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OBJECTIVES: This study aimed to assess the effect of needle insertion angle on pain during labial infiltration anesthesia in the anterior maxillary region. MATERIAL AND METHODS: In this parallel-design randomized clinical trial, participants were randomly assigned to four groups for labial infiltration anesthesia of the anterior maxilla. Local anesthesia was performed with needle orientation parallel to the longitudinal axis of the tooth using a conventional syringe (Syringe-0), needle at α angle with a conventional syringe (Syringe-α), computer-controlled local anesthetic delivery (CCLAD) device parallel to the longitudinal axis of the tooth (CCLAD-0), and CCLAD at α angle (CCLAD-α). The heart rate (HR), blood pressure (BP), and respiratory rate (RR) of participants were measured before needle insertion, immediately after needle insertion, and immediately after the injection by a vital signs monitor. The level of pain experienced by participants was quantified using a numerical rating scale (NRS). Data were analyzed by repeated-measures ANOVA and regression models (α = 0.05). RESULTS: Thirty-six participants aged from 21 to 60 years, with a mean age of 35.36 years were recruited. The mean pain scores were 7.44, 4.67, 2.89, and 0.67 in groups Syringe-0, Syringe-α, CCLAD-0, and CCLAD-α, respectively (p < 0.001). Age and sex had no significant effect on pain scores (p = 0.914 and p = 0.702, respectively). The four groups had no significant difference in vital signs (p > 0.05). CONCLUSIONS: Injection at an α angle and the application of CCLAD can be used in clinical practice to decrease the pain experienced by participants during labial infiltration anesthesia of the anterior maxilla. TRIAL REGISTRATION: Iranian Registry of Clinical Trials: IRCT20230719058849N1.

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OBJECTIVE: This study aimed to optimize the formulation of magnetically targeted lidocaine microspheres, reduce the microsphere particle size, and increase the drug loading and encapsulation rate of lidocaine. The optimized microspheres were characterized, and their pharmacokinetics and effective radii of action were studied. METHODS: The preparation of magnetically targeted lidocaine microspheres was optimized using ultrasonic emulsification-solvent evaporation. The Box-Behnken design method and response surface method were used for optimization. The optimized microspheres were characterized and tested for their in vitro release. Blood concentrations were analyzed using a non-compartment model, and the main pharmacokinetic parameters (half-life (t1/2 ), maximum blood concentration, area under the blood concentration-time curve (AUC), time to peak (Tmax ), and mean retention time (MRT) were calculated. Pathological sections were stained to study the safety of the microsphere tissues. A rabbit sciatic nerve model was used to determine the "standard time (t0 )" and effective radius of the microspheres. RESULTS: The optimized lidocaine microspheres exhibited significantly reduced particle size and increased drug loading and encapsulation rates. Pharmacokinetic experiments showed that the t1/2 , Tmax , and MRT of magnetically targeted lidocaine microspheres were significantly prolonged in the magnetic field, and the AUC0-48 and AUC0-∞ were significantly decreased. Its pharmacodynamic radius was 31.47 mm. CONCLUSION: Magnetically targeted lidocaine microspheres provide sustained long-lasting release, neurotargeting, nerve blocking, and high tissue safety. This preparation has a significantly low blood concentration and a slow release in vivo, which can reduce local anesthetic entry into the blood. This may be a novel and effective method for improving postoperative comfort and treating chronic pain. This provides a countermeasure for exploring the size of the magnetic field for the application of magnetic drug-carrying materials.

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INTRODUCTION: Both thoracic epidural analgesia and thoracic paravertebral analgesia are effective techniques to control pain and minimize the stress response following thoracic surgery. We hypothesized that continuous neuraxial techniques may be associated with a decrease in the incidence of postoperative mortality after thoracotomy. Additionally, we aimed to identify subgroup populations that may benefit more from neuraxial anesthesia. METHOD: 1620 patients who underwent open thoracotomy were included in this retrospective study from the German Thoracic Registry database at four university hospitals. All-cause inpatient mortality was determined for patients who had and did not have neuraxial anesthesia. Logistic regression was used to adjust for and explore various covariates. RESULTS: Continuous neuraxial analgesia was associated with a lower overall mortality in the postoperative period (2.9%, 23/796 vs 5.3%, 44/824, p=0.02) only after the univariate analysis but not the multivariable analysis (OR 0.49, 95 % CI 0.237 to 1.12, p=0.15). In patients with epidural or paravertebral catheters, mortality was significantly lower in the following subgroups: age >75 (5/113 vs 18/77, OR 0.1, 95% CI 0.02 to 0.67, p=0.02), American Society of Anesthesiologists Performance Score >III (11//97 vs 33/155, OR 0.32, 95% CI 0.11 to 0.89, p=0.03), chronic kidney disease (5/83 vs 16/77, OR 0.16, 95% CI 0.03 to 0.82, p=0.03), and postoperative sepsis (9/21 vs 17/25, OR 0.13, 95% CI 0.07 to 0.44, p<0.01). CONCLUSIONS: Neuraxial analgesic techniques are associated with reductions in postoperative mortality after open thoracic surgery in selected patients.

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BACKGROUND: Current understanding of the mechanism of action of the pericapsular nerve group (PENG) block is primarily based on cadaver studies. We performed an imaging study in patients undergoing hip surgery to enhance the understanding of the analgesic mechanisms following a PENG block. MATERIALS AND METHODS: 10 patients scheduled for hip surgery received an ultrasound-guided PENG block with 18 mL of 0.5% ropivacaine mixed with 2 mL of a contrast agent. After completion of the block, a high-resolution CT scan was performed to obtain a three-dimensional reconstruction of the injectate's dispersion. RESULTS: The CT imaging revealed that injectate was mainly confined to the epimysium of the iliacus and the psoas muscle, with a minor spread to the hip capsule. Contrast dye was detected within the iliacus and/or the psoas muscle in all patients. No observed spread to either the subpectineal plane or the obturator foramen was detected. CONCLUSION: Our study suggests that the analgesic effect of the PENG block may be related to the block of the branches of the femoral nerve traveling within the iliopsoas muscle without a spread pattern commensurate with the block of the obturator nerve. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov Registry (NCT06062134).

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Purpose: This study aimed to investigate the impact of ultrasound-guided, bilateral, low level (T8-T9) deep serratus anterior plane (DSAP) blocks on postoperative recovery quality and postoperative analgesia in patients undergoing trans-subxiphoid robotic thymectomy (TRT). Methods: 39 patients undergoing TRT were randomized to receive either low DSAP block under general anesthesia (Group S) or the sham block (Group C) on each side. The primary outcome was the QoR-40 score at postoperative day (POD) 1. Secondary outcomes included numeric rating scale (NRS) scores over time, postoperative 48 hours opioid consumption, QoR-40 scores at POD 2, 30, and 90. Results: The QoR-40 scores on POD1-2 were higher in Group S than in Group C [179.1 (4.9) vs 167.7 (2.8), P < 0.01; 187.7 (4.6) vs 178.1 (3), P < 0.01, respectively]. Pain scores were significantly lower in Group S, both during resting and motion at postoperative 6h, 12h, and 24h (P < 0.05 for each). The total amount of sufentanil consumed in the first 48 h was lower in Group S than in Group C [61.4 (4.9) vs 78.9 (4.6), P < 0.001]. Conclusion: The bilateral low DSAP blocks enhanced the QoR-40 for 2 days postoperatively, relieved postsurgical pain, and reduced opioid consumption during the early postoperative period in patients undergoing TRT.

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INTRODUCTION: Interdigital block and transthecal block through the flexor sheath are commonly used techniques for the anesthesia of isolated fingers. The wide-awake local anesthetic no-tourniquet technique is a relatively new approach for local anesthesia during finger procedures. The anatomical spread of local anesthetics with the wide-awake local anesthetic no tourniquet technique has not been described adequately.This anatomical study aimed to assess the distribution of a local anesthetic dye solution to the digital nerves. The study was designed to compare the nerve staining effect using the wide-awake local anesthetic no tourniquet and the transthecal and interdigital techniques in cadavers. We hypothesized that the wide-awake local anesthetic no tourniquet technique stains digital nerves more effectively than the interdigital and transthecal digital injection techniques. METHODS: 14 blocks were performed using anatomical landmarks. 2 mL of a mixture of local anesthetic, methylene blue, and contrast medium were injected. Before dissection, the specimens were passed through an X-ray scanner to assess the spread of the mixture. Finally, anatomical dissections were performed to evaluate the specific hand nerve implications. RESULTS: In the wide-awake local anesthetic no tourniquet group, the local anesthetics spread to the nerves of each finger but not the common nerve. In the transthecal and interdigital groups, the spread extended from the common nerve to the lateral aspect of the adjacent fingers. CONCLUSION: The wide-awake local anesthetic no tourniquet technique was as effective as conventional techniques in the digital blockade, achieving specific spread on the targeted nerves.

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BACKGROUND AND AIMS: Anterior quadratus lumborum block is a truncal block, applied in close proximity to the lumbar plexus, potentially causing lower limb weakness. This trial aimed to evaluate whether a unilateral anterior quadratus lumborum block caused quadriceps muscle weakness compared with placebo. METHODS: In this randomized, non-inferiority, triple-blind trial, 20 healthy volunteers received an active unilateral anterior quadratus lumborum block with 30 mL ropivacaine 0.75% and a placebo block on the contralateral side. Primary outcome was change in maximal quadriceps muscle strength from baseline to 60 min postblock compared with placebo. Secondary outcomes were change in single-leg 6 m timed hop test, change in Timed-Up and Go test, change in mean arterial pressure from baseline to 30 min postblock and dermatomal affection. RESULTS: There was no statistically significant difference in changes in maximal quadriceps muscle strength between active and placebo block; 15.88 N (95% CI -12.19 to +43.94), pnon-inf=0.003, indicating non-inferiority. Timed-Up and Go test was performed significantly faster 60 min postblock; -0.23 s (95% CI -0.38 to -0.08, p=0.005). Mean change in mean arterial pressure from baseline to 30 min postblock was 4.25 mm Hg (95% CI 0.24 to 8.26, p=0.04). Dermatome testing revealed an affection primarily of the lower abdomen (Th10-L1) with the active block. CONCLUSION: In this randomized controlled trial including healthy volunteers a unilateral anterior quadratus lumborum block does not cause statistical or clinical significant motor block of the quadriceps muscle compared with placebo. When administered correctly, the block can be used for procedures where early postoperative mobilization is essential. TRIAL REGISTRATION NUMBER: NCT05023343.

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BACKGROUND: The dural puncture epidural technique has been shown in some studies to improve the onset and quality of the initiation of labor analgesia compared with the standard epidural technique. However, few studies have investigated whether this technique confers advantages during the maintenance of analgesia. This randomized double-blinded controlled study compared dural puncture epidural analgesia with standard epidural analgesia when analgesia was maintained using programmed intermittent epidural boluses. METHODS: 400 parturients requesting epidural labor analgesia were randomized to have analgesia initiated with a test dose of 3 mL lidocaine 1.5% with epinephrine 15 µg, followed by 12 mL ropivacaine 0.15% mixed with sufentanil 0.5 µg/mL using the dural puncture epidural or the standard epidural technique. After confirming satisfactory analgesia, analgesia was maintained with ropivacaine 0.1% and sufentanil 0.5 µg/mL via programmed intermittent epidural boluses (fixed volume 8 mL, intervals 40 min). We compared local anesthetic consumption, pain scores, obstetric and neonatal outcomes and patient satisfaction. RESULTS: A total of 339 patients completed the study and had data analyzed. There were no differences between the dural puncture epidural and standard epidural groups in ropivacaine consumption (mean difference -0.724 mg, 95% CI of difference -1.450 to 0.001 mg, p=0.051), pain scores, time to first programmed intermittent epidural bolus, the number of programmed intermittent epidural boluses, the number of manual epidural boluses, obstetric outcome or neonatal outcome. Patient satisfaction scores were statistically higher in the dural puncture epidural group but the absolute difference in scores was small. CONCLUSION: Our findings suggest that when labor analgesia is maintained using the programmed intermittent epidural bolus method, there is no significant advantage to initiating analgesia using the dural puncture epidural compared with the standard epidural technique. TRIAL REGISTRATION NUMBER: ChiCTR2200062349.

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INTRODUCTION: Injecting mixtures of local anesthetics with or without adjuvants is a common practise in regional and particularly obstetric anesthesia to decrease block onset time and/or augment epidural analgesia for cesarean section. While evidence on the efficacy of this practise is equivocal, little is known about its safety in terms of the pharmacologic compatibility of local anesthetics. METHODS: We assessed the grade of crystallization in individual mixtures of seven local anesthetics (bupivacaine, ropivacaine, lidocaine, procaine, chloroprocaine, mepivacaine, prilocaine) with or without four adjuvants (sodium bicarbonate, dexamethasone, clonidine, fentanyl) using a semiquantitative light microscopy scale (ranging from 0 to 5), repeatedly for up to 60 min and performed correlation analysis between grade of crystallization and initial solution pH. RESULTS: Of the 50 mixtures tested, 26 showed grades of crystallization ≥4 at admixture and 41 showed grades of crystallization ≥4 after 60 min. The addition of adjuvants to local anesthetic mixtures did not substantially change the grades of crystallization. Bupivacaine has a slightly lower precipitation tendency, compared with ropivacaine. A moderate relationship was found between initial pH and grade of crystallization after 15 min for the adjuvant mixtures (R=0.33, p=0.04), but not at other time points. DISCUSSION: The preparation of local anesthetic (±adjuvant) mixtures leads to high grades of crystallization, which increase over 60 min and appear independent of solution pH. The risk of mixing medications with unknown physical or chemical compatibility profiles in regional anesthesia should be critically appraised and its clinical significance elucidated in future translational research.