Extended reality navigation for pain procedures: a narrative review

BACKGROUND

Extended reality (XR) technology, encompassing virtual reality, augmented reality, and mixed reality, has been widely studied for procedural navigation in surgical specialties. Similar to how ultrasound transformed regional anesthesia, XR has the potential to reshape how anesthesiologists and pain physicians perform procedures to relieve pain.

OBJECTIVE

This narrative review examines the clinical benefits of XR for navigation in various pain procedures. It defines key terms and concepts related to XR technology and explores characteristics of procedures that are most amenable to XR-based navigation. Finally, it suggests best practices for developing XR navigation systems and discusses the role of emerging technology in the future of XR in regional anesthesia and pain medicine.

EVIDENCE REVIEW

A search was performed across PubMed, Embase, and Cochrane Central Register of Controlled Trials for primary literature investigating the clinical benefits of XR navigation for pain procedures.

FINDINGS

Thirteen studies using XR for procedural navigation are included. The evidence includes randomized controlled trials, retrospective studies, and case series.

CONCLUSIONS

Early randomized controlled trials show potential for XR to improve procedural efficiency, but more comprehensive research is needed to determine if there are significant clinical benefits. Case reports demonstrate XR's utility in generating patient-specific navigation plans when difficult anatomy is encountered. Procedures that facilitate the generation and registration of XR images are most conducive to XR navigation, whereas those that rely on frequent re-imaging will continue to depend on traditional modes of navigation.

0.25% bupivacaine-1% lidocaine vs 0.5% bupivacaine for ultrasound-guided infraclavicular brachial plexus block: a randomized controlled trial

INTRODUCTION

In an effort to shorten onset time, a common practice is to add lidocaine to bupivacaine. In the setting of infraclavicular block, it is unclear what the block characteristics of this practice are compared with bupivacaine alone. We hypothesized that bupivacaine alone increases the duration of motor block, sensory block, and postoperative analgesia while resulting in a slower onset time compared with a bupivacaine and lidocaine mixture.

METHODS

40 patients receiving ultrasound-guided infraclavicular brachial plexus block were randomly assigned to receive either 35 mL of 0.25% bupivacaine and 1% lidocaine or 0.5% bupivacaine, both associated with perineural adjuvants (epinephrine 5 µg/mL and dexamethasone 4 mg). After the block was performed, a blinded observer evaluated the success of the block, the onset time, and the incidence of surgical anesthesia. Postoperatively, a blinded observer contacted patients who had successful blocks to inquire about the duration of motor block, sensory block, postoperative analgesia, and the presence of rebound pain.

RESULTS

When comparing patients having bupivacaine alone versus bupivacaine and lidocaine, the mean (SD) motor block duration was 28.4 (5.2) vs 18.9 (3.1) hours, respectively; the mean difference 9.5 hours (95% CI 6.5 to 12.4; p<0.001); the mean (SD) sensory block duration was 29.3 (5.8) vs 18.7 (4.0) hours, respectively; the mean difference 10.6 hours (95% CI 7.1 to 14.0; p<0.001); the mean (SD) postoperative analgesia duration was 38.3 (7.4) vs 24.3 (6.6) hours, respectively; the mean difference 14 hours (95% CI 9.2 to 18.8; p<0.001); and the median (IQR) onset time was 35 (15) vs 20 (10) min, respectively; p<0.001. No other significant differences were detected.

CONCLUSIONS

Compared with mixed bupivacaine-lidocaine, 0.5% bupivacaine significantly prolongs sensorimotor block and postoperative analgesia at the expense of a delayed onset time.

TRIAL REGISTRATION NUMBER

NCT05834023.

Bilateral ultrasound-guided maxillary and mandibular combined nerves block reduces morphine consumption after double-jaw orthognathic surgery: a randomized controlled trial

BACKGROUND

Double-jaw surgeries are known to be painful and to require opioids. Maxillary (V2) and mandibular (V3) nerves block could provide adequate pain management with minimal opioid-related side effects. Our main objective was to evaluate the analgesic effect of bilateral ultrasound-guided V2 and V3 combined nerves block in patients undergoing double-jaw orthognathic surgery.

METHODS

In this single-blind, randomized control study, 50 patients were prospectively allocated to either bilateral ultrasound-guided V2 and V3 combined nerves block or intraoral infiltration of local anesthetic. Primary outcome was the cumulative oral morphine equivalent (OME) consumption assessed at postoperative day 1. Secondary outcomes were cumulative OME consumption and pain scores in recovery room and at postoperative day 2, intraoperative anesthetic consumption, and opioid-related side effects. Preoperative anxiety was investigated by the Amsterdam Preoperative Anxiety and Information Scale (APAIS).

RESULTS

Compared with infiltration, ultrasound-guided regional anesthesia reduced cumulative OME consumption on day 1 (45.7±37.6 mg vs 25.5±19.8 mg, respectively, mean difference of -20.1 (95% CI -37.4 to -2.9) mg, p=0.023) and day 2 (64.5±60 mg vs 35.8±30.2 mg, respectively, mean difference of -28.7 (95% CI -55.9 to -1.43) mg, p=0.040). Interestingly, worst pain score and cumulative OME consumptions on day 2 were positively correlated with the APAIS (Pearson's correlation coefficient of 0.42 (p=0.003) and 0.39 (p=0.006), respectively).

CONCLUSION

Bilateral ultrasound-guided V2 and V3 combined nerves block reduces postoperative opioid consumption by about 50% in patients undergoing double-jaw surgery.

TRIAL REGISTRATION NUMBER

NCT05351151.

Anesthesia start time documentation accuracy where peripheral nerve block is the primary anesthetic

INTRODUCTION

When used as the primary anesthetic, nerve blocks are not billed as separate procedures. In this scenario, the anesthesia start (AStart) time should include the block procedural time. We measured how often AStart time was documented before the nerve block was placed in the preoperative area, and compared cases where a block team performed the nerve block and cases where the intraoperative anesthesia attending supervised the nerve block. We hypothesized that the involvement of a regional anesthesia team would lead to more accurate documentation of AStart. We also estimated the lost revenue due to inaccurate start time documentation.

METHODS

The study population were patients undergoing surgery with a peripheral nerve block as the primary anesthetic. For this analysis, AStart occurring less than 10 min before the in-operating room time was defined as potentially inaccurate. Lost potential revenue was estimated by taking the difference between the documented time of local anesthetic administration and the documented AStart time.

RESULTS

A total of 745 cases were analyzed. Overall, 439 cases (58%) cases were identified as having potentially inaccurate start times. There were higher rates of inaccurate AStart documentation by the block team (316/482, 65.5%) compared with blocks supervised by the in-room anesthesia attendings (123/263, 46.7%, p<0.001). Overall, the estimated loss in billable revenue during the study period was a total of $70 265.

CONCLUSIONS

The performance of primary regional anesthesia procedure by a block team increased the incidence of inaccurate documentation and uncaptured potential revenue. There is need for education about accurate nerve block documentation for anesthesiologists, especially when separate teams are used.

Fascial plane approach to anesthetizing the radial, median, and ulnar nerves: an educational review

Brachial plexus block provides effective anesthesia and analgesia for upper extremity surgery but requires injection of large anesthetic volumes near major vascular structures. Moreover, the extensive motor and sensory loss produced by plexus block often exceeds the neural distribution needed for corresponding surgical procedures.High-resolution ultrasound facilitates selective nerve blocks at nearly every level of the upper extremity. We present fascial plane injection techniques for selective radial, median, and ulnar nerve blocks. These techniques can be used to match sensory distribution with specific surgical procedures. They are performed using low anesthetic volumes and without proximity to nerves or vascular structures. In this article, fresh cadaver dissections with corresponding ultrasound images are used to demonstrate stepwise fascial plane techniques for the radial, median, and ulnar nerves. These techniques are performed using familiar anatomic landmarks.Practical applications of these techniques are demonstrated for commonly performed procedures of the upper extremity. Corresponding injection volumes with duration of postoperative analgesia are presented. Selected injections are described for both surgical anesthesia and postoperative analgesia.Selective fascial plane injections can provide surgical anesthesia and postoperative analgesia in settings that might otherwise require much larger volumes of local anesthetic. These selective nerve blocks can match sensory loss with the anatomic pain distribution in each patient. Reliable techniques for selective nerve blocks of the upper extremity can expand the capabilities for ultrasound-guided regional anesthesia.

New insight into the vasto-adductor membrane for safer adductor canal blockade

Background

: This study aimed to identify exact anatomical landmarks and ideal injection volumes for safe adductor canal blocks (ACB).

Methods

: Fifty thighs from 25 embalmed adult Korean cadavers were used. The measurement baseline was the line connecting the anterior superior iliac spine (ASIS) to the midpoint of the patellar base. All target points were measured perpendicular to the baseline. The relevant cadaveric structures were observed using ultrasound (US) and confirmed in living individuals. US-guided dye injection was performed to determine the ideal volume.

Results

: The apex of the femoral triangle was 25.3 ± 2.2 cm distal to the ASIS on the baseline and 5.3 ± 1.0 cm perpendicular to that point. The midpoint of the superior border of the vasto-adductor membrane (VAM) was 27.4 ± 2.0 cm distal to the ASIS on the baseline and 5.0 ± 1.1 cm perpendicular to that point. The VAM had a trapezoidal shape and was connected as an aponeurosis between the medial edge of the vastus medialis muscle and lateral edge of the adductor magnus muscle. The nerve to the vastus medialis penetrated the muscle proximal to the superior border of the VAM in 70% of specimens. The VAM appeared on US as a hyperechoic area connecting the vastus medialis and adductor magnus muscles between the sartorius muscle and femoral artery.

Conclusions

: Confirming the crucial landmark, the VAM, is beneficial when performing ACB. It is advisable to insert the needle obliquely below the superior VAM border, and a 5 mL injection is considered sufficient.

Ultrasound-guided fascial plane blocks for post-breast surgery pain syndrome

INTRODUCTION

Persistent pain following breast surgery is common and may be challenging to treat. In patients refractory to conservative treatments, ultrasound-guided fascial plane blocks of thoracic nerves can be a useful option.

RESULTS

This type of neuro blockade technique provides advantages in terms of safety and efficacy that are convenient for physicians managing refractory and complex cases of post-breast surgery syndrome.

CONCLUSION

This technical review aims to present an up-to-date summary of the most common ultrasound-guided fascial plane blocks for chronic pain in post-breast surgery patients, provide a detailed technical description of each intervention, and propose preferred injections based on the anatomical location of the pain.

Prospective evaluation of the safety of ultrasound-guided cervical medial branch blocks using the in-plane technique

BACKGROUND

While fluoroscopic guidance is currently the imaging standard for cervical medial branch blocks (CMBBs), ultrasound guidance (USG) offers several potential safety advantages such as real-time needle visualization and the ability to detect and avoid critical soft tissue vascular or neural structures. However, no large-scale trials have examined the safety of USG for CMBB.

METHODS

Five hundred patients undergoing 2308 individual block levels were recruited using a prospective cohort design, and blocks were performed in an outpatient office setting using an in-plane USG technique. Primary outcomes included immediate block-related complication, as well as delayed occurrences, in the following 2 weeks. Vascular structures adjacent to the target area, as well as the occurrence of vascular breach, were recorded.

RESULTS

Three minor immediate complications were noted (two subcutaneous hematomas, one vasovagal reaction) comprising 0.13% of blocks (0.03% to 0.38%; 95% two-sided CI), and no delayed events were recorded (0% to 0.16%; 97.5% one-sided CI). Blood vessels were detected and avoided in 8.2% of blocks, and vascular breach was noted in 0.52% of blocks (0.27% to 0.91%; 95% two-sided CI).

CONCLUSION

When performed using an in-plane technique by experienced operators, USG CMBB was found to be safe, with rare minor immediate complications and no further adverse event reported in the following 2 weeks.

TRIAL REGISTRATION NUMBER

NCT04852393.

Ultrasound-guided erector spinae plane block in patients with chronic lumbar facet joint pain: A prospective case-controlled study

PURPOSE

The aim was to evaluate the efficacy of ultrasound-guided erector spinae plane (ESP) block and compare with the conventional physical therapy in chronic low back pain (LBP).

MATERIALS AND METHODS

This prospective case-controlled study included patients with chronic LBP. Their clinical and demographic data were obtained, and they were divided into two groups for conventional physical therapy and ESP blocks. Prior to treatment, on the first day, the second week, and the third month, the Oswestry Disability Index (ODI) and visual analog scale (VAS) pain score were evaluated.

RESULTS

The study included 43 patients, 21 in the ESP block group and 22 in the conventional physical therapy group. The VAS in movement was higher in the ESP block group at baseline (p = 0.047). On the first day after the treatments, the ESP block group showed lower resting (p < 0.001) and movement (p = 0.001) VAS values than the conventional physical therapy group. At the end of 3 months, both groups had improved VAS and ODI scores (all p < 0.001).

CONCLUSION

US-guided ESP block might be considered a successful, safe, and technically simple alternative treatment in patients with chronic LBP to control pain and reduce the cost of physical therapy and lost workdays.

Adductor canal block techniques do not lead to involvement of sciatic nerve branches: a radiological cadaveric study

INTRODUCTION

Low and high volume mid-thigh (ie, distal femoral triangle) and distal adductor canal block approaches are frequently applied for knee surgical procedures. Although these techniques aim to contain the injectate within the adductor canal, spillage into the popliteal fossa has been reported. While in theory this could improve analgesia, it might also result in motor blockade due to coverage of motor branches of the sciatic nerve. This radiological cadaveric study, therefore, investigated the incidence of coverage of sciatic nerve divisions after various adductor canal block techniques.

METHODS

Eighteen fresh, unfrozen and unembalmed human cadavers were randomized to receive ultrasound-guided distal femoral triangle or distal adductor canal injections, with 2 mL or 30 mL injectate volume, on both sides (36 blocks in total). The injectate was a 1:10 dilution of contrast medium in local anesthetic. Injectate spread was assessed using whole-body CT with reconstructions in axial, sagittal and coronal planes.

RESULTS

No coverage of the sciatic nerve or its main divisions was found. The contrast mixture spread to the popliteal fossa in three of 36 nerve blocks. Contrast reached the saphenous nerve after all injections, whereas the femoral nerve was always spared.

CONCLUSIONS

Adductor canal block techniques are unlikely, even when using larger volumes, to block the sciatic nerve, or its main branches. Furthermore, injectate reached the popliteal fossa in a small minority of cases, yet if a clinical analgesic effect is achieved by this mechanism is still unknown.

Spread of local anesthetic injected in the paravertebral space, intertransverse processes space, and erector spinae plane: a cadaveric model

INTRODUCTION

Paraspinal fascial plane blocks have become popular and include the erector spinae plane (ESP) and intertransverse process (ITP) blocks. Controversy exists regarding the exact mechanism(s) of these blocks. We aimed to evaluate the spread of local anesthetic (LA) following ESP and ITP blocks as compared with paravertebral (PV) blocks in a cadaveric model.

METHOD

Single-injection ultrasound guided ESP (n=5), ITP (n=5), and PV (n=5) blocks were performed in 15 fresh cadaver hemithoraces. The extent of LA spread within the erector spinae fascial plane, involvement of the dorsal ramus, and distribution within the PV space, were qualitatively described.

RESULTS

The spread of LA following ESP block extended eight vertebral levels in a cranio-caudal direction, involving the dorsal ramus at each level, but without LA spread into the PV space nor to the ventral rami. LA spread following ITP block extended 1-2 vertebral levels within the PV space and 7 vertebral levels within the erector spinae fascial plane. The spread of LA following PV blocks extended 2-4 vertebral levels, involving the ventral and dorsal ramus at each level, but without LA spread into the ESP.

CONCLUSION

Based on the results of this cadaveric experimental model of paraspinal fascial plane blocks, LA spread following ITP blocks extends into both the PV space and the erector spine fascial plane, and thus may offer a more favorable analgesic profile than ESP blocks.

Dorsal root ganglion: a key to understanding the therapeutic effects of the erector spinae plane (ESP) and other intertransverse process blocks?

Since its description in 2016, the erector spinae plane block (ESPB) has become a widely employed regional anesthetic technique and kindled interest in a range of related techniques, collectively termed intertransverse process blocks. There has been ongoing controversy over mechanism of action of the ESPB, mainly due to incongruities between results of cutaneous sensory testing, clinical efficacy studies, and investigations into the neural structures that are reached by injected local anesthetic (LA). This paper reviews the spread of LA to the paravertebral and epidural space and the cutaneous anesthesia in ESPB, with specific emphasis on the dorsal root ganglion (DRG). We hypothesize that the DRG, due to its unique and complex microarchitecture, represents a key therapeutic target for modulation of nociceptive signaling in regional anesthesia. This paper discusses how the anatomical and physiological characteristics of the DRG may be one of the factors underpinning the clinical analgesia observed in ESPB and other intertransverse process blocks.

Deep parasternal intercostal plane nerve block: an anatomical study

INTRODUCTION

The superficial and deep parasternal intercostal plane (DPIP) blocks are two new blocks for thoracic pain. There are limited cadaveric studies evaluating the dye spread with these blocks. In this study, we examined the dye spread of an ultrasound-guided DPIP block in a human cadaveric model.

METHODS

Five ultrasound-guided DPIP blocks were performed in four unembalmed human cadavers using an in-plane approach with a linear transducer oriented in a transverse plane adjacent to the sternum. Twenty milliliters of 0.1% methylene blue were injected between ribs 3 and 4 into the plane deep to the internal intercostal muscles and superficial to the transversus thoracis muscle layer. The chest muscles were dissected, and the extent of dye spread was documented in both cephalocaudal and mediolateral directions.

RESULTS

The transversus thoracis muscle slips were stained in all cadavers from 4 to 6 levels. Intercostal nerves were dyed in all specimens. Four levels of intercostal nerves were dyed in each specimen with variability in number of levels stained above and below the level of the injection.

CONCLUSIONS

The DPIP block spreads along the tissue plane above the transversus thoracis muscles to multiple levels to dye the intercostal nerves in this cadaver study. This block may be of clinical value for analgesia in anterior thoracic surgical procedures.

Local anesthetic dosing and toxicity of adult truncal catheters: a narrative review of published practice

BACKGROUND/IMPORTANCE

Anesthesiologists frequently use truncal catheters for postoperative pain control but with limited characterization of dosing and toxicity.

OBJECTIVE

We reviewed the published literature to characterize local anesthetic dosing and toxicity of paravertebral and transversus abdominis plane catheters in adults.

EVIDENCE REVIEW

We searched the literature for bupivacaine or ropivacaine infusions in the paravertebral or transversus abdominis space in humans dosed for 24 hours. We evaluated bolus dosing, infusion dosing and cumulative 24-hour dosing in adults. We also identified cases of local anesthetic systemic toxicity and toxic blood levels.

FINDINGS

Following screening, we extracted data from 121 and 108 papers for ropivacaine and bupivacaine respectively with a total of 6802 patients. For ropivacaine and bupivacaine, respectively, bolus dose was 1.4 mg/kg (95% CI 0.4 to 3.0, n=2978) and 1.0 mg/kg (95% CI 0.18 to 2.1, n=2724); infusion dose was 0.26 mg/kg/hour (95% CI 0.06 to 0.63, n=3579) and 0.2 mg/kg/hour (95% CI 0.06 to 0.5, n=3199); 24-hour dose was 7.75 mg/kg (95% CI 2.1 to 15.7, n=3579) and 6.0 mg/kg (95% CI 2.1 to 13.6, n=3223). Twenty-four hour doses exceeded the package insert recommended upper limit in 28% (range: 17%-40% based on maximum and minimum patient weights) of ropivacaine infusions and 51% (range: 45%-71%) of bupivacaine infusions. Toxicity occurred in 30 patients and was associated with high 24-hour dose, bilateral catheters, cardiac surgery, cytochrome P-450 inhibitors and hypoalbuminemia.

CONCLUSION

Practitioners frequently administer ropivacaine and bupivacaine above the package insert limits, at doses associated with toxicity. Patient safety would benefit from more specific recommendations to limit excessive dose and risk of toxicity.

No evidence of fascicular injury following a low-volume intraneural injection of the median nerve: a cadaveric study

BACKGROUND

The test dose or hydrolocation technique allows rapid detection of spread location. Though its primary aim is to enhance safety in peripheral nerve blocks, evidence on the potential risks of an intraneural test aliquot is lacking. We conducted a cadaveric study to evaluate the risk of fascicular injury following a low-volume (<1 mL) intraneural injection of the median nerve.

METHODS

Ten upper limbs from fresh unembalmed human cadavers were studied. In-plane ultrasound-guided intraneural injections of the median nerve were performed at mid, proximal, and distal locations using 1 mL of methylene blue and heparinized blood solution. Nerves were extracted and samples immersed in 10% buffered formalin for 4 weeks. Perpendicular 3 mm slices were obtained for H&E staining and light microscopy analysis. Our main objective was to assess the number of injured fascicles. Secondarily, we evaluated the pattern of intraneural spread. Fascicular injury was defined as the presence perineurium or axonal disruption and/or the presence of erythrocytes inside a nerve fascicle.

RESULTS

Thirty injections were performed in 10 median nerves. Sonographic swelling was confirmed in 100% of the cases. 352 histological sections were analyzed to assess study outcomes. The mean number of fascicles on each section of median nerve was 20±6 covering 49%±7% of the nerve area. No evidence of axonal disruption nor intra-fascicular erythrocytes was found in any of the analyzed sections.

CONCLUSIONS

Low-volume intraneural injections do not result in evident fascicular injury. Our findings support the use of a test dose in ultrasound-guided regional anesthesia.

Beyond traditional therapies: a network meta-analysis on the treatment efficacy for chronic phantom limb pain

BACKGROUND

Phantom limb pain (PLP) frequently affects individuals with limb amputations. When PLP evolves into its chronic phase, known as chronic PLP, traditional therapies often fall short in providing sufficient relief. The optimal intervention for chronic PLP remains unclear.

OBJECTIVE

The objectives of this network meta-analysis (NMA) were to examine the efficacy of different treatments on pain intensity for patients with chronic PLP.

EVIDENCE REVIEW

We searched Medline, EMBASE, Cochrane CENTRAL, Scopus, and CINAHL EBSCO, focusing on randomized controlled trials (RCTs) that evaluated interventions such as neuromodulation, neural block, pharmacological methods, and alternative treatments. An NMA was conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The primary outcome was pain score improvement, and the secondary outcomes were adverse events.

FINDINGS

The NMA, incorporating 12 RCTs, indicated that neuromodulation, specifically repetitive transcranial magnetic stimulation, provided the most substantial pain improvement when compared with placebo/sham groups (mean difference=-2.9 points, 95% CI=-4.62 to -1.18; quality of evidence (QoE): moderate). Pharmacological intervention using morphine was associated with a significant increase in adverse event rate (OR=6.04, 95% CI=2.26 to 16.12; QoE: low).

CONCLUSIONS

The NMA suggests that neuromodulation using repetitive transcranial magnetic stimulation may be associated with significantly larger pain improvement for chronic PLP. However, the paucity of studies, varying patient characteristics across each trial, and absence of long-term results underscore the necessity for more comprehensive, large-scale RCTs.

PROSPERO REGISTRATION NUMBER

CRD42023455949.

Plantar compartment block for hallux valgus surgery: a proof-of-concept anatomic and clinical study

BACKGROUND

Hallux valgus surgery is associated with moderate to severe postoperative pain. We hypothesized that a plantar compartment block may be a good technique for postoperative analgesia. We describe an anatomic approach to ultrasound-guided plantar compartment block and assess the clinical efficacy of the block for outpatient surgery.

METHODS

The anatomic study was aimed to describe the plantar compartment, using both dissection methods and imaging, and to define a volume of local anesthetic. Patients scheduled for hallux valgus surgery with a popliteal sciatic nerve block, and combined plantar compartment and peroneal blocks were included in the clinical study. Data on attaining the criteria for rapid exit from the outpatient center, duration of sensory and analgesic block, visual analog scale (VAS) values for postoperative pain at rest and during movement, and the consumption of morphine as rescue analgesia were recorded.

RESULTS

Plane-by-plane dissections and cross-sections were done in five cadaveric lower limbs. The medial calcaneal nerve divides into medial plantar and lateral plantar nerves in the upper part of the plantar compartment. These nerves were surrounded by 5 mL of colored gelatin, and 10 mL of injectates dye spread to the medial calcaneal branches. Thirty patients (26 women) were included in the clinical study. There were no failures of surgical block. Ninety per cent of patients successfully passed functional testing for ambulatory exit from the center within 5 hours (25th-75th centiles, 3.8-5.5 hours). The median duration of plantar compartment sensory block was 17.3 hours (10.5-21.5 hours), and the first request for rescue analgesic was 11.75 hours (10.5-23 hours) after surgery. The median VAS score for maximum pain reported within the 48-hour period was 2 (1-6). Twelve patients received 2.5 mg (0-5 mg) of morphine on day 1. Patients were highly satisfied and no adverse events were noted.

CONCLUSIONS

This anatomic description of the ultrasound-guided plantar compartment block reported the injection area to target the medial and lateral plantar nerves with 5 mL of local anesthetic. Normal walking without assistance is attained rapidly with this regional anesthesia technique, and the time to request postoperative analgesia after hallux valgus surgery is long.

TRIAL REGISTRATION NUMBER

NCT03815422.

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.

Empirical guide to a safe thoracic paravertebral block based on dimensions of paravertebral space when ultrasound visualization is challenging

Although ultrasound (US) guidance is the mainstay technique for performing thoracic paravertebral blocks, situations arise when US imaging is limited due to subcutaneous emphysema or extremely deep structures. A detailed understanding of the anatomical structures of the paravertebral space can be strategic to safely and accurately perform a landmark-based or US-assisted approach. As such, we aimed to provide an anatomic roadmap to assist physicians. We examined 50 chest CT scans, measuring the distances of the bony structures and soft-tissue surrounding the thoracic paravertebral block at the 2nd/3rd (upper), 5th/6th (middle), and 9th/10th (lower) thoracic vertebral levels. This review of radiology records controlled for individual differences in body mass index, gender, and thoracic level. Midline to the lateral aspect of the transverse process (TP), the anterior-to-posterior distance of TP to pleura, and rib thickness range widely based on gender and thoracic level. The mean thickness of the TP is 0.9±0.1 cm in women and 1.1±0.2 cm in men. The best target for initial needle insertion from the midline (mean length of TP minus 2 SDs) distance would be 2.5 cm (upper thoracic)/2.2 cm (middle thoracic)/1.8 cm (lower thoracic) for females and 2.7 cm (upper)/2.5 cm (middle)/2.0 cm (lower thoracic) for males, with consideration that the lower thoracic region allows for a lower margin of error in the lateral dimension because of shorter TP. There are different dimensions for the key bony landmarks of a thoracic paravertebral block between males and females, which have not been previously described. These differences warrant adjustment of landmark-based or US-assisted approach to thoracic paravertebral space block for male and female patients.

Neurological injury following peripheral nerve blocks: a narrative review of estimates of risks and the influence of ultrasound guidance

BACKGROUND

Peripheral nerve injury or post-block neurological dysfunction (PBND) are uncommon but a recognized complications of peripheral nerve blocks (PNB). A broad range of its incidence is noted in the literature and hence a critical appraisal of its occurrence is needed.

OBJECTIVE

In this review, we wanted to know the pooled estimates of PBND and further, determine its pooled estimates following various PNB over time. Additionally, we also sought to estimate the incidence of PBND with or without US guidance.

EVIDENCE REVIEW

A literature search was conducted in six databases. For the purposes of the review, we defined PBND as any new-onset sensorimotor disturbances in the distribution of the performed PNB either attributable to the PNB (when reported) or reported in the context of the PNB (when association with a PNB was not mentioned). Both prospective and retrospective studies which provided incidence of PBND at timepoints of interest (>48 hours to <2 weeks; >2 weeks to 6 weeks, 7 weeks to 5 months, 6 months to 1 year and >1 year durations) were included for review. Incidence data were used to provide pooled estimates (with 95% CI) of PBND at these time periods. Similar estimates were obtained to know the incidence of PBND with or without the use of US guidance. Additionally, PBND associated with individual PNB were obtained in a similar fashion with upper and lower limb PNB classified based on the anatomical location of needle insertion.

FINDINGS

The overall incidence of PBND decreased with time, with the incidence being approximately 1% at <2 weeks' time (Incidence per thousand (95% CI)= 9 (8; to 11)) to approximately 3/10 000 at 1 year (Incidence per thousand (95% CI)= 0. 3 (0.1; to 0.5)). Incidence of PBND differed for individual PNB with the highest incidence noted for interscalene block.

CONCLUSIONS

Our review adds information to existing literature that the neurological complications are rarer but seem to display a higher incidence for some blocks more than others. Use of US guidance may be associated with a lower incidence of PBND especially in those PNBs reporting a higher pooled estimates. Future studies need to standardize the reporting of PBND at various timepoints and its association to PNB.

The efficacy of injecting a distillate of the pitcher plant (Sarraceniaceae) adjacent to the palmar digital nerves of horses to ameliorate lameness caused by digital pain

This study aimed to determine the efficacy of instilling extract of the pitcher plant around the palmar digital nerves of horses to ameliorate digit pain causing lameness. Five mixed breed horses were recruited. Horses were determined to be lame because of pain in the distal portion of one or both thoracic limbs by a positive response to a basisesamoid nerve block using 2%^mepivacaine hydrochloride. Gait was evaluated pre- and post-nerve block at 30 min, 3, 7,14 and 21 days. At the 3-week evaluation, the basisesamoid nerve block was repeated using the extract, and the gait was evaluated at similar times. Lameness was evaluated objectively using a wireless, inertial, sensor-based, motion analysis system. The basisesamoid nerve block significantly ameliorated lameness at 30 min when gait was evaluated, but it had no significant effect on lameness after this time. The product containing extract of the pitcher plant had no significant effect on lameness when administered as a basisesamoid nerve block at any time. Extract of the pitcher plant administered adjacent to the medial and lateral palmar digital nerves (i.e., a basisesamoid nerve block) had no efficacy in ameliorating lameness in the distal portion of one or both thoracic limbs. Extract of the pitcher plant likely has no value for treating horses for chronic pain when administered as a regional nerve block.

Liposomal bupivacaine in transversus abdominis plane blocks for lower abdominal surgery

BACKGROUND

Transversus abdominis plane blocks are an established method of postoperative analgesia for abdominopelvic surgeries. Liposomal bupivacaine is an extended-release formulation of bupivacaine providing up to 72 h of analgesia. This study aims to determine if transversus abdominis plane blocks performed with liposomal bupivacaine are associated with reduced opioid consumption and level of pain intensity compared to conventional bupivacaine in patients undergoing lower abdominal surgery.

METHODS

This retrospective cohort study was conducted at a single institution between December 2020 and December 2021. After institutional review board approval, we identified patients who underwent lower abdominopelvic surgery with transversus abdominis plane blocks done with liposomal or conventional bupivacaine and collected demographic, clinical, and procedural information for analysis. We compared total opioid consumption over 72-h postoperatively in milligram morphine equivalents (MME), frequency of opioid utilization, and average level of pain intensity between groups. These outcomes were also evaluated after adjusting for covariates. Data were presented as mean ± SD, median [IQR] or frequency (%), as appropriate; p < 0.05 was accepted as significant.

RESULTS

A total of 178 patients met inclusion criteria, with 79 patients receiving an admixture of liposomal bupivacaine and conventional bupivacaine and 99 patients receiving conventional bupivacaine. The liposomal bupivacaine group had a median opioid consumption 72-h postoperatively of 47.5 [18-91.8] MME compared to 88 [43.8-160] MME in the conventional bupivacaine group, p = 0.045. Differences in opioid consumption between the groups did not reach statistical significance after adjustment for demographic and clinical characteristics, p = 0.11. There was no significant difference in frequency of opioid use or average pain intensity.

CONCLUSION

Transversus abdominis plane blocks using an admixture of liposomal bupivacaine conventional bupivacaine are not associated with decreased opioid consumption or reduced pain up to 72 h following elective abdominopelvic surgery.

Danger, Danger, Gaston Labat! Does zero-shot artificial intelligence correlate with anticoagulation guidelines recommendations for neuraxial anesthesia?

INTRODUCTION

Artificial intelligence and large language models (LLMs) have emerged as potentially disruptive technologies in healthcare. In this study GPT-3.5, an accessible LLM, was assessed for its accuracy and reliability in performing guideline-based evaluation of neuraxial bleeding risk in hypothetical patients on anticoagulation medication. The study also explored the impact of structured prompt guidance on the LLM's performance.

METHODS

A dataset of 10 hypothetical patient stems and 26 anticoagulation profiles (260 unique combinations) was developed based on American Society of Regional Anesthesia and Pain Medicine guidelines. Five prompts were created for the LLM, ranging from minimal guidance to explicit instructions. The model's responses were compared with a "truth table" based on the guidelines. Performance metrics, including accuracy and area under the receiver operating curve (AUC), were used.

RESULTS

Baseline performance of GPT-3.5 was slightly above chance. With detailed prompts and explicit guidelines, performance improved significantly (AUC 0.70, 95% CI (0.64 to 0.77)). Performance varied among medication classes.

DISCUSSION

LLMs show potential for assisting in clinical decision making but rely on accurate and relevant prompts. Integration of LLMs should consider safety and privacy concerns. Further research is needed to optimize LLM performance and address complex scenarios. The tested LLM demonstrates potential in assessing neuraxial bleeding risk but relies on precise prompts. LLM integration should be approached cautiously, considering limitations. Future research should focus on optimization and understanding LLM capabilities and limitations in healthcare.

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.

Infraspinatus-teres minor (ITM) interfascial block: a novel approach for combined suprascapular and axillary nerve block

BACKGROUND

Combined suprascapular and axillary nerve block could be an analgesic option for shoulder pain control. The current description of this technique requires performing the block procedures at two different sites without consideration for catheter placement. We hypothesized that a single site injection to the interfascial plane between the infraspinatus and teres minor would result in an injectate spread to the suprascapular and axillary nerves.

METHODS

We performed 10 injections with this approach using 25 mL dye solution in 10 shoulders of five unembalmed cadavers. Also, we described three case reports, two single-injection cases and one catheter-placement case, using this approach in patients with acute postsurgical pain and chronic pain in their shoulder region.

RESULTS

In cadaveric evaluations, dye spreading to the suprascapular nerves on the infraspinatus fossa and the spinoglenoid notch cephalad and axillary nerves in the quadrilateral space caudally were observed in all injections. In addition, the most posterolateral part of the joint capsule was stained in 8 out of 10 injections. There was no dye spreading on the nerves to the subscapularis or lateral pectoral nerves. Clinically successful analgesia with no adverse events was achieved in all three cases.

CONCLUSION

Our anatomical and clinical observations demonstrated that an injection to the interfascial plane between the infraspinatus and teres minor consistently achieved injectate spreading to both suprascapular and axillary nerves, which innervate the glenohumeral joint.

Local anesthetic dosing and toxicity of pediatric truncal catheters: a narrative review of published practice

BACKGROUND/IMPORTANCE

Despite over 30 years of use by pediatric anesthesiologists, standardized dosing rates, dosing characteristics, and cases of toxicity of truncal nerve catheters are poorly described.

OBJECTIVE

We reviewed the literature to characterize dosing and toxicity of paravertebral and transversus abdominis plane catheters in children (less than 18 years).

EVIDENCE REVIEW

We searched for reports of ropivacaine or bupivacaine infusions in the paravertebral and transversus abdominis space intended for 24 hours or more of use in pediatric patients. We evaluated bolus dosing, infusion dosing, and cumulative 24-hour dosing in patients over and under 6 months. We also identified cases of local anesthetic systemic toxicity and toxic blood levels.

FINDINGS

Following screening, we extracted data from 46 papers with 945 patients.Bolus dosing was 2.5 mg/kg (median, range 0.6-5.0; n=466) and 1.25 mg/kg (median, range 0.5-2.5; n=294) for ropivacaine and bupivacaine, respectively. Infusion dosing was 0.5 mg/kg/hour (median, range 0.2-0.68; n=521) and 0.33 mg/kg/hour (median, range 0.1-1.0; n=423) for ropivacaine and bupivacaine, respectively, consistent with a dose equivalence of 1.5:1.0. A single case of toxicity was reported, and pharmacokinetic studies reported at least five cases with serum levels above the toxic threshold.

CONCLUSIONS

Bolus doses of bupivacaine and ropivacaine frequently comport with expert recommendations. Infusions in patients under 6 months used doses associated with toxicity and toxicity occurred at a rate consistent with single-shot blocks. Pediatric patients would benefit from specific recommendations about ropivacaine and bupivacaine dosing, including age-based dosing, breakthrough dosing, and intermittent bolus dosing.

Postoperative analgesic effects of the quadratus lumborum block in pediatric patients: a systematic review and meta-analysis

Background

This study assessed the postoperative analgesic efficacy and safety of the quadratus lumborum block (QLB) in pediatric patients.

Methods

Electronic databases were searched for studies comparing the QLB to conventional analgesic techniques in pediatric patients. The primary outcome was the need for rescue analgesia 12 and 24 hours after surgery. Secondary outcomes covered the Face-Legs-Activity-Cry-Consolability Scale (FLACC) scores at various time points; parental satisfaction; time to the first rescue analgesia; hospitalization time; block execution time; block failure rates, and adverse events.

Results

Sixteen randomized controlled trials were analyzed involving 1,061 patients. The QLB significantly reduced the need for rescue analgesia both at 12 and 24 hours after surgery (12 hours, relative risk [RR]: 0.45; 95% confidence interval [CI]: 0.01, 0.88; 24 hours, RR: 0.51; 95% CI: 0.31, 0.70). In case of 24 hours after surgery, type 1 QLB significantly reduced the need for rescue analgesia (RR: 0.56; 95% CI: 0.36, 0.76). The QLB also exhibited lower FLACC scores at 1 hour (standardized mean difference [SMD]: -0.87; 95% CI: -1.56, -0.18) and 6 hours (SMD: -1.27; 95% CI: -2.33, -0.21) following surgery when compared to non-QLB. Among QLBs, type 2 QLB significantly extended the time until the first rescue analgesia (SMD: 1.25; 95% CI: 0.84, 1.67). No significant differences were observed in terms of parental satisfaction, hospitalization time, block execution time, block failure, or adverse events between QLB and non-QLB groups.

Conclusions

The QLB provides non-inferior analgesic efficacy and safety to conventional methods in pediatric patients.

Comparison of international medical costs for interventional pain treatment: a focus on Korea and Japan

Background

The rise in national health care costs has emerged as a global problem given the ever-aging population and rapid development of medical technology. The utilization of interventional pain management has, similarly, shown a continued rise worldwide. This study evaluates the differences in the medical costs in the field of interventional pain treatment (IPT) between two countries: Korea and Japan.

Methods

Korean medical insurance costs for 2019 related to pain management focused on IPT were compared to those of Japan. Purchasing power parity (PPP) was used to adjust the exchange rate differences and to compare prices in consideration of the respective societies' economic power.

Results

The cost of trigger point injections in Japan was 1.06 times higher than that of Korea, whereas the perineural and intraarticular injection prices were lower in Japan. The cost of epidural blocks was higher in Japan compared to Korea in both cervical/thoracic and lumbar regions. As for blocks of peripheral branches of spinal nerves, the cost of scapular nerve blocks in Japan was lower than that in Korea, given a PPP ratio 0.09. For nerve blocks in which fluoroscopy guidance is mandatory, the costs of epidurography in Japan were greater than those in Korea, given a PPP ratio 1.04.

Conclusions

This is the first comparative study focusing on the medical costs related to IPT between Korea and Japan, which reveals that the costs differed along various categories. Further comparisons reflecting more diverse countries and socio-economic aspects will be required.

Contralateral oblique view can prevent dural puncture in fluoroscopy-guided cervical epidural access: a prospective observational study

INTRODUCTION

Although the contralateral oblique (CLO) view at 50°±5° is clinically useful for cervical epidural access, no previous studies have confirmed its safety. This prospective observational study was conducted to assess the safety profile, including the risk of dural puncture, in fluoroscopically guided cervical epidural access using the CLO view.

METHODS

In cervical epidural access using the CLO view, the incidence of dural puncture was investigated as the primary outcome. Other intraprocedural complications, including intravascular entry, subdural entry, spinal cord injury and vasovagal injury, and postprocedural complications were investigated as secondary outcomes. Procedural variables including first-pass success, final success, needling time, total number of needle passes and false loss of resistance (LOR) were evaluated.

RESULTS

Of the 393 patients who underwent cervical interlaminar epidural access were included for analysis, no instances of dural puncture or spinal cord injury were observed. The incidence of intravascular entry, vasovagal reaction and subdural entry were 3.1%, 0.5% and 0.3%, respectively. All procedures were successfully performed, with 85.0% of first-pass success rate. The mean needling time was 133.8 (74.9) s. The false-positive and false-negative LOR rates were 8.2% and 2.0%, respectively. All needle tips were visualized clearly during the procedure.

CONCLUSIONS

The fluoroscopy-guided CLO view at 50°±5° avoided dural puncture or spinal cord injury and decreased the incidence of false LOR during cervical epidural access with a paramedian approach.

TRIAL REGISTRATION NUMBER

NCT04774458.

Effect of anterior quadratus lumborum block with ropivacaine on the immune response after laparoscopic surgery in colon cancer: a substudy of a randomized clinical trial

BACKGROUND

Surgery induces a temporal change in the immune system, which might be modified by regional anesthesia. Applying a bilateral preoperative anterior quadratus lumborum block has proven to be a safe and effective technique in pain management after abdominal and retroperitoneal surgery, but the effect on the immune response is not thoroughly investigated.

METHODS

This study is a substudy of a randomized, controlled, double-blinded trial of patients undergoing laparoscopic hemicolectomy due to colon cancer. Twenty-two patients were randomized to undergo either a bilateral anterior quadratus lumborum nerve block with a total of 60 mL ropivacaine 0.375% or placebo with corresponding isotonic saline injections. The main objective of this exploratory substudy was to investigate the systemic immune response in the first postoperative day by examining changes in blood transcript levels (n=750) and stimulated secretion of cytokines (n=17) on ex vivo activation with microbial ligands and anti-CD3/CD28.

RESULTS

Using unsupervised data analysis tools, we observed no effect of the bilateral anterior quadratus lumborum nerve block on gene expression in immune cells (permutational multivariate analysis of variance using distance matrices: F=0.52, p=0.96), abundances of major immune cell populations (Wilcoxon rank-sum test: p>0.05), and stimulated cytokine secretion (Wilcoxon rank-sum test: p>0.05).

CONCLUSIONS

Our study provides evidence that administration of bilateral anterior quadratus lumborum nerve block as a part of a multimodal analgesic regimen in an enhanced recovery after surgery for laparoscopic hemicolectomy in this cohort does not alter the systemic immune response.Trial registration number NCT03570541.

Association of thoracic epidural analgesia and hospital length of stay for patients undergoing thoracotomy: a retrospective cohort analysis

INTRODUCTION

Regional anesthesia has been shown to be efficacious for analgesia in patients who underwent thoracotomies. The objective of this study was to analyze the association of epidurals and peripheral regional anesthesia with time to hospital discharge for these patients.

METHODS

This was a retrospective cohort study using National Surgical Quality Improvement Program dataset from 2014 to 2020. Propensity-matched cohorts were assembled based on use of regional anesthesia, peripheral regional anesthesia, or epidural. Fine-Gray competing risk regressions were used to explore the association between regional anesthesia use and rate of discharge. The subdistribution hazard ratio (HR) represented relative discharge rates, and in-hospital death was a competing event. A sensitivity analysis was subsequently performed in which patients with American Society of Anesthesiologists score ≥4 were removed.

RESULTS

There were 4350 patients included in this analysis, in which 472 (10.8%) received a peripheral regional anesthesia nerve block and 565 (13.0%) received thoracic epidural analgesia. The subdistribution HR for rate of discharge in the epidural versus non-epidural cohort was 1.09 (95% CI 1.01 to 1.18), thus epidurals were associated with an increased rate of discharge over time. However, this benefit was no longer apparent with the sensitivity analysis. The subdistribution HR for rate of discharge in the peripheral regional anesthesia versus no regional anesthesia cohort was 1.26 (95% CI 1.15 to 1.39), thus peripheral regional anesthesia was associated with an increased rate of discharge over time. This benefit remained even with the sensitivity analysis.

CONCLUSIONS

Thoracic epidural use when compared with no regional anesthesia was associated with decreased length of stay following thoracotomy in our primary analysis. The difference was no longer apparent with the sensitivity analysis. Peripheral regional anesthesia was associated with decreased length of stay even after sensitivity analysis.

Efficacy of the intertransverse process block: single or multiple injection? A randomized, non-inferiority, blinded, cross-over trial in healthy volunteers

INTRODUCTION

The intertransverse process block is increasingly used to ameliorate postoperative pain following a plethora of surgical procedures involving the thoracic wall. Nevertheless, the optimal approach and cutaneous extent of the sensory block are currently unknown. We aimed to further describe the intertransverse process block, single injection versus multiple injection, and we hypothesized that the single-injection intertransverse process block is a non-inferior technique.

METHODS

Twelve healthy male volunteers were cross-over randomized to receive either single-injection intertransverse process block with 21 mL ropivacaine 7.5 mg/mL, including two sham injections, at the thoracic level T4/T5 or multiple-injection intertransverse process block with three injections of 7 mL ropivacaine 7.5 mg/mL at the thoracic levels T2/T3, T4/T5 and T6/T7 at the first visit. At the second visit, the other technique was applied on the contralateral hemithorax. A non-inferiority margin of 1.5 anesthetized thoracic dermatomes was chosen.

RESULTS

The mean difference (95% CI) in the number of anesthetized thoracic dermatomes was 0.82 (-0.41 to 2.05) pnon-inf<0.01 indicating non-inferiority favoring the single-injection technique.Both techniques anesthetized the ipsilateral thoracic wall and demonstrated contralateral cutaneous involvement to a variable extent. The multiple-injection intertransverse process block anesthetized a significantly larger cutaneous area on the posterior hemithorax and decreased mean arterial pressure at 30 and 60 min postblock application. Thoracic thermography showed no intermodality temperature differences yet compared with baseline temperatures both techniques showed significant differences.

CONCLUSIONS

Single-injection intertransverse process block is non-inferior to multiple injection in terms of anesthetized thoracic dermatomes. Both techniques generally anesthetize the hemithoracic wall to a variable extent.

EU CLINICAL TRIALS REGISTER

2022-501312-34-01.

Intraoperative landmark-based genicular nerve block versus periarticular infiltration for postoperative analgesia in total knee arthroplasty: a randomized non-inferiority trial

INTRODUCTION

Genicular nerve blocks (GNBs) are an emerging technique that have been used as a part of multimodal analgesia for total knee arthroplasty. The efficacy of intraoperative landmark-based GNBs, a recently introduced technique, has been established. We hypothesized that it would provide non-inferior postoperative analgesia compared with periarticular infiltration (PAI) when combined with continuous adductor canal block.

METHODS

This study randomized 140 patients undergoing total knee arthroplasty to receive either intraoperative landmark-based GNB (GNB group) or PAI (PAI group), with 139 completing the study. The primary outcomes were the pain scores at rest and during movement at 12 hours postoperatively on an 11-point Numerical Rating Scale; the non-inferiority margin was 1. Pain scores at additional time points, intravenous morphine consumption, time to first rescue analgesia, functional performance and muscle strength tests, and sleep disturbance were also assessed.

RESULTS

At 12 hours postoperatively, the PAI and GNB groups had median resting pain scores of 0 (0-2) and 0 (0-2), respectively. The median difference was 0 (95% CI -0.4 to 0.4, p=1), with the 95% CI upper limit below the prespecified non-inferiority margin. The median pain score during movement was 1.5 (0-2.3) and 2 (1-3.1) in the PAI and GNB groups, respectively. The median difference was 0.9 (95% CI 0.3 to 1.6, p=0.004), failing to demonstrate non-inferiority. The GNB group had higher intravenous morphine consumption at 12 hours postoperatively and a shorter time to first rescue analgesia.

CONCLUSIONS

GNB compared with PAI provides non-inferior resting pain relief. Non-inferiority was not established for pain during movement.

TRIAL REGISTRATION NUMBER

TCTR20220406001 (www.thaiclinicaltrials.org).

Innervation of thumb carpometacarpal joint: implications for diagnostic block and denervation procedures

INTRODUCTION

Osteoarthritis (OA) of the thumb carpometacarpal (CMC) joint is a common disorder that negatively impacts hand function. Denervation of the thumb CMC joint has emerged as a viable treatment option. However, the innervation pattern of the thumb CMC joint is controversial. Therefore, the objective of this study was to identify the articular branches supplying the thumb CMC joint and to document their relationship to anatomical landmarks to provide the foundation for image-guided diagnostic block and denervation procedures.

METHODS

In 10 formalin-embalmed upper limb specimens articular branches supplying the thumb CMC joint were dissected from their origin to termination. A frequency map documenting the number of articular branches was generated. The frequency map enabled visualization and comparison of the relative area of innervation of the thumb CMC joint by each articular branch.

RESULTS

The thumb CMC joint received innervation from six nerves. These were the deep branch of ulnar nerve (DBUN), dorsal articular nerve (DAN) of the first interosseus space, thenar branch of median nerve (TBMN), palmar cutaneous branch of median nerve (PCBMN), lateral antebrachial cutaneous nerve (LACN) and superficial branch of the radial nerve (SBRN) and/or their branches. Each nerve was found to innervate different aspects of the joint. The DBUN and DAN were found to innervate the posteromedial aspect of the thumb CMC joint, the TBMN and PCBMN anterior/anteromedial aspects, LACN posterolateral/lateral/anterior aspects and SBRN posterolateral/anterolateral aspects.

CONCLUSIONS

The thumb CMC joint was innervated by articular branches originating from the SBRN, DAN, LACN, PCBMN, TBMN and DBUN. The documented anatomical relationships provide the foundation to inform selective diagnostic block and denervation of the thumb CMC joint. Further investigations are needed to assess the clinical implications of the current study.

THE EFFECTIVENESS OF FORAMINAL ROOT BLOCK IN RELIEVING SCIATIC PAIN DUE TO LUMBAR DISC HERNIATION

Objective

To evaluate the clinical profile, pain improvement, and the need for surgical interventions in patients undergoing transforaminal block with the use of corticosteroids and anesthetics.

Methods

This is a prospective, randomized, double-blind study with 45 patients with unilateral radicular pain in their lower limbs and a single-segment lumbar disc herniation diagnosis. In the intervention group, transforaminal blocks with bupivacaine, dexamethasone, and clonidine were applied and in the control group, distilled water and bupivacaine. The Oswestry questionnaire was applied.

Results

We included 24 female (53.4%) and 21 male patients (46.6%). Of those with an occupation, 85.71% (n = 30) were relieved from their duties due to their illness and 14.29% (n = 5) continued to work with limitations. Those who underwent transforaminal block with an injection of corticosteroids, clonidine, and anesthetics showed immediate relief. However, such effect failed to alleviate patients' symptoms after three weeks. We observed that 52% of patients showed varying degrees of improvement. The control group experienced mild pain relief after one week, which also failed to last after three weeks. Moreover, 50% of patients improved in varying degrees.

Conclusion

Further studies with larger samples, new epidemiological data, and longer follow-ups are necessary to validate our hypotheses. Level of Evidence II, Prospective Study.