24, 36, and 48 hours, the presence of hemidiaphragmatic paralysis at 30 min after the performance of the blocks and in the post-anesthesia care unit, consumption of intraoperative and postoperative narcotics, opioid-related side effects, and patient satisfaction at 24 hours.

Results: No intergroup differences were found in postoperative pain scores, proportion of patients with complete sensorimotor blockade, intraoperative/postoperative opioid consumption, side effects, and patient satisfaction at 24 hours. Compared with combined ICB-SSNB, ISB resulted in a higher incidence of hemidiaphragmatic paralysis 30 min after the block and in the post-anesthesia care unit (68% vs 0%; and 88% vs 0%, respectively; both p<0.001).

Conclusion: Compared with ISB, combined ICB-anterior SSNB results in equivalent postoperative analgesia while circumventing the risk of hemidiaphragmatic paralysis. Further confirmatory trials are required. Future studies should also investigate whether combined ICB- anterior SSNB can provide surgical anesthesia for shoulder surgery.

Trial registration number: NCT05444517.