Pericapsular nerve group block: a 3D CT scan imaging study to determine the spread of injectate.

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).

Effect of bilateral low serratus anterior plane block on quality of recovery after trans-subxiphoid robotic thymectomy: Results of a randomized placebo-controlled trial.

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.

No quadriceps muscle weakness following anterior quadratus lumborum block compared with placebo: a randomized, non-inferiority, blinded, volunteer trial.

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.

Comparative anatomical study of digital block with the WALANT, interdigital, and transthecal techniques.

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.

Comparison of the dural puncture epidural and the standard epidural techniques in patients having labor analgesia maintained using programmed epidural boluses: a prospective double-blinded randomized clinical trial.

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.

Crystallization of mixtures of local anesthetics with and without select adjuvants: a semiquantitative light microscopy analysis.

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.

Frequency and features of medical emergencies at a teaching dental hospital in Saudi Arabia: a 14-year retrospective observational study.

BACKGROUND: This study aimed to determine the nature, frequency, and characteristics of medical emergencies occurring at the King Abdulaziz University Dental Hospital. MATERIALS AND METHODS: The incident reports of medical emergencies recorded at the King Abdulaziz University Dental Hospital from January 2008 to December 2022 were retrospectively reviewed. The annual/overall incidence of medical emergency events was calculated per 100,000 patients. The following characteristics of the patients/events were evaluated: age, gender, operator, procedure, location, timing of treatment, administration of local anesthesia, past medical history, symptoms, diagnosis, outcome, and disposition. Multivariable logistic regression models were used to investigate the associations of these characteristics with two outcomes: syncope and transfer to the emergency room (ER). RESULTS: The incidence of emergency events was 17.4 per 100,000 patients. Syncope and hypoglycemia were the most common emergencies. Most incidents recovered, with only 13% requiring transfer to the ER. Undergoing no procedure and American Society of Anesthesiologists (ASA) class 2,3 were associated with syncope. Undergoing a general dental procedure, ASA class 2,3, and a diagnosis other than hypoglycemia and syncope were associated with transfer to the ER. CONCLUSIONS: The incidence of medical emergencies was low. Dental practitioners need to remain aware of the contributing factors, such as past medical history and anxiety, but medical emergencies can occur in healthy individuals as well. Preparation of the dental office, training of the personnel, and proper recording of the events are essential components of a well-established medical emergency protocol in dental institutions.

Comparison of pain relief in soft tissue tumor excision: anesthetic injection using an automatic digital injector versus conventional injection.

BACKGROUND: The pain caused by local anesthetic injection can lead to patient anxiety prior to surgery, potentially necessitating sedation or general anesthesia during the excision procedure. In this study, we aim to compare the pain relief efficacy and safety of using a digital automatic anesthetic injector for local anesthesia. METHODS: Thirty-three patients undergoing excision of a benign soft tissue tumor under local anesthesia were prospectively enrolled from September 2021 to February 2022. A single-blind, randomized controlled study was conducted. Patients were divided into two groups by randomization: the experimental group with digital automatic anesthetic injector method (I-JECT group) and the control group with conventional injection method. Before surgery, the Amsterdam preoperative anxiety information scale was used to measure the patients' anxiety. After local anesthetic was administered, the Numeric Pain Rating Scale was used to measure the pain. The amount of anesthetic used was divided by the surface area of the lesion was recorded. RESULTS: Seventeen were assigned to the conventional group and 16 to the I-JECT group. The mean Numeric Pain Rating Scale was 1.75 in the I-JECT group and 3.82 in conventional group. The injection pain was lower in the I-JECT group (p< 0.01). The mean Amsterdam preoperative anxiety information scale was 11.00 in the I-JECT group and 9.65 in conventional group. Patient's anxiety did not correlate to injection pain regardless of the method of injection (p= 0.47). The amount of local anesthetic used per 1 cm 2 of tumor surface area was 0.74 mL/cm2 in the I-JECT group and 2.31 mL/cm2 in the conventional group. The normalization amount of local anesthetic was less in the I-JECT group (p< 0.01). There was no difference in the incidence of complications. CONCLUSION: The use of a digital automatic anesthetic injector has shown to reduce pain and the amount of local anesthetics without complication.

Mepivacaine dosing for spinal anesthesia in pediatric orthopedic surgery: a retrospective chart review.

BACKGROUND: Mepivacaine is an intermediate-acting local anesthetic used for spinal anesthesia in adults. Currently, there are no published dosing guidelines for spinal mepivacaine in patients under age 18. AIMS: The purpose of this study is to describe the clinically used doses of mepivacaine by weight and age for orthopedic surgery in pediatrics. METHODS: We performed a retrospective chart review of patients aged 0-18 who received mepivacaine for spinal anesthesia from 2016 to 2022. We performed a secondary analysis for patients aged 0-18 who received spinal anesthesia with bupivacaine or chloroprocaine. RESULTS: The data extraction yielded 3627 single-shot mepivacaine spinals. Patient age ranged from 5 to 18 years. Median dosage in milligrams/kilograms (mg/kg) of mepivacaine was calculated for each age group. Our analysis revealed that dosage in mg/kg decreased by patient age and began to plateau at age 15. Bupivacaine was the most common single-shot spinal agent in patients under age 10. After age 10, mepivacaine was more common. Chloroprocaine began to be used in patients older than 8 years. CONCLUSIONS: We describe mepivacaine dosage as a function of age and weight in patients younger than 18 years. As age and weight increased, a lower dose of mepivacaine per kg was administered for spinal anesthesia.

Paravertebral and erector spinae plane blocks decrease length of stay compared with local infiltration analgesia in autologous breast reconstruction.

BACKGROUND: Autologous breast reconstruction is associated with significant pain impeding early recovery. Our objective was to evaluate the impact of replacing surgeon-administered local infiltration with preoperative paravertebral (PVB) and erector spinae plane (ESP) blocks for latissimus dorsi myocutaneous flap reconstruction. METHODS: Patients who underwent mastectomy with latissimus flap reconstruction from 2018 to 2022 were included in three groups: local infiltration, PVB, and ESP blocks. Block effect on postoperative length of stay (LOS) and the association between block status and pain, opioid consumption, time to first analgesic, and postoperative antiemetic administration were assessed. RESULTS: 122 patients met the inclusion criteria for this retrospective cohort study: no block (n=72), PVB (n=26), and ESP (n=24). On adjusted analysis, those who received a PVB block had a 20-hour shorter postoperative stay (95% CI 11 to 30; p<0.001); those who received ESP had a 24-hour (95% CI 15 to 34; p<0.001) shorter postoperative stay compared with the no block group, respectively. Using either block was associated with a reduction in intraoperative opioids (23 morphine milligram equivalents (MME)), 95% CI 14 to 31, p<0.001; ESP versus no block: 23 MME, 95% CI 14 to 32, p<0.001). CONCLUSIONS: Replacing surgical infiltration with PVB and ESP blocks for autologous breast reconstruction reduces LOS. The comparable reduction in LOS suggests that ESP may be a viable alternative to PVB in patients undergoing latissimus flap breast reconstruction following mastectomy. Further research should investigate whether ESP or PVB have better patient outcomes in complex breast reconstruction.

Subcostal TAP block: one or two sequential injections? A cadaveric study.

BACKGROUND AND OBJECTIVES: The subcostal transversus abdominis plane block (scTAPB) provides analgesia to the anterior abdominal wall but analgesic spread following a single injection remains modest and variable. The oblique scTAPB, which is performed with a continuous injection during needle progression into the TAP along the oblique subcostal line, may extend the block to the whole anterior abdominal wall but needle progression by hydrodissection may be difficult, explaining why this block is not widely used. This study investigated if two sequential scTAPB injections (2scTAPI) may reach more nerves than a single scTAPB (1scTAPI). METHODS: After institutional approval and under ultrasound guidance, a single injection of 20 mL of blue dye was performed in 16 cadaveric subjects into the TAP along the costal margin and lateral to the semilunaris line (1scTAPI). On the opposite side, a 20 mL of green solution was split into two injections (2scTAPI), using one injection medial and one lateral to the semilunaris line. Dye spread was assessed via gross anatomical dissection using an indirect method to quantify the involvement of the anterior cutaneous branches of the intercostal nerves with each technique. A nerve was considered stained if the dye was observed in the TAP, reaching the costal margin aligned with the bony extremity of its corresponding rib. RESULTS: According to the spread to the costal margin, the estimated median number of consecutive nerves reached by dye after 2scTAPI was 5 (IQR 5-6) vs 3 (IQR 3-4) for 1scTAPI (p=0.00001). Spread after 2scTAPI suggested coverage of nerves originating from T8 to T12 in 85% of the subjects, and from T7 to T12 in 5 out of 17 cases. Spread following the 1scTAPI suggested coverage of nerves from T9 to T11 in most cases. CONCLUSIONS: In a cadaveric model, a larger spread at the costal margin was obtained after 2scTAPI, suggesting a greater coverage of anterior branches of abdominal wall nerves compared with 1scTAPI. Clinical studies are needed to confirm these results.

Inhibition of the glutamatergic PVT-NAc projections attenuates local anesthetic-induced neurotoxic behaviors.

INTRODUCTION: Local anesthetic-induced neurotoxicity contributes to perioperative nerve damage; however, the underlying mechanisms remain unclear. Here, we investigated the role of the paraventricular thalamus (PVT)-nucleus accumbens (NAc) projections in neurotoxicity induced by ropivacaine, a local anesthetic agent. METHODS: Ropivacaine (58 mg/kg, intraperitoneal administration) was used to construct the local anesthetic systemic toxicity (LAST) mice model. We first identified neural projections from the PVT to the NAc through the expression of a retrograde tracer and virus. The inhibitory viruses (rAAV-EF1α-DIO-hm4D(Gi)-mCherry-WPREs: AAV2/retro and rAAV-CaMKII-CRE-WPRE-hGh: AAV2/9) were injected into the mice model to assess the effects of the specific inhibition of the PVT-NAc pathway on neurological behaviors in the presence of clozapine-N-oxide. The inhibition of the PVT-NAc pathway was evaluated by immunofluorescence staining of c-Fos-positive neurons and Ca2+ signals in CaMKIIa neurons. RESULTS: We successfully identified a circuit connecting the PVT and NAc in C57BL/6 mice. Ropivacaine administration induced the activation of the PVT-NAc pathway and seizures. Specific inhibition of NAc-projecting CaMKII neurons in the PVT was sufficient to inhibit the neuronal activity in the NAc, which subsequently decreased ropivacaine-induced neurotoxicity. CONCLUSION: These results reveal the presence of a dedicated PVT-NAc circuit that regulates local anesthetic-induced neurotoxicity and provide a potential mechanistic explanation for the treatment and prevention of LAST.

Effects of combined dexamethasone and dexmedetomidine as adjuncts to peripheral nerve blocks: a systematic review with meta-analysis and trial sequential analysis.

BACKGROUND/IMPORTANCE: The effects of combining dexamethasone and dexmedetomidine on block duration are unclear. OBJECTIVE: To investigate the effects of combining dexamethasone and dexmedetomidine on block duration. EVIDENCE REVIEW: Systematic review of randomized controlled trials (RCTs) from Medline, Embase, CENTRAL, CINAHL, the Web of Science, and BIOSIS until June 8, 2023. RCTs with adults undergoing surgery with a peripheral nerve block randomized to combined dexamethasone and dexmedetomidine versus placebo or other adjuncts were eligible. Primary outcome was duration of analgesia. We performed meta-analysis, trial sequential analysis, risk of bias-2, and Grading Recommendations Assessment, Development, and Evaluation assessment. FINDINGS: We included 9 RCTs with 14 eligible comparisons. The combination of dexamethasone and dexmedetomidine was compared with placebo in three RCTs (173 participants), dexamethasone in seven (569 participants), and dexmedetomidine in four (281 participants). The duration of analgesia was likely increased with the combination versus placebo (mean difference 460 min, 95% CI 249 to 671) and versus dexmedetomidine (mean difference 388 min, 95% CI 211 to 565). The duration was likely similar with the combination versus dexamethasone (mean difference 50 min, 95% CI -140 to 239). The certainty of the evidence was moderate because most trials were at high risk of bias. CONCLUSIONS: Combined dexamethasone and dexmedetomidine likely increased the duration of analgesia when compared with placebo and dexmedetomidine. The combination likely provided a similar duration of analgesia as dexamethasone. Based on this systematic review, it seems reasonable to use dexamethasone as the sole adjunct if the goal is to increase the duration of analgesia.

Differential nerve blockade to explain anterior thoracic analgesia without sensory blockade after an erector spinae plane block may be wishful thinking.

Ultrasound-guided erector spinae plane block (ESPB) is currently used as a component of multimodal analgesic regimen in a multitude of indications but the mechanism by which it produces anterior thoracic analgesia remains a subject of controversy. This is primarily the result of ESPB's failure to consistently produce cutaneous sensory blockade (to pinprick and cold sensation) over the anterior hemithorax. Nevertheless, ESPB appears to provide 'clinically meaningful analgesia' in various clinical settings. Lately, it has been proposed that the discrepancy between clinical analgesia and cutaneous sensory blockade could be the result of differential nerve blockade at the level of the dorsal root ganglion. In particular, it is claimed that at a low concentration of local anesthetic, the C nerve fibers would be preferentially blocked than the Aδ nerve fibers. However, the proposal that isolated C fiber mediated analgesia with preserved Aδ fiber mediated cold and pinprick sensation after an ESPB is unlikely, has never been demonstrated and, thus, without sufficient evidence, cannot be attributed to the presumed analgesic effects of an ESPB.

Cutaneous sensory block area of the ultrasound-guided subcostal transversus abdominis plane block: an observational study.

BACKGROUND AND OBJECTIVES: The transversus abdominis plane block (TAP) can be applied using different approaches, resulting in varying cutaneous analgesic distributions. This study aimed to assess the cutaneous sensory block area (CSBA) after ultrasound-guided TAP (US-TAP) using the subcostal approach. METHODS: Thirty patients undergoing elective laparoscopic cholecystectomy received a subcostal US-TAP with 20 mL 2.5 mg/mL ropivacaine bilaterally. Measurements were performed 150 min after block application. The CSBA was mapped using cold sensation and a sterile marker, photodocumented, and transferred to a transparency. The area of the CSBA was calculated from the transparencies. RESULTS: The median CSBA of the subcostal US-TAP was 174 cm2 (IQR 119-219 cm2; range 52-398 cm2). In all patients, the CSBA had a periumbilical distribution. In 42 of the 60 (70%) unilateral blocks, the CSBA had both an epigastric and infraumbilical component; in 12 of the 60 (20%) unilateral blocks, it covered only the epigastrium; and in 4 of the 60 (7%) unilateral blocks, it had only an infraumbilical distribution. No CSBA was found in 2 of the 60 (3%) unilateral blocks. In none of the patients did the CSBA cover the abdominal wall lateral to a vertical line through the anterior superior iliac spine. CONCLUSION: The subcostal US-TAP results in a heterogeneous non-dermatomal CSBA with varying size and distribution across the medial abdominal wall.