Prokinetic agents for the treatment of postoperative ileus in adults: a review of the literature

Sterilization of free-ranging female capybaras (Hydrochoerus hydrochaeris): a comparison between two surgical techniques

This study evaluated two surgical sterilization techniques in free-ranging female capybaras (n = 21). The first group underwent uterine horn ligature (HL; n = 11), while the second was subjected to partial salpingectomy (S; n = 10). We assessed total operative time, incision length, the ease of identifying reproductive structures, the adequacy of exposure for surgical performance through flank or midline approaches, and the extent of abdominal viscera manipulation for each method. The HL method emerged as faster, with an average operative time difference of 16 minutes. In the S group, a flank mini-laparotomy over the ovarian topography facilitated easy exposure of the ipsilateral ovary and uterine tube, enabling ligature and partial resection of the uterine tube but not the uterine horn exposure. However, accessing the contralateral uterine tube without a bilateral incision was impractical, thus prolonging the total operative time due to the need for patient repositioning and new antisepsis procedures. Conversely, a post-umbilical approach for the HL method necessitated only one mini-laparotomy incision, offering ample uterine exposure for hysterotomy in pregnant females. Both methods involved minimal abdominal viscera manipulation and resulted in no fatalities or postoperative complications. Although direct comparison is limited by the distinct sterilization techniques and surgical approaches, this study underscores the challenges and surgical access of each method. Our findings endorse the HL technique as an effective contraception method for female capybaras to prevent the birth of seronegative offspring that could amplify Rickettsia sp., the causative agent of Brazilian spotted fever.

Does Chewing Gum Lead to Earlier Postoperative Gastrointestinal Recovery in Children? A Systematic Review and Meta-analysis

INTRODUCTION

Postoperative ileus is a common occurrence among children undergoing major operations, including gastrointestinal and spinal surgeries. Preliminary evidence in adults suggests that chewing gum plays a role in accelerating the return of postoperative gastrointestinal function. However, evidence is scarce in the paediatric population. The aim of this study was to investigate whether chewing gum has benefits for children.

METHODS

We searched PubMed, Medline, Embase, and Cochrane Trials databases for randomised controlled trials that compare gum chewing with standard care after elective surgery in children from 1st Jan 2005 to 31st July 2021. We assessed the identified trials for quality and performed a systematic review and meta-analysis in accordance with PRISMA and registered in PROSPERO (CRD42022358801). The main outcome measures examined were time to flatus and stool postoperatively, time to tolerate oral intake, and length of hospital stay, which were analysed using fixed effects models. We also examined clinical complication rates and postoperative pain control.

RESULTS

We included six eligible trials, with a total of 357 enrolled patients. The intervention was well tolerated without complications. There was no significant difference in time to flatus (-2.86 h; 95 % CI: -6.2 to 0.47 h, p = 0.09), time to stool (-6.39 h; 95 % CI: -13.9 to 1.2 h, p = 0.1), time to tolerate oral intake (-0.03 days; 95 % CI: -0.15 to 0.1 days, p = 0.68), and length of hospital stay (0.08 days; 95 % CI: -0.07 to 0.22 days, p = 0.29). Postoperative pain control (opioid consumption, pain score, nausea score) was similar in both groups (p > 0.05).

CONCLUSION

Current evidence demonstrates that gum chewing is not associated with earlier postoperative gastrointestinal recovery in children. Future adequately powered and well-designed trials are necessary to evaluate any clinical benefit of chewing gum for children and whether it could result differences in healthcare satisfaction.

LEVEL OF EVIDENCE

I.

The influence of diabetes on postoperative complications following colorectal surgery

Background

Diabetes mellitus has been commonly associated with poor surgical outcomes. The aim of this meta-analysis was to assess the impact of diabetes on postoperative complications following colorectal surgery.

Methods

Medline, Embase and China National Knowledge Infrastructure electronic databases were reviewed from inception until May 9th 2020. Meta-analysis of proportions and comparative meta-analysis were conducted. Studies that involved patients with diabetes mellitus having colorectal surgery, with the inclusion of patients without a history of diabetes as a control, were selected. The outcomes measured were postoperative complications.

Results

Fifty-five studies with a total of 666,886 patients comprising 93,173 patients with diabetes and 573,713 patients without diabetes were included. Anastomotic leak (OR 2.407; 95% CI 1.837–3.155; p < 0.001), surgical site infections (OR 1.979; 95% CI 1.636–2.394; p < 0.001), urinary complications (OR 1.687; 95% CI 1.210–2.353; p = 0.002), and hospital readmissions (OR 1.406; 95% CI 1.349–1.466; p < 0.001) were found to be significantly higher amongst patients with diabetes following colorectal surgery. The incidence of septicemia, intra-abdominal infections, mechanical failure of wound healing comprising wound dehiscence and disruption, pulmonary complications, reoperation, and 30-day mortality were not significantly increased.

Conclusions

This meta-analysis and systematic review found a higher incidence of postoperative complications including anastomotic leaks and a higher re-admission rate. Risk profiling for diabetes prior to surgery and perioperative optimization for patients with diabetes is critical to improve surgical outcomes.

Electronic supplementary material

The online version of this article (10.1007/s10151-020-02373-9) contains supplementary material, which is available to authorized users.

Pretreatment with transcutaneous electrical acupoint stimulation to prevent postoperative ileus in patients undergoing laparoscopic colon surgery: study protocol for a randomised controlled trial

INTRODUCTION

Postoperative ileus (POI), a common complication after surgery, severely affects postoperative recovery. It is unclear whether pretreatment with transcutaneous electrical acupoint stimulation (TEAS) can improve recovery from POI. This trial will evaluate the effects of pretreatment with TEAS on POI.

METHODS AND ANALYSIS

This will be a prospective, randomised controlled trial. American Society of Anesthesiologists (ASA) physical status classification I-III level patients, aged 18-75 years and scheduled for laparoscopic colon surgery, will be included in the study. It is planned that 146 subjects will be randomised to the TEAS and sham TEAS (STEAS) groups. The groups will undergo two sessions of TEAS/STEAS daily for 3 days before surgery, with a final TEAS/STEAS treatment 30 min before anaesthesia. The primary endpoint of the study will be time to first defaecation. Secondary endpoints will include time to first flatus, time to tolerance of oral diet, GI-2 (composite outcome of time to first defaecation and time to tolerance of oral diet), time to independent walking, length of hospital stay, postoperative pain Visual Analogue Scale score on the first 3 days after surgery, analgesic requirements, complications and plasma concentrations of interferon-β (IFN-β), IFN-γ, interleukin-6 (IL-6) and IL-1β. Multiple linear regression will be used to identify independent predictors of outcome measures.

ETHICS AND DISSEMINATION

This study has been approved by the Chinese Registered Clinical Trial Ethics Review Committee (No. ChiECRCT-20170084). The results of the trial will be published in an international peer-reviewed journal.

TRIAL REGISTRATION NUMBER

This study has been registered with the Chinese Clinical Trial Registry (No. ChiCTR-INR-17013184).

TRIAL STATUS

The study was in the recruitment phase at the time of manuscript submission.

Effect of Acupuncture on Postoperative Ileus after Distal Gastrectomy for Gastric Cancer

Purpose

Acupuncture has recently been accepted as a treatment option for managing postoperative ileus (POI) and various functional gastrointestinal disorders. Therefore, we conducted a prospective randomized study to evaluate the effect of acupuncture on POI and other surgical outcomes in patients who underwent gastric surgery.

Materials and Methods

Thirty-six patients who underwent distal gastrectomy for gastric cancer from March to December 2015 were randomly assigned to acupuncture or non-acupuncture (NA) groups at 1:1 ratio. The acupuncture treatment was administered treatment once daily for 5 consecutive days starting at postoperative day 1. The primary outcome measure was the number of remnant sitz markers in the small intestine on abdominal radiograph. The secondary outcome measure was the surgical outcome, including the times to first flatus, first defecation, start of water intake, and start of soft diet, as well as length of hospital stay and laboratory findings.

Results

The acupuncture group had significantly fewer remnant sitz markers in the small intestine on postoperative days 3 and 5 compared to those in the NA group. A significant difference was observed in the numbers of remnant sitz markers in the small intestine with respect to group differences by time (P<0.0001). The acupuncture group showed relatively better surgical outcomes than those in the NA group, but the differences were not statistically significant.

Conclusions

In this clinical trial, acupuncture promoted the passage of sitz markers, which may reflect the possibility of reducing POI after distal gastrectomy.

Effect of Acupuncture on Reducing Duration of Postoperative Ileus After Gastrectomy in Patients with Gastric Cancer: A Pilot Study Using Sitz Marker

OBJECTIVES

Postoperative ileus (POI) is a common problem after abdominal surgery. Acupuncture is being accepted as an option for reducing POI and managing various functional gastrointestinal disorders. Therefore, this pilot study was conducted to evaluate the effect of acupuncture on reducing duration of POI and other surgical outcomes in patients who underwent gastric surgery.

DESIGN

A prospective, randomized, controlled pilot study was conducted on patients who underwent gastric cancer surgery from January 2013 to December 2013. Ten patients were randomly assigned into the acupuncture (A) or nonacupuncture (NA) groups at a 1:1 ratio.

INTERVENTIONS

The acupuncture treatment was performed by Korean traditional medicine doctors (KMDs). The style of acupuncture was Korean. In the A group, acupuncture treatment was given once daily for 5 consecutive days starting on postoperative day 1. Each patient received acupuncture at 16 acupoints based on expert consensus provided by qualified and experienced KMDs. No acupuncture treatment was performed in the NA group.

OUTCOME MEASURES

The primary outcome measure was the number of remnant Sitz markers in the small intestine on abdominal radiography. Secondary outcome measures were time to first flatus, start of sips water, start of soft diet, hospital stay, and laboratory findings.

RESULTS

The A group had significantly fewer remnant Sitz markers in the small intestine on postoperative days 3 and 5 compared with those in the NA group (p = 0.025 and 0.005). A significant difference was observed in the numbers of remnant Sitz marker in the small intestine with respect to time difference by group (p = 0.019). The A group showed relatively better surgical outcomes, but without statistical significance.

CONCLUSIONS

Although further studies are warranted, acupuncture may reduce duration of POI after gastric surgery and could be a potential factor in enhanced recovery after surgery protocols.

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.

Gastrointestinal motility problems in critical care: a clinical perspective

Advances in surgery, anesthesia and intensive care have led to a dramatic increase in the number of patients who spend time in our intensive care units (ICU). Gastrointestinal (GI) motility disorders are common complications in the intensive care setting and are predictors of increased mortality and length of the stay in the ICU. Several risk factors for developing GI motility problems in the ICU setting have been identified and include sepsis, being on mechanical ventilation and the use of vasopressors, opioids or anticholinergic medications. Our focus is on the most common clinical manifestations of GI motor dysfunction in the ICU patient: gastroesophageal reflux, gastroparesis, ileus and acute pseudo-obstruction of the colon.

Identification of clinical outcome measures for recovery of gastrointestinal motility in postoperative ileus

OBJECTIVE

To identify clinical hallmarks associated with recovery of gastrointestinal transit.

BACKGROUND

Impaired gastrointestinal transit or postoperative ileus largely determines clinical recovery after abdominal surgery. However, validated clinical hallmarks of gastrointestinal recovery to evaluate new treatments and readiness for discharge from the hospital are lacking.

METHODS

Gastric emptying and colonic transit were scintigraphically assessed from postoperative day 1 to 3 in 84 patients requiring elective colonic surgery and were compared with clinical parameters. The clinical hallmark that best reflected recovery of gastrointestinal transit was validated using data from a multicenter trial of 320 segmental colectomy patients.

RESULTS

Seven of 84 patients developed a major complication with paralytic ileus characterized by total inhibition of gastrointestinal motility and were excluded from further analysis. In the remaining patients, recovery of colonic transit (defined as geometric center of radioactivity ≥2 on day 3), but not gastric emptying, was significantly correlated with clinical recovery (ρ = -0.59, P < 0.001). Conversely, the combined outcome measure of tolerance of solid food and having had defecation (SF + D) (area under the curve = 0.9, SE = 0.04, 95% CI = 0.79-0.95, P < 0.001), but not time to first flatus, best indicated recovery of gastrointestinal transit with a positive predictive value of 93% (95% CI = 78-99). Also in the main clinical trial, multiple regression analysis revealed that SF + D best predicted the duration of hospital stay.

CONCLUSIONS

Our data indicate that the time to SF + D best reflects recovery of gastrointestinal transit and therefore should be considered as primary outcome measure in future clinical trials on postoperative ileus.(Netherlands National Trial Register, number NTR1884 and NTR222).

Improvements in safety and recovery following cystectomy: reassessing the role of pre-operative bowel preparation and interventions to speed return of post-operative bowel function

For radical cystectomy, historical practice trends have favored the use of preoperative bowel preparations to reduce complications, including surgical site infections, ileus, and anastomotic leaks. However, emerging data has questioned this practice. Postoperative cystectomy care also remains in flux, as new pharmacologic agents that may potentiate earlier return of bowel function are studied. We review the current literature with regards to preoperative and postoperative cystectomy bowel management.

Safety and efficacy of ulimorelin administered postoperatively to accelerate recovery of gastrointestinal motility following partial bowel resection: results of two randomized, placebo-controlled phase 3 trials

BACKGROUND

Gastrointestinal recovery is a critical milestone after bowel resection with postoperative ileus resulting in increased risk of complications and prolonged hospitalization.

OBJECTIVE

The aim of this study is to evaluate the efficacy and safety of ulimorelin, a ghrelin receptor agonist given postoperatively in 2 identically designed phase 3 studies (ClinicalTrials.gov NCT01285570 and NCT01296620).

DESIGN

This investigation is designed as a multicenter, double-blind, randomized, parallel-group study.

SETTINGS

This study involves hospital inpatients.

PATIENTS

Adult patients undergoing partial bowel resection were included.

INTERVENTION

Thirty-minute intravenous infusions (160 µg/kg, 480 µg/kg ulimorelin, or placebo) once daily were started within 60 minutes after the end of surgery and ended at the first of the following: primary efficacy end point fulfilled (defined below), hospital discharge, or 7 days treatment.

MAIN OUTCOME MEASURES

The primary efficacy end point was the time from the end of surgery to the composite end point of the later of first bowel movement and tolerance of solid food. Safety was assessed with the use of standard assessments including adverse events and laboratory tests.

RESULTS

Ulimorelin Study of Efficacy and Safety 007, n = 332 patients; Ulimorelin Study of Efficacy and Safety 008, n = 330 patients: in both studies, the primary efficacy end point and the secondary efficacy outcomes, which included postsurgical time to first bowel movement, tolerance of solid food, and discharge eligibility, did not differ significantly among patients treated with either dose of ulimorelin versus placebo. Rates of serious adverse events were comparable across all treatment groups. There was no statistically significant difference from placebo in regard to events of interest, namely nausea, vomiting, ileus as an adverse event, nasogastric tube reinsertion, anastomotic complications, and infections.

LIMITATIONS

A possible limitation is the variance inherent in surgery and comorbidities.

CONCLUSIONS

Although the efficacy of ulimorelin in reducing the duration of postoperative ileus was not demonstrated in these studies, intravenous ulimorelin at doses of 160 µg/kg and 480 µg/kg was generally well tolerated in postcolectomy patients. Similar to other promotility agents, ulimorelin may find an application in other indications better suited to its attributes.

Electroacupuncture reduces duration of postoperative ileus after laparoscopic surgery for colorectal cancer

BACKGROUND & AIMS

We investigated the efficacy of electroacupuncture in reducing the duration of postoperative ileus and hospital stay after laparoscopic surgery for colorectal cancer.

METHODS

We performed a prospective study of 165 patients undergoing elective laparoscopic surgery for colonic and upper rectal cancer, enrolled from October 2008 to October 2010. Patients were assigned randomly to groups that received electroacupuncture (n = 55) or sham acupuncture (n = 55), once daily from postoperative days 1-4, or no acupuncture (n = 55). The acupoints Zusanli, Sanyinjiao, Hegu, and Zhigou were used. The primary outcome was time to defecation. Secondary outcomes included postoperative analgesic requirement, time to ambulation, and length of hospital stay.

RESULTS

Patients who received electroacupuncture had a shorter time to defecation than patients who received no acupuncture (85.9 ± 36.1 vs 122.1 ± 53.5 h; P < .001) and length of hospital stay (6.5 ± 2.2 vs 8.5 ± 4.8 days; P = .007). Patients who received electroacupuncture also had a shorter time to defecation than patients who received sham acupuncture (85.9 ± 36.1 vs 107.5 ± 46.2 h; P = .007). Electroacupuncture was more effective than no or sham acupuncture in reducing postoperative analgesic requirement and time to ambulation. In multiple linear regression analysis, an absence of complications and electroacupuncture were associated with a shorter duration of postoperative ileus and hospital stay after the surgery.

CONCLUSIONS

In a clinical trial, electroacupuncture reduced the duration of postoperative ileus, time to ambulation, and postoperative analgesic requirement, compared with no or sham acupuncture, after laparoscopic surgery for colorectal cancer. ClinicalTrials.gov number, NCT00464425.

Pathogenesis and clinical and economic consequences of postoperative ileus

Postoperative ileus is a preventable disease with surprising economic consequences. Understanding the triad of dysmotility in conjunction with an enhanced recovery program improves patient outcome, decreases length of stay in hospital, and lowers the cost. Alvimopan and other investigational promotility medications can help attain these goals. Surgeons should avoid labeling all postoperative abdominal distention as ileus, which not only prevents timely diagnosis and treatment of early postoperative small bowel obstruction or acute colonic pseudo-obstruction but also increases patient morbidity and mortality.

Postoperative ileus: strategies for reduction

Postoperative Ileus (POI) is a frequent, frustrating occurrence for patients and surgeons after abdominal surgery. Despite significant research investigating how to reduce this multi-factorial phenomenon, a single strategy has not been shown to reduce POI's significant effects on length of stay (LOS) and hospital costs. Perhaps the most significant cause of POI is the use of narcotics for analgesia. Strategies that target inflammation and pain reduction such as NSAID use, epidural analgesia, and laparoscopic techniques will reduce POI but are accompanied by a simultaneous reduction in opioid use. Pharmacologic means of stimulating gut motility have not shown a positive effect, and the routine use of nasogastric tubes only increases morbidity. Recent multi-site phase III trials with alvimopan, a peripherally acting mu-antagonist, have shown significant reductions in POI and LOS by 12 and 16 hours, respectively, by blunting the effects of narcotics on gut motility while sparing centrally mediated analgesia. Use of alvimopan, along with a multi-modal postoperative treatment plan involving early ambulation, feeding, and avoiding nasogastric tubes, will likely be the crux of POI treatment and prevention.

Safety and efficacy of methylnaltrexone in shortening the duration of postoperative ileus following segmental colectomy: results of two randomized, placebo-controlled phase 3 trials

PURPOSE

Postoperative ileus contributes to surgical morbidity and is associated with prolonged hospitalization and increased health care costs. The efficacy and safety of the peripherally acting μ-opioid receptor antagonist methylnaltrexone in shortening the duration of postoperative ileus following segmental colectomy was evaluated.

METHODS

Two identically designed, multicenter, double-blind, parallel-group, placebo-controlled studies randomly assigned patients undergoing segmental colectomy (study 1, N = 515; study 2, N = 533) to receive 12 or 24 mg of methylnaltrexone intravenously or placebo every 6 hours starting within 90 minutes of surgery completion, continuing for up to 10 days or up to 24 hours after gastrointestinal recovery. The primary efficacy end point was the time from the end of surgery to the first bowel movement. Safety was evaluated via standard assessments (ie, adverse events and related withdrawals, physical examinations, laboratory tests, vital signs, electrocardiograms) and assessment of surgical complications.

RESULTS

The primary and secondary efficacy outcomes (time to discharge eligibility, time to hospital discharge, and clinically meaningful events of nausea and vomiting following segmental colectomy) did not differ significantly between patients treated with either a dose of methylnaltrexone or with placebo. Rates of adverse events and serious adverse events were comparable across all treatment groups in both studies. The most commonly observed adverse events were nausea, pyrexia, and vomiting.

CONCLUSIONS

Although the efficacy of methylnaltrexone in reducing the duration of postoperative ileus was not demonstrated in these studies, intravenous methylnaltrexone at doses of 12 mg and 24 mg was safe, in general, and well tolerated in postcolectomy patients. The utility of intravenous methylnaltrexone in treating postoperative ileus remains unproven.

Anesthetic Routines: The Anesthesiologist's Role in GI Recovery and Postoperative Ileus

All patients undergoing bowel resection experience postoperative ileus, a transient cessation of bowel motility that prevents effective transit of intestinal contents or tolerance of oral intake, to varying degrees. An anesthesiologist plays a critical role, not only in the initiation of surgical anesthesia, but also with the selection and transition to effective postoperative analgesia regimens. Attempts to reduce the duration of postoperative ileus have prompted the study of various preoperative, perioperative, and postoperative regimens to facilitate gastrointestinal recovery. These include modifiable variables such as epidural anesthesia and analgesia, opioid-sparing anesthesia and analgesia, fluid restriction, colloid versus crystalloid combinations, prokinetic drugs, and use of the new peripherally acting mu-opioid receptor (PAM-OR) antagonists. Review and appropriate adaptation of these multiple modifiable interventions by anesthesiologists and their surgical colleagues will facilitate implementation of a best-practice management routine for bowel resection procedures that will benefit the patient and the healthcare system.

Pathogenesis and clinical and economic consequences of postoperative ileus

Postoperative ileus (POI) occurs frequently in patients undergoing major abdominal surgery; and only recently has there been renewed interest in understanding the pathogenesis, etiology, clinical manifestations, and clinical and economic consequences related to POI. This interest has been spurred by the potential access to novel pharmaceutical options for the management of POI. POI has a complex and multimodal pathophysiology including neurogenic, inflammatory, hormonal, and pharmacologic components. The clinical manifestations are clinically obvious and include abdominal distention, pain, nausea, vomiting, and inability to pass stools or tolerate a solid diet. Prolonged ileus has been defined as persistence of these symptoms for more than 4 days after major abdominal surgery; however the goal should be to reduce the incidence of these symptoms immediately after surgery. Clearly, the magnitude of the surgical stress and usage of opioid analgesia are the predominant causes of POI. The unappreciated sequelae of POI include increased rates in adverse surgical wound healing, reduced ambulation, atelectasis, pneumonia, urinary infections, and deep vein thrombosis. The secondary impact of these complications includes increased hospital length of stay, resource use, and healthcare costs. POI is common and the impact is underestimated. The addition of alvimopan as the first in class μ-opioid inhibitor has demonstrated consistent benefit in reducing the incidence and impact of POI with reductions in length of hospital stay. POI is a common, and underappreciated complication of major abdominal surgery, and clinicians should be aware of the clinical care options, including novel pharmaceutical agents, that can successfully reduce the incidence of this postoperative complication.

Postoperative ileus: Impact of pharmacological treatment, laparoscopic surgery and enhanced recovery pathways

Almost all patients develop postoperative ileus (POI) after abdominal surgery. POI represents the single largest factor influencing length of stay (LOS) after bowel resection, and has great implications for patients and resource utilization in health care. New methods to treat and decrease the length of POI are therefore of great importance. During the past decade, a substantial amount of research has been performed evaluating POI, and great progress has been made in our understanding and treatment of POI. Laparoscopic procedures, enhanced recovery pathways and pharmacologic treatment have been introduced. Each factor has substantially contributed to decreasing the length of POI and thus LOS after bowel resection. This editorial outlines resource utilization of POI, normal physiology of gut motility and pathogenesis of POI. Pharmacological treatment, fast track protocols and laparoscopic surgery can each have significant impact on pathways causing POI. The optimal integration of these treatment options continues to be assessed in prospective studies.

The role of mast cell stabilization in treatment of postoperative ileus: a pilot study

OBJECTIVES

Although postoperative ileus (POI) is considered multifactorial, intestinal inflammation resulting from manipulation-induced mast cell activation is recognized as an important pathophysiological mechanism. Therefore, mast cell stabilization may represent a new therapeutic approach to shortening POI. The aim of this paper was to study the effect of ketotifen, a mast cell stabilizer, on postoperative gastrointestinal transit in patients who underwent abdominal surgery.

METHODS

In this pilot study, 60 patients undergoing major abdominal surgery for gynecological malignancy with standardized anesthesia were randomized to treatment with ketotifen (4 or 12 mg) or placebo. Patients were treated for 6 days, starting 3 days before surgery. Gastric emptying of liquids, selected as a primary outcome parameter, was measured 24 h after surgery using scintigraphy. Secondary end points were (scintigraphically assessed) colonic transit, represented as geometrical center of activity (segment 1(cecum) to 7(stool)) and clinical parameters.

RESULTS

Gastric retention 1 h after liquid intake was significantly reduced by 12 mg (median 3% (1-7), P=0.01), but not by 4 mg ketotifen (18% (3-45), P=0.6) compared with placebo (16% (5-75)). Twenty-four hour colonic transit in placebo was 0.8 (0.0-1.1) vs. 1.2 (0.2-1.4) colon segments in the 12 mg ketotifen group (P=0.07). Abdominal cramps were significantly relieved in patients treated with 12 mg ketotifen, whereas other clinical parameters were not affected.

CONCLUSIONS

Ketotifen significantly improves gastric emptying after abdominal surgery and warrants further exploration of mast cell stabilizers as putative therapy for POI.

Gum chewing reduces postoperative ileus? A systematic review and meta-analysis

BACKGROUND

An important cause of delayed recovery from intestinal surgery is postoperative ileus. Gum chewing is a form of sham feeding, which could encourage gastrointestinal motility through cephalic-vagal stimulation.

METHODS

We sought to identify all randomized controlled trials comparing gum chewing with standard care after elective intestinal surgery. We searched electronic databases (Cochrane, Embase, and PubMed), reference lists and contacted authors to obtain further data. We assessed the identified trials for quality and performed a meta-analysis and systematic review. The main outcome measures examined were time to flatus and stool postoperatively and length of hospital stay, which were analysed using random effect models. We also examined clinical complication rates.

RESULTS

We identified nine eligible trials that had enrolled a total of 437 patients. The intervention was well tolerated and complication rates were low. There was statistical evidence of heterogeneity for the three main outcomes. Pooled estimates showed a reduction in time to flatus by 14 h (95% CI: -20 to -8h, p=0.001), time to bowel movement by 23 h (95% CI: -32 to -15 h, p<0.001) and a reduction in length of hospital stay by 1.1 days (95% CI: -1.9 to -0.2 days, p=0.016).

CONCLUSIONS

Chewing sugarless gum following elective intestinal resection is associated with improved outcomes. Insufficient data were available to demonstrate a reduced rate of clinical complications or reduced cost. An adequately powered, methodologically rigorous trial of gum chewing is required to confirm if there are any benefits and if these result in differences in clinical outcomes such as infection.

Methylnaltrexone, a new peripherally acting mu-opioid receptor antagonist being evaluated for the treatment of postoperative ileus

Postoperative ileus (POI), a transient impairment of bowel function, is considered an inevitable response after open abdominal surgery. It leads to significant patient morbidity and increased hospital costs and length of stay. The pathophysiology is multifactorial, involving neurogenic, hormonal, inflammatory and pharmacologic mediators. Several treatments have been shown to reduce the duration of POI, and a multimodal approach combining several of these interventions seems to be the most effective treatment option. Various drug therapies have been evaluated for the treatment of POI, although most have not shown any benefit. Peripherally active mu-opioid receptor antagonists are a new class of compounds that selectively block the peripheral (i.e., gastrointestinal [GI]) effects of opioids while preserving centrally mediated analgesia. Recently, alvimopan was approved in the US for the treatment of POI after abdominal surgery with bowel resection. Methylnaltrexone is a peripherally active mu-opioid receptor antagonist that has been shown to antagonize the inhibitory effects of opioids on GI transit without impairing analgesia. Phase II data indicated that methylnaltrexone was effective for improving GI recovery, reducing POI and shortening the time to discharge readiness in patients who underwent segmental colectomy. Two Phase III trials have been completed, and one is underway at present. Preliminary results from the two completed trials indicate that methylnaltrexone was not better than placebo for the primary or secondary outcomes. Further analyses of these data, clinical trial designs and the various dosage forms are necessary to determine the potential role of methylnaltrexone in the treatment of POI.

Effect of bisacodyl on postoperative bowel motility in elective colorectal surgery: a prospective, randomized trial

BACKGROUND

Postoperative ileus is a common condition after abdominal surgery. Many prokinetic drugs have been evaluated including osmotic laxatives. The data on colon-stimulating laxatives are scarce. This prospective, randomized, double-blind trial investigates the effect of the colon-stimulating laxative bisacodyl on postoperative ileus in elective colorectal resections.

MATERIALS AND METHODS

Between November 2004 and February 2007, 200 consecutive patients were randomly assigned to receive either bisacodyl or placebo. Primary endpoint was time to gastrointestinal recovery (mean time to first flatus passed, first defecation, and first solid food tolerated; GI-3). Secondary endpoints were incidence and duration of nasogastric tube reinsertion, incidence of vomiting, length of hospital stay, and visual analogue scores for pain, cramps, and nausea.

RESULTS

One hundred sixty-nine patients were analyzed, and 31 patients discontinued the study. Groups were comparable in baseline demographics. Time to GI-3 was significantly shorter in the bisacodyl group (3.0 versus 3.7 days, P = 0.007). Of the single parameters defining GI-3, there was a 1-day difference in time to defecation in favor to the bisacodyl group (3.0 versus 4.0 days, P = 0.001), whereas no significant difference in time to first flatus or tolerance of solid food was seen. No significant difference in the secondary endpoints was seen. Morbidity and mortality did not differ between groups.

CONCLUSION

Bisacodyl accelerated gastrointestinal recovery and might be considered as part of multimodal recovery programs after colorectal surgery.

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.

New therapies in the treatment of postoperative ileus after gastrointestinal surgery

Postoperative ileus after gastrointestinal surgery results from many factors, including the effects of surgical trauma, anesthetic agents, hyperactivity of the sympathetic nervous system, local inflammatory reactions, and the use of opioids in the postoperative period. Postoperative ileus can lead to potential complications and may prolong patients' hospitalization, thereby leading to an increase in healthcare costs. There have been recent efforts to improve the understanding of the pathogenesis of postoperative ileus and to develop new treatments to prevent or minimize its occurrence. Here, we present a review of the factors related to the development of postoperative ileus and new therapies directed at its prevention.

Systemic prokinetic pharmacologic treatment for postoperative adynamic ileus following abdominal surgery in adults

BACKGROUND

Postoperative adynamic bowel atony interferes with recovery following abdominal surgery. Prokinetic pharmacologic drugs are widely used to accelerate postoperative recovery.

OBJECTIVES

To evaluate the benefits and harms of systemic acting prokinetic drugs to treat postoperative adynamic ileus in patients undergoing abdominal surgery.

SEARCH STRATEGY

Trials were identified by computerised searches of the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and the Cochrane Colorectal Cancer Group specialised register. The reference lists of included trials and review articles were tracked and authors contacted.

SELECTION CRITERIA

Randomised controlled parallel-group trials (RCT) comparing the effect of systemically acting prokinetic drugs against placebo or no intervention.

DATA COLLECTION AND ANALYSIS

Four reviewers independently extracted the data and assessed trial quality. Trial authors were contacted for additional information if needed.

MAIN RESULTS

Thirty-nine RCTs met the inclusion criteria contributing a total of 4615 participants. Most trials enrolled a small number of patients and showed moderate to poor (reporting of) methodological quality, in particular regarding allocation concealment and intention-to-treat analysis. Fifteen systemic acting prokinetic drugs were investigated and ten comparisons could be summarized. Six RCTs support the effect of Alvimopan, a novel peripheral mu receptor antagonist. However, the trials do not meet reporting guidelines and the drug is still in an investigational stage. Erythromycin showed homogenous and consistent absence of effect across all included trials and outcomes. The evidence is insufficient to recommend the use of cholecystokinin-like drugs, cisapride, dopamine-antagonists, propranolol or vasopressin. Effects are either inconsistent across outcomes, or trials are too small and often of poor methodological quality. Cisapride has been withdrawn from the market due to adverse cardiac events in many countries. Intravenous lidocaine and neostigmine might show a potential effect, but more evidence on clinically relevant outcomes is needed. Heterogeneity among included trials was seen in 10 comparisons. No major adverse drug effects were evident.

AUTHORS' CONCLUSIONS

Alvimopan may prove to be beneficial but proper judgement needs adherence to reporting standards. Further trials are needed on intravenous lidocaine and neostigmine. The remaining drugs can not be recommended due to lack of evidence or absence of effect.

Randomized controlled trial of bisacodyl suppository versus placebo for postoperative ileus after elective colectomy for colon cancer

OBJECTIVE

To compare the use of bisacodyl suppository with placebo in resolving postoperative ileus after elective colectomy in a randomized controlled trial.

METHODS

Twenty elective colectomy patients were randomized to receive either bisacodyl or placebo suppository on the third postoperative day. Outcomes included time to first defaecation, length of hospital stay, and postoperative complications. Participants and the primary investigator were unaware of the treatment assignment.

RESULTS

All 10 participants in the bisacodyl group defaecated on the third postoperative day, while participants in the placebo group defaecated on days 3 (2/10), 4 (5/10) and 5 (3/10) (p < 0.001). The average lengths of hospital stay for the bisacodyl and placebo groups were 8.5 +/- 2.7 days and 10.4 +/- 5.3 days, respectively (p = 0.325). No significant complications occurred in either group.

CONCLUSION

Bisacodyl suppository seems to be effective and safe in resolving postoperative ileus after elective colectomy in colon cancer patients.

Alvimopan, for postoperative ileus following bowel resection: a pooled analysis of phase III studies

OBJECTIVE

To obtain further analysis regarding specific outcomes and alvimopan doses in bowel resection (BR) patients.

SUMMARY BACKGROUND DATA

Although postoperative ileus (POI) is common after BR, there is currently no recognized treatment or prevention available. Alvimopan, a novel, peripherally active mu-opioid receptor antagonist, accelerated GI recovery after BR or hysterectomy in 3 phase III trials.

METHODS

A pooled retrospective subset analysis of BR patients in alvimopan phase III trials was performed. Randomized BR patients received alvimopan 6 mg (n = 397), 12 mg (n = 413), or placebo (n = 402) >or=2 hours before surgery and twice daily until hospital discharge for <or=7 days. The primary endpoint of each trial was time to recovery of GI function. Hospital discharge order (DCO) written, readmission, and morbidities were also assessed. Cox proportional hazard models were used to analyze treatment effects on time-to-event endpoints.

RESULTS

Alvimopan (6 or 12 mg) significantly accelerated GI recovery (GI-3; hazard ratio = 1.28 and 1.38, respectively; P <or= 0.001 for both). Alvimopan significantly accelerated time to DCO written by 16 hours for 6 mg and 18 hours for 12 mg (P < 0.001 for both) from a mean of 147 hours for placebo. Alvimopan-treated patients had reduced postoperative morbidity compared with placebo, and incidence of prolonged hospital stay or readmission was significantly reduced (P < 0.001). Tolerability profiles were similar among groups.

CONCLUSIONS

Alvimopan significantly accelerated GI recovery in BR patients. A 12-mg dose provided more consistent benefits across both sexes and all ages. Postoperative morbidity rates, prolonged hospital stay, and rates of hospital readmission were significantly reduced. Alvimopan reduces the consequences of POI after BR.

In vitro characterization of the effects of endomorphin 1 and 2, endogenous ligands for μ-opioid receptors, on mouse colonic motility

The effects of endomorphin 1 (EM1) and 2 (EM2) in colonic motility remain unknown. We investigated the effects and mechanisms of these endomorphins (EMs) on the colonic motility in vitro by applying various neural blocking agents and various opioid receptor antagonists. EMs (10(-9) to 10(-6)M) displayed significant stimulatory effects on the basal tonus or spontaneous activity of mouse colon but not of stomach and small intestine. It is noteworthy that the contractile actions of EMs varied slightly among different regions of colonic longitudinal muscle layers, whereas the contractile responses induced by EMs were significantly different among different regions of circular muscle layers. EMs-induced longitudinal or circular muscle contractions were not significantly affected by atropine, N(G)-nitro-l-arginine methyl ester, phentolamine, propranolol and methysergide. Tetrodotoxin, indomethacin and naloxone completely abolished the EMs-induced colonic contractions. Surprisingly, EMs (10(-7)M)-induced longitudinal muscle contractions were significantly attenuated by nor-binaltorphimine (3x10(-6)M). By contrast, pretreatment with naltrindole (10(-6)M) did not significantly affect EMs-induced longitudinal or circular muscle contractions. Interestingly, the circular muscle contractions in response to EM2 (10(-7)M) were not fully blocked by beta-funaltrexamine (6x10(-6)M). Naloxonazine (10(-6)M) almost fully antagonized the EMs-induced longitudinal or circular muscle contractions, and these effects could be only partially reversed by extensive washing. All the results indicated that the mechanisms and sites of actions of EMs were region-specific. Furthermore, these findings showed that the activation of multiple subtypes of opioid receptors, possibly including mu(1) (naloxonazine-sensitive), mu(2) and even other forms of muORs (beta-FNA-insensitive), was required for EMs-induced mouse colonic motility.

Treatment of Postoperative Ileus After Bowel Surgery with Low-Dose Intravenous Erythromycin

OBJECTIVES

Treatment of postoperative ileus remains unsatisfactory. Erythromycin (EM), a macrolide antibiotic, has prokinetic effects on the gut. We investigated whether intravenous erythromycin decreases the time to the return of normal bowel function after bowel surgery in patients with bladder cancer and interstitial cystitis who have undergone cystectomy and urinary diversion.

METHODS

We conducted a double-blind, randomized, placebo-controlled study of 22 volunteers. On the first postoperative day, patients began receiving intravenous erythromycin (125 mg) or placebo every 8 hours (maximum of 21 doses). The patients' ability to tolerate a general diet and return of bowel function was monitored.

RESULTS

A general diet was tolerated at a median of 9 days postoperatively for the EM arm and 8 for the placebo arm (P = 0.60). The first bowel sounds were detected at an average of 2 postoperative days for the EM arm and 3 for the placebo arm (P = 0.88). First flatus was present an average of 5 days postoperatively for both study arms (P = 0.35). The first bowel movement was present an average of 6 days postoperatively for the EM arm and 5 for the placebo arm (P = 0.98).

CONCLUSIONS

No significant difference was found between EM and placebo with regard to the onset of bowel sounds, passage of flatus, passage of the first bowel movement, and the time to tolerate a general diet. These data indicate that erythromycin is not useful in improving postoperative bowel function.

Meta-analysis: Alvimopan vs. placebo in the treatment of post-operative ileus

BACKGROUND

Alvimopan is a selective, competitive mu-opioid receptor antagonist with limited oral bioavailability which may be used to reduce length of post-operative ileus.

AIM

The study compared alvimopan with placebo following bowel resection or total abdominal hysterectomy.

METHODS

A meta-analysis of randomized-controlled trials published between 2001 and 2006 of alvimopan vs. placebo was performed. The primary efficacy end-points were composite measures of passage of flatus, stool, and tolerance of solid food (GI-3) and passage of stool and tolerance of solid food (GI-2). The incidence of treatment emergent adverse events was assessed.

RESULTS

Five trials matched the selection criteria, reporting on 2195 patients. A total of 1521 (69.3%) had alvimopan and 674 (30.7%) placebo. GI-3 significantly improved (hazard ratio 1.30; 95% confidence intervals 1.16, 1.45, P < 0.001), as did GI-2 (hazard ratio 1.61; 95% confidence intervals 1.26, 2.05, P < 0.001) on alvimopan 12 mg. Time to discharge (hazard ratio 1.26; 95% confidence intervals 1.13, 1.40, P < 0.001), time to bowel motion (hazard ratio 1.74; 95% confidence intervals 1.29, 2.35, P < 0.001), and time to solid food (hazard ratio 1.14; 95% confidence intervals 1.01, 1.30, P < 0.04) also improved significantly. No difference was noted in the incidence of treatment emergent adverse events.

CONCLUSIONS

Alvimopan showed significant advantages over placebo in restoring gastro-intestinal function, and reduced time to discharge following major abdominal surgery, with acceptable side 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.

Current Choices—Good or Bad—for the Proactive Management of Postoperative Ileus: A Surgeon’s View

Postoperative ileus (POI) is frequently experienced by many patients undergoing abdominal operations and other surgical procedures. Postoperative ileus causes physical discomfort and may increase risk for prolonged hospital length of stay. Despite its prevalence, there is currently no accepted standard definition of POI and, consequently, no standardized mode of prevention or treatment; it is no wonder that a variety of management approaches for POI have been developed. Some of these include alternative surgical techniques such as laparoscopic or endoscopic procedures to minimize trauma and help lessen the release of endogenous mediators of POI. Others have evaluated alternate analgesic regimens such as thoracic epidural anesthetics to avoid stimulating opioid receptors in the gut. These approaches have had varying results. Other pharmacologic attempts to reduce POI have focused on the blockade of opioid receptors to prevent opioid-induced GI-related adverse effects. A new class of agents, peripherally acting mu-opioid-receptor antagonists such as methylnaltrexone and alvimopan, may improve the pharmacologic management of POI and reshape the current paradigm of multimodal management of POI. Protocols that incorporate these agents may offer yet another avenue to mitigate the adverse effects of POI, and thus help improve surgical outcomes. To date, alvimopan has been shown in phase 3 clinical trials to significantly reduce the duration of POI while maintaining satisfactory analgesia and reducing length of hospital stay. Combinations of strategies with demonstrated effectiveness such as early feeding, epidural analgesia, laparoscopic surgery, and peripherally acting mu-opioid-receptor antagonists may help transform the management of POI into an effective multimodal paradigm that targets the diverse etiologic factors leading to this common clinical problem. Clearly, all surgical team members are crucial in the optimal implementation of such multimodal approaches.

Capsule endoscopy: improving transit time and image view

AIM

To evaluate the effect of various methods of small bowel preparation on the transit time and the quality of visualization of the entire small bowel mucosa.

METHODS

Ninety-five patients underwent capsule endoscopy (CE) by easily swallowing the capsule. They were divided into three study groups according to the preparation used: group A (n = 26) by polyethylene glycol (PEG) liter or with sodium phosphate (SP) 12 h prior to the CE study; group B (n = 29) by erythromycin 1 h prior to the CE study; and group C (n = 40) without any preparation. Visualization ranged from good to satisfactory to poor.

RESULTS

The gastric emptying time in the group prepared with erythromycin was shorter but without statistical significance and the small bowel transit time was unaffected. In elderly subjects prepared by PEG or SP, the gastric emptying time was significantly longer (163.7 min, P = 0.05). The transit times of the three sub-groups were not affected by gender or pathology. The grade of cleaning of the entire study group was 3.27+/-1.1. The erythromycin group presented significantly the worst quality of images (P = 0.05) compared to the other sub-groups. Age, gender, and pathology had no effect on the quality of the cleaning of the small bowel in the sub-groups. One (1.05%) case had no natural excretion.

CONCLUSION

Erythromycin markedly reduces gastric emptying time, but has a negative effect on the quality of the image in the small bowel. The preparation of elderly subjects with PEG or SP has a negative effect on the small bowel transit time.

Alvimopan, a peripherally acting mu-opioid receptor antagonist, compared with placebo in postoperative ileus after major abdominal surgery

BACKGROUND

Alvimopan is a peripherally acting mu-opioid receptor (PAM-OR) antagonist for accelerating gastrointestinal recovery after surgery.

METHODS

Patients undergoing open laparotomy (bowel resection, n = 418; hysterectomy, n = 197) were randomized to receive alvimopan 6 or 12 mg or placebo orally > or = 2 h before surgery and then b.i.d. until hospital discharge (up to 7 days). The primary efficacy endpoint was time to gastrointestinal (GI) recovery (measured by toleration of solid food and passage of flatus/stool; GI-3). Secondary endpoints included time to GI-2 recovery (toleration of solid food and passage of stool) and hospital discharge order written (DCO).

RESULTS

Alvimopan did not significantly accelerate GI-3 compared with placebo [6 mg: hazard ratio (HR) = 1.20, p = 0.080; 12 mg: HR = 1.24, p = 0.038). However, after adjustment for significant covariates (sex/surgical duration), benefits were significant for both doses (6 mg: HR = 1.24, p = 0.037; 12 mg: HR = 1.26, p = 0.028). Alvimopan also significantly accelerated time to GI-2 (6 mg: HR = 1.37, p = 0.008; 12 mg: HR = 1.33, p = 0.018) and DCO (6 mg: HR = 1.31, p = 0.008; 12 mg: HR = 1.28, p = 0.015). Adverse events were similar between groups.

CONCLUSIONS

Alvimopan (6 or 12 mg) accelerates GI recovery and is well tolerated in patients undergoing open laparotomy.

Capsule endoscopy: Improving transit time and image view

AIM: To evaluate the effect of various methods of small bowel preparation on the transit time and the quality of visualization of the entire small bowel mucosa.

METHODS: Ninety-five patients underwent capsule endoscopy (CE) by easily swallowing the capsule. They were divided into three study groups according to the preparation used: group A (n = 26) by polyethylene glycol (PEG) liter or with sodium phosphate (SP) 12 h prior to the CE study; group B (n = 29) by erythromycin 1 h prior to the CE study; and group C (n = 40) without any preparation. Visualization ranged from good to satisfactory to poor.

RESULTS: The gastric emptying time in the group prepared with erythromycin was shorter but without statistical significance and the small bowel transit time was unaffected. In elderly subjects prepared by PEG or SP, the gastric emptying time was significantly longer (163.7 min, P = 0.05). The transit times of the three sub-groups were not affected by gender or pathology. The grade of cleaning of the entire study group was 3.27 ± 1.1. The erythromycin group presented significantly the worst quality of images (P = 0.05) compared to the other sub-groups. Age, gender, and pathology had no effect on the quality of the cleaning of the small bowel in the sub-groups. One (1.05%) case had no natural excretion.

CONCLUSION: Erythromycin markedly reduces gastric emptying time, but has a negative effect on the quality of the image in the small bowel. The preparation of elderly subjects with PEG or SP has a negative effect on the small bowel transit time.

Phase III trial of alvimopan, a novel, peripherally acting, mu opioid antagonist, for postoperative ileus after major abdominal surgery

PURPOSE

Postoperative ileus presents significant clinical challenges that potentially prolong hospital stay, contribute to readmission, and increase morbidity. There is no approved treatment for postoperative ileus. Alvimopan is a novel, peripherally acting, mu opioid receptor antagonist currently in development for the management of postoperative ileus.

METHODS

Patients undergoing partial colectomy or simple or radical hysterectomy were randomized to receive alvimopan 6 mg (n = 152), alvimopan 12 mg (n = 146), or placebo (n = 153) orally 2 hours before surgery and twice daily thereafter until discharge or for up to seven days. The primary efficacy end point, time to return of gastrointestinal function, was a composite measure of passage of flatus or stool and tolerating solid food. Secondary end points included time to the hospital discharge order written. Adverse events were monitored throughout the study.

RESULTS

Mean time to gastrointestinal recovery was significantly reduced in patients treated with alvimopan 6 mg vs. placebo (hazard ratio = 1.45; P = 0.003), with a smaller reduction seen with alvimopan 12 mg (hazard ratio = 1.28; P = 0.059). Mean time to the hospital discharge order written was significantly accelerated in patients treated with alvimopan 6 mg (hazard ratio = 1.50; P < 0.001). The most common treatment-emergent adverse events across all treatment groups were nausea, vomiting, and hypotension; the incidence of nausea and vomiting was reduced by 53 percent in the alvimopan 12-mg group.

CONCLUSIONS

In patients undergoing major abdominal surgery, alvimopan accelerated gastrointestinal recovery and time to the hospital discharge order written compared with placebo and was well tolerated.

A survey of perceptions and attitudes among European surgeons towards the clinical impact and management of postoperative ileus

OBJECTIVE

Postoperative ileus (POI) can negatively affect patient recovery and morbidity, yet the lack of an internationally accepted definition and clinical management pathway for this condition suggest POI may be under-recognized as a clinical problem. The purpose of this survey was therefore to assess current attitudes of surgeons towards the clinical impact and management of POI.

SUBJECTS AND METHODS

Telephone interviews were conducted with 230 surgeons from hospitals in the UK, France, Germany, Italy and Spain.

RESULTS

Across Europe, there are differences in the terms surgeons use to refer to delayed recovery of gastrointestinal (GI) function and the symptoms, concerns and risks they associate with this condition. Furthermore, there is marked variation in the attitudes of European surgeons towards minimizing the risk of delayed recovery of GI function and in the strategies to manage POI. Additionally, some of the measures applied most commonly by European surgeons are in contrast to evidence in the literature indicating that they have no benefit for quicker resolution of GI function.

CONCLUSION

The results suggest that there is a need for clearer definition of the factors that constitute POI, increased recognition of the impact of this condition and improved understanding of the most effective peri-/postoperative care for surgical patients.

Postoperative pathophysiology and choice of incision

In the few days following major surgical procedures, there are three main physiologic processes which are amenable to surgical management: restoration of fluid and electrolyte homeostasis, management of pain, and attention to gastrointestinal function. New information regarding optimizing the management of these processes is presented, which may accelerate recovery and give improved comfort following abdominal surgery. The type of incision used seems not to be a major factor in such recovery.

Alvimopan, a novel, peripherally acting mu opioid antagonist: results of a multicenter, randomized, double-blind, placebo-controlled, phase III trial of major abdominal surgery and postoperative ileus

OBJECTIVE

To demonstrate that alvimopan (6 or 12 mg) accelerates recovery of gastrointestinal (GI) function in patients undergoing laparotomy for bowel resection or radical hysterectomy.

SUMMARY BACKGROUND DATA

Postoperative ileus (POI) following laparotomy may increase morbidity and extend hospitalization. Opioids can contribute to the duration of POI. Alvimopan is a novel opioid receptor antagonist in development for the management of POI.

METHODS

A total of 510 patients scheduled for bowel resection or radical hysterectomy were randomized (1:1:1) to receive alvimopan 6 mg, alvimopan 12 mg, or placebo orally > or =2 hours before surgery, then twice a day (b.i.d.) until hospital discharge or for up to 7 days. The primary efficacy end point was a composite of time to recovery of upper and lower GI function. An associated secondary end point was time to hospital discharge order written.

RESULTS

The modified intent-to-treat population included 469 patients (451 bowel resection and 18 radical hysterectomy patients). Time to recovery of GI function was accelerated for the alvimopan 6 mg (hazard ratio [HR] = 1.28; P < 0.05) and 12 mg (HR = 1.54; P < 0.001) groups with a mean difference of 15 and 22 hours, respectively, compared with placebo. The time to hospital discharge order written was also accelerated in the alvimopan 12 mg group (HR = 1.42; P = 0.003) with a mean difference of 20 hours compared with placebo. The incidence of adverse events was similar among treatment groups.

CONCLUSIONS

Alvimopan accelerated GI recovery and time to hospital discharge order written compared with placebo in patients undergoing laparotomy and was well tolerated.

Mechanisms of postoperative ileus

Postoperative ileus is an iatrogenic condition that follows abdominal surgery. Three main mechanisms are involved in its causation, namely neurogenic, inflammatory and pharmacological mechanisms. In the acute postoperative phase, mainly spinal and supraspinal adrenergic and non-adrenergic pathways are activated. Recent studies, however, show that the prolonged phase of postoperative ileus is caused by an enteric molecular inflammatory response and the subsequent recruitment of leucocytes into the muscularis of the intestinal segments manipulated during surgery. This inflammation impairs local neuromuscular function and activates neurogenic inhibitory pathways, inhibiting motility of the entire gastrointestinal tract. The mechanisms underlying the recruitment of the inflammatory cells, and their interaction with the intestinal afferent innervation, are discussed. Finally, opioids administered for postoperative pain control also contribute to a large extent to the reduction in propulsive gastrointestinal motility observed after abdominal surgery.

Opioid-induced bowel dysfunction: pathophysiology and potential new therapies

Opioid treatment for postoperative or chronic pain is frequently associated with adverse effects, the most common being dose-limiting and debilitating bowel dysfunction. Postoperative ileus, although attributable to surgical procedures, is often exacerbated by opioid use during and following surgery. Postoperative ileus is marked by increased inhibitory neural input, heightened inflammatory responses, decreased propulsive movements and increased fluid absorption in the gastrointestinal tract. The use of opioids for chronic pain is characterised by a constellation of symptoms including hard dry stools, straining, incomplete evacuation, bloating, abdominal distension and increased gastroesophageal reflux. The current management of opioid-induced bowel dysfunction among patients receiving opioid analgesics consists primarily of nonspecific ameliorative measures. Intensive investigations into the mode of action of opioids have characterised three opioid receptor classes -mu, delta and kappa- that mediate the myriad of peripheral and central actions of opioids. Activation of mu-opioid receptors in the gastrointestinal tract is responsible for inhibition of gut motility, whereas receptors in the central nervous system mediate the analgesic actions of opioids. Blocking peripheral opioid receptors in the gut is therefore a logical therapeutic target for managing opioid-induced bowel dysfunction. Available opioid antagonists such as naloxone are of limited use because they are readily absorbed, cross the blood-brain barrier, and act at central opioid receptors to reverse analgesia and elicit opioid withdrawal. Methylnaltrexone and alvimopan are recently developed opioid antagonists with activity that is restricted to peripheral receptors. Both have recently shown the ability to reverse opioid-induced bowel dysfunction without reversing analgesia or precipitating central nervous system withdrawal signs in non-surgical patients receiving opioids for chronic pain. In addition, recent clinical studies with alvimopan suggest that it may normalise bowel function without blocking opioid analgesia in abdominal laparotomy patients with opioid-related postoperative ileus.

Postoperative ileus: progress towards effective management

The pathogenesis of postoperative ileus (PI) is multifactorial, and includes activation of inhibitory reflexes, inflammatory mediators and opioids (endogenous and exogenous). Accordingly, various strategies have been employed to prevent PI. As single-modality treatment, continuous postoperative epidural analgesia including local anaesthetics has been most effective in the prevention of PI. Choice of anaesthetic technique has no major impact on PI. Minimally invasive surgery reduces PI, in accordance with the sustained reduction in the inflammatory responses, while the effects of early institution of oral nutrition on PI per se are minor. Several pharmacological agents have been employed to resolve PI (propranolol, dihydroergotamine, neostigmine, erythromycin, cisapride, metoclopramide, cholecystokinin, ceruletide and vasopressin), most with either limited effect or limited applicability because of adverse effects. The development of new peripheral selective opioid antagonists is promising and has been demonstrated to shorten PI significantly. A multi-modal rehabilitation programme including continuous epidural analgesia with local anaesthetics, enforced nutrition and mobilisation may reduce PI to 1-2 days after colonic surgery.

Small intestinal transit does not adequately represent postoperative paralytic ileus in rats

Small intestinal transit (SIT) has often been regarded as an index of pathophysiological state of postoperative ileus (PI) in rats. The reliability of SIT as an index of PI was examined in the present study. PI was induced via abdominal surgery (i.e., laparotomy with evisceration and manipulation) in rats. For one group of PI-induced rats, SIT of a charcoal test meal was measured. When necessary, the physical state (i.e., severity and site of distension) of the gastrointestinal (GI) tract in each rat was visually examined. For another group of PI-induced rats, abdominal X-ray radiographs were obtained after introducing the barium sulfate suspension. The abdomen was then opened and the physical state of the GI tract was visually examined. The SIT was decreased in most of the PI-induced rats, and the GI distension was observed, with substantial intersubject variations, in all of the PI-induced rats. However, no linear relationship was evident between the SIT and the severity of GI distension (e.g., at 20 h after PI induction). Instead, the severity and site of GI distension could be monitored by the X-ray radiology. Therefore, the use of SIT as an index of Pi should be substantially limited.

The effect of the herbal medicine dai-kenchu-to on post-operative ileus

Post-operative ileus (PI) is an inevitable adverse consequence of abdominal surgical procedures. We performed a randomized study of the effects of the herbal medicine dai-kenchu-to (DKT) on 24 patients with PI. Patients received either 15 g of oral DKT or placebo daily for 14 days. The effects on upper gastrointestinal motility, frequency of secondary operation and recurrence of PI were investigated. The frequency of surgical operation was significantly lower in patients receiving DKT compared with placebo. Oral administration of DKT was clinically effective for PI in reducing both the need for further surgery and the recurrence of PI.