Mechanisms of postoperative ileus

Continuous intravenous lidocaine in the treatment of paralytic ileus due to severe spinal cord injury

Paralytic ileus is a major concern in the acute phase of spinal cord injury. Classical treatment with neostigmine is often ineffective. Continuous intravenous (i.v.) lidocaine infusion has been previously proposed intra and post-operatively in order to decrease the duration of post-operative ileus after abdominal surgery. We report the cases of seven patients suffering from complete paralytic spinal cord injury-related ileus with colectasy resistant to neostigmine, who were treated by i.v. lidocaine infusion.

Methylnaltrexone in the treatment of opioid-induced constipation

Constipation is a significant problem related to opioid medications used to manage pain. This review attempts to outline the latest findings related to the therapeutic usefulness of a μ opioid receptor antagonist, methylnaltrexone in the treatment of opioid-induced constipation. The review highlights methylnaltrexone bromide (Relistor™; Progenics/Wyeth) a quaternary derivative of naltrexone, which was recently approved in the United States, Europe and Canada. The Food and Drug Administration in the United States approved a subcutaneous injection for the treatment of opioid bowel dysfunction in patients with advanced illness who are receiving palliative care and when laxative therapy has been insufficient. Methylnaltrexone is a peripherally restricted, μ opioid receptor antagonist that accelerates oral-cecal transit in patients with opioid-induced constipation without reversing the analgesic effects of morphine or inducing symptoms of opioid withdrawal. An analysis of the mechanism of action and the potential benefits of using methylnaltrexone is based on data from published basic research and recent clinical studies.

Immune modulation in gastrointestinal disorders: new opportunities for therapeutic peptides?

Inflammation is the response of vascularized tissues to injury, irritation and infection. Nearly always, the inflammatory response is successfully resolved and, when necessary, a process of wound healing is initiated. Nowhere in the body is this homeostatic process more challenging than in the gastrointestinal (GI) tract, where the microbial flora sits in very close proximity to the mucosal immune system, separated only by an epithelial cell barrier. Delicate regulatory systems of the mucosal immune system determine mucosal permeability and response to bacterial flora, and aberrations in this system result in acute or chronic inflammatory conditions. Examples of such are two commonly occurring inflammatory GI disorders: inflammatory bowel disease and postoperative ileus. Inflammatory bowel disease is the result of a chronic and excessive mucosal immune response, whereas postoperative ileus represents a transient condition of GI tract paralysis that is the result of an inflammatory response to abdominal surgery. The clinical management of both conditions is very challenging and depends heavily on the possibility of modulating the host immune response. In this brief report, we highlight the role of neuropeptides in GI physiology and immune regulation, discuss a recently discovered endogenous anti-inflammatory pathway mediated by the ChemR23 receptor and speculate on the therapeutic potential of peptides that bind G-protein-coupled receptors in the management of inflammation in the GI tract.

Jejunal cholinergic, nitrergic, and soluble guanylate cyclase activity in postoperative ileus

BACKGROUND

In animal models of postoperative ileus (POI), inflammation of the intestine plays an important role in the pathogenesis of POI. Changes in alpha(2)-adrenoceptors and nitrergic regulation have been proposed to be implicated. The aim of our study was to investigate the presynaptic alpha(2)-receptor-mediated control of cholinergic nerve activity, the nitrergic nerve activity, and the possible role of soluble guanylate cyclase (sGC) during the inflammatory phase of POI.

METHODS

Ileus was induced by anesthesia and manipulation of the rat jejunum. Rats were treated with the sGC inhibitors methylene blue or ODQ; nonoperated animals served as controls. After 24 h, plasma and jejunal tissue were collected for biochemical assays, nitric oxide synthase-1 (NOS-1)-immunohistochemistry, acetylcholine (Ach)-release experiments, and muscle tension experiments.

RESULTS

In all operated animal groups, myeloperoxidase activity was significantly increased, which indicates initiation of an inflammatory response. The alpha(2)-adrenoceptor agonist UK14,304 reduced electrically induced Ach-release similarly in operated and nonoperated animals. In strips of operated animals, electrically induced nitrergic relaxations were decreased, whereas relaxations induced by exogenous nitric oxide (NO) remained unchanged compared with control. The number of myenteric neurons and the percentage of NOS-1-positive neurons were not influenced. Plasmatic cyclic guanosine monophosphate (cGMP) levels were decreased in all operated groups, whereas jejunal cGMP levels were unchanged compared with nonoperated controls; treatment with sGC inhibitors did not reduce plasmatic cGMP levels.

CONCLUSIONS

This study demonstrates that presynaptic alpha(2)-receptor mediated control of intestinal cholinergic nerve activity is unchanged during manipulation-induced inflammation. However, this inflammation induces impaired nitrergic neurotransmission related to decreased NOS-1 activity in the nitrergic nerves.

Proinflammatory role of leukocyte-derived Egr-1 in the development of murine postoperative ileus

BACKGROUND & AIMS

Early growth response gene-1 (Egr-1) is an important inflammatory transcription factor. We hypothesize that leukocyte-derived Egr-1 plays a key inflammatory role in causing postoperative ileus.

METHODS

Wild-type, Egr-1 knockout, and chimera mice (constructed by irradiation followed by injection with Egr-1(+/+) or Egr-1(-/-) bone marrow) were subjected to surgical manipulation of the gastrointestinal tract to induce ileus. Reverse-transcription polymerase chain reaction, Western blot, and immunohistochemistry quantified and localized Egr-1. Lumenal transit of nonabsorbable fluorescein isothiocyanate-labeled dextran and in vitro organ bath techniques measured functional gastrointestinal motility. Inflammatory mediator expressions were measured by Griess reaction, enzyme-linked immunosorbent assay, and multiplex Luminex assay.

RESULTS

Intestinal manipulation rapidly and significantly induced Egr-1 messenger RNA and protein within the inflamed muscularis externa. Egr-1 was colocalized early to smooth muscle and enteric neurons and later in extravasated monocytes after surgery when postoperative ileus was functionally prominent. The functional severity of postoperative ileus was significantly ameliorated in mice deficient in Egr-1(-/-) and chimera wild-type mice transplanted with Egr-1(-/-) bone marrow, whereas knockout mice with Egr-1(+/+) bone marrow again displayed significant ileus. Motility was mechanistically associated in Egr-1(-/-) gene deficiency with a down-regulation in the release of nitric oxide, prostanoids, monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha, interleukin-6, interleukin-1, and granulocyte colony-stimulating factor, as well as a decrease in the recruitment of leukocytes into the manipulated muscle wall of the intestine compared with wild-type mice.

CONCLUSIONS

Leukocyte-derived Egr-1 plays an early critical inflammatory role in the initiation of the postoperative inflammatory response, which leads to a prolonged decreased in gastrointestinal motility after intestinal surgery.

Postoperative ileus--an update on preventive techniques

This article reviews techniques currently used to prevent or reduce the duration of postoperative ileus (POI), which is considered an undesirable stress response to major abdominal surgery that leads to discomfort, morbidity and prolonged hospital stay. In several randomized studies, a number of techniques have been demonstrated to reduce the occurrence and/or duration of POI: thoracic epidural analgesia with local anesthetics, peripheral opioid antagonists, laxatives, chewing gum, intravenous and incisional local anesthetics, and avoidance of routine nasogastric intubation and fluid excess. Early institution of oral feeding and laparoscopic surgery might also be effective, but there is less clear evidence available to support their use. When some of these techniques are combined as part of the concept of multimodal postoperative rehabilitation (fast-track surgery), the duration of POI after open or laparoscopic abdominal surgery can be reduced to 24-48 h in most patients. There is a need for data on the effect of these techniques on POI when applied to major upper abdominal surgeries and emergency abdominal operations (e.g. trauma, peritonitis, etc.).

Clinical trial: alvimopan for the management of post-operative ileus after abdominal surgery: results of an international randomized, double-blind, multicentre, placebo-controlled clinical study

BACKGROUND

Post-operative ileus (POI) affects most patients undergoing abdominal surgery.

AIM

To evaluate the effect of alvimopan, a peripherally acting mu-opioid receptor antagonist, on POI by negating the impact of opioids on gastrointestinal (GI) motility without affecting analgesia in patients outside North America.

METHODS

Adult subjects undergoing open abdominal surgery (n = 911) randomly received oral alvimopan 6 or 12 mg, or placebo, 2 h before, and twice daily following surgery. Opioids were administered as intravenous patient-controlled analgesia (PCA) or bolus injection. Time to recovery of GI function was assessed principally using composite endpoints in subjects undergoing bowel resection (n = 738).

RESULTS

A nonsignificant reduction in mean time to tolerate solid food and either first flatus or bowel movement (primary endpoint) was observed for both alvimopan 6 and 12 mg; 8.5 h (95% CI: 0.9, 16.0) and 4.8 h (95% CI: -3.2, 12.8), respectively. However, an exploratory post hoc analysis showed that alvimopan was more effective in the PCA (n = 317) group than in the non-PCA (n = 318) group. Alvimopan was well tolerated and did not reverse analgesia.

CONCLUSION

Although the significant clinical effect of alvimopan on reducing POI observed in previous trials was not reproduced, this trial suggests potential benefit in bowel resection patients who received PCA.

Alvimopan and COX-2 inhibition reverse opioid and inflammatory components of postoperative ileus

Our objective was to investigate the therapeutic potential of peripheral opioid antagonism with alvimopan and anti-inflammatory cyclooxygenase 2 (COX-2) inhibition in an animal model of postoperative ileus with pain management. Intestinal manipulation was conducted in mice and rats with or without postoperative morphine injection. Rodents were orally fed non-digestible fluorescein (FITC)-labelled dextran and transit measured after a period of 90 min. The immunomodulatory effects of morphine and alvimopan were determined on nitric oxide released from the organ cultured muscularis externa. Surgical manipulation of the intestine resulted in a delay in gastrointestinal transit after 24 h that worsened with exogenous morphine. Alvimopan did not significantly alter transit of control or manipulated animals, but significantly antagonized the transit delaying effects of morphine. However, when the inflammatory component was robust enough to obscure a further opioid induced delay in gastrointestinal transit, alvimopan ceased to be effective in improving postoperative intestinal function. Cyclooxygenase 2 inhibition significantly diminished the inflammatory component of postoperative ileus. Surgical manipulation resulted in an increased release of nitric oxide from the inflamed isolated muscularis externa in 24-h organ culture which was not altered by morphine or alvimopan. Two distinct mechanisms exist which participate in postoperative bowel dysfunction: a local inflammatory response which is antagonized by COX-2 inhibition, and a morphine-induced alteration in neural function which can be blocked with alvimopan.

Mentation on the immunological modulation of gastrointestinal motility

The immunological modulation of gastrointestinal motility is currently one of the most dynamic and fascinating areas of enteric research, as investigators are beginning to focus their studies on the pathophysiology of various gastrointestinal dysmotilities. The new fruits of this investigative initiative has resulted in the appearance of a fascinating series of articles which demonstrate that intestinal inflammatory events alter a distinct population of enteric neurons and that these alterations last long past the apparent resolution of the inciting event. Studies over the past few years have unequivocally demonstrated that the muscularis externa itself is an active and complex immunological compartment with unique features. The rodent muscularis externa is constitutively populated by a dense network of muscularis macrophages throughout the entire gastrointestinal tract. Although few other leukocytes are present in the rodent, the human muscularis is densely populated by both macrophages and mast cells. Postoperative ileus and endotoxin-induced ileus have turned out to be extremely useful rodent models to elucidate the importance of muscularis leukocytes in causing intestinal dysfunction. Using models of ileus, studies have demonstrated that a complex molecular inflammatory scenario is triggered within the muscularis externa, which consists of MAP kinase phosphorylation, transcriptior factor activation and the subsequent induction of various cytokines, chemokines and, importantly, smooth muscle inhibitory substances, such as nitric oxide and prostaglandins from iNOS and COX-2. This local molecular inflammatory milieu leads to leukocyte extravasation. Data suggests that the muscularis macrophage network is the conductor of the molecular and cellular inflammatory responses which causes ileus.

Experimental endometriosis in the rat is correlated with colonic motor function alterations but not with bacterial load

Endometriosis commonly presents with symptoms that mimic chronic gastrointestinal disorders. The authors used the autotransplantion model of endometriosis in rats to investigate the possible underlying mechanisms. After the rats were killed, the presence of endometriotic vesicles, colonic inflammation, and white blood cell (WBC) numbers in the peritoneal fluid was determined. Sections of colon and of jejunum were collected for measurement of myeloperoxidase (MPO) activity and bacterial counts, and isometric recording in response to acetylcholine was measured in segments of longitudinal and circular smooth muscle. Experimental animals had significantly more colonic damage, MPO activity, and WBC numbers than controls did. There was no significant difference in the total bacterial load; however, experimental animals demonstrated an increased tension in the longitudinal muscle, which correlated with WBC numbers and colonic damage. In summary, this study presents evidence for a significant effect of peritoneal endometriosis on colonic function and integrity, which may help explain the gastrointestinal symptoms associated with this disease.

Experimental pancreatitis disturbs gastrointestinal and colonic motility in mice: effect of the prokinetic agent tegaserod

Acute pancreatitis remains a potentially life-threatening disease associated with gastrointestinal motility disturbances. Prokinetic agents may be useful to overcome these motility disturbances. In this study, we investigated the effect of acute necrotizing pancreatitis (ANP) on gastrointestinal motility in female mice and evaluated the effect of tegaserod, a prokinetic 5-hydroxytryptamine-4 (5HT4) receptor agonist. ANP was induced by feeding mice a choline-deficient ethionine-supplemented diet during 72 h. In vivo intestinal motility was measured as the geometric centre (GC) of 25 glass beads 30-120-360 min after gavage. Colonic peristaltic activity was studied using a modified Trendelenburg set-up. ANP significantly decreased GC 30-120-360 min after bead gavage, associated with a significant increase of myeloperoxidase in the proximal small intestine and colon, but not in the stomach or distal small intestine. Tegaserod significantly ameliorated GC 360 min after bead gavage in control and pancreatitis mice. In isolated colonic segments, ANP significantly decreased the amplitude of peristaltic waves and increased the interval between peristaltic contractions. Tegaserod normalized the disturbed interval. In conclusion, ANP impairs gastric, small intestinal and colonic motility in mice. Tegaserod improves ANP-induced motility disturbances in vivo and in vitro, suggesting a therapeutic benefit of prokinetic 5HT4 receptor agonists in the treatment of pancreatitis-induced ileus.

Edema-induced intestinal dysfunction is mediated by STAT3 activation

Increased signal transducer and activator of transcription 3 (STAT3) activation has been shown to be associated with intestinal dysfunction. The purpose of this study was to investigate the role of STAT3 in edema-induced intestinal dysfunction. Intestinal edema was induced in male Sprague-Dawley rats by a combination of mesenteric venous hypertension and fluid resuscitation (RESUS + VH). Resuscitation fluid alone (RESUS), venous hypertension alone (VH), and sham-operated rats (CONTROL) were used as controls. Edema development, STAT3 DNA binding activity, nuclear translocation, and phosphorylation were measured in rat distal small intestinal muscularis. A significant amount of edema development was measured in the RESUS + VH rats compared with CONTROL and VH from 30 min to 6 h after surgery. Edema developed in the RESUS group at 30 min postsurgery but resolved before 2 h postsurgery. A significant increase in STAT3 DNA binding activity was observed from 30 min to 6 h after surgery in the edematous RESUS + VH group compared with nonedematous CONTROL. In addition, a significant increase in STAT3 nuclear translocation and phosphorylation was measured in the RESUS + VH group 2 and 6 h after surgery. No significant increases in STAT3 activation were observed in either the RESUS or VH groups compared with CONTROL. Rats in both the RESUS + VH and CONTROL groups were pretreated with AG490 (5 mg/kg, i.p.) to block STAT3 activation. Signal transducer and activator of transcription 3 inhibition attenuated edema-induced decrease in intestinal contractile activity and myosin light chain phosphorylation. We conclude from these data that edema-induced decreases in intestinal contractile activity are mediated, at least in part, by STAT3 activation.

Oral erythromycin accelerates impaired gastrointestinal motility after endoscopic mucosal resection

Gastrointestinal motility may be impaired after endoscopic mucosal resection of gastric lesions. We investigated whether oral erythromycin could improve motility. Twenty patients were divided randomly into groups that received oral omeprazole with or without erythromycin. Motility was recorded overnight at 3 days before and 4 days after endoscopic resection using a microtransducer probe. In the group without erythromycin, gastric phase III activity decreased significantly after endoscopic resection, while it was increased significantly by erythromycin (P < 0.01). After resection, there were significantly more gastric phase III events in the erythromycin group (P < 0.05). The interval between the start of the evening meal and the initial gastric phase III activity was significantly prolonged after resection, while this interval was significantly shortened by erythromycin (P < 0.05). The gastric phase III cycle length was also significantly shortened by erythromycin (P < 0.05). Postprandial and fasting gastrointestinal motility were impaired after endoscopic resection, and postprandial as well as fasting motility were improved by oral erythromycin.

Systemic lidocaine shortens length of hospital stay after colorectal surgery: a double-blinded, randomized, placebo-controlled trial

OBJECTIVE

To characterize the beneficial effects of perioperative systemic lidocaine on length of hospital stay, gastrointestinal motility, and the inflammatory response after colorectal surgery.

SUMMARY BACKGROUND DATA

Surgery-induced stimulation of the inflammatory response plays a major role in the development of several postoperative disorders. Local anesthetics possess anti-inflammatory activity and are thought to positively affect patients' outcome after surgery. This double-blinded, randomized, and placebo-controlled trial aimed to evaluate beneficial effects of systemic lidocaine and to provide insights into underlying mechanisms.

METHODS

Sixty patients undergoing colorectal surgery, not willing or unable to receive an epidural catheter, were randomly assigned to lidocaine or placebo treatment. Before induction of general anesthesia, an intravenous lidocaine bolus (1.5 mg/kg) was administered followed by a continuous lidocaine infusion (2 mg/min) until 4 hours postoperatively. Length of hospital stay, gastrointestinal motility, and pain scores were recorded and plasma levels or expression of pro- and anti-inflammatory mediators determined.

RESULTS

Lidocaine significantly accelerated return of bowel function and shortened length of hospital stay by one day. No difference could be observed in daily pain ratings. Elevated plasma levels of IL-6, IL-8, complement C3a, and IL-1ra as well as expression of CD11b, L- and P-selectin, and platelet-leukocyte aggregates were significantly attenuated by systemic lidocaine.

CONCLUSIONS

Perioperative intravenous lidocaine not only improved gastrointestinal motility but also shortened length of hospital stay significantly. Anti-inflammatory activity modulating the surgery-induced stress response may be one potential mechanism. Systemic lidocaine may thus provide a convenient and inexpensive approach to improve outcome for patients not suitable for epidural anesthesia.

Gastric electrical stimulation modulates hypothalamic corticotropin-releasing factor-producing neurons during post-operative ileus in rat

High-frequency/low-energy gastric electrical stimulation (GES) is an efficient therapy to treat gastric emptying-related disorders but its mechanism of action remains poorly understood. We aimed to assess the effects of high-frequency/low-energy GES on corticotropin-releasing factor (CRF)-producing neurons in the paraventricular nucleus of the hypothalamus (PVN), which are involved in gastric ileus induced by laparotomy. Two electrodes were implanted in the rat gastric antrum during laparotomy, then stimulation (amplitude: 2 mA; pulse duration 330 micros; frequency: 2 Hz; 1 min ON/2 min OFF) or sham stimulation (control group) were applied. Using immunohistochemistry, the number of c-Fos protein-expressing neurons (c-Fos protein-immunoreactive cells, Fos-IR) was quantified in the PVN after 1 h of stimulation. The number of neurons expressing simultaneously c-Fos protein and CRF mRNA was measured by means of immunocytochemistry combined with in situ hybridization. Finally, c-Fos and CRF mRNA levels in the hypothalamus were determined by in situ hybridization or quantitative reverse transcriptase-polymerase chain reaction. Fos-IR in the PVN was significantly decreased 1 h after GES (P<0.05) but was not affected by sub-diaphragmatic vagotomy. The number of neurons containing c-Fos protein and CRF mRNA was lower in the GES group compared with the control group (P<0.05). In addition, c-Fos and CRF mRNA levels in the PVN were significantly decreased by GES (P<or=0.05). It is concluded that acute GES reduces the number of CRF-producing neurons and decreases CRF expression in the PVN during post-operative gastric ileus.

Mechanisms underlying feed intolerance in the critically ill: Implications for treatment

Malnutrition is associated with poor outcomes in critically ill patients. Although nutritional support is yet to be proven to improve mortality in non-malnourished critically ill patients, early enteral feeding is considered best practice. However, enteral feeding is often limited by delayed gastric emptying. The best method to clinically identify delayed gastric emptying and feed intolerance is unclear. Gastric residual volume (GRV) measured at the bedside is widely used as a surrogate marker for gastric emptying, but the value of GRV measurement has recently been disputed. While the mechanisms underlying delayed gastric emptying require further investigation, recent research has given a better appreciation of the pathophysiology. A number of pharmacological strategies are available to improve the success of feeding. Recent data suggest a combination of intravenous metoclopramide and erythromycin to be the most successful treatment, but novel drug therapies should be explored. Simpler methods to access the duodenum and more distal small bowel for feed delivery are also under investigation. This review summarises current understanding of the factors responsible for, and mechanisms underlying feed intolerance in critical illness, together with the evidence for current practices. Areas requiring further research are also highlighted.

In vitro effects of bethanechol on specimens of intestinal smooth muscle obtained from the duodenum and jejunum of healthy dairy cows

OBJECTIVE

To describe the in vitro effects of bethanechol on contractility of smooth muscle preparations from the small intestines of healthy cows and define the muscarinic receptor subtypes involved in mediating contraction.

SAMPLE POPULATION

Tissue samples from the duodenum and jejunum collected immediately after slaughter of 40 healthy cows.

PROCEDURES

Cumulative concentration-response curves were determined for the muscarinic receptor agonist bethanechol with or without prior incubation with subtype-specific receptor antagonists in an organ bath. Effects of bethanechol and antagonists and the influence of intestinal location on basal tone, maximal amplitude (A(max)), and area under the curve (AUC) were evaluated.

RESULTS

Bethanechol induced a significant, concentration-dependent increase in all preparations and variables. The effect of bethanechol was more pronounced in jejunal than in duodenal samples and in circular than in longitudinal preparations. Significant inhibition of the effects of bethanechol was observed after prior incubation with muscarinic receptor subtype M(3) antagonists (more commonly for basal tone than for A(max) and AUC). The M(2) receptor antagonists partly inhibited the response to bethanechol, especially for basal tone. The M(3) receptor antagonists were generally more potent than the M(2) receptor antagonists. In a protection experiment, an M(3) receptor antagonist was less potent than when used in combination with an M(2) receptor antagonist. Receptor antagonists for M(1) and M(4) did not affect contractility variables.

CONCLUSIONS AND CLINICAL RELEVANCE

Bethanechol acting on muscarinic receptor sub-types M(2) and M(3) may be of clinical use as a prokinetic drug for motility disorders of the duodenum and jejunum in dairy cows.

Postoperative Ileus-Related Morbidity Profile in Patients Treated with Alvimopan after Bowel Resection

BACKGROUND

Postoperative ileus (POI), an interruption of coordinated bowel motility after operation, is exacerbated by opioids used to manage pain. Alvimopan, a peripherally acting mu-opioid receptor antagonist, accelerated gastrointestinal (GI) recovery after bowel resection in randomized, double-blind, placebo-controlled, multicenter phase III POI trials. The effect of alvimopan on POI-related morbidity for patients who underwent bowel resection was evaluated in a post-hoc analysis.

STUDY DESIGN

Incidence of POI-related postoperative morbidity (postoperative nasogastric tube insertion or POI-related prolonged hospital stay or readmission) was analyzed in four North American trials for placebo or alvimopan 12 mg administered 30 minutes or more preoperatively and twice daily postoperatively until hospital discharge (7 or fewer postoperative days). GI-related adverse events and opioid consumption were summarized for each treatment. Estimations of odds ratios of alvimopan to placebo and number needed to treat (NNT) to prevent one patient from experiencing an event of POI-related morbidity were derived from the analysis.

RESULTS

Patients receiving alvimopan 12 mg were less likely to experience POI-related morbidity than patients receiving placebo (odds ratio = 0.44, p < 0.001). Fewer patients receiving alvimopan (alvimopan, 7.6%; placebo, 15.8%; NNT = 12) experienced POI-related morbidity. There was a lower incidence of postoperative nasogastric tube insertion, and other GI-related adverse events on postoperative days 3 to 6 in the alvimopan group than the placebo group. Opioid consumption was comparable between groups.

CONCLUSIONS

Alvimopan 12 mg was associated with reduced POI-related morbidity compared with placebo, without compromising opioid-based analgesia in patients undergoing bowel resection. Relatively low NNTs are clinically meaningful and reinforce the potential benefits of alvimopan for the patient and health care system.

Blockade of p38 mitogen-activated protein kinase pathway ameliorates delayed intestinal transit in burned rats

BACKGROUND

Burn injury has been shown to impair intestinal transit. p38 mitogen-activated protein kinase (MAPK) has been shown to be involved in the production of proinflammatory mediators such as interleukin (IL)-1beta, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). The aims of this study were to investigate the effects of SB203580, a specific p38 MAPK inhibitor, on intestinal transit and to elucidate its possible mechanism.

METHODS

Burn rats and sham rats were divided into 4 groups: saline, S-methylisothiourea (a selective iNOS inhibitor), nimesulide (a selective COX-2 inhibitor), or SB203580. Intestinal transit was measured using phenol red and assessed using the geometric center. The protein or gene expression of NOS, COX-2, and IL-1beta were measured by real-time reverse-transcription polymerase chain reaction or Western blot analysis. p38 MAPK activity or myeloperoxidase (MPO) activity was determined by using the p38 MAPK assay kit or MPO assay kit.

RESULTS

Intestinal transit was delayed significantly with burn injury, improved significantly with S-methylisothiourea and nimesulide, but almost completely normalized with SB203580. p38 MAPK activity, MPO activity, iNOS, COX-2, and IL-1beta protein or gene expression increased markedly after burn injury. SB203580 inhibited p38 MAPK and MPO activity, and reduced iNOS, COX-2, and IL-1beta protein or gene expression.

CONCLUSIONS

Burn-induced delayed intestinal transit is associated with the p38 MAPK pathway. Inhibition of the p38 MAPK pathway ameliorates delayed intestinal transit, at least in part, by inhibiting iNOS, COX-2, and IL-1beta expression. Thus, p38 MAPK could represent a novel target for therapy of gut dysmotility after burn injury.

Treatment of opioid-induced gut dysfunction

Opioid analgesics are the mainstay in the treatment of moderate-to-severe pain, yet their use is frequently associated with adverse effects, the most common and debilitating being constipation. Opioid-induced motor stasis results from blockade of gastrointestinal peristalsis and fluid secretion, and reflects the action of the endogenous opioid system in the gut. Methylnaltrexone and alvimopan are new investigational drugs that selectively target peripheral mu-opioid receptors because they are poorly absorbed in the intestine and do not enter the brain. Clinical studies have proved the concept that these drugs prevent opioid-induced bowel dysfunction without interfering with analgesia. As reviewed in this article, opioid receptor antagonists with a peripherally restricted site of action also hold therapeutic promise in postoperative ileus and chronic constipation due to the fact that they have been found to stimulate intestinal transit.

Effect of Postoperative Analgesia on Major Postoperative Complications: A Systematic Update of the Evidence

BACKGROUND

Few individual clinical trials have had sufficient subject numbers to definitively determine the effects of postoperative analgesia on major outcomes.

METHODS

We systematically searched the Medline and the Cochrane Library databases for the past decade and focused on meta-analyses and large, randomized, controlled trials.

RESULTS

Eighteen meta-analyses, 10 systematic reviews, 8 additional randomized, controlled trials, and 2 observational database articles were identified for review or comment. Epidural analgesia with local anesthetics has the greatest theoretical potential to affect major outcomes and has been the most thoroughly investigated technique. The majority of evidence favors an ability of epidural analgesia to reduce postoperative cardiovascular and pulmonary complications only after major vascular surgery or in high-risk patients. This finding may become irrelevant because of rapid conversion of major surgery to minimally invasive techniques (e.g., endoluminal abdominal aortic repair) that carry less risk of complications. There is also consistent evidence that epidural analgesia with local anesthetics is associated with faster resolution of postoperative ileus after major abdominal surgery. Again, this finding may also become irrelevant with the adoption of laparoscopic techniques and multimodal fast-track programs for abdominal surgery. There is no current evidence that perineural analgesia, continuous wound catheters using local anesthetics, IV patient-controlled analgesia with opioids, or addition of multimodal systemic analgesics have any clinically significant beneficial effect on postoperative complications.

CONCLUSIONS

Overall, there is insufficient evidence to confirm or deny the ability of postoperative analgesic techniques to affect major postoperative mortality or morbidity. This is primarily due to typically insufficient subject numbers to detect differences in currently low incidences of postoperative complications.

Electrothermal bipolar vessel sealing device vs. ultrasonic coagulating shears in laparoscopic colectomies: a comparative study

BACKGROUND

Many devices are available for vascular control during laparoscopic colorectal procedures. Ultrasonic coagulating shears (UCS), vascular staplers, titanium or plastic clips, and electrothermal bipolar vessel sealing (EBVS) are currently used according to the surgeon's preference. This study aimed to compare EBVS Ligasure with UCS.

METHODS

We report the outcome of 200 consecutive unselected patients who underwent laparoscopic colorectal resections of which 100 were performed with EBVS Ligasure (from September 2004 to December 2005, group 1) and 100 with UCS harmonic scalpel (from December 2002 to June 2004, group 2). Only the following three types of operation were performed: right colectomy (RC), left colectomy (LC), and low anterior resections (LAR). Emergency procedures have been excluded. The same attending surgical teams performed or supervised all procedures. Operating time, blood loss, complications, and postoperative hospital stay were investigated.

RESULTS

Age, gender, previous surgical abdominal procedures, and ASA risk were similar between the two groups, as well as was the percentage of malignant cases (74% vs. 71%, respectively). There were 32 vs. 37 RC, 50 vs. 47 LC, and 18 vs. 16 LAR in groups 1 and 2, respectively. There was no mortality in either group. A conversion to open surgery and two major complications occurred in group 2. There were no statistically significant differences in mean operating time (111 vs. 133, 140 vs. 176, and 153 vs. 201 min) and in the mean postoperative hospital stay (5.2 vs. 6.1, 6.5 vs. 7.1, and 6.8 vs 7.3 days) for RC, LC, and LAR between group 1 and 2, respectively. We do report interesting data about statistically significant differences in the blood loss: 115 vs. 370, 150 vs. 455, and 185 vs. 495 ml for RC (p < 0.001), LC (p < 0.001), and LAR (p = 0.002) between group 1 and group 2, respectively.

CONCLUSIONS

In our laparoscopic colorectal experience, EBVS Ligasure has proven safe and effective in vessel sealing. Patients in whom this device was used had less blood loss and slight advantages in operating time and postoperative hospital stay.

Physiology and immunology of the cholinergic antiinflammatory pathway

Cytokine production by the immune system contributes importantly to both health and disease. The nervous system, via an inflammatory reflex of the vagus nerve, can inhibit cytokine release and thereby prevent tissue injury and death. The efferent neural signaling pathway is termed the cholinergic antiinflammatory pathway. Cholinergic agonists inhibit cytokine synthesis and protect against cytokine-mediated diseases. Stimulation of the vagus nerve prevents the damaging effects of cytokine release in experimental sepsis, endotoxemia, ischemia/reperfusion injury, hemorrhagic shock, arthritis, and other inflammatory syndromes. Herein is a review of this physiological, functional anatomical mechanism for neurological regulation of cytokine-dependent disease that begins to define an immunological homunculus.

Prospective randomized, double-blind, placebo-controlled study of pre- and postoperative administration of a COX-2-specific inhibitor as opioid-sparing analgesia in major colorectal surgery

PURPOSE

To demonstrate the opioid-sparing effect and reduction in postoperative ileus obtained with valdecoxib 40 mg administered pre- and postoperatively in patients undergoing colorectal resection.

METHODS

Patients for elective colorectal resection from December 2002 to June 2004 were randomized to receive either valdecoxib or placebo with standard patient-controlled analgesia (PCA) morphine. In the study arm, the first dose of valdecoxib 40 mg was administered orally as close as possible to 1 h prior to the start of surgery. Each subsequent dose was administered at 24-h intervals up to 120 h. Patients in the control arm were served placebos at the same time-points.

RESULTS

Forty patients were enrolled in the study arm and 39 (excluding one protocol violation) in the control arm. The groups were comparable in age, sex, American Society of Anesthesiology status, body mass index, incision length, and duration and types of operations. Mean PCA doses at 12 and 24 h were 18.6 and 28.3 mg in the study arm vs 26.2 and 41.2 mg in controls, representing a one-third opioid reduction. Bowel sound and movement first appeared at medians of 12 and 72 h in the study arm vs 24 and 84 h, respectively, in controls (P < 0.05). Tolerance of solid diet was at a median of 60 h and discharge at a median of 4 days in the study arm vs 72 h and 6 days in controls (P < 0.05 and P < 0.01, respectively). Seven (18%) morbidities occurred in the control vs six (15%) in the study arm.

CONCLUSIONS

Patients treated with a cyclo-oxygenase 2-specific inhibitor have a shorter recovery time when compared with patients on a standard postoperative PCA morphine-only regimen after colorectal resection.

Fast-track surgery in laparoscopic radical prostatectomy: basic principles

Fast-track surgery describes innovative treatment concepts ensuring a faster convalescence phase. The aim of this study was to allow hospital discharge 3 days after surgery without additional complications in patients receiving LRPE for localized prostate cancer. Twenty-five patients each were randomized in the study groups to verify if a fast-track regimen could be transferred into clinical routine. The perioperative data, early complications, hospital stay as well as readmission rate were analyzed. The mean postoperative stay was 3.6 days in the fast-track group versus 6.7 days in the conventional group. The overall complications were significantly less in the fast-track procedure. The readmission rate was low and not significant. Patients receiving an LRPE benefit from a suitable fast-track concept. The postoperative hospital stay could be shortened nearly by half with a significantly decreased overall complication rate. Thus, fast-track concepts might contribute to saving resources in the long term. However, more evidence based on larger prospective trials is needed to achieve optimal quality of life for patients perioperatively.

The role of COX-2 inhibitors in the treatment of postoperative pain

Postoperative pain requires treatment not only to provide comfort to patients but also to improve postoperative outcome. Anti-inflammatory compounds are an important component of multimodal analgesia in the postoperative period. The newer cyclooxygenase (COX)-2 inhibitors are as effective as classical nonsteroidal anti-inflammatory drugs (NSAIDs) in this setting. However, COX-2 inhibitors offer a number of advantages over NSAIDs when used to treat postoperative pain. These include a reduced incidence of gastrointestinal ulceration and no inhibitory effect on platelet function and thereby a reduced risk of blood loss. Other benefits are less impairment of bone healing and no induction of bronchospasm in patients with aspirin-sensitive asthma. Increased cardiovascular thromboembolic events by COX-2 inhibitors have been reported after coronary artery bypass graft surgery only, but in general, surgery studies the incidence of such complications was comparable to placebo. Overall, COX-2 inhibitors offer a number of advantages over classical NSAIDs in the postoperative pain setting, but require the same caution with regard to renal effects.

Review of the pathophysiology and management of postoperative ileus

Investigations in the pathophysiology and treatment of postoperative ileus continue to evolve. Bowel rest is no longer a mandatory component of postoperative recovery. Tolerance of enteral nutrition and normalization of the abdominal examination are more accurate indications of the resolution of postoperative ileus than passage of flatus or first bowel movement. A multimodal "fast track" recovery approach incorporated into a clinical pathway provides a more rapid return of intestinal function and shortened hospital stay in patients undergoing major, uncomplicated gastrointestinal surgery.

The effect of anesthetic technique on early postoperative gastric emptying: comparison of propofol-remifentanil and opioid-free sevoflurane anesthesia

PURPOSE

A postoperative decrease in the gastric emptying (GE) rate may delay the early start of oral feeding and alter the bioavailability of orally administered drugs. The aim of this study was to compare the effect on early gastric emptying between two anesthetic techniques.

METHODS

Fifty patients (age, 19-69 years) undergoing day-case laparoscopic cholecystectomy were randomly assigned to received either total intravenous anesthesia with propofol/remifentanil/rocuronium (TIVA; n = 25) or inhalational opioid-free anesthesia with sevoflurane/rocuronium (mask induction; GAS; n = 25). Postoperative gastric emptying was evaluated by the acetaminophen method. After arrival in the recovery unit, acetaminophen (paracetamol) 1.5 g was given through a nasogastric tube, and blood samples were drawn during a 2-h period. The area under the serum-acetaminophen concentration curve from 0-60 min (AUC60), the maximal concentration (Cmax), and the time to reach C-max (Tmax) were calculated.

RESULTS

Twelve patients were excluded due to surgical complications (e.g., conversion to open surgery) and difficulty in drawing blood samples (TIVA, n = 7; GAS, n = 5). Gastric emptying parameters were (mean +/- SD): TIVA, AUC60, 2458 +/- 2775 min.micromol.l(-1); Cmax, 71 +/- 61 micromol.l(-1); and Tmax, 81 +/- 37 min; and GAS, AUC60, 2059 +/- 2633 min.micromol.l(-1); Cmax, 53 +/- 53 micromol.l(-1); and Tmax, 83 +/- 41 min. There were no significant differences between groups.

CONCLUSION

There was no major difference in early postoperative gastric emptying between inhalation anesthesia with sevoflurane versus total intravenous anesthesia with propofol-remifentanil. Both groups showed a pattern of delayed gastric emptying, and the variability in gastric emptying was high. Perioperative factors other than anesthetic technique may have more influence on gastric emptying.

Intestinal edema decreases intestinal contractile activity via decreased myosin light chain phosphorylation

OBJECTIVE

The purpose of this study was to investigate the effects of interstitial edema on intestinal contractile activity.

DESIGN

Randomized animal study.

SETTING

University laboratory.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTION

Intestinal edema was induced in rats by a combination of fluid infusion and mesenteric venous hypertension. Rats were divided into four groups: CONTROL, sham; RESUS, saline infusion only; RESUS+VH, saline infusion and venous hypertension; and VH, venous hypertension only. Edema development, basal contractile activity, maximum agonist-induced contractile response (measured as total force generation during the first 2 mins after carbachol treatment), and myosin light chain phosphorylation were measured in the distal small intestine.

MEASUREMENTS AND MAIN RESULTS

The amount of interstitial fluid, indicated by the wet-to-dry ratio, increased significantly in both the RESUS and RESUS+VH groups as early as 30 mins after surgery compared with the CONTROL group. Whereas the tissue fluid remained significantly elevated in the RESUS+VH group up to 6 hrs after surgery, the RESUS group wet-to-dry ratios returned to CONTROL group levels by 2 hrs after surgery. Basal contractile activity was significantly less in the RESUS+VH group compared with either the RESUS group or the CONTROL group 6 hrs after surgery. Maximum contractile response decreased significantly in the RESUS+VH group compared with the RESUS group. Basal contractile activity and maximum contractile response did not change significantly in the VH group compared with the CONTROL group. The phosphorylated fraction of myosin light chain was significantly lower in the RESUS+VH group compared with the CONTROL group at 0.5, 2, and 6 hrs after surgery.

CONCLUSION

We conclude that edema decreases myosin light chain phosphorylation, leading to decreased intestinal contractile activity.

Induction of heme oxygenase-1 improves impaired intestinal transit after burn injury

BACKGROUND

Burn injury has been shown to impair intestinal transit. The induction of heme oxygenase (HO)-1, the rate-limiting enzyme in heme degradation, has been demonstrated to provide protection against various injuries. The aim of this study was to investigate whether the induction of HO-1 by hemin would improve impaired intestinal transit after burn injury.

METHODS

Burn/sham rats were divided into 3 groups: saline solution, hemin (HO-1 inducer), and hemin plus tin protoporphyrin IX. Intestinal transit was measured with the use of phenol red and assessed with the geometric center. The gene and/or protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, interleukin (IL)-1beta, HO-1, and p38 mitogen-activated protein kinase (p38 MAPK) was measured by real-time polymerase chain reaction and/or by Western blot analysis.

RESULTS

Intestinal transit was delayed with burn injury and improved significantly with the induction of HO-1; burn injury significantly activated p38 MAPK and myeloperoxidase and increased gene and/or protein expression of iNOS, COX-2, IL-1beta, and HO-1. The administration of hemin led to a significant decrease in the activation of p38 MAPK and myeloperoxidase and the gene and/or protein expression of iNOS, COX-2, and IL-1beta.

CONCLUSION

The induction of HO-1 improves burn-induced delayed intestinal transit. The beneficial effect of hemin treatment could be linked, at least in part, to the down-regulation of iNOS, COX-2, and IL-1beta expression, which suggests that the induction of HO-1 may provide an effective therapeutic measure for gut dysmotility after burn injury.

["Fast-track surgery": Perioperative management]

The multimodal therapeutic concept of fast-track surgery is directed against the pathophysiologic functional changes following elective surgery. This concept has been proven to reduce postoperative morbidity and convalescence. This benefit is based on an interdisciplinary approach by surgeons, anaesthesiologists, nurses, and physiotherapy staff to optimise perioperative care in order to decrease surgically-induced stress. Fast-track surgery after elective colorectal surgery has been shown to reduce the rate of postoperative complications and shorten hospital stay significantly. A prerequisite for successfully implementing this concept is the willingness of the participating surgeons to abandon conventional traditions. In addition to abdominal procedures, the basic concept of fast-track surgery has been successfully instituted in other surgical fields, such as urology.

Methylnaltrexone, a novel peripheral opioid receptor antagonist for the treatment of opioid side effects

Methylnaltrexone is an investigational peripheral opioid receptor antagonist, a quaternary derivative of naltrexone. Methylnaltrexone has greater polarity and lower lipid solubility, thus it does not cross the blood-brain barrier in humans. Methylnaltrexone offers the therapeutic potential to block or reverse the undesired side effects of opioids that are mediated by receptors located in the periphery (e.g., in the gastrointestinal tract), without affecting analgesia or precipitating the opioid withdrawal symptoms that are predominantly mediated by receptors in the CNS. This article reviews preclinical studies and clinical opioid bowel dysfunction trial data, and briefly discusses other potential roles of this compound in clinical practice.

Products of cyclooxygenase-2 depress duodenal function in rats subjected to abdominal surgery

AIM

Abdominal surgery evokes powerful biological responses that affect gastrointestinal functions. Here we investigate the role of the cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) isoforms in post-operative duodenal ileus.

METHODS

Proximal duodenum of anesthetized rats was perfused in situ with isotonic or hypotonic (50 mM) NaCl. Mucosal bicarbonate secretion, motility, mucosal permeability and effluent osmolality were determined in the absence and presence of different COX inhibitors.

RESULTS

The majority of control animals had no or few duodenal contractions and bicarbonate secretion averaged 10.9 +/- 1.4 micromol cm(-1) h(-1). These 'paralytic' controls responded to hypotonic NaCl with a small increase in mucosal permeability. In control animals exhibiting spontaneous duodenal contractions, the bicarbonate secretion was 50% higher and the hypotonicity-induced net increase in mucosal permeability sevenfold higher than in 'paralytic' controls. Treatment with the selective COX-2 inhibitors rofecoxib or parecoxib induced duodenal motility, increased bicarbonate secretion and potentiated the hypotonicity-induced increase in mucosal permeability. COX-2-inhibited animals had a twofold greater capacity to adjust luminal osmolality than 'paralytic' controls. The selective COX-1 inhibitor SC-560 only transiently stimulated motility and bicarbonate secretion and the hypotonicity-induced increase in mucosal permeability was smaller than in COX-2-inhibited animals.

CONCLUSIONS

Abdominal surgery increases the synthesis of prostanoids, particularly via the COX-2 isoform. This compromises the ability of the duodenum to contract and to secrete HCO and to adjust luminal osmolality possibly via altered mucosal permeability. It is proposed that studies of gastrointestinal functions in animals subjected to abdominal surgery should include animals pre-treated with a COX-2 inhibitor.

Gut motor function: immunological control in enteric infection and inflammation

Alteration in gastrointestinal (GI) motility occurs in a variety of clinical settings which include acute enteritis, inflammatory bowel disease, intestinal pseudo-obstruction and irritable bowel syndrome (IBS). Most disorders affecting the GI tract arise as a result of noxious stimulation from the lumen via either microbes or chemicals. However, it is not clear how injurious processes initiated in the mucosa alter function in the deeper motor apparatus of the gut wall. Activation of immune cells may lead to changes in motor-sensory function in the gut resulting in the development of an efficient defence force which assists in the eviction of the noxious agent from the intestinal lumen. This review addresses the interface between immune and motor system in the context of host resistance based on the studies in murine model of enteric nematode parasite infection. These studies clearly demonstrate that the infection-induced T helper 2 type immune response is critical in producing the alterations of infection-induced intestinal muscle function in this infection and that this immune-mediated alteration in muscle function is associated with host defence mechanisms. In addition, by manipulating the host immune response, it is possible to modulate the accompanying muscle function, and this may have clinical relevance. These observations not only provide valuable information on the immunological control of gut motor function and its role in host defence in enteric infection, but also provide a basis for understanding pathophysiology of gastrointestinal motility disorders such as in IBS.

Peripheral opioids for functional GI disease: a reappraisal

Opioids have been used medicinally and recreationally for thousands of years. The clinical use of opioids for gastrointestinal conditions has been limited by central nervous system side effects. A new generation of peripheral opioid receptor ligands free of central nervous system side effects is being developed. Clinical trials with the peripherally acting mu opioid receptor antagonists' alvimopan and N-methylnaltrexone show promise for improving postoperative ileus- and opioid-induced constipation. Likewise, preliminary studies with the peripherally acting kappa opioid agonist fedotozine showed promise in the treatment of irritable bowel syndrome (IBS) and functional dyspepsia. Further studies are on hold presumably due to lack of efficacy in subsequent studies. However, clinical studies are underway for newer kappa opioid agonists such as asimadoline and ADL 10-0101.

Alvimopan for the Management of Postoperative Ileus

OBJECTIVE:

To review the pharmacology, pharmacokinetics, clinical efficacy, safety, dosage, and administration of alvimopan, a peripherally acting μ-opioid receptor antagonist, in the management of postoperative ileus (POI).

DATA SOURCES:

A literature search (1980–October 2004%) applying the terms alvimopan, ADL 8–2698, and LY246736 was conducted using MEDLINE. Information was also obtained from scientific congress abstracts and data on file with the manufacturer.

STUDY SELECTION AND DATA EXTRACTION:

Studies and abstracts investigating alvimopan and POI were considered for inclusion; however, they were restricted to English-language articles.

DATA SYNTHESIS:

Alvimopan is a novel, peripherally acting μ-opioid receptor antagonist that is currently under evaluation for the management of POI. POI presents significant clinical challenges that can delay patient recovery and contribute to increased morbidity and prolonged hospitalization after surgery. Clinical trials have demonstrated that alvimopan, at oral doses of 6 and 12 mg, can accelerate time to recovery of gastrointestinal (GI) function and time to hospital discharge following abdominal surgery. The incidence of adverse events with alvimopan therapy was shown to be similar to that of placebo.

CONCLUSIONS:

Alvimopan is well tolerated and effective at accelerating GI recovery and time to discharge in patients who have undergone bowel resection or hysterectomy when administered prior to surgery and twice daily thereafter until discharge or for up to 7 days. Alvimopan potentially offers significant benefits for patients with POI over currently available treatments.

Preventing prolonged post-operative ileus in gastric cancer patients undergoing gastrectomy and intra-peritoneal chemotherapy

AIM: To assess the efficacy of metoclopramide (Met) for prevention of prolonged post-operative ileus in advanced gastric cancer patients undergoing D2 gastrectomy and intra-peritoneal chemotherapy (IPC).

METHODS: Thirty-two advanced gastric cancer patients undergoing D2 gastrectomy and IPC were allocated to two groups. Sixteen patients received Met immediately after operation (group A), and 16 did not (group B). Another 16 patients who underwent D2 gastrectomy without IPC were enrolled as the control group (group C). All patients had received epidural pain control. The primary endpoints were time to first post-operative flatus and time until oral feeding with a soft diet without discomfort. Secondary endpoints were early complications during hospitalization.

RESULTS: Gender, the type of resection, operating time, blood loss, tumor status and amount of narcotics were comparable in the three groups. However, the group C patients were older than those in groups A and B (67.5±17.7 vs 56.8±13.2, 57.5±11.7 years, P = 0.048). First bowel flatus occurred after 4.35±0.93 d in group A, 4.94±1.37 d in group B, and 4.71±1.22 d in group C (P>0.05). Oral feeding of a soft diet was tolerated 7.21±1.92 d after operation in group A, 10.15±2.17 d in group B, and 7.53±1.35 d in group C (groups A and C vs group B, P<0.05). There was no significant difference in respect to the first flatus among the three groups. However, the time of tolerating oral intake with soft food in groups A and C patients was significantly shorter than that in group B patients. Levels of C-reactive protein (CRP) were significantly lower in group C and there was a more prominent and prolonged response in CRP level in patients undergoing IPC. The incidence of post-operative complications was similar in the three groups except for prolonged post-operative ileus. There was no increased risk of anastomotic leakage in patients receiving Met.

CONCLUSION: The results suggest that a combination of intravenous Met and epidural pain control may be required to achieve a considerable decrease in time to resumption of oral soft diet in advanced gastric cancer patients who underwent gastrectomy and IPC. Furthermore, the administration of Met did not increase anastomotic leakage. Met has a role in the prevention of prolonged post-operative ileus.

Stimulation of the vagus nerve attenuates macrophage activation by activating the Jak2-STAT3 signaling pathway

Acetylcholine released by efferent vagus nerves inhibits macrophage activation. Here we show that the anti-inflammatory action of nicotinic receptor activation in peritoneal macrophages was associated with activation of the transcription factor STAT3. STAT3 was phosphorylated by the tyrosine kinase Jak2 that was recruited to the alpha7 subunit of the nicotinic acetylcholine receptor. The anti-inflammatory effect of nicotine required the ability of phosphorylated STAT3 to bind and transactivate its DNA response elements. In a mouse model of intestinal manipulation, stimulation of the vagus nerve ameliorated surgery-induced inflammation and postoperative ileus by activating STAT3 in intestinal macrophages. We conclude that the vagal anti-inflammatory pathway acts by alpha7 subunit-mediated Jak2-STAT3 activation.

Alvimopan, a selective peripherally acting mu-opioid antagonist

Alvimopan is a novel, peripherally acting mu-opioid antagonist that is being developed for the management of acute postoperative ileus and for the reversal of the delayed gastrointestinal and colonic transit that result in symptoms such as constipation, nausea and motility disorders in patients treated with opiate analgesics. There is a clinical need for effective medications for the treatment of postoperative ileus and opiate-induced constipation and other motility disorders. This review addresses the basic and applied pharmacology and current evidence for the use of the medication, alvimopan, in clinical gastroenterology.