Gastrointestinal myoelectric and clinical patterns of recovery after laparotomy

Electrogastrography for psychophysiological research: Practical considerations, analysis pipeline, and normative data in a large sample

Electrogastrography (EGG) is the noninvasive electrophysiological technique used to record gastric electrical activity by means of cutaneous electrodes placed on the abdomen. EGG has been so far mostly used in clinical studies in gastroenterology, but it represents an attractive method to study brain-viscera interactions in psychophysiology. Compared to the literature on electrocardiography for instance, where practical recommendations and normative data are abundant, the literature on EGG in humans remains scarce. The aim of this article is threefold. First, we review the existing literature on the physiological basis of the EGG, pathways of brain-stomach interactions, and experimental findings in the cognitive neuroscience and psychophysiology literature. We then describe practical issues faced when recording the EGG in young healthy participants, from data acquisition to data analysis, and propose a semi-automated analysis pipeline together with associated MATLAB code. The analysis pipeline aims at identifying a regular rhythm that can be safely attributed to the stomach, through multiple steps. Finally, we apply these recording and analysis procedures in a large sample (N = 117) of healthy young adult male and female participants in a moderate (<5 hr) to prolonged (>10 hr) fasting state to establish the normative distribution of several EGG parameters. Our results are overall congruent with the clinical gastroenterology literature, but suggest using an electrode coverage extending to lower abdominal locations than current clinical guidelines. Our results indicate a marginal difference in EGG peak frequency between male and female participants, and that the gastric rhythm becomes more irregular after prolonged fasting.

Cutaneous Patches to Monitor Myoelectric Activity of the Gastrointestinal Tract in Postoperative Pediatric Patients

PURPOSE

Limited means exist to assess gastrointestinal activity in pediatric patients postoperatively. Recently, myoelectric gastrointestinal activity recorded by cutaneous patches has been shown in adult patients to be predictive of clinical return of gastrointestinal function postoperatively. The aim of this case series is to demonstrate the feasibility of this system in pediatric patients and to correlate myoelectric signals with return of bowel function clinically.

METHODS

Pediatric patients undergoing abdominal surgery were recruited to have wireless patches placed on the abdomen within two hours postoperatively. Myoelectric data were transmitted wirelessly to a mobile device with a user-interface and forwarded to a cloud server where processing algorithms identified episodes of motor activity, quantified their parameters and nominally assigned them to specific gastrointestinal organs based on their frequencies.

RESULTS

Three patients (ages 5 months, 4 year, 16 year) were recruited for this study. Multiple patches were placed on the older subjects, while the youngest had a single patch due to space limitations. Rhythmic signals of the stomach, small intestine, and colon could be identified in all three subjects. Patients showed gradual increase in myoelectric intestinal and colonic activity leading up to the first recorded bowel movement.

CONCLUSION

Measuring myoelectric intestinal activity continuously using a wireless patch system is feasible in a wide age range of pediatric patients. The increase in activity over time correlated well with the patients' return of bowel function. More studies are planned to determine if this technology can predict return of bowel function or differentiate between physiologic ileus and pathologic conditions.

Randomized controlled trial on efficacy of oligomeric formula (HINE E-GEL®) versus polymeric formula (MEIN®) enteral nutrition after esophagectomy for esophageal cancer with gastric tube reconstruction

The efficacy of early enteral nutrition after esophageal cancer surgery has been reported. However, the choice of formula and management of diarrhea are important to achieve the goal of enhanced recovery after surgery. The aim of this study is to assess the frequency of diarrhea/completion rate of enteral nutrition regimen as primary endpoints and the postoperative nutritional status/body composition analysis/operative morbidity as secondary endpoints was compared between the two nutrition groups. Among the 122 patients who underwent esophagectomy for esophageal cancer between December 2015 and September 2017, 67 patients who met the eligibility criteria were randomly assigned to receive enteral nutrition with either HINE E-GEL® (HINE group; n = 33) or MEIN® (MEIN group; n = 34). The incidence of diarrhea was significantly lower in the HINE group (18.2 % vs. 64.7 %, P < 0.001). The score of Bristol scale of POD 6/7 was significantly lower in the HINE group (P = 0.019/P = 0.006, respectively). The completion rate of enteral nutrition regimen was significantly higher in the HINE group (97.4 % vs. 86.6 %, P = 0.002). The Controlling Nutritional Status scores and total protein levels at 6 months after surgery were significantly better in the HINE group (P = 0.030 and P = 0.023, respectively), indicating improved tendency in nutritional status in the HINE group. However, there were no significant differences in Prognostic Nutritional Index values, blood test results, rapid turnover proteins, body mass index, or body composition between the two groups. HINE E-GEL compared with MEIN may reduce the frequency of diarrhea, enabling patients to adhere to the scheduled enteral nutrition plan. Also, maintenance of nutritional status with HINE E-GEL was comparable or potentially better in some nutrition components to that with MEIN, indicating that HINE E-GEL can be an option for enteral nutrition following esophageal surgery to achieve the goal of successful completion of scheduled enteral nutrition and smooth transition to the normal diet.

Colon Myoelectric Activity Measured After Open Abdominal Surgery with a Noninvasive Wireless Patch System Predicts Time to First Flatus

BACKGROUND

Passage of flatus after abdominal surgery signals resolution of physiological postoperative ileus (POI) and often, particularly after complex open surgeries, serves as the trigger to initiate oral feeding. To date, there is no objective tool that can predict time to flatus allowing for timely feeding and optimizing recovery. In an open, prospective study, we examine the use of a noninvasive wireless patch system that measures electrical activity from gastrointestinal smooth muscles in predicting time to first flatus.

METHODS

Eighteen patients who underwent open abdominal surgery at El Camino Hospital, Mountain View, CA, were consented and studied. Immediately following surgery, wireless patches were placed on the patients' anterior abdomen. Colonic frequency peaks in the spectra were identified in select time intervals and the area under the curve of each peak times its duration was summed to calculate cumulative myoelectrical activity.

RESULTS

Patients with early flatus had stronger early colonic activity than patients with late flatus. At 36 h post-surgery, a linear fit of time to flatus vs cumulative colonic myoelectrical activity predicted first flatus as much as 5 days (± 22 h) before occurrence.

CONCLUSIONS

In this open, prospective pilot study, noninvasive measurement of colon activity after open abdominal surgery was feasible and predictive of time to first flatus. Interventions such as feeding can potentially be optimized based on this prediction, potentially improving outcomes, decreasing length of stay, and lowering costs.

Colonic Electromechanical Abnormalities Underlying Post-operative Ileus: A Systematic and Critical Review

Post-operative ileus (POI) is an inevitable consequence of major abdominal surgery, and may be prolonged in up to 30% of patients. Ileus is commonly presumed to result from paralysis of the GI tract, though there is little direct evidence to support this view. The aim of this review is to systematically search and critically review the literature investigating post-operative colonic electrical and mechanical activity. MEDLINE and Embase databases were systematically searched for articles investigating post-operative colonic motor or electrical activity in human patients. Nineteen original articles investigating post-operative colonic motor or electrical activity were identified. Most studies have used low-resolution techniques, with intermittent recordings of colonic motility. Numerous studies have shown that colonic electrical and motor activity does not cease routinely following surgery, but is of abnormal character for 3–6 days following laparotomy. One recent high-resolution manometry study identified hyperactive cyclic motor patterns occurring in the distal colon on the first post-operative day. Low-resolution studies have shown colonic slow waves are not inhibited by surgery, and are present even in the immediate post-operative period. Recovery of normal motility appears to occur in a proximal to distal direction and is temporally correlated with the clinical return of bowel function. No studies have investigated motility specifically in prolonged POI. Future studies should use high-resolution techniques to accurately characterise abnormalities in electrical and mechanical function underlying POI, and correlate these changes with clinical recovery of bowel function.

Clinical pathway after gastrectomy for gastric cancer: A case series of laparoscopic gastrectomy and early oral intake with "iEat™"

INTRODUCTION

We investigated the validity of the clinical pathway of early oral intake using a special type of food "iEat™" for patients after laparoscopic gastric cancer surgery.

METHODS

Fifty-two patients who underwent laparoscopic surgery for gastric cancer between April 2012 and October 2013 were the participants. We provided postoperative care in accordance with a clinical pathway for laparoscopic gastrectomy that begins oral intake with "iEat™ the day after surgery. We examined complications resulting from oral intake, postoperative complications, and the length of postoperative hospital stay.

RESULTS

Of the 52 patients, 30 underwent distal gastrectomy and 22 underwent total gastrectomy. 50 patients was able to start early oral intake in accordance with our clinical pathway. No anastomotic leak complications were observed, and 9 patients (17.3%) developed complications as results of surgery. There was no complication related to early oral intake with "iEat™". Re-operation were performed in two cases. Overall mean and median postoperative hospital stays were 8.3 days and 6 days, respectively. There was a single case of hospital re-admission. The completion rate of this early oral intake clinical pathway was 86.5%.

CONCLUSION

Clinical pathway of recovery program combined laparoscopic suregry and early oral intake with "iEat™" could be useful for gastric cancer. This study indicates that using non-liquid food like iEat™ can be feasiblel, and water or liquid food don't have to be used in early oral feeding after laparoscopic gastrectomy.

Hyperactive cyclic motor activity in the distal colon after colonic surgery as defined by high-resolution colonic manometry

BACKGROUND

Recovery after colonic surgery is invariably delayed by disturbed gut motility. It is commonly assumed that colonic motility becomes quiescent after surgery, but this hypothesis has not been evaluated rigorously. This study quantified colonic motility through the early postoperative period using high-resolution colonic manometry.

METHODS

Fibre-optic colonic manometry was performed continuously before, during and after surgery in the left colon and rectum of patients undergoing right hemicolectomy, and in healthy controls. Motor events were characterized by pattern, frequency, direction, velocity, amplitude and distance propagated.

RESULTS

Eight patients undergoing hemicolectomy and nine healthy controls were included in the study. Colonic motility became markedly hyperactive in all operated patients, consistently dominated by cyclic motor patterns. Onset of cyclic motor patterns began to a minor extent before operation, occurring with increasing intensity nearer the time of surgery; the mean(s.d.) active duration was 12(7) per cent over 3 h before operation and 43(17) per cent within 1 h before surgery (P = 0.024); in fasted controls it was 2(4) per cent (P < 0·001). After surgery, cyclic motor patterns increased markedly in extent and intensity, becoming nearly continuous (active duration 94(13) per cent; P < 0·001), with peak frequency 2-4 cycles per min in the sigmoid colon. This postoperative cyclic pattern was substantially more prominent than in non-operative controls, including in the fed state (active duration 27(20) per cent; P < 0·001), and also showed higher antegrade velocity (P < 0·001).

CONCLUSION

Distal gut motility becomes markedly hyperactive with colonic surgery, dominated by cyclic motor patterns. This hyperactivity likely represents a novel pathophysiological aspect of the surgical stress response. Hyperactive motility may contribute to gut dysfunction after surgery, potentially offering a new therapeutic target to enhance recovery.

Bowel Sounds Are Not Associated With Flatus, Bowel Movement, or Tolerance of Oral Intake in Patients After Major Abdominal Surgery

BACKGROUND

Auscultation for bowel sounds has been advocated by some clinicians as a method to determine the resolution of postoperative ileus.

OBJECTIVE

Our primary aim was to prospectively evaluate the relationships between bowel sounds and the ability to tolerate oral intake in patients after major abdominal surgery. Secondarily we aimed to evaluate relationships among bowel sounds, flatus and bowel movement, and oral intake.

DESIGN

This was a prospective, blinded observational study.

SETTINGS

The study was conducted at Western Pennsylvania Hospital.

PATIENTS

A total of 124 adult patients undergoing major abdominal surgery were included.

MAIN OUTCOME MEASURES

Data were collected by medical students blinded to the purpose of the study for 10 days postoperatively or until discharge, including the presence of bowel sounds (auscultation for 1 minute), flatus, bowel movement, and tolerance of oral intake (defined as ingestion of ≥1000 mL/24 h and each subsequent day without vomiting). Associations between paired variables were determined using ϕ coefficient testing.

RESULTS

The study population consisted of 51 men and 73 women, with a mean age of 64 years (range, 20-92 y). The majority of patients (78/124 (63%)) underwent colorectal resection. The median length of hospital was 6 days. Bowel sounds were not associated with flatus, bowel movement, or tolerance of oral intake throughout the study period. The positive predictive value of bowel sounds in predicting flatus and bowel movement was low in the early postoperative period and remained <25% in predicting tolerance of oral intake throughout the study period. The analysis was repeated, including only those patients undergoing colorectal procedures, and was essentially unchanged. Flatus correlated with bowel movement in the first 6 days postoperation, but neither flatus nor bowel movement was associated with tolerance of oral intake.

LIMITATIONS

The rate of tolerance of oral intake was relatively modest throughout the study period.

CONCLUSIONS

Bowel sounds are not associated with flatus, bowel movement, or tolerance of oral intake after major abdominal surgery.

Chewing gum for enhancing early recovery of bowel function after caesarean section

BACKGROUND

Caesarean sections (CS) are the most frequent major surgery in the world. A transient impairment of bowel motility is expected after CS. Although this usually resolves spontaneously within a few days, it can cause considerable discomfort, require symptomatic medication and delay hospital discharge, thus increasing costs. Chewing gum in the immediate postoperative period is a simple intervention that may be effective in enhancing recovery of bowel function in other types of abdominal surgeries.

OBJECTIVES

To assess the effects of chewing gum to reduce the duration of postoperative ileus and to enhance postoperative recovery after a CS.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (20 June 2016), LILACs (20 June 2016), ClinicalTrials.gov (20 June 2016), WHO International Clinical Trials Registry Platform (ICTRP) (20 June 2016) and the reference lists of retrieved studies.

SELECTION CRITERIA

All randomised controlled trials comparing chewing gum versus usual care, for women in the first 24 hours after a CS. We included studies published in abstract form only.Quasi-randomised, cross-over or cluster-randomised trials were not eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected the studies for inclusion, extracted data and assessed the risk of bias following standard Cochrane methods. We present dichotomous outcome results as risk ratio (RR) with 95% confidence intervals (CI) and continuous outcome results as mean differences (MD) and 95% CI. We pooled the results of similar studies using a random-effects model in case of important heterogeneity. We used the GRADE approach to assess the overall quality of evidence.

MAIN RESULTS

We included 17 randomised trials (3149 participants) conducted in nine different countries. Seven studies (1325 women) recruited exclusively women undergoing elective CS and five studies (833 women) only included women having a primary CS. Ten studies (1731 women) used conventional feeding protocols (nil by mouth until the return of intestinal function). The gum-chewing regimen varied among studies, in relation to its initiation (immediately after CS, up to 12 hours later), duration of each session (from 15 to 60 minutes) and number of sessions per day (three to more than six). All the studies were classified as having a high risk of bias due to the nature of the intervention, women could not be blinded and most of the outcomes were self-reported.Primary outcomes of this review: for the women that chewed gum, the time to passage of first flatus was seven hours shorter than those women in the 'usual care' control group (MD -7.09 hours, 95% CI -9.27 to -4.91 hours; 2399 women; 13 studies; random-effects Tau² = 14.63, I² = 95%, very low-quality evidence). This effect was consistent in all subgroup analyses (primary and repeat CS, time spent chewing gum per day, early and conventional feeding protocols, elective and non-elective CS and time after CS when gum-chewing was initiated). The rate of ileus was on average over 60% lower in the chewing-gum group compared to the control (RR 0.39, 95% CI 0.19 to 0.80; 1139 participants; four studies; I² = 39%, low-quality evidence). Tolerance to gum-chewing appeared to be high. Three women in one study complained about the chewing gum (but no further information was provided) and none of the studies reported adverse effects (eight studies, 925 women, low-quality evidence).Secondary outcomes of this review: the time to passage of faeces occurred on average nine hours earlier in the intervention group (MD -9.22 hours, 95% CI -11.49 to -6.95 hours; 2016 participants; 11 studies; random-effects Tau² = 12.53, I² = 93%, very low-quality evidence). The average duration of hospital stay was shorter in the intervention compared to the control group (MD -0.36 days, 95% CI -0.53 to -0.18 days; 1489 participants; seven studies; random-effects Tau² = 0.04, I² = 92%). The first intestinal sounds were heard earlier in the intervention than in the control group (MD -4.56 hours, 95% CI -6.18 to -2.93 hours; 1729 participants; nine studies; random-effects Tau² = 5.41, I² = 96%). None of the studies assessed women's satisfaction in relation to having to chew gum. The need for analgesia or antiemetic agents did not differ between the intervention and control groups (average RR 0.50, 95% CI 0.12 to 2.13; 726 participants; three studies; random-effects Tau² = 0.79, I² = 69%).

AUTHORS' CONCLUSIONS

This review found 17 randomised controlled trials (involving 3149 women). We downgraded the quality of the evidence for time to first passage of flatus and of faeces and for adverse effects/intolerance to gum chewing because of the high risk of bias of the studies (due to lack of blinding and self-report). For time to first flatus and faeces, we downgraded the quality of the evidence further because of the high heterogeneity in these meta-analyses and the potential for publication bias based on the visual inspection of the funnel plots. The quality of the evidence for adverse effects/tolerance to gum chewing and for ileus was downgraded because of the small number of events. The quality of the evidence for ileus was further downgraded due to the unclear risk of bias for the assessors evaluating this outcome.The available evidence suggests that gum chewing in the immediate postoperative period after a CS is a well tolerated intervention that enhances early recovery of bowel function. However the overall quality of the evidence is very low to low.Further research is necessary to establish the optimal regimen of gum-chewing (initiation, number and duration of sessions per day) to enhance bowel function recovery and to assess potential adverse effects of and women's satisfaction with this intervention. New studies also need to assess the compliance of the participants to the recommended gum-chewing instructions. Future large, well designed and conducted studies, with better methodological and reporting quality, will help to inform future updates of this review and enhance the body of evidence for this intervention.

Alvimopan combined with enhanced recovery strategy for managing postoperative ileus after open abdominal surgery: a systematic review and meta-analysis

BACKGROUND

To assess the efficacy and safety of alvimopan in conjunction with enhanced recovery strategy, compared with this strategy alone, in management of postoperative ileus in patients undergoing open abdominal surgery.

METHODS

Electronic databases were comprehensively searched for relevant randomized controlled trials. We were interested in doses of 6 and 12 mg. The efficacy end points included the time to recovery of full gastrointestinal (GI) function (a composite end point measured by the time to first toleration of solid food [SF] and the time to first passage of stool, GI-2), the recovery of upper (SF) or the lower (the time to first bowel movement, BM) GI function, and the length of hospital stay (the time to discharge order written). Safety end points included GI-related, non-GI-related, and serious adverse events. These parameters were all analyzed by RevMan 5.3 software.

RESULTS

Nine randomized controlled trials involving 4075 patients were enrolled in this study. The pooled results showed that alvimopan significantly decreased the time to GI-2 recovery (6 mg, hazard ratio [HR] = 1.45, P < 0.00001; 12 mg, HR = 1.59, P < 0.00001), BM (6 mg, HR = 1.54, P < 0.00001; 12 mg, HR = 1.74, P = 0.0002), and the time to discharge order written (6 mg, HR = 1.37, P < 0.00001; 12 mg, HR = 1.34, P < 0.00001) compared with the placebo group. However, SF was significantly reduced in 6 mg group (HR = 1.23, P = 0.008) rather than 12 mg group (HR = 1.14, 95% confidence interval 1.00, 1.30, P = 0.04). The incidence of some GI-related and serious adverse events were significantly lower in the alvimopan group than the placebo group, and the dose of 12 mg was superior to 6 mg in this regard.

CONCLUSIONS

Alvimopan can accelerate recovery of GI function (especially for the lower GI tract), shorten the length of hospital stay, and reduce postoperative ileus-related morbidity without compromising opioid analgesia in an enhanced recovery setting.

The virtual intestine: in silico modeling of small intestinal electrophysiology and motility and the applications

The intestine comprises a long hollow muscular tube organized in anatomically and functionally discrete compartments, which digest and absorb nutrients and water from ingested food. The intestine also plays key roles in the elimination of waste and protection from infection. Critical to all of these functions is the intricate, highly coordinated motion of the intestinal tract, known as motility, which is coregulated by hormonal, neural, electrophysiological and other factors. The Virtual Intestine encapsulates a series of mathematical models of intestinal function in health and disease, with a current focus on motility, and particularly electrophysiology. The Virtual Intestine is being cohesively established across multiple physiological scales, from sub/cellular functions to whole organ levels, facilitating quantitative evaluations that present an integrative in silico framework. The models are also now finding broad physiological applications, including in evaluating hypotheses of slow wave pacemaker mechanisms, smooth muscle electrophysiology, structure-function relationships, and electromechanical coupling. Clinical applications are also beginning to follow, including in the pathophysiology of motility disorders, diagnosing intestinal ischemia, and visualizing colonic dysfunction. These advances illustrate the emerging potential of the Virtual Intestine to effectively address multiscale research challenges in interdisciplinary gastrointestinal sciences.

The impact of surgical excisions on human gastric slow wave conduction, defined by high-resolution electrical mapping and in silico modeling

BACKGROUND

Gastric contractions are coordinated by slow waves, generated by interstitial cells of Cajal (ICC). Gastric surgery affects slow wave conduction, potentially contributing to postoperative gastric dysfunction. However, the impact of gastric cuts on slow waves has not been comprehensively evaluated. This study aimed to define consequences of surgical excisions on gastric slow waves by applying high-resolution (HR) electrical mapping and in silico modeling.

METHODS

Patients undergoing gastric stimulator implantation (n = 10) underwent full-thickness stapled excisions (25 × 15 mm, distal corpus) for histological evaluation, enabling HR mapping (256 electrodes; 36 cm(2) ) over and adjacent to excisions. A biophysically based in silico model of bidirectionally coupled ICC networks was developed and applied to investigate the underlying conduction mechanisms and importance of excision orientation.

KEY RESULTS

Normal gastric slow waves propagated aborally (3.0 ± 0.2 cpm). Excisions induced complete conduction block and wavelets that rotated around blocks, then propagated rapidly circumferentially distal to the blocks (8.5 ± 1.2 vs normal 3.6 ± 0.4 mm/s; p < 0.01). This 'conduction anisotropy' homeostatically restored antegrade propagating gastric wavefronts distal to excisions. Excisions were associated with complex dysrhythmias in five patients: retrograde propagation (3/10), ectopics (3/10), functional blocks (2/10), and collisions (1/10). Simulations demonstrated conduction anisotropy emerged from bidirectional coupling within ICC layers and showed transverse incision length and orientation correlated with the degree of conduction distortion.

CONCLUSIONS & INFERENCES

Orienting incisions in the longitudinal gastric axis causes least disruption to electrical conduction and motility. However, if transverse incisions are made, a homeostatic mechanism of gastric conduction anisotropy compensates by restoring aborally propagating wavefronts. Complex dysrhythmias accompanying excisions could modify postoperative recovery in susceptible patients.

Peritoneal mast cell degranulation and gastrointestinal recovery in patients undergoing colorectal surgery

BACKGROUND

Degranulation of peritoneal mast cells (MCs) induced by intestinal manipulation has been proposed as a pathophysiological factor in postoperative ileus (POI). We aimed to explore the relationship between peritoneal and colonic MC degranulation and gastrointestinal (GI) recovery following colectomy.

METHODS

Patients undergoing elective laparoscopic cholecystectomy (using a laparoscope and small abdominal incisions, n = 14), and elective laparoscopic (n = 32) or open partial colectomy (through a large abdominal incision, n = 10) were studied. MC protease tryptase and chymase were studied in peritoneal fluid at the beginning, middle, and end of each surgical intervention. Density of MCs in colectomy samples were examined and oro-caecal transit time by breath test, GI function recovery by clinical composite endpoint GI-2 and association between MC proteases and clinical recovery.

KEY RESULTS

Open and laparoscopic colectomy caused greater peritoneal release of tryptase and chymase (323.0 ng/mL [IQR: 53.05-381.4] and 118.6 ng/mL [IQR: 53.60-240.3]), than cholecystectomy (41.64 ng/mL [IQR: 11.17-90.93]) at the end of the surgical intervention. However, there were no differences between laparoscopic and open colectomy. Increased peritoneal protease release during surgery was observed in patients who developed POI after colectomy.

CONCLUSIONS & INFERENCES

Colorectal surgery causes protease release from peritoneal MCs. Protease release does not differ between both types of colectomy (laparoscopy vs laparotomy). However, MC activation is increased in colectomy patients developing POI. Therefore, degranulation of peritoneal MCs as a factor contributing to human POI after colectomy might be considered in future studies as a target to avoid POI.

Perspectives on the importance of postoperative ileus

Post-operative ileus (POI) is a common condition after surgery. Failure to restore adequate bowel function after surgery generates a series of complications and it is associated to patients frustration and discomfort, worsening their perioperative experience. Even mild POI can be source of anxiety and could be perceived as a drop out from the "straight-forward" pathway. Enhanced recovery programmes have emphasized the importance of early commencement of oral diet, avoiding the ancient dogmata of prolonged gastric decompression and fasting. These protocols with early oral feeding and mobilization have led to improved perioperative management and have decreased hospital length of stay, ameliorating patient's postoperative experience as well. Nonetheless, the incidence of POI is still high especially after major open abdominal surgery. In order to decrease the incidence of POI, minimally-invasive surgical approaches and minimization of surgical manipulation have been suggested. From a pharmacological perspective, a meta-analysis of pro-kinetics showed beneficial results with alvimopan, although its use has been limited by the augmented risk of myocardial infarction and the high costs. A more simple approach based on the postoperative use of chewing-gum has provided some benefits in restoring bowel function. From an anaesthesiological perspective, epidural anaesthesia/analgesia does not only reduce the postoperative consumption of systemic opioids but directly improve gastrointestinal function and should be considered where possible, at least for open surgical procedures. POI represents a common and debilitating complication that should be challenged with multi-disciplinary approach. Prospective research is warranted on this field and should focus also on patient s reported outcomes.

Clinical endpoint, early detection, and differential diagnosis of postoperative ileus: a systematic review of the literature

BACKGROUND

This systematic review summarizes evidence regarding clinical endpoints, early detection, and differential diagnosis of postoperative ileus (POI).

METHODS

Using MEDLINE, EMBASE, Cochrane, and Web-of-Science, we identified 2,084 articles. Risk of bias and level of evidence (LOE) of the included articles were determined, and relevant results were summarized.

RESULTS

Eleven articles were included, most of which with substantial risks of bias. Bowel motility studies revealed that defecation together with solid food tolerance is the most representative clinical endpoint of POI (LOE: 2b); other clinical signs (e.g. bowel sounds, passage of flatus) did not correlate with a full recovery of bowel motility. Inflammatory parameters including interleukin (IL)-6, IL-1, and TNF-α might assist in an early detection of prolonged POI (LOE: 4). Clinical manifestations (e.g. nausea, vomiting, abdominal distension, bowel sounds, flatus) and X-ray examinations provided limited aid to the differential diagnosis of POI, while CT with Gastrografin had the best specificity and sensitivity (both 100%; LOE: 1c).

CONCLUSIONS

Postoperative defecation together with tolerance of solid food intake seems to be the best clinical endpoint of POI. CT has the best differential diagnostic value between POI and other complications. Prospective studies with a high LOE are in great need.

Facilitating return of bowel function after colorectal surgery: alvimopan and gum chewing

Postoperative ileus is common after colorectal surgery, and has a huge impact on hospital LOS. With the impeding cost crisis in the United States, safely reducing length of stay is essential. Chewing gum and pharmacological treatment with alvimopan are safe, simple tools to reduce postoperative ileus and its associated costs. Future research will determine if integrating these tools with laparoscopic procedures and enhanced recovery pathways is a best practice in colorectal surgery.

The incidence of postoperative ileus in patients who underwent robotic assisted radical prostatectomy

Introduction

Our aim was to examine the incidence and risk factors of postoperative ileus among patients who underwent robot–assisted radical prostatectomy (RARP).

Material and methods

We retrospectively reviewed 239 patients who underwent RARP transperitoneally between February 2009 and December 2011. Patients switched to open surgery were excluded. We defined postoperative ileus as intolerance of a solid diet continued until the third postoperative day and beyond. By Clavien classification, we evaluated the perioperative complications that cause or contribute to postoperative ileus. Similarly, we analyzed the impact of anesthesia risk score on the incidence of postoperative ileus.

Results

The study included 228 patients. The mean period to tolerate solid food was 1.24 days. Only 6 patients experienced postoperative ileus, all of whom were treated with a conservative approach. The two groups differed significantly in the duration of abdominal drainage, hospital stay, modified Clavien classification, and the presence of comorbidity diabetes mellitus (P <0.5 for all factors). Multiple logistic regression analysis revealed that diabetes mellitus was an independent risk factor for postoperative ileus.

Conclusions

We suggest that diabetes mellitus is an independent risk factor for postoperative ileus in patients undergoing robot–assisted radical prostatectomy.

Postoperative ileus in colorectal surgery: is there any difference between laparoscopic and open surgery?

Background: Postoperative ileus is a major complication of patients undergoing abdominal surgery. The purpose of this study was to determine the effects of operative time and the method of surgery on postoperative ileus.

Methods: After institutional review board approval, 121 patients were studied in two groups. Group 1 consisted of 86 patients with colorectal cancers and Group 2 included 35 patients with diverticulitis. Various surgical procedures were performed in both groups. In all patients, the nasogastric (NG) tube was removed after termination of surgery. Clear liquids were offered commencing on the first postoperative day, followed by a regular diet as tolerated. GI-1 was the postoperative time to toleration of clear liquids, whereas GI-2 was the postoperative time to first bowel movement or flatus and toleration of a regular diet. Statistical analysis was performed using a linear regression model by disease with the first bowel movement or flatus as the dependent variable and operative time and category as explanatory variables.

Results: Vomiting after oral feeding occurred in 18 (20.9%) patients with cancer and in 7 (20.0%) patients with diverticular disease. An NG tube was reinserted in 13 (15.1%) patients in the cancer group and in 3 (8.6%) patients in the diverticular disease group. In patients with cancer, the duration of operation was associated with GI-2 (P = 0.011), whereas in patients with diverticulitis, the duration of operation was associated with GI-1 (P = 0.001) and GI-2 (P = 0.044). In the diverticulitis group, a significant relationship was found between GI-2 and operative category (P = 0.03).

Conclusion: Longer operations led to more prolonged postoperative ileus after both laparoscopy and laparotomy, regardless of malignant or benign pathology. In anticipation of and/or following longer operations, surgeons should consider measures to shorten postoperative ileus.

Randomized clinical trial on the effect of coffee on postoperative ileus following elective colectomy

Background

Postoperative ileus is a common problem after abdominal surgery. It was postulated that coffee intake would decrease postoperative ileus after colectomy.

Methods

This was a multicentre parallel open-label randomized trial. Patients with malignant or benign disease undergoing elective open or laparoscopic colectomy were assigned randomly before surgery to receive either coffee or water after the procedure (100 ml three times daily). The primary endpoint was time to first bowel movement; secondary endpoints were time to first flatus, time to tolerance of solid food, length of hospital stay and perioperative morbidity.

Results

A total of 80 patients were randomized, 40 to each group. One patient in the water arm was excluded owing to a change in surgical procedure. Patient characteristics were similar in both groups. In intention-to-treat analysis, the time to the first bowel movement was significantly shorter in the coffee arm than in the water arm (mean(s.d.) 60·4(21·3) versus 74·0(21·6) h; P = 0·006). The time to tolerance of solid food (49·2(21·3) versus 55·8(30·0) h; P = 0·276) and time to first flatus (40·6(16·1) versus 46·4(20·1) h; P = 0·214) showed a similar trend, but the differences were not significant. Length of hospital stay (10·8(4·4) versus 11·3(4·5) days; P = 0·497) and morbidity (8 of 40 versus 10 of 39 patients; P = 0·550) were comparable in the two groups.

Conclusion

Coffee consumption after colectomy was safe and was associated with a reduced time to first bowel action. Registration number: NCT01079442 (http://www.clinicaltrials.gov).

[Evaluation of changes made in the peri-operative care in patients submitted to elective abdominal surgery]

OBJECTIVE

To evaluate the results of the introduction of new measures to accelerate the postoperative recovery of patients undergoing elective abdominal surgery.

METHODS

We observed 162 patients and interviewed them on two distinct periods: the first between October to December 2009 (n = 81) comprised patients who underwent conventional perioperative monitoring (pre-intervention) and the second between March and May 2010 (n = 81), formed by a new group of patients, submitted to the new protocol of perioperative monitoring. Data collection in the two periods occurred without the knowledge of the professionals in the service. The variables were: indication for preoperative nutritional support, duration of fasting, post-operative volume of hydration, use of catheters and drains, length of stay and postoperative morbidity.

RESULTS

when comparing the two periods we observed a decrease of 2.5 hours in the time of preoperative fasting (p = 0.0002) in the post-intervention group. As for the reintroduction of oral diet, there was no difference between the two periods (p = 0.0007). When considering the patients without postoperative complications, there was a significantly decreased length of stay (p = 0.001325). There was a reduction of approximately 50% in antibiotic use in the post-intervention group (p = 0.00001).

CONCLUSION

The adoption of multidisciplinary perioperative measures is feasible within our reality, and although there was no statistically significant changes in the present study, it may improve morbidity and reduce length of stay in general surgery.

A randomized study comparing outcomes of stapled and hand-sutured anastomoses in patients undergoing open gastrointestinal surgery

Although stapling is an alternative to hand-suturing in gastrointestinal surgery, recent trials specifically designed to evaluate differences between the two in surgery time, anastomosis time, and return to bowel activity are lacking. This trial compared the outcomes of the two in subjects undergoing open gastrointestinal surgery. Adult subjects undergoing emergency or elective surgery requiring a single gastric, small, or large bowel anastomosis were enrolled into this open-label, prospective, randomized, interventional, parallel, multicenter, controlled trial. Randomization was assigned in a 1:1 ratio between the hand-sutured group (n = 138) and the stapled group (n = 142). Anastomosis time, surgery time, and time to bowel activity were collected and compared as primary endpoints. A total of 280 subjects were enrolled from April 2009 to September 2010. Only the time of anastomosis was significantly different between the two arms: 17.6 ± 1.90 min (stapled) and 20.6 ± 1.90 min (hand-sutured). This difference was deemed not clinically or economically meaningful. Safety outcomes and other secondary endpoints were similar between the two arms. Mechanical stapling is faster than hand-suturing for the construction of gastrointestinal anastomoses. Apart from this, stapling and hand-suturing are similar with respect to the outcomes measured in this trial.

Can the intestinal dysmotility of critical illness be differentiated from postoperative ileus?

Gastrointestinal dysmotility is commonly noted in the intensive care unit and postoperative settings. Characterized by delayed passage of stool and flatus, nausea, vomiting, and abdominal distention, the condition is associated with nutritional deficiencies, risk of aspiration, and considerable allocation of health care resources. Knowledge of gastrointestinal function in health and illness continues to expand. While the factors that precipitate ileus differ between postoperative and critically ill patients, the two clinical scenarios seem to have similar mechanisms and share many of the same pathophysiologic patterns. By reviewing and comparing the literature on the respective mechanisms and contributing factors generated in these separate clinical settings, a common more comprehensive management strategy may be derived with the potential for newer innovative therapeutic options.

Treatment of postoperative ileus with choline citrate--results of a prospective, randomised, placebo-controlled, double-blind multicentre trial

OBJECTIVES

This was a prospective, randomised, placebo-controlled, double-blind multicentre trial to analyse the efficacy of choline citrate in patients with postoperative ileus (POI) after elective colorectal surgery.

METHODS

From October 2005 until June 2008, 122 patients with POI were randomised to receive choline citrate or placebo. One hundred twenty patients were evaluable for tolerability and 107 patients were evaluable for efficacy. The treatment group, 47% (50/107), received 300.2 mg choline citrate intravenously, while the placebo group, 53% (57/107), received sodium chloride. Injections were performed every 12 h until defecation.

RESULTS

Demographic data analysis did not show clinically differences between both groups. Operative procedures included 40% (43/107) hemicolectomy, 38% (41/107) sigmoid resection and 22% (23/107) other colorectal resections. Defecation occurred after an average of 91.8 ± 26.6 h postoperatively in the treatment group, vs. 96.7 ± 35.2 h in the placebo group (p = 0.805). After laparoscopy, defecation occurred after 78.7 ± 25.3 h, vs. 99.2 ± 31.6 h after laparotomy (p = 0.001). Serious adverse effects occurred in 2% (1/60) in the treatment group, vs. 3% (2/60) in the placebo group. None of the events have been assessed as related to the study medication.

CONCLUSION

An efficacy of choline citrate in the treatment of POI after elective colorectal surgery could not be verified. The problem of POI requiring drug treatment seems to be less frequent than suggested by the literature. With technical advances in surgery, especially laparoscopic and fast track surgery, the frequency of POI will further decrease in the future.

Origin and propagation of human gastric slow-wave activity defined by high-resolution mapping

Slow waves coordinate gastric motility, and abnormal slow-wave activity is thought to contribute to motility disorders. The current understanding of normal human gastric slow-wave activity is based on extrapolation from data derived from sparse electrode recordings and is therefore potentially incomplete. This study employed high-resolution (HR) mapping to reevaluate human gastric slow-wave activity. HR mapping was performed in 12 patients with normal stomachs undergoing upper abdominal surgery, using flexible printed circuit board (PCB) arrays (interelectrode distance 7.6 mm). Up to six PCBs (192 electrodes; 93 cm(2)) were used simultaneously. Slow-wave activity was characterized by spatiotemporal mapping, and regional frequencies, amplitudes, and velocities were defined and compared. Slow-wave activity in the pacemaker region (mid to upper corpus, greater curvature) was of greater amplitude (mean 0.57 mV) and higher velocity (8.0 mm/s) than the corpus (0.25 mV, 3.0 mm/s) (P < 0.001) and displayed isotropic propagation. A marked transition to higher amplitude and velocity activity occurred in the antrum (0.52 mV, 5.9 mm/s) (P < 0.001). Multiple (3-4) wavefronts were found to propagate simultaneously in the organoaxial direction. Frequencies were consistent between regions (2.83 +/- 0.35 cycles per min). HR mapping has provided a more complete understanding of normal human gastric slow-wave activity. The pacemaker region is associated with high-amplitude, high-velocity activity, and multiple wavefronts propagate simultaneously. These data provide a baseline for future HR mapping studies in disease states and will inform noninvasive diagnostic strategies.

Systematic review and meta-analysis of chewing-gum therapy in the reduction of postoperative paralytic ileus following gastrointestinal surgery

BACKGROUND

Postoperative ileus has long been considered an inevitable consequence of gastrointestinal surgery. It prolongs hospital stay, increases morbidity, and adds to treatment costs. Chewing is a form of sham feeding reported to stimulate bowel motility. This analysis examines the value of chewing-gum therapy in treatment of postoperative ileus.

METHODS

A search for randomized, controlled trials studying elective gastrointestinal surgery was undertaken using MEDLINE, Embase, Cochrane Controlled Trials Register, and reference lists. Outcomes were extracted including time to first flatus and bowel motion, length of stay, and complications. Statistical analysis was undertaken using the weighted mean difference (WMD) and random-effects model with 95% confidence intervals (CI).

RESULTS

Seven studies with 272 patients were included. For time to first flatus the analysis favored treatment with a WMD of 12.6 h (17%) reduction (95% CI -21.49 to -3.72; P = 0.005). For time to first bowel motion, treatment was favored with a WMD of 23.11 h (22%) reduction (95% CI -34.32 to -11.91; P < 0.001). For length of stay, the analysis showed a nonsignificant trend toward treatment with WMD of 23.88 h (12%) reduction (95% CI -53.29 to +5.53; P = 0.11). There were no significant differences in complication rates.

CONCLUSIONS

Chewing-gum therapy following open gastrointestinal surgery is beneficial in reducing the period of postoperative ileus, although without a significant reduction in length of hospital stay. These outcomes are not significant for laparoscopic gastrointestinal surgery.

Mechanisms and potential applications of intestinal electrical stimulation

PURPOSE

Electrical stimulation of the gut has recently been under intensive investigation and various studies have revealed therapeutic potentials of gastrointestinal electrical stimulation for gastrointestinal motility disorders and obesity. While there have been a number of reviews on gastric electrical stimulation, there is a lack of systematic reviews on intestinal electrical stimulation. The aim of this review is to provide an overview on the effects, mechanisms, and applications of intestinal electrical stimulation.

RESULTS

We evaluated published data on intestinal electrophysiology, pathophysiology, and different methodologies on intestinal electrical stimulation and its possible mechanisms in both research and clinical settings using the MEDLINE database for English articles from 1963 to 2008. Based on this systematic review, intestinal electrical stimulation has been reported to alter intestinal slow waves, contractions and transit; the effects were mediated via both vagal and adrenergic pathways. Intestinal electrical stimulation has been reported to have potentials for treating various intestinal motility disorders and obesity.

CONCLUSIONS

It is concluded that intestinal electrical stimulation may have promising applications for treating motility disorders associated with altered intestinal contractile activity. The most recent studies have revealed possible applications of intestinal electrical stimulation for the treatment of obesity. Basic research results are promising; however, further clinical studies are needed to bring IES from bench to bedside.

Myoelectric activity of the ileum, cecum, proximal loop of the ascending colon, and spiral colon in cows with naturally occurring cecal dilatation-dislocation

OBJECTIVE

To analyze myoelectric activity of the ileum, cecum, proximal loop of the ascending colon (PLAC), and spiral colon in cows with naturally occurring cecal dilatation-dislocation (CDD) and compare findings with those in healthy cows.

ANIMALS

8 CDD-affected and 6 healthy control cows.

PROCEDURES

Immediately after diagnosis, CDD-affected cows underwent surgery; control cows underwent a similar surgical procedure. Before completion of surgery, 8 bipolar silver electrodes were implanted in the ileum (n = 2), cecum (1), PLAC (1), and spiral colon (4) of each cow. Beginning the day after surgery, intestinal myoelectric activity was recorded daily (8-hour period) for 4 days; data were analyzed by use of specialized software programs. Quantitative variables of myoelectric activity were compared between groups.

RESULTS

Cows of both groups recovered without complications after surgery. In control cows, physiologic myoelectric activity was recorded in all intestinal segments on all days after surgery. Apparently normal myoelectric activity was evident in the ileum of CDD-affected cows on the first day after surgery, but myoelectric activity patterns in the cecum, PLAC, and spiral colon were variable with no organized cyclic myoelectric patterns, incomplete or normally organized migrating myoelectric complexes, and slow normalization over time.

CONCLUSIONS AND CLINICAL RELEVANCE

After surgery for CDD, normal myoelectric patterns were disrupted in the large intestine of cows, especially in the spiral colon. Clinical recovery with effective transit of ingesta occurred before normalization of myoelectric activity in the large intestine. Therapeutic protocols for restoration or normalization of spiral colon motility should be developed for treatment of CDD-affected cattle.

Origin and propagation of the slow wave in the canine stomach: the outlines of a gastric conduction system

Slow waves are known to originate orally in the stomach and to propagate toward the antrum, but the exact location of the pacemaker and the precise pattern of propagation have not yet been studied. Using assemblies of 240 extracellular electrodes, simultaneous recordings of electrical activity were made on the fundus, corpus, and antrum in open abdominal anesthetized dogs. The signals were analyzed off-line, pathways of slow wave propagation were reconstructed, and slow wave velocities and amplitudes were measured. The gastric pacemaker is located in the upper part of the fundus, along the greater curvature. Extracellularly recorded slow waves in the pacemaker area exhibited large amplitudes (1.8 +/- 1.0 mV) and rapid velocities (1.5 +/- 0.9 cm/s), whereas propagation in the remainder of the fundus and in the corpus was slow (0.5 +/- 0.2 cm/s) with low-amplitude waveforms (0.8 +/- 0.5 mV). In the antrum, slow wave propagation was fast (1.5 +/- 0.6 cm/s) with large amplitude deflections (2.0 +/- 1.3 mV). Two areas were identified where slow waves did not propagate, the first in the oral medial fundus and the second distal in the antrum. Finally, recordings from the entire ventral surface revealed the presence of three to five simultaneously propagating slow waves. High resolution mapping of the origin and propagation of the slow wave in the canine stomach revealed areas of high amplitude and rapid velocity, areas with fractionated low amplitude and low velocity, and areas with no propagation; all these components together constitute the elements of a gastric conduction system.

A randomized trial of rocking-chair motion on the effect of postoperative ileus duration in patients with cancer recovering from abdominal surgery

Patients who undergo abdominal surgery experience a phenomenon commonly called postoperative ileus (POI). Standard of care requires patients to get out of bed, sit in a chair, and begin ambulating the first postoperative day. No evidence supports standard care activities reduce POI duration. Rocking-chair motion has shown promise in reducing POI duration. Sixty-six participants were randomized into 2 groups. The experimental group (n = 34) received standard care plus the rocking-chair intervention; the control group (n = 32) received standard care. Participants in the experimental group had shorter duration of POI, no effect on medication use, and time to discharge.

Effect of the ghrelin receptor agonist TZP-101 on colonic transit in a rat model of postoperative ileus

Ghrelin, the natural ligand of the growth hormone secretagogue receptor (ghrelin receptor), is an orexigenic gut hormone with prokinetic action in the upper gastrointestinal tract. Previously we have shown in a rodent model of postoperative ileus that the synthetic ghrelin receptor agonist TZP-101 prevents the delay in gastric emptying and improves small intestinal transit. The goal of the present study was to investigate whether TZP-101 affects colonic transit and food intake in rats with postoperative ileus. Fasted rats were treated with morphine and subjected to laparotomy under isoflurane anesthesia. Following surgery the animals were placed in clean home cages and fecal pellet output and food intake were monitored for 48 h. TZP-101 or vehicle were administered as 3 i.v. bolus infusions at 0 h, 2 h and 4 h post-surgery. TZP-101 (0.03-1 mg/kg) dose-dependently decreased the time to first bowel movement and increased fecal pellet output measured at 12 h and 24 h post-surgery compared to the vehicle. The administration of TZP-101 was not associated with a significant alteration in food intake. In conclusion, this study provides the first experimental evidence that a novel ghrelin receptor agonist improves large bowel function in rats with postoperative ileus, suggesting that TZP-101 may be useful in the clinic to accelerate upper gastrointestinal transit and to shorten the time to the first bowel movement following 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.

Role of bile in intestinal motility after massive liver resection in conscious rats

AIM

To investigate the effect of 90% partial hepatectomy (90% PHx) and the involvement of bile on ileal motility in conscious rats.

METHODS

Two strain gauge force transducers were chronically implanted in the ileum of each of 20 rats. The rats were divided into four groups, three of which underwent 90% PHx. The experiments were performed with the rats in a conscious, fasted state. After ileal motility was recorded, bile or saline was perfused into the duodenum of each rat in two of the 90% PHx groups. The effects of the perfusion on ileal motility were observed and recorded using the motility index (MI), defined as the area under the contraction cues after surgery and expressed as the ratio to the MI in the preoperational motility. The time of the first passage of stool after surgery was recorded.

RESULTS

A typical migrating motor complex (MMC) pattern was observed in normal fasted rats. Increased MMC cycle lengths and a decreased MI at 1 day and 3 days after 90% PHx were observed. The MMC after 90% PHx was characterized by an increased duration of Phase 2-like activity. The MMC cycle length, the MI, and the time of the first passage of stool after 90% PHx were improved by perfusion of bile into the duodenum through the biliary cannula but were not influenced by perfusion of saline into the duodenum through the biliary cannula.

CONCLUSION

The MMC cycle length and the MI were inhibited after 90% PHx, with the involvement of decreased bile flow into the gastrointestinal tract by liver resection.

Postoperative colonic motility after tropisetron and a standardized meal in patients undergoing conventional colorectal surgery

BACKGROUND

Early postoperative enteral nutrition is advantageous for the recovery of colonic motility but may be limited by abdominal distension, nausea, and vomiting. We aimed to investigate the tolerance of a standardized meal after pretreatment with the 5-hydroxytryptamine-3-receptor antagonist tropisetron and to study the concomitant colonic motility.

METHODS

Colonic motility and tone were recorded on postoperative day 1 to 3 with a combined manometry/barostat recording catheter in 12 patients who underwent open colorectal surgery with an anastomosis in the distal colon or rectum. The study protocol consisted of 30 min of baseline recordings followed by 5 mg of tropisetron intravenously. Then, motility was recorded for another 30 min before patients ingested a standardized meal to trigger the gastrocolonic response. Postprandial motility was recorded for the subsequent 60 min.

RESULTS

The colonic motility index increased after administration of tropisetron on all three postoperative days (day 1: 34+/-11 vs 122+/-48, day 2: 55+/-19 vs 101+/-25, and day 3: 42+/-16 vs 93+/-33 mmHg/min; p<0.05). No further increase of the motility index was observed postprandially. Frequency and amplitude of contractions were virtually unaffected by tropisetron and the meal. Barostat bag volume decreased postprandially in the proximal bag on the third, and in the distal bag on the first and second postoperative day (p<0.05). Patients' condition was unaffected by the standardized meal after tropisetron administration.

CONCLUSIONS

Tropisetron may enhance colonic motility in the early postoperative period; however, the gastrocolonic response was impaired thereafter. High caloric food intake is well tolerated early after surgery after tropisetron pretreatment.

Postoperative nausea and vomiting

Nausea and vomiting following surgery may either occur as postoperative nausea and vomiting, which is a condition that is mainly related to anesthesia, or as secondary to postoperative ileus, which denotes inhibition of gastrointestinal motility following surgery. Postoperative ileus is a multifactorial event with several contributing mechanisms. Although postoperative nausea and vomiting pathophysiology has been quite well-studied little is known about it. There are multiple targets for treatment, prevention, and its successful empirical management e.g. by 5-HT(3) receptor antagonists. This review describes different aspects of the pathophysiology of postoperative ileus and postoperative nausea and vomiting, their relevance to postoperative care, and the standardized approach to manage postoperative nausea and vomiting that was established by Apfel and coworkers. Despite the recent advances in the understanding and treatment of conditions that trigger nausea and vomiting in the postoperative period, these symptoms remain a significant problem that affects patients' recovery, comfort, and treatment cost.

Drug absorption from the small intestine in immediate postoperative patients

BACKGROUND

The effects of surgery on gastric emptying have been documented for a considerable time, but less is known about the effects in the small intestine. It is thought that there is minimal diminution in the absorptive capacity of the small intestine after operation, although there is no literature on drug absorption in the early period after surgery. This study investigated drug absorption from the small bowel in patients undergoing abdominal surgery.

METHODS

A prospective study of patients undergoing major abdominal surgery in which patients acted as their own preoperative controls was carried out. Patients were administered the test substances, acetaminophen and (99m)TcDTPA, before operation and 2 days after operation. Small intestine transit times, plasma concentrations and other pharmacokinetic variables were compared using Student's paired t-test. Two complementary studies were carried out to establish pharmacokinetic parameters.

RESULTS

There were no significant differences in the pre- and postoperative values of t(max), area under the curve, and area under the moment curve (AUMC) before and after operation (P>0.05). There were significant differences between the pre- and postoperative values of C(max) [C(max (preop))>C(max (postop)); P<0.05] and the pre- and postoperative values of mean residence time (MRT) [MRT((preop))<MRT((postop)); P<0.01].

CONCLUSIONS

Drug absorption from the small bowel in the postoperative patient does not differ significantly from its preoperative absorptive capacity.

Does Gum Chewing Ameliorate Postoperative Ileus? Results of a Prospective, Randomized, Placebo-Controlled Trial

BACKGROUND

A preliminary report has been interpreted to suggest that gum chewing reduces duration of postcolectomy ileus.

STUDY DESIGN

We rigorously tested this hypothesis in a prospective, randomized, placebo-controlled study. Patients undergoing open colectomy (n = 66) were randomized to receive 1 of 3 postoperative regimens beginning on postoperative day 1: sips (control, n = 21); sips and accupressure wrist bracelet (placebo, n = 23); and sips and gum chewing (treatment, n = 22). Patients were unaware of which regimen constituted placebo or treatment; end points were assessed by blinded investigators. Power was set a priori at 85% to detect a 0.75-day difference in time to first postoperative passage of flatus between placebo and treatment groups. Groups were compared using the log-rank test.

RESULTS

Groups were equivalent with respect to demographic and surgical characteristics. Median times to first postoperative passage of flatus were as follows: sips, 67 hours; bracelet and sips, 72 hours; gum and sips, 60 hours (p = 0.384). There were no significant differences in time to passage of first bowel movement, time until patients were ready for discharge, or time until actual discharge among the three groups. Inpatient and 30-day followup demonstrated no difference in frequency or distribution of postoperative complications.

CONCLUSIONS

In contrast to findings of a preliminary study, our clinical trial suggests that gum chewing, although safe, does not reduce duration of postcolectomy ileus.