Visualization of the pelvic nerves using magnetic resonance imaging for rectal cancer surgery.

BACKGROUND: This study evaluated the visualization of the pelvic nerves using magnetic resonance imaging (MRI) combined with computed tomography (CT) to synthesize three-dimensional (3D) reconstruction images of the pelvic organs. METHODS: The CT and MRI scans were performed for patients with rectal cancer who underwent surgery. The out-of-phase image of LAVA-Flex was used to identify the pelvic nerves. The images of the pelvic nerves were extracted from the MRI scans, and those of the arteries and rectum and pelvis were extracted from the CT scans. Each extracted organ image was used to synthesize 3D reconstruction images. RESULTS: The MRI scan allowed adequate visualization of the pelvic splanchnic nerves, inferior hypogastric plexus, and obturator nerves. The comparison of 3D reconstruction images and intraoperative findings showed matched images. CONCLUSION: We visualized the pelvic nerves using MRI and synthesized 3D reconstruction images of the pelvic organs. Preoperative confirmation of the location of the pelvic organs is important to prevent unanticipated injury during rectal cancer surgery.

Fluoroscopic anterior approach versus ultrasound guided superior hypogastric plexus neurolysis in cancer pelvic pain: a randomized controlled study.

BACKGROUND: Cancer-related pelvic pain can be difficult and debilitating to treat. Superior hypogastric plexus neurolysis (SHPN) is a good choice for adequate pain relief with fewer side effects. The current study compared between fluoroscopic anterior approach and ultrasound guided SHPN in the management of cancer-related pelvic pain. METHODS: Patients were randomly allocated into two equal groups. The ultrasound group (US group) (n = 48) received SHPN by an ultrasound-guided anterior approach using 3 ml 5% bupivacaine plus 20 ml 10% phenol, while the fluoroscopy group (n = 48) received SHPN by a fluoroscopy-guided anterior approach using 3 ml 5% bupivacaine plus 20 ml 10% phenol. RESULTS: The time of the procedure was shorter in the fluoroscopic group (21.31 ± 4.79 min) than the US group (24.88 ± 6.02 min) (P = 0.002). Patient satisfaction was higher in the fluoroscopy group (5.38 ± 1.482) than the US group (2.98 ± 1.495) (P˂0.001). The need for analgesia using morphine was significantly limited in each group, at 1, 2 and 3 months intervals (P1˂0.001, P2 ˂0.001 and P3 ˂0.001). There were statistically significant differences between both groups regarding fatigue at baseline, drowsiness at 3 months, nausea and vomiting at 1, 2 and 3 months and anorexia at 3 months. Group comparison also revealed statistically significant differences regarding depression at one month, anxiety at 2 and 3 months and insomnia at baseline. CONCLUSION: The fluoroscopic anterior approach SHPN was more superior than the US guided SHPN regarding the time of the procedure and patient satisfaction, while both technique were similar regarding the numeric rating scale and the complications during block. TRIAL REGISTRATION: Registered in the ClinicalTrials.gov (Identifier: NCT05299047) at 28/03/2022.

A Comprehensive Update of the Superior Hypogastric Block for the Management of Chronic Pelvic Pain.

PURPOSE OF REVIEW: This is a comprehensive review of the superior hypogastric block for the management of chronic pelvic pain. It reviews the background, including etiology, epidemiology, and current treatment available for chronic pelvic pain. It then presents the superior hypogastric block and reviews the seminal and most recent evidence about its use in chronic pelvic pain. RECENT FINDINGS: Several definitions exist for chronic pelvic pain (CPP), making the diagnosis more challenging for the clinician; however, they commonly describe continuous pain lasting 6 months in the pelvis, with an overwhelming majority of patients being reproductive-aged women. This pain is often one of mechanical, inflammatory, or neuropathic. It is generally underdiagnosed and affects anywhere between 5 and 26% of women. The diagnosis of chronic pelvic pain is clinical, consisting of mainly of a thorough history and physical and ruling out other causes. The pathophysiology is often endometriosis (70%) and also includes PID, adhesions, adenomyosis, uterine fibroids, chronic processes of the GI and urinary tracts, as well as pelvic-intrinsic musculoskeletal causes. Treatment includes physical therapy, cognitive behavioral therapy, and oral and parenteral opioids. Interventional techniques provide an added tier of treatment and may help to reduce the requirement for chronic opioid use. Superior hypogastric plexus block is one of the available interventional techniques; first described in 1990, it has been shown to provide long-lasting relief in 50-70% of patients who underwent the procedure. Two approaches described so far, both under fluoroscopy, have seen similar results. More recently, ultrasound and CT-guided procedures have also been described with similar success. The injectate includes local anesthetic, steroids, and neurolytic agents such as phenol or ethanol. CPP is a common debilitating condition. It is diagnosed clinically and is underdiagnosed globally. Current treatments can be helpful at times but may fall short of satisfactory pain relief. Interventional techniques provide an added layer of treatment as well as reduce the requirement for opioids. Superior hypogastric plexus block provides long-lasting relief in many patients, regardless of approach. Evidence level is limited, and further RCTs could help provide better tools for evaluation and patient selection.

Pulsed Radiofrequency of the Sacral Roots Improves the Success Rate of Superior Hypogastric Plexus Neurolysis in Controlling Pelvic and Perineal Cancer Pain.

BACKGROUND: Superior hypogastric plexus neurolytic (SHP-N) block is the mainstay management for pelvic cancer pain of visceral origin when oral opioids fail due to inefficacy or intolerance to side effects. Unfortunately, SHP-N has the potential to control pelvic pain in 62%-72% of patients at best, because chronic pelvic pain may assume additional characteristics other than visceral. OBJECTIVE: Combining SHP-N with pulsed radiofrequency (PRF) of the sacral roots might block most of the pain characteristics emanating from the pelvic structures and improve the success rate of SHP-N in controlling pelvic and perineal cancer pain. STUDY DESIGN: This study was a prospective randomized controlled clinical trial. SETTINGS: The research took place in the interventional pain unit of a tertiary center in the university hospital. METHODS: Fifty-eight patients complaining of cancer-related chronic pelvic and perineal pain were randomized to either the PRF + SHP group (n = 29), which received SHP-N combined with PRF of the sacral roots S2-4, or the SHP group (n = 29), which received SHP-N alone. The outcome variables were the percentage of patients who showed a > 50% reduction in their Visual Analog Scale (VAS) pain score, the VAS pain score, and global perceived effect evaluated during a 3-month follow-up period. RESULTS: The percentage of patients who showed a > 50% reduction in their VAS pain score was significantly higher in the SHP + PRF group compared to the SHP group when assessed at one month (92.9% [n = 26] vs 57.7% [n = 15]; P = .003) and 3 months (85.7% [n = 24) vs 53.8% [n = 14]; P = .01) post procedure, respectively. However, no significant difference was observed between the 2 groups at the 6-month evaluation (SHP + PRF [57.1% (n = 16)] vs SHP [50% (n = 13)]; P = .59). There was a statistically significant reduction of VAS in the SHP + PRF group in comparison to the SHP group at one month (2.8 ± 0.9 vs 3.5 ± 1.2 [mean difference, -0.7 (95% confidence interval [CI], -1.29 to -0.1), P = .01]), 2 months (2.8 ± 0.9 vs 3.5 ± 1.2 [mean difference, -0.64 (95% CI, -1.23 to -0.05), P = .03]), and 3 months (2.7 ± 1 vs 3.4 ± 1.2 [mean difference, -0.67 (95% CI, -1.29 to -0.05)], P = .03]) post procedure, respectively; however, the 2 groups did not significantly differ at 2 weeks, 4, 5, and 6 months post procedure. Regarding postprocedural analgesic consumption, there were trends towards reduced opioid consumption at all postprocedural measured time points in the SHP+PRF group compared to the SHP group; these differences reached statistical significance at 2 months (median, 30 [interquartile range (IQR), 0.00-30] vs median, 45 [IQR, 30-90]; P = .046) and 3 months (median, 0.00 [IQR, 0.00-30] vs median, 30 [IQR, 0.00-67.5]; P = .016) post procedure, respectively. LIMITATIONS: The study follow-up period is limited to 6 months only. CONCLUSIONS: SHP-N combined with PRF of the sacral roots (S2, 3, 4) provided a better analgesic effect than SHP-N alone for patients with chronic pelvic and perineal pain related to pelvic cancer. TRIAL REGISTRY: ClinicalTrials.gov. NCT03228316. KEY WORDS: Pelvic pain, pulsed radiofrequency, sacral roots, superior hypogastric plexus.

Keep Your Landmarks Close and the Hypogastric Nerve Closer: An Approach to Nerve-sparing Endometriosis Surgery.

OBJECTIVE: Excisional techniques used to surgically treat deep infiltrating endometriosis (DIE) can result in inadvertent damage to the autonomic nervous system of the pelvis, leading to urinary, anorectal, and sexual dysfunction [1-4]. This educational video illustrates the autonomic neuroanatomy of the pelvis, identifying the predictable location of the hypogastric nerve in relation to other pelvic landmarks, and demonstrates a surgical technique for sparing the hypogastric nerve and inferior hypogastric plexus. DESIGN: Using didactic schematics and medical drawings, we discuss and illustrate the autonomic neuroanatomy of the pelvis. With annotated laparoscopic footage, we demonstrate a stepwise approach for identifying, dissecting, and preserving the hypogastric nerve during pelvic surgery. SETTING: Tertiary care academic hospitals: Mount Sinai Hospital in Toronto, Ontario, Canada, and S. Orsola Hospital in Bologna, Italy. INTERVENTIONS: Radical excision of DIE with adequate identification and sparing of the hypogastric nerve and inferior hypogastric plexus bilaterally was performed, following an overview of pelvic neuroanatomy. The superior hypogastric plexus was described and the hypogastric nerve, the most superficial and readily identifiable component of the inferior hypogastric plexus, was identified and used as a landmark to preserve autonomic bundles in the pelvis. The following steps, illustrated with laparoscopic footage, describe a surgical technique developed to identify and preserve the hypogastric nerve and the deeper inferior hypogastric plexus without the need for more extensive pelvic dissection to the level of the sacral nerve roots: (1) transperitoneal identification of the hypogastric nerve, with a pulling maneuver for confirmation; (2) opening of the retroperitoneum at the level of the pelvic brim and retroperitoneal identification of the ureter; (3) medial dissection and identification of the hypogastric nerve; and (4) lateralization of the hypogastric nerve, allowing for safe resection of DIE. CONCLUSION: The hypogastric nerve follows a predictable course and can be identified, dissected, and spared during pelvic surgery, making it an important landmark for the preservation of pelvic autonomic innervation.

Pelvic plexus block to provide better anesthesia in transperineal template-guided prostate biopsy: a randomised controlled trial.

BACKGROUND: To evaluate the efficacy of pelvic plexus block (PPB) in relief pain during transperineal template-guided prostate biopsy (TTPB), compared with conventional periprostatic nerve block (PNB). METHODS: From July 2016 to August 2017, 245 patients who were performed TTPB in Clinical Medical College of Yangzhou University were recruited. The patients were randomized into three groups using a random number table. Group-1 received prostate capsule local anesthesia with 22 ml of 1% lidocaine. Group-2 additionally received PNB on the basis of Group-1. To perform PNB, 5 ml 1% lidocaine was injected into the region of prostatic neurovascular bundle situated in the angle of prostate-bladder-seminal vesicle. Group-3 received prostate capsule local anesthesia plus PPB (5 ml of 1% lidocaine injection into the pelvic plexus which located on lateral to the bilateral seminal vesicle apex). The patients' pain and satisfaction were evaluated by visual analogue scale and visual numerical scale, respectively. RESULTS: The age, total prostate volume, PSA and the number of cores were comparable among the three groups. The visual analog scale scores of group-3 were significantly lower than group-2 during biopsy (P = 0.003). Conversely, the visual numeric scale scores were higher in group-3 (P = 0.039). Both the group-2 and group-3 outperformed the group-1 in alleviating pain and had a higher quantification of satisfaction. There were no significant differences in the pain scores or the satisfaction scores at 30 min after the procedure among the three groups. CONCLUSIONS: The analgesic efficacy of PPB guided by Doppler ultrasound in TTPB was better than that of PNB and both were superior to no nerve block. TRIAL REGISTRATION: ChiCTR-IOR-17013533 , 01/06/2016.

Computed Tomography-Guided Superior Hypogastric Plexus Block for Secondary Dysmenorrhea in Perimenopausal Women.

BACKGROUND Refractory abdominal pain during menstruation severely affects patients' quality of life and simultaneously places enormous psychological burdens on patients and their families. Several treatments for secondary dysmenorrhea are available; however, none can permanently treat all types of secondary dysmenorrhea. Since pain is transmitted by the nerves, we hypothesized that a neurolytic block could be used as a treatment for refractory abdominal pain during menstruation. We sought to investigate the therapeutic efficacy and safety of computed tomography (CT)-guided superior hypogastric plexus block for secondary dysmenorrhea. MATERIAL AND METHODS We performed CT-guided neurolytic block of the superior hypogastric plexus by bilaterally administering 4 mL of a dehydrated alcohol solution in 25 patients from January 2014 to February 2016. The degree of pain and its impact on the patients' mood and quality of life were evaluated using the visual analogue scale, Hospital Anxiety and Depression Scale, and 36-Item Short Form Survey before and after therapy, and the data were statistically analyzed using analysis of variance and t test. RESULTS The degrees of pain were significantly (p<0.05) decreased after neurolytic block (from 7.74±1.14 to 2.96±1.55). The patients showed significantly (p<0.05) less anxiety and improved bodily pain with mental health status. CONCLUSIONS Secondary dysmenorrhea can be effectively and safely treated with a neurolytic block of the superior hypogastric plexus.

A step towards stereotactic navigation during pelvic surgery: 3D nerve topography.

BACKGROUND: Long-term morbidity after multimodal treatment for rectal cancer is suggested to be mainly made up by nerve-injury-related dysfunctions. Stereotactic navigation for rectal surgery was shown to be feasible and will be facilitated by highlighting structures at risk of iatrogenic damage. The aim of this study was to investigate the ability to make a 3D map of the pelvic nerves with magnetic resonance imaging (MRI). METHODS: A systematic review was performed to identify a main positional reference for each pelvic nerve and plexus. The nerves were manually delineated in 20 volunteers who were scanned with a 3-T MRI. The nerve identifiability rate and the likelihood of nerve identification correctness were determined. RESULTS: The analysis included 61 studies on pelvic nerve anatomy. A main positional reference was defined for each nerve. On MRI, the sacral nerves, the lumbosacral plexus, and the obturator nerve could be identified bilaterally in all volunteers. The sympathetic trunk could be identified in 19 of 20 volunteers bilaterally (95%). The superior hypogastric plexus, the hypogastric nerve, and the inferior hypogastric plexus could be identified bilaterally in 14 (70%), 16 (80%), and 14 (70%) of the 20 volunteers, respectively. The pudendal nerve could be identified in 17 (85%) volunteers on the right side and in 13 (65%) volunteers on the left side. The levator ani nerve could be identified in only a few volunteers. Except for the levator ani nerve, the radiologist and the anatomist agreed that the delineated nerve depicted the correct nerve in 100% of the cases. CONCLUSION: Pelvic nerves at risk of injury are usually visible on high-resolution MRI with dedicated scanning protocols. A specific knowledge of their course and its application in stereotactic navigation is suggested to improve quality of life by decreasing the likelihood of nerve injury.

The Optimal Approach for a Superior Hypogastric Plexus Block.

INTRODUCTION: Superior hypogastric plexus block (SHGPB) is technically difficult, and an accurate procedure is required to avoid potential complications. We attempted to determine the reference angles for fluoroscopy-assisted SHGPB and to establish a predictor as a guide to select the optimal approach between the classic posterior approach and transdiscal approach. METHODS: Abdominopelvic computed tomography (CT) scans from 268 patients diagnosed with pelvic malignancies were examined. The oblique and axial angles needed for the fluoroscope were measured both for posterior and transdiscal approaches by simulating the needle trajectory on CT imaging. We developed an SHGPB index defined by the ratio (%) of the interposterior iliac border distance to the L5 body transverse diameter, which represents the relative transverse diameter of the bony pelvis. We evaluated whether it can help select the optimal approach for the SHGPB between the posterior and transdiscal approaches. RESULTS: Males had a significantly smaller angle than females (right oblique angle for posterior approach, males 14 [range 12 to 17] degrees vs. females 19 [range 16 to 23] degrees; P < 0.001). An SHGPB index of < 150 was an independent predictor for failure of the classic posterior approach (odds ratio 31.3, 95% confidence interval 5.1 to 104.7). CONCLUSIONS: The optimal right oblique angle of fluoroscopy for the posterior approach is 13° to 15° in males and 19° to 20° in females. The transdiscal approach may be favored over the posterior approach when the bony pelvis is narrow relative to the target vertebral body, which can be measured by the SHGPB index being < 150.

Ultrasound-Guided Superior Hypogastric Plexus Block: A Cadaveric Feasibility Study with Fluoroscopic Confirmation.

Plancarte first described a fluoroscopy-guided superior hypogastric plexus block to manage pelvic pain in 1990. Modifications have since been described using different imaging modalities. Ultrasound-guided approach has been described in a clinical outcome study. However, the accuracy of an ultrasound-guided method has never been validated by alternative imaging. We conducted an experiment aiming to develop ultrasound-guided superior hypogastric plexus block using human cadavers in the supine position. Final needle position and spread of a radiopaque contrast was verified by fluoroscopy, a standard imaging tool. The needle approach to the L5 vertebral body was performed in the short axis as has been recommended. Injection of radiopaque contrast revealed unilateral and cephalad spread to the L5/S1 disk. Additional transabdominal long-axis scanning of the lumbosacral segment was and the needle trajectory was modified to aim for the apex of the L5/S1 disk. Bilateral spread was achieved by strict midline placement of the needle tip and real-time observation of injection. The modified ultrasound-guided technique resulted in a similar spread of injectate as the traditional fluoroscopy-guided technique that in a clinical scenario would offer complete block of the superior hypogastric plexus.

Ilioinguinal and iliohypogastric nerves cannot be selectively blocked by using ultrasound guidance: a volunteer study.

BACKGROUND: Ilioinguinal (IL) and iliohypogastric (IH) nerve blocks are used in patients with chronic postherniorrhaphy pain. The present study tested the hypothesis that our method, previously developed in cadavers, blocks the nerves separately and selectively in human volunteers. METHODS: We blocked the IL and the IH nerves in 16 volunteers in a single-blinded randomized cross-over setting under direct ultrasound visualization, by injecting two times the ED95 volume of 1% mepivacaine needed to block a peripheral nerve. The anaesthetized skin areas were tested by pinprick and marked on the skin. A digital photo was taken. For further analysis, the parameterized picture data were transformed into a standardized and unified coordinate system to compare and calculate the overlap of the anaesthetized skin areas of the two nerves on each side. An overlap <25% was defined as selective block. RESULTS: Fifty nerve blocks could be analysed. The mean volume injected to block a single nerve was 0.9 ml. Using ultrasound, we observed spread from one nerve to the other in 12% of cases. The overlap of the anaesthetized skin areas of the nerves was 60.3% and did not differ after exclusion of the cases with visible spread of local anaesthetic from one nerve to the other. CONCLUSIONS: The IL and IH nerves cannot be selectively blocked even if volumes below 1 ml are used. The most likely explanation is the spread of local anaesthetic from one nerve to the other, although this could not be directly observed in most cases.

Ultrasound-guided trunk and core blocks in infants and children.

Regional anesthetic techniques for perioperative analgesia in children are being increasingly utilized with the reported advantages of providing superior analgesia, decreasing opioid consumption, and reducing opioid-related adverse effects. The following article reviews the available literature regarding core and trunk blocks in infants and children; specifically, transversus abdominis plane, ilioinguinal/iliohypogastric nerve, rectus sheath, lumbar plexus, and paravertebral and intercostal nerve blockade. The common indications and potential complications and adverse effects for each block are presented. Additionally, the anatomy and techniques needed for their performance are reviewed. Finally, a summary of the relevant literature in relation to each peripheral nerve block technique is included.

Ultrasound-guided ilioinguinal/iliohypogastric nerve blocks for persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial.

BACKGROUND: Ilioinguinal and iliohypogastric nerve blocks are used in the clinical management of persistent inguinal postherniorrhaphy pain, but no controlled studies have been published on the subject. In this controlled study, we investigated the analgesic and sensory effects of ultrasound-guided blocks of the ilioinguinal and iliohypogastric nerves with lidocaine. METHODS: A randomized, double-blind, placebo-controlled, crossover trial in 12 patients with severe persistent inguinal postherniorrhaphy pain, including a control group of 12 healthy controls, was performed. Assessments included pain ratings under standardized conditions with numerical rating scale (0-10), sensory mapping to a cool roller, and quantitative sensory testing (QST), in the groin regions, before and after each ultrasound-guided block. A needle approach of 1 to 2 cm superior and medial to the anterior superior iliac spine was used. Outcomes were changes in pain ratings, sensory mapping, and QST compared with preblock values. Lidocaine responders were a priori defined by a pain reduction of ≥80% after lidocaine block and ≤25% after placebo block, nonresponders by pain reduction of <80% after lidocaine block and ≤25% after placebo block, and placebo responders by pain reduction of >25% after placebo block. RESULTS: One of 12 pain patients was a lidocaine responder, 6 patients were nonresponders, and 5 patients were placebo responders. No consistent QST changes were observed in patients after the lidocaine block. In 10 of 12 healthy controls, a cool hypoesthesia area developed in the groin after the lidocaine block. Furthermore, QST assessments demonstrated significantly decreased suprathreshold heat pain perception in the groin after lidocaine versus placebo blocks (95% confidence interval = -3.5 to -0.5, P = 0.008). CONCLUSION: Ultrasound-guided lidocaine blocks of the ilioinguinal and iliohypogastric nerves, at the level of the anterior superior iliac spine, are not useful in diagnosis and management of persistent inguinal postherniorrhaphy pain.

The relative position of ilioinguinal and iliohypogastric nerves in different age groups of pediatric patients.

BACKGROUND: Ilioinguinal nerve (IIN) and iliohypogastric nerve (IHN) blocks provide good perioperative pain relief for children undergoing inguinal procedures such as inguinal hernia repair, orchiopexy, and hydrocelectomy. The aim of this ultrasound imaging study is to compare the relative anatomical positions of IIN and IHN in different age groups of pediatrics. METHODS: Two-hundred children (aged 1-82 months, ASA I or II) undergoing day-case surgery were consecutively included in this study. Following the induction of general anesthesia, an ultrasonographic exam was performed using a high-frequency linear probe that was placed on an imaginary line connecting the anterior superior iliac spine (ASIS) to the umbilicus. RESULTS: There were significant differences in ASIS-IIN (distance from ASIS to IIN), ASIS-IHN (distance from the ASIS to the IHN), and IIN-IHN (distance between IIN and IHN) between the age groups: <12 months (n=84), 12-36 months (n=80), and >37 months (n=36). However, IIN-Peritoneum (distances from IIN to peritoneum), skin-IIN, and skin-IHN (depth of IIN and IHN relative to skin) were similar in three groups. ASIS-IIN and ASIS-IHN showed significantly positive correlations with age. CONCLUSIONS: Age should be considered when placing a needle in landmark techniques for pediatric II/IH nerve blocks. However, needle depth should be confirmed by the fascial click due to the lack of predictable physiologic factors.

Ultrasound imaging for regional anesthesia in infants, children, and adolescents: a review of current literature and its application in the practice of extremity and trunk blocks.

The use of ultrasound guidance has provided an opportunity to perform many peripheral nerve blocks that would have been difficult to perform in children based on pure landmark techniques due to the potential for injection into contiguous sensitive vascular areas. This review article provides the readers with techniques on ultrasound-guided peripheral nerve blocks of the extremities and trunk with currently available literature to substantiate the available evidence for the use of these techniques. Ultrasound images of the blocks with corresponding line diagrams to demonstrate the placement of the ultrasound probe have been provided for all the relevant nerve blocks in children. The authors hope that this review will stimulate further research into ultrasound-guided regional anesthesia in infants, children, and adolescents and stimulate more randomized controlled trials to provide a greater understanding of the anatomy and physiology of regional anesthesia in pediatrics.

Defining the reliability of sonoanatomy identification by novices in ultrasound-guided pediatric ilioinguinal and iliohypogastric nerve blockade.

BACKGROUND: The ilioinguinal (II)/iliohypogastric (IH) nerve block is a safe, frequently used block that has been improved in efficacy and safety by the use of ultrasound guidance. We assessed the frequency with which pediatric anesthesiologists with limited experience with ultrasound-guided regional anesthesia could correctly identify anatomical structures within the inguinal region. Our primary outcome was to compare the frequency of correct identification of the transversus abdominis (TA) muscle with the frequency of correct identification of the II/IH nerves. We used 2 ultrasound machines with different capabilities to assess a potential equipment effect on success of structure identification and time taken for structure identification. METHODS: Seven pediatric anesthesiologists with <6 mo experience with ultrasound-guided regional anesthesia performed a total of 127 scans of the II region in anesthetized children. The muscle planes and the II and IH nerves were identified and labeled. The ultrasound images were reviewed by a blinded expert to mark accuracy of structure identification and time taken for identification. Two ultrasound machines (Sonosite C180plus and Micromaxx, both from Sonosite, Bothell, WA) were used. RESULTS: There was no difference in the frequency of correct identification of the TA muscle compared with the II/IH nerves (chi(2) test, TA versus II, P = 0.45; TA versus IH, P = 0.50). Ultrasound machine selection did show a nonsignificant trend in improving correct II/IH nerve identification (II nerve chi(2) test, P = 0.02; IH nerve chi(2) test, P = 0.04; Bonferroni corrected significance 0.17) but not for the muscle planes (chi(2) test, P = 0.83) or time taken (1-way analysis of variance, P = 0.07). A curve of improving accuracy with number of scans was plotted, with reliability of TA recognition occurring after 14-15 scans and II/IH identification after 18 scans. CONCLUSIONS: We have demonstrated that although there is no difference in the overall accuracy of muscle plane versus II/IH nerve identification, the muscle planes are reliably identified after fewer scans of the inguinal region. We suggest that a reliable end point for the inexperienced practitioner of ultrasound-guided II/IH nerve block may be the TA/internal oblique plane where the nerves are reported to be found in 100% of cases.

Ultrasound versus landmark-based technique for ilioinguinal-iliohypogastric nerve blockade in children: the implications on plasma levels of ropivacaine.

BACKGROUND: Ilioinguinal-iliohypogastric nerve blockade (INB) is associated with high plasma concentrations of local anesthetics (LAs) in children. Ultrasonographic guidance enables exact anatomical administration of LA, which may alter plasma levels. Accordingly, we compared plasma levels of ropivacaine after ultrasonographic versus landmark-based INB. METHODS: After induction of general anesthesia, 66 children (8-84 mo) scheduled for inguinal hernia repair received INB with 0.25 mL/kg of ropivacaine 0.5% (1.25 mg/kg) either by a landmark-based (n = 31) or by an ultrasound-guided technique (n = 35). Ropivacaine plasma levels were measured before (0) and 5, 10, 20, and 30 min after the LA injection, using high-performance liquid chromatography. Maximum plasma concentrations (C(max)), time to C(max) (t(max)), the absorption rate constant (k(a)), the speed of rise of the plasma concentration at Time 0 (dC(0)/dt), and area under the curve value (AUC) were determined. RESULTS: The ultrasound-guided technique resulted in higher C(max) (sd), k(a), dC(0)/dt, and AUC values and shorter t(max) compared with the landmark-based technique (C(max): 1.78 [0.62] vs 1.23 [0.70] microg/mL, P < 0.01; k(a): 14.4 [10.7] vs 11.7 [11.4] h(-1), P < 0.05; dC(0)/dt: 0.26 [0.12] vs 0.15 [0.03] microg/mL . min, P < 0.01; AUC: 42.4 [15.9] vs 27.2 [18.1] microg . 30 min/mL, P < 0.001; t(max): 20.4 [8.6] vs 25.3 [7.6] min, P < 0.05). CONCLUSIONS: The pharmacokinetic data indicate faster absorption and higher maximal plasma concentration of LA when ultrasound was used as a guidance technique for INB compared with the landmark-based technique. Thus, a reduction of the volume of LA should be considered when using an ultrasound-guided technique for INB.