A study to improve identification of the retroperitoneal course of iliohypogastric, ilioinguinal, femorocutaneous and genitofemoral nerves during laparoscopic triple neurectomy.

BACKGROUND: Laparoscopic triple neurectomy is an available treatment option for chronic groin pain, but a poor working knowledge of the retroperitoneal neuroanatomy makes it an unsafe technique. OBJECT: Describe the retroperitoneal course of iliohypogastric, ilioinguinal, lateral femoral cutaneous and genitofemoral nerves, to guide the surgeon who operates in this region. METHODS: Fifty adult cadavers were dissected resulting in 100 anatomic specimens. Additionally, 30 patients were operated for refractory chronic inguinal pain, using laparoscopic triple neurectomy. All operations and dissections were photographed. Measurements were made between the nerves of the lumbar plexus and various landmarks: interneural distances in a vertical midline plane, posterior or anterior iliac spine and branch presentation model. RESULTS: The ilioinguinal and iliohypogastric nerves were independent in 78% (Type II) and separated by an average of 2.5 ± 0.8 cm. In surgery study, only 38% were recognized as Type II and at a significantly greater distance (3.5 ± 1.2 cm, p < 0.001). The distance between ilioinguinal and lateral femoral cutaneous nerves was also greater during surgery, with statistical significance (5.1 ± 1.5 versus 4.2 ± 1.5, p < 0.005). The distance of the nerves to their bone references were not statistically different. The genitofemoral nerve emerged from the psoas major muscle in 20% as two separate branches (Type II), regardless of the study. The lateral femoral cutaneous nerve had a mean distance of 0.98 ± 1.6 cm medial to the anterior superior iliac spine. CONCLUSION: The identification of the IH, II, FC and GF nerves is essential to reduce the rate of failures in the treatment of CGP. The frequent anatomical variations of the lumbar plexus nerves make knowledge of their courses in the retroperitoneal space essential to ensure safe surgery. The location of the nerves in the LTN is distorted by up to 1 cm. regarding references in the cadavers.

Abdominal Vagal Afferents Modulate the Brain Transcriptome and Behaviors Relevant to Schizophrenia.

Reduced activity of vagal efferents has long been implicated in schizophrenia and appears to be responsible for diminished parasympathetic activity and associated peripheral symptoms such as low heart rate variability and cardiovascular complications in affected individuals. In contrast, only little attention has been paid to the possibility that impaired afferent vagal signaling may be relevant for the disorder's pathophysiology as well. The present study explored this hypothesis using a model of subdiaphragmatic vagal deafferentation (SDA) in male rats. SDA represents the most complete and selective vagal deafferentation method existing to date as it leads to complete disconnection of all abdominal vagal afferents while sparing half of the abdominal vagal efferents. Using next-generation mRNA sequencing, we show that SDA leads to brain transcriptional changes in functional networks annotating with schizophrenia. We further demonstrate that SDA induces a hyperdopaminergic state, which manifests itself as increased sensitivity to acute amphetamine treatment and elevated accumbal levels of dopamine and its major metabolite, 3,4-dihydroxyphenylacetic acid. Our study also shows that SDA impairs sensorimotor gating and the attentional control of associative learning, which were assessed using the paradigms of prepulse inhibition and latent inhibition, respectively. These data provide converging evidence suggesting that the brain transcriptome, dopamine neurochemistry, and behavioral functions implicated in schizophrenia are subject to visceral modulation through abdominal vagal afferents. Our findings may encourage the further establishment and use of therapies for schizophrenia that are based on vagal interventions.SIGNIFICANCE STATEMENT The present work provides a better understanding of how disrupted vagal afferent signaling can contribute to schizophrenia-related brain and behavioral abnormalities. More specifically, it shows that subdiaphragmatic vagal deafferentation (SDA) in rats leads to (1) brain transcriptional changes in functional networks related to schizophrenia, (2) increased sensitivity to dopamine-stimulating drugs and elevated dopamine levels in the nucleus accumbens, and (3) impairments in sensorimotor gating and the attentional control of associative learning. These findings may encourage the further establishment of novel therapies for schizophrenia that are based on vagal interventions.

Vagal afferent activation suppresses systemic inflammation via the splanchnic anti-inflammatory pathway.

Electrical stimulation of the vagus nerve (VNS) is a novel strategy used to treat inflammatory conditions. Therapeutic VNS activates both efferent and afferent fibers; however, the effects attributable to vagal afferent stimulation are unclear. Here, we tested if selective activation of afferent fibers in the abdominal vagus suppresses systemic inflammation. In urethane-anesthetized rats challenged with lipopolysaccharide (LPS, 60 µg/kg, i.v.), abdominal afferent VNS (2 Hz for 20 min) reduced plasma tumor necrosis factor alpha (TNF) levels 90 min later by 88% compared with unmanipulated animals. Pre-cutting the cervical vagi blocked this anti-inflammatory action. Interestingly, the surgical procedure to expose and prepare the abdominal vagus for afferent stimulation ('vagal manipulation') also had an anti-inflammatory action. Levels of the anti-inflammatory cytokine IL-10 were inversely related to those of TNF. Prior bilateral section of the splanchnic sympathetic nerves reversed the anti-inflammatory actions of afferent VNS and vagal manipulation. Sympathetic efferent activity in the splanchnic nerve was shown to respond reflexly to abdominal vagal afferent stimulation. These data demonstrate that experimentally activating abdominal vagal afferent fibers suppresses systemic inflammation, and that the efferent neural pathway for this action is in the splanchnic sympathetic nerves.

Different processing of CAPA and pyrokinin precursors in the giant mealworm beetle Zophobas atratus (Tenebrionidae) and the boll weevil Anthonomus grandis grandis (Curculionidae).

Capa and pyrokinin (pk) genes in hexapods share a common evolutionary origin. Using transcriptomics and peptidomics, we analyzed products of these genes in two beetles, the giant mealworm beetle (Zophobas atratus; Tenebrionidae) and the boll weevil (Anthonomus grandis grandis; Curculionidae). Our data revealed that even within Coleoptera, which represents a very well-defined group of insects, highly different evolutionary developments occurred in the neuropeptidergic system. These differences, however, primarily affect the general structure of the precursors and differential processing of mature peptides and, to a lesser degree, the sequences of the active core motifs. With the differential processing of the CAPA-precursor in Z. atratus we found a perfect example of completely different products cleaved from a single neuropeptide precursor in different cells. The CAPA precursor in abdominal ganglia of this species yields primarily periviscerokinins (PVKs) whereas processing of the same precursor in neurosecretory cells of the subesophageal ganglion results in CAPA-tryptoPK and a novel CAPA-PK. Particularly important was the detection of that CAPA-PK which has never been observed in the CNS of insects before. The three different types of CAPA peptides (CAPA-tryptoPK, CAPA-PK, PVK) each represent potential ligands which activate different receptors. In contrast to the processing of the CAPA precursor from Z. atratus, no indications of a differential processing of the CAPA precursor were found in A. g. grandis. These data suggest that rapid evolutionary changes regarding the processing of CAPA precursors were still going on when the different beetle lineages diverged. The sequence of the single known PVK of A. g. grandis occupies a special position within the known PVKs of insects and might serve asa basis to develop lineage-specific peptidomimetics capable of disrupting physiological processes regulated by PVKs.

Home-Based Transabdominal Interferential Electrical Stimulation for Six Months Improves Paediatric Slow Transit Constipation (STC).

BACKGROUND: Transcutaneous electrical stimulation (TES) for one to two months has produced some improvement in treatment-resistant slow-transit constipation (STC) in children. Optimal parameters for treatment are not known. It is possible that more improvement would occur with stimulation for longer. This study examined the effectiveness of stimulation for six months. METHODS: Children with STC confirmed by nuclear transit study (NTS) were enrolled prospectively. All had chronic constipation for greater than two years and had failed medical treatment. TES was performed for one hour/day for six months using the INF 4160 (Fuji Dynamics) portable stimulator and 4 cm × 4 cm electrodes near the belly button and on the back. Families kept bowel diaries and completed PEDSQLCore QOL (4.0) questionnaires before and at end of treatment. RESULTS: Sixty-two children (34 females; seven years, 2-16 year) with STC were studied. Defecation frequency increased in 57/62 (91%, mean ± SEM pre- 1.49 ± 0.20 vs. post- 3.25 ± 0.25 defecation/week, p < 0.0001) with the number with ≥3BA increasing from 6 to 37 (10-59%). Soiling frequency decreased from 4.8 to 1.1 days/week (p <0.001). Abdominal pain decreased from 1.7 to 0.3 days/week (<0.0001), and spontaneous urge to defecate improved. Quality of life (p < 0.01), mean transit index and gastric emptying on NTS improved (p < 0.005). CONCLUSION: Treatment-resistant STC responds to TES using interferential current across the abdomen when given daily for many months. Battery operated stimulators allowed stimulation at home for an hour each day. Stimulation for six months produced clinically significant improvement in defecation frequency, soiling, abdominal pain, urge to defecate, and quality of life in half of these chronic patients.

Short-Term Interferential Transabdominal Electrical Stimulation Did Not Change Oral-Rectal Transit Time in Piglets.

BACKGROUND: Transcutaneous electrical stimulation (TES) using interferential current (IFC) is a new therapeutic treatment for constipation. Clinical studies show that TES-IFC for 3-6 months improves colonic transit, but it is not clear if short-term stimulation affects transit or the effect requires longer to develop. The aim of this study was to determine if TES-IFC for only four days affects oral-rectal transit time in healthy pigs. METHODS: Twenty-two 4-5-week old large white female piglets had transit studies during week 4 and week 5 by placing a capsule containing 18 radiopaque plastic markers in the esophagus under anesthetic followed by x-rays at 6, 30, 54, and 78 hours. Animals were randomly assigned to active or control groups. The active group received TES for 30 min daily for four days. Interferential current was applied through four electrodes (4 × 4 cm), with two para-spinal just below the last rib and two on the belly at the same level. Stimulation was at 4000 Hz and 4080-4160 Hz with currents crossing through the abdominal cavity. RESULTS: Whole bowel transit times ranged from 7.7 to 72.2 hours, stomach transit from <1 to 63 hours, and bowel with rectum transit time from 5 to 53 hours. Transit times were the same for the control (median 28.4 hours) and TES-IFC (23.0 hours) groups in the prestimulation and stimulation weeks (control 23.0, TES-IFC 19.8 hours) with no change within or between groups. CONCLUSION: Four days of half-hour TES-IFC daily in healthy 5-week-old piglets did not change oral-rectal transit time.

Cognitive effects of subdiaphragmatic vagal deafferentation in rats.

Vagal afferents are a crucial neuronal component of the gut-brain axis and mediate the information flow from the viscera to the central nervous system. Based on the findings provided by experiments involving vagus nerve stimulation, it has been suggested that vagal afferent signaling may influence various cognitive functions such as recognition memory and cognitive flexibility. Here, we examined this hypothesis using a rat model of subdiaphragmatic vagal deafferentation (SDA), the most complete and selective abdominal vagal deafferentation method existing to date. We found that SDA did not affect working memory in a nonspatial alternation task, nor did it influence short-, intermediate-, and long-term object recognition memory. SDA did also not affect the acquisition of positively reinforced left-right discrimination learning, but it facilitated the subsequent reversal left-right discrimination learning. The SDA-induced effects on reversal learning emerged in the absence of concomitant changes in motivation towards the positive reinforcer, indicating selective effects on cognitive flexibility. Taken together, these findings suggest that the relative contribution of vagal afferent signaling to cognitive functions is limited. At the same time, our study demonstrates that cognitive flexibility, at least in the domains of positively reinforced learning, is subjected to visceral modulation through abdominal vagal afferents.

Sexual dysfunction following rectal cancer surgery.

INTRODUCTION: Sexual and urological problems after surgery for rectal cancer are common, multifactorial, inadequately discussed, and untreated. The urogenital function is dependent on dual autonomic sympathetic and parasympathetic innervation, and four key danger zones exist that are at risk for nerve damage during colorectal surgery: one of these sites is in the abdomen and three are in the pelvis. The aim of this study is to systematically review the epidemiology of sexual dysfunction following rectal cancer surgery, to describe the anatomical basis of autonomic nerve-preserving techniques, and to explore the scientific evidence available to support the laparoscopic or robotic approach over open surgery. METHODS: According to the PRISMA guidelines, a comprehensive literature search of studies evaluating sexual function in patients undergoing rectal surgery for cancer was performed in Medline, Scopus, Web of Science, Embase, and Cochrane Central Register of controlled trials. RESULTS: An increasing number of studies assessing the incidence and prevalence of sexual dysfunction following multimodality treatment for rectal cancer has been published over the last 30 years. Significant heterogeneity in the prevalence of sexual dysfunction is reported in the literature, with rates between 5 and 90%. CONCLUSIONS: There is no evidence to date in favor of any surgical approach (open vs laparoscopic vs robotic). Standardized diagnostic tools should be routinely used to prospectively assess sexual function in patients undergoing rectal surgery.

Anatomical study of the iliohypogastric, ilioinguinal, and genitofemoral nerves using high-resolution ultrasound.

INTRODUCTION: In this study we aimed to determine whether high-resolution ultrasound (US) can identify the iliohypogastric (IH), ilioinguinal (II), and genitofemoral (GF) nerves and their relations. METHODS: This investigation, initially undertaken in cadavers, was followed by a high-resolution US study in 30 healthy adult volunteers (180 nerves) by 2 musculoskeletal radiologists on separate occasions, using 2 different approaches (proximal to distal and distal to proximal). A 0-3 scale was used to assess nerve visibility. Location and course of the IH, II, and GF nerves and their relations to adjacent anatomical structures were analyzed. RESULTS: Nerves and their terminal branches were better visualized with the distal-to-proximal approach (P < 0.05). Visualization of the terminal branches was possible in up to 60% of volunteers. CONCLUSIONS: High-resolution ultrasound (US) can identify the IH, II, and GF nerves at the level of the abdominal wall and the terminal branches in the majority of volunteers.

Resection of Ileoinguinal and Ileohypogastric Nerves Combined with Gluing in Modified Lichtenstein Repair.

We conducted a cohort trial to investigate the relevance of resection of the ilioinguinal and iliohypogastric nerves in combination with mesh fixation with BioGlue™ (CryoLife® Inc., Kennsaw, Georgia) in modified Lichtenstein repair to the development of chronic pain and hernia recurrence.1 In all, 430 patients underwent Lichtenstein repair. In 247 patients the mesh was fixed by means of glue, and in 183 patients it was fixed with conventional sutures. In all cases the inguinal nerves N. ilioinguinalis and N. iliohypogastricus were located and resected after identification to prevent nerve reaction to the mesh. The pain intensity was measured with a numeric analogous scale (NAS) 24 hours after surgery. All complications were recorded with a follow-up of up to 5 years. There was a significantly lower pain intensity level in the gluing group compared with the suture group 24 hours after surgery (0.016 t test). The level was 3.8±2.4 in bilateral hernia and 3.3±2.1 in unilateral hernia in the gluing group. It was 4.7±3.3 in unilateral and 3.7±2.2 in bilateral hernia in the suture group. The cut-suture time was lower in the gluing group. There were no severe pain syndromes (NAS≥4) in the gluing group and only 1.1% in the suture group. There was a higher incidence of non-bacterial wound infections in the gluing group (3.6%) than in the suture group (1.1%). The rate of recurrence after 5 years amounted to 2.0% in the gluing group and 2.2% in the suture group. The technique of using BioGlue™ for mesh fixation combined with systematic nerve dissection reduces acute and chronic postoperative pain after modified Lichtenstein repair. Only 2 of 430 patients suffered from severe chronic pain. Combined gluing and systematic resection of the inguinal nerves is more comfortable than standard Lichtenstein repair.

Pain reported during prolonged standing is associated with reduced anticipatory postural adjustments of the deep abdominals.

Within the context of low back pain, the measurement of deep abdominal anticipatory postural adjustments (APAs) during rapid limb movement has received much interest. There is dispute about the association between APAs and back pain. Moreover, there is limited evidence examining compensatory postural adjustments (CPAs) in back pain. This study examined the relationship between APAs and CPAs with pain reported in the low back during 2 h of prolonged standing. Twenty-six participants with no history of severe back pain performed 2-h prolonged standing. APAs and CPAs of the deep abdominal muscles (transverse abdominis/internal obliques) were measured by surface electromyography during rapid shoulder flexion and extension. APAs and CPAs measured pre-standing revealed symmetrical anticipatory activity, but an asymmetry between the different sides of the abdominal wall for CPAs. APAs and CPAs measured pre-standing were not associated with pain reported during standing. For the whole group, APA amplitudes were reduced post-standing during shoulder flexion (p = 0.005). Pain reported during standing was associated with the changes in APA amplitudes post-standing (rs = 0.43, p = 0.002). These findings support previous research using hypertonic saline injections to induce back pain that showed reduced APA amplitudes, and extends findings to suggest pain does not effect compensatory postural adjustments.

Postoperative ileus: mechanisms and future directions for research.

Postoperative ileus (POI) is an abnormal pattern of gastrointestinal motility characterized by nausea, vomiting, abdominal distension and/or delayed passage of flatus or stool, which may occur following surgery. Postoperative ileus slows recovery, increases the risk of developing postoperative complications and confers a significant financial load on healthcare institutions. The aim of the present review is to provide a succinct overview of the clinical features and pathophysiological mechanisms of POI, with final comment on selected directions for future research.Terminology used when describing POI is inconsistent, with little differentiation made between the obligatory period of gut dysfunction seen after surgery ('normal POI') and the more clinically and pathologically significant entity of a 'prolonged POI'. Both normal and prolonged POI represent a fundamentally similar pathophysiological phenomenon. The aetiology of POI is postulated to be multifactorial, with principal mediators being inflammatory cell activation, autonomic dysfunction (both primarily and as part of the surgical stress response), agonism at gut opioid receptors, modulation of gastrointestinal hormone activity and electrolyte derangements. A final common pathway for these effectors is impaired contractility and motility and gut wall oedema. There are many potential directions for future research. In particular, there remains scope to accurately characterize the gastrointestinal dysfunction that underscores an ileus, development of an accurate risk stratification tool will facilitate early implementation of preventive measures and clinical appraisal of novel therapeutic strategies that target individual pathways in the pathogenesis of ileus warrant further investigation.

Transversus abdominis plane (TAP) blocks.

Transversus abdominis plane (TAP) blocks are a relatively new regional anesthetic technique used in a multimodal approach to provide postoperative analgesia of the anterolateral abdominal wall. The technique for placing TAP blocks has evolved from a landmark technique to an ultrasound-guided technique. There are 3 common approaches for accessing the TAP: subcostal, midaxillary, and ilioinguinal-iliohypogastric. The distribution of local anesthetic and the extent of sensory blockade differs with each of these approaches. The approach used is contingent on the type and location of the surgical procedure. Overall, TAP blocks reduce postoperative pain and opioid requirements, resulting in fewer side effects such as nausea and vomiting, respiratory depression, and sedation. Future studies should examine which type, concentration, and volume of local anesthetics are most effective.

Inguinal field block for femoral artery exposure during endovascular aneurysm repair.

PURPOSE: To analyze the feasibility and outcomes of an inguinal field block (IFB) for femoral artery exposure in patients undergoing elective endovascular aneurysm repair (EVAR). METHODS: Between January 2004 and June 2012, 784 patients (597 men; mean age 76 years) underwent elective EVAR via surgical cutdown to the common femoral arteries. The data from these procedures were retrospectively analyzed to determine the technical feasibility of IFB, need for conversion to general anesthesia, mortality, and complication rate. RESULTS: IFB was successfully performed in 768 (97.9%) patients. Conversion from IFB to general anesthesia was necessary in 11 (1.4%) patients owing to patient discomfort (n=3, 0.4%), anxiety (n=5, 0.6%), and persistent patient movement (n=3, 0.4%). The remaining 5 (0.7%) patients underwent EVAR under general anesthesia because they refused IFB. Technical success of EVAR was 99.7%; the mean operation time was 84 minutes and the radiation time was 13 minutes. The mean hospital stay was 3.7 days; no patient required intensive care. At 6 months, there were no reports of local/systemic complications related to IFB, such as infection, seroma, hematoma, nerve injury, or allergic/toxic reactions. CONCLUSION: Our study demonstrated that performing EVAR with femoral cutdown under IFB is a feasible, safe, and effective surgical and anesthetic combination, with very little need for conversion to general anesthesia.

Neuroanatomy of the female abdominopelvic region: A review with application to pelvic pain syndromes.

Pelvic pain can be a life altering disease. Multiple pathologies can affect this region resulting in neurologic issues. Therefore, a thorough understanding of the nerve supply to this region is important for the clinician who treats such patients. The current review outlines the anatomy of the nervous system of the abdominopelvic region with special attention to this anatomy in the female.

Transversus abdominis block: clinical uses, side effects, and future perspectives.

Poorly controlled acute pain during the postoperative setting after abdominal surgery can be detrimental to the patient. Current pain management practices for the postoperative abdominal surgery patient rely heavily on opioids, which are associated with many unwanted side effects. Recently, interest surrounding regional anesthesia has been growing owing to its demonstrated efficacy and safety outcomes. More specifically, the transversus abdominis plane (TAP) block procedure has attracted attention owing to its ability to successfully block peripheral pain signaling in the abdomen, its ease of use, few complications, and its greater acceptability. A majority of the studies published has demonstrated the successful reduction in pain in many abdominal surgical procedures using local anesthetics during the TAP block. However, the short duration of the pain block causes the patient to still rely on other analgesics throughout the additional postoperative days. Preliminary studies using continuous infusion catheters placed in the TAP has been one of the ways to prolong the nerve block in the abdomen; however, technical and operational issues currently limit the widespread adoption of this method. In this review, current studies will be presented and summarized to update the field on the potential benefits of the TAP block procedure, in addition to providing insight into the future direction of the drugs that could be used for TAP block.

Proteomic characterization of the abdominal ganglion of Aplysia californica-a protein resource for neuroscience.

Aplysia californica (AC) is a widely used model for testing learning and memory. Although ESTs have been generated, proteomics studies on AC proteins are limited. Studies at the protein level, however, are mandatory, not only due to the fact that studies at the nucleic acid level are not allowing conclusions about PTMs. A gel-based proteomics method was therefore applied to carry out protein profiling in abdominal ganglia from AC. Abdominal ganglia were extirpated, proteins extracted and run on 2DE with subsequent in-gel digestion with trypsin, chymotrypsin, and partially by subtilisin. Peptides were identified using a nano-LC-ESI-LTQ-FT-mass spectrometer. MS/MS data were analyzed by searching the NCBI nonredundant public AC EST database and the NCBI nonredundant public AC protein database. A total of 477 different proteins represented by 363 protein spots were detected and were assigned to different protein pathways as for instance signaling (receptors, protein kinases, and phosphatases), metabolism, protein synthesis, handling and degradation, cytoskeleton and structural, oxido-redox, heat shock and chaperone, hypothetical, predicted and unnamed proteins. The generation of a protein map of soluble proteins shows the existence of so far hypothetical and predicted proteins and is allowing and challenging further work at the protein level, in particular in the field of neuroscience.

Clinical effectiveness of transversus abdominis plane (TAP) block in abdominal surgery: a systematic review and meta-analysis.

AIM: Reduced opioid use in the immediate postoperative period is associated with decreased complications. This study aimed to determine the effect of transversus abdominis plane (TAP) block on morphine requirements 24 h after abdominal surgery. Secondary outcomes included the effect of TAP block on morphine use 48 h after surgery, incidence of postoperative nausea and vomiting (PONV) and impact on reported pain scores (visual analogue scale). METHOD: A systematic review of the literature was conducted for randomised controlled trials (RCTs) evaluating the effects of TAP block in adults undergoing abdominal surgery. For continuous data, weighted mean differences (WMD) were formulated; for dichotomous data, odds ratios (OR) were calculated. Results were produced with a random effects model with 95% confidence intervals (CI). RESULTS: Nine studies, including published and unpublished data, containing a total of 413 patients were included. Of these 205 received a TAP block and 208 a placebo. Cumulative morphine utilization was statistically significantly reduced at 24 h. [WMD=23.71mg (38.66-8.76); P=0.002] and 48h [WMD=38.08mg (18.97-57.19); P<0.0001] in patients who received a TAP block and the incidence of PONV was significantly reduced [OR=0.41(0.22-0.74); P=0.003]. There was a nonsignificant reduction in the visual analogue scales of postoperative pain [WMD=0.73cm (1.84-0.38), P=0.2]. There were no reported adverse events following TAP block. CONCLUSION: Transversus abdominis plane block is safe, reduces postoperative morphine requirements, nausea and vomiting and possibly the severity of pain after abdominal surgery. It should be considered as part of a multimodal approach to anaesthesia and enhanced recovery in patients undergoing abdominal surgery.

Brief reports: plasma ropivacaine concentrations after ultrasound-guided rectus sheath block in patients undergoing lower abdominal surgery.

A rectus sheath block can provide postoperative analgesia for midline incisions. However, information regarding the pharmacokinetics of local anesthetics used in this block is lacking. In this study, we detail the time course of ropivacaine concentrations after this block. Thirty-nine patients undergoing elective lower abdominal surgery were assigned to 3 groups receiving rectus sheath block with 20 mL of different concentrations of ropivacaine. Peak plasma concentrations were dose dependent, and there were no significant differences in the times to peak plasma concentrations. The present data also suggested a slower absorption kinetics profile for ropivacaine after rectus sheath block than other compartment blocks.