Gastrointestinal myoelectric and clinical patterns of recovery after laparotomy

Post operative neutrophilic inflammation in equine small intestine after manipulation and ischaemia

REASONS FOR PERFORMING STUDY

Post operative ileus (POI) remains an important cause of post operative morbidity and mortality in the horse. However, clinical progression of naturally occurring cases of POI in both horse and man does not entirely support the 'neurogenic' hypothesis as the sole mechanism of POI; and the hypothesis that inflammation plays a major role at 12-24 h after surgery requires validation.

HYPOTHESIS

An inflammatory infiltrate in the muscularis externa and myenteric plexus of equine jejunum is present 18 h following a period of ischaemia.

METHODS

Samples of normal jejunum, jejunum from the proximal resection margins of clinical cases and jejunum obtained 18 h after 1 or 2 h ischaemia or manipulation alone were evaluated for neutrophil infiltration. Samples obtained 18 h after surgery were additionally evaluated for leucocyte activation using calprotectin immunohistochemistry. Results were evaluated by ANOVA and P < 0.05 was considered significant.

RESULTS

Significant neutrophilic inflammation was identified in the samples from the proximal resection margins of clinical cases compared to uninjured jejunum. In experimental cases, neutrophilic inflammation appeared to be increased further by 18 h and was identified through all intestinal layers, particularly in the serosa, fascial planes around circular and longitudinal muscle fibres, and myenteric plexus. This elevated level of neutrophilic inflammation was mirrored by an increased number of calprotectin-positive cells in these intestinal layers, indicating leucocyte activation.

CONCLUSIONS

Significant neutrophilic inflammation occurs in equine jejunal myenteric layers 18 h after surgery.

POTENTIAL RELEVANCE

This neutrophilic inflammation coincides with the clinical time point at which POI is identified and may indicate that inflammatory pathways, rather than solely neurogenic pathways, are responsible for POI in the horse.

Brief inhalation of low-dose carbon monoxide protects rodents and swine from postoperative ileus

OBJECTIVE

Carbon monoxide (CO), an endogenous byproduct of heme metabolism, is produced at high levels in injured tissue via induction of heme-oxygenase-1 activity, where it contributes to the modulation of proinflammatory processes. Alone, CO has potent anti-inflammatory effects in models of acute and chronic inflammation. In rodents, inhalation of low concentrations of CO (250 ppm) for 24 hrs protects against postoperative gastrointestinal ileus. The current study determined whether shorter exposures and lower concentrations were equally protective and whether CO treatment would be effective in a large animal species (swine) managed under conditions approximating the clinical setting.

DESIGN

Dosing studies were first performed in rats by exposing them to CO (30-250 ppm) or air by inhalation for 1 or 3 hrs before anesthesia. An effective dosing regimen was then selected for testing in swine. Postoperative ileus in both species was induced by laparotomy and mild compression (running) of the small intestine.

MEASUREMENTS AND MAIN RESULTS

In rats, inhalation of 75 ppm CO for 3 hrs before anesthesia and surgery ameliorated the surgically induced delay in gastrointestinal transit to levels achieved using 250 ppm for 24 hrs. Swine treated with 250 ppm CO for the same time period exhibited significantly improved postoperative intestinal circular muscle contractility in vitro and gastrointestinal transit in vivo. Carboxyhemoglobin concentrations measured after termination of CO exposure averaged 5.8% (baseline, 1.5%). No deleterious effects on heart rate, oxygen saturation, blood chemistries, and serum electrolytes were observed.

CONCLUSIONS

These findings demonstrate that inhalation of a low concentration of CO before surgery attenuates postoperative ileus in rodents and, more importantly, in a large animal species without risk to well-being during surgery or perioperatively. Exposures need not be prolonged, with significant benefit occurring with a 3-hr pretreatment.

Effect of adding ketorolac to intravenous morphine patient-controlled analgesia on bowel function in colorectal surgery patients--a prospective, randomized, double-blind study

BACKGROUND

Postoperative ileus (PI) is the transient impairment of bowel motility due to surgical trauma and the associated physiological responses. Postoperative ileus results in patient discomfort, increases gastrointestinal risks, prolongs hospital stay and increases medical expenses. In this study, we investigated the effect of patient-controlled analgesia (PCA) morphine with or without ketorolac on bowel functions in patients after colorectal surgeries.

METHODS

A total of 79 patients who received elective colorectal resection were randomly allocated into two groups receiving either intravenous PCA morphine (M group) or intravenous PCA morphine plus ketorolac (K group). Recovery of bowel functions (bowel movement, passage of flatus, and soft diet intake), pain scores, morphine consumption, time for first ambulation, and opioid-related side-effects were recorded.

RESULTS

Patients in the K group received 29% less morphine than patients in the M group with comparable pain scores. The first bowel movement (1.5 [0.7-1.9] vs. 1.7 [1.0-2.8] days, P < 0.05) and the first ambulation (2.2 +/- 1.0 vs. 2.8 +/- 1.2 days, P < 0.05) were significantly earlier in the K group than in the M group. The time of the first flatus passing, the first intake of soft diet, and duration of hospital stay were not significantly different between the two groups.

CONCLUSIONS

The results of this study suggest that addition of ketorolac to intravenous morphine PCA provides an opioid-sparing effect but has limited benefit in shortening the duration of bowel immobility and time to first ambulation. These findings imply that postoperative ileus is attributable to multiple factors in addition to morphine consumption.

Randomized controlled trial comparing the controlled rehabilitation with early ambulation and diet pathway versus the controlled rehabilitation with early ambulation and diet with preemptive epidural anesthesia/analgesia after laparotomy and intestinal resection

BACKGROUND

Multimodal postoperative care regimens accelerate recovery after abdominal surgery. The benefit of thoracic epidural (TE) analgesia over patient-controlled analgesia (PCA) remains unproven when used with a fast-track postoperative care plan.

METHODS

Fifty-six patients undergoing major intestinal resection, and on a fast-track postoperative care plan, were randomized to preemptive TE or PCA. Patients were evaluated at standard time points for pain score, quality of life (Short Form-36), and complications. Oral analgesia was substituted for TE and PCA on the second postoperative day. Discharge criteria were identical for both groups.

RESULTS

Six patients (20.6%) had a failed epidural. There was no difference in length of stay (5.8 versus 6.2 days, TE versus PCA, P = .55), total length of stay (including readmissions), pain scores, quality of life, complications, or hospital costs at any time point.

CONCLUSION

TE offers no advantage over PCA for patients undergoing major intestinal resections who are on a fast-track postoperative care plan using PCA.

The impact of early nutrition on metabolic response and postoperative ileus

PURPOSE OF REVIEW

Early nutrition has been evaluated and used as a possible strategy to decrease the negative impact of the metabolic response to injury and postoperative ileus. The metabolic response to injury, be it surgical or traumatic, is a physiological mechanism that, according to the magnitude and duration of the event, can impact on the patient's morbidity and survival. The adequate initial approach is a determinant factor that might influence its outcome. Simultaneously, gastrointestinal tract motility is transiently impaired, leading to the so-called postoperative ileus. The latter not only causes patient discomfort, but is also related to abdominal complications and worsening of the nutritional status, as well as increased length of hospital stay and costs.

RECENT FINDINGS

Multimodal surgical strategies such as preoperative intake of a carbohydrate drink, together with patient education of the postoperative care plan, efficacious analgesia and early nutrition have been described to significantly decrease the stress response and improve the ileus. Therefore, these strategies accelerate rehabilitation and, as a consequence, decrease complications and length of hospital stay and its related costs.

SUMMARY

Understanding perioperative pathophysiology and implementing care regimes through a multimodal approach in order to reduce the stress of the operation and the related postoperative ileus are major challenges. These factors will certainly impact on patient outcomes.

Myoelectric activity in the intestines of healthy dairy cows during the recovery period after implantation of permanent electrodes

OBJECTIVE

To describe myoelectric patterns in the intestines of cows after electrode implantation.

ANIMALS

7 lactating Simmental-Red Holstein cows.

PROCEDURE

Cows were implanted with 7 pairs of bipolar silver electrodes (1 each in the ileum, cecum, and proximal loop of the ascending colon (PLAC) and 4 in the spiral colon). Myoelectric activity was monitored during 10 periods within the first 3 weeks after surgery. Recordings from the first 2 weeks were compared with recordings from the third week, which was considered a steady-state condition.

RESULTS

Significant changes over time were detected for 18 of 57 variables, including 3 variables describing myoelectric activity of the ileum, 6 variables of the cecum, 6 variables of the PLAC, and 3 variables of the spiral colon. Compared with values for the steady-state condition, 16 variables differed significantly for the 14-day period after surgery (7 variables until day 11, 2 variables until day 8, 4 variables until day 5, 1 variable until day 3, and 2 variables until day 2 after electrode implantation). None of the variables had significant changes that lasted only 1 day after surgery.

CONCLUSIONS AND CLINICAL RELEVANCE

Significant changes were observed for several variables of myoelectric activity in all intestinal segments until as late as 11 days after electrode implantation, whereas a steady-state condition was reached 14 days after surgery. Effects of drugs, manipulations, or nutrition regimens on myoelectric activity of the bovine digestive tract should be evaluated no sooner than 2 weeks after electrode implantation.

Tyrphostin AG 126 inhibits development of postoperative ileus induced by surgical manipulation of murine colon

Manipulation of the bowel during abdominal surgery leads to a period of ileus, which is most severely manifested after procedures that directly involve the colon. Ileus is associated with the increased expression of proinflammatory cytokines and chemokines, a leukocytic infiltration into the muscularis, and the release of mediators from resident and infiltrating leukocytes that directly inhibit intestinal smooth muscle contractility. Phosphorylation of tyrosine residues on regulatory proteins by protein tyrosine kinases (PTKs) occurs at multiple steps in the signaling cascades that regulate the expression of proinflammatory genes. The purpose of this study was to determine whether inhibition of PTK activity will attenuate the inflammatory response associated with colonic ileus and lead to improved function. Using a rodent model of colonic postoperative ileus, we demonstrate that a single bolus injection of the PTK inhibitor tyrphostin AG 126 (15 mg/kg sc) before surgery significantly attenuates the surgically induced impairment of colonic contractility both in vivo and in vitro. Improvement in function was associated with a reduction in magnitude of inflammatory cell infiltrate and with a decrease in transcription of genes encoding proinflammatory mediators IL-1beta and monocyte chemoattractant protein (MCP)-1, inducible nitric oxide synthase, and cyclooxygenase-2. Furthermore, tyrphostin AG 126 pretreatment significantly inhibited activation of multifactorial transcription factor NF-kappaB, which could form the basis for reduction in proinflammatory mediator expression. These data demonstrate for the first time that inhibition of PTK activity may represent a novel approach for management of ileus in the clinical setting.

Clinical application of prokinetics

Intestinal stasis or ileus is a significant cause of mortality and morbidity in horses and has been attributed to a variety of causes, including loss of intrinsic or extrinsic electrical activity, incoordination of contractile activity from regional stimuli, and dissociation between electrical and mechanical activity. Proposed mechanisms include systemic shock, electrolyte disturbances, persistent luminal distention, ischemia, inflammation, peritonitis, endotoxemia, and anesthesia. Because the cause of ileus is likely multifactorial, a variety of pharmaceutics have been used to target specific causes. Prokinetics are defined as agents that facilitate or enhance the net movement of feed material down the length of the intestinal tract and do not simply produce an uncoordinated increase in local contractile activity. The primary objective of pharmaceutic intervention is to augment the pathways that stimulate motility or attenuate the inhibitory neurons that predominantly suppress activity. The objective of this article is to summarize the actions of prokinetic agents available and suggest clinical applications.

Postoperative ileus: etiologies and interventions

This article will review the pathophysiology of postoperative ileus, with emphasis on potential therapeutic targets, and examine the efficacy of pharmacologic and nonpharmacologic interventions. Proposed mechanisms include actuation of spinal and local sympathetic neural reflexes, inflammatory mediation, and exacerbation by anesthetic or surgical procedures. Some procedures or agents have shown clinical benefit, and these include use of laparoscopic surgery, thoracic epidurals, nonsteroidal anti-inflammatory drugs, and opiate antagonists. Other procedures may be helpful with low risk of adverse effects. These include early feeding and ambulation, laxatives, and possibly neostigmine.

Neostigmine increases postoperative colonic motility in patients undergoing colorectal surgery

BACKGROUND

Gastrointestinal motility is frequently impaired after abdominal surgery. We investigated the effects of neostigmine on colonic motility in patients after colorectal surgery and in healthy volunteers.

METHODS

Colonic motility was recorded by a manometry/barostat system in 12 patients after left colonic or rectal resection during baseline and after the intravenous administration of increasing doses of neostigmine on postoperative days 1, 2, and 3. In addition, colonic motility was recorded in 7 healthy volunteers.

RESULTS

Neostigmine increased the colonic motility index. This increase was from 135 +/- 28 mm Hg/min at baseline to 574 +/- 219 mm Hg/min after administration of 5 microg/kg neostigmine on day 3 after surgery (mean +/- SEM, P <.05). In healthy volunteers, neostigmine at a dose of 5 microg/kg increased the colonic motility index from 184 +/- 73 to 446 +/- 114 mm Hg/min (P <.05). Barostat bag volumes decreased dose-dependently after neostigmine administration in patients as well as in volunteers, indicating an increase in colonic tone.

CONCLUSIONS

Colonic motility and tone increased after neostigmine administration at a dose of 5 microg/kg in postoperative patients and in healthy volunteers. Neostigmine can be used to stimulate colonic motility after colorectal surgery and has a similar effect postoperatively as in healthy volunteers.

Preoperative intraluminal application of capsaicin increases postoperative gastric and colonic motility in rats

In a model to investigate postoperative gastrointestinal motility with strain gauge transducers in awake rats, we tested the effects of intraluminal capsaicin infusion into the cecum 2 days or 14 days prior to abdominal surgery. Acute infusion of capsaicin into the cecum for 30 minutes increased the gastric, small intestinal, and colonic motility index by up to 115%, 34%, and 59%, respectively, compared to vehicle infusion. Intraluminal capsaicin infusion 2 days prior to abdominal surgery significantly increased the intraoperative gastric and colonic motility index by 166% and 100%, respectively, compared to vehicle, but had no effect on small intestinal motility. The postoperative decrease in gastric or colonic motility was completely prevented by capsaicin pretreatment, representing a 73% and a 72% increase in the motility index during the first postoperative hour and a 40% and a 29% increase in the motility index during the second postoperative hour compared to vehicle, whereas the postoperative decrease in small intestinal motility was not altered by capsaicin pretreatment. In contrast, intraluminal capsaicin infusion 14 days prior to abdominal surgery had no effect on postoperative inhibition of gastrointestinal motility. Our results suggest that capsaicin-sensitive visceral afferent C-fibers, presumably of the submucosa, play an important role in mediating postoperative ileus. Intraluminal capsaicin does probably ablate these nerve fibers temporarily, with no systemic side effects observed with the use of the tail flick test as a measure of skin nociception.

Risk factors associated with development of postoperative ileus in horses

OBJECTIVE

To determine risk factors associated with development of postoperative ileus in horses undergoing surgery for colic.

DESIGN

Case-control study.

ANIMALS

69 horses that developed ileus after surgery for colic and 307 horses that did not develop postoperative ileus.

PROCEDURE

Signalment, history, clinicopathologic data, treatment, lesions, and outcome were obtained from medical records.

RESULTS

Variables associated with increased risk of postoperative ileus included age > 10 years, Arabian breed, PCV > or = 45%, high serum concentrations of protein and albumin, anesthesia > 2.5 hours' duration, surgery > 2 hours' duration, resection and anastomosis, and lesions in the small intestine. Enterotomy reduced the risk of postoperative ileus. After multivariate logistic regression, the final model included the variables Arabian breed, PCV > or = 45%, lesion type, duration of surgery (> 2 hours vs < or = 2 hours), and pelvic flexure enterotomy.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that by evaluating certain factors, horses at increased risk of postoperative ileus may be recognized before the condition develops. Preventative treatment and early intervention may be instituted in these horses. Shortening surgery time and performing an enterotomy may decrease the probability of horses developing postoperative ileus.

Postoperative ileus: a preventable event

BACKGROUND

Postoperative ileus has traditionally been accepted as a normal response to tissue injury. No data support any beneficial effect of ileus and indeed it may contribute to delayed recovery and prolonged hospital stay. Efforts should, therefore, be made to reduce such ileus.

METHODS

Material was identified from a Medline search of the literature, previous review articles and references cited in original papers. This paper updates knowledge on the pathophysiology and treatment of postoperative ileus.

RESULTS AND CONCLUSION

Pathogenesis mainly involves inhibitory neural reflexes and inflammatory mediators released from the site of injury. The most effective method of reducing ileus is thoracic epidural blockade with local anaesthetic. Opioid-sparing analgesic techniques and non-steroidal anti-inflammatory agents also reduce ileus, as does laparoscopic surgery. Of the prokinetic agents only cisapride is proven beneficial; the effect of early enteral feeding remains unclear. However, postoperative ileus may be greatly reduced when all of the above are combined in a multimodal rehabilitation strategy.

Postoperative colonic motility and tone in patients after colorectal surgery

PURPOSE

Colonic motility is crucial for the resolution of postoperative ileus. However, few data are available on postoperative colonic motility and no data on postoperative colonic tone. We aimed to characterize postoperative colonic tone and motility in patients.

METHODS

Nineteen patients were investigated with combined barostat and manometry recordings after left colonic surgery. During surgery a combined recording catheter was placed in the colon with two barostat bags and four manometry channels cephalad to the anastomosis. Recordings were performed twice daily from Day 1 to Day 3 after surgery.

RESULTS

Manometry showed an increasing colonic motility index, which was a mean (+/- standard error of the mean) of 37 +/- 5 mmHg/minute on Day 1, 87 +/- 19 mmHg/minute on Day 2, and 102 +/- 13 mmHg/minute on Day 3 (P < 0.05 for Day 1 vs. Day 2 and Day 2 vs. Day 3). Low barostat bag volumes indicating a high colonic tone were observed on Day 1 after surgery and increased subsequently (barostat bag I was 19 +/- 4, 32 +/- 6, and 32 +/- 6 ml; barostat bag II was 13 +/- 1, 19 +/- 3, and 22 +/- 5 ml on Days 1, 2, and 3, respectively; for both barostat bags P < 0.05 for Day 1 vs. Day 2 but not Day 2 vs. Day 3).

CONCLUSIONS

Colonic motility increased during the postoperative course. The low barostat bag volumes indicated a high colonic tone postoperatively which would correspond to a contracted rather than to a distended colon. High colonic tone postoperatively may be relevant for pharmacologic treatment of postoperative ileus.

Surgical manipulation of the gut elicits an intestinal muscularis inflammatory response resulting in postsurgical ileus

OBJECTIVE

To investigate the pathophysiologic mechanisms that lead to ileus after abdominal surgery.

SUMMARY BACKGROUND DATA

The common supposition is that more invasive operations are associated with a more extensive ileus. The cellular mechanisms of postsurgical ileus remain elusive, and few studies have addressed the mechanisms.

METHODS

Rats were subjected to incremental degrees of surgical manipulation: laparotomy, eventration, "running," and compression of the bowel. On postsurgical days 1 and 7, muscularis infiltrates were characterized immunohistochemically. Circular muscle activity was assessed using mechanical and intracellular recording techniques in vitro.

RESULTS

Surgical manipulation caused an increase in resident phagocytes that stained for the activation marker lymphocyte function-associated antigen (LFA-1). Incremental degrees of manipulation also caused a progressive increase in neutrophil infiltration and a decrease in bethanechol-stimulated contractions. Compression also caused an increase in other leukocytes: macrophages, monocytes, dendritic cells, T cells, natural killer cells, and mast cells.

CONCLUSION

The data support the hypothesis that the degree of gut paralysis to cholinergic stimulation is directly proportional to the degree of trauma, the activation of resident gut muscularis phagocytes, and the extent of cellular infiltration. Therefore, postsurgical ileus may be a result of an inflammatory response to minimal trauma in which the resident macrophages, activated by physical forces, set an inflammatory response into motion, leading to muscle dysfunction.

Effects of surgery on the pharmacokinetic parameters of drugs

As with other forms of stress, surgery is a time of fluctuating haemodynamics, physiological shifts, intense metabolic changes, and protein catabolism and anabolism. At times, these changes can occur within hours. There is a reasonable body of literature concerning the adverse effects of surgery on gastric emptying, but not on the effects of surgery on the distribution, metabolism and excretion of drugs. Gastric emptying is diminished or absent following major procedures, which prevent the delivery of orally administered drugs to their major site of absorption, the small bowel. Changes in the paracellular absorption of drugs may occur postoperatively, although transcellular absorption appears to be unimpaired. Distribution is affected by changes in blood volume, alterations in circulation, increases in the extracellular fluid and changes in the circulating plasma protein levels, such as albumin and alpha 1-acid glycoprotein. Little is known about alterations in drug metabolism following surgery. However, it has been shown that systemic hypoxia alters the function of some of the cytochrome P450 (CYP) system and increased levels of cytokines have an effect on the metabolism of at least 1 drug. In addition, the renal elimination of drugs is affected in patients postoperatively, although the effects of biliary clearance in this period are difficult to determine. Despite the lack of research into pharmacokinetics during the postoperative period, and given the immense and often sudden changes observed in patients post-surgery, it is reasonable to recommend vigilance with respect to drug therapy during this period.

A model to investigate postoperative ileus with strain gauge transducers in awake rats

BACKGROUND

Postoperative ileus influences patients well-being, hospital stay, and health cost, and postoperative inhibition of colonic motility is a major contributor to postoperative ileus. Experimental models for investigating postoperative ileus are needed. In particular, recording of postoperative colonic motility in awake rats has not been described yet.

MATERIAL AND METHODS

Gastric, small intestinal, and colonic motility were recorded with strain gauge transducers in awake rats, and the effects of anesthesia and abdominal surgery on gastrointestinal motility were investigated.

RESULTS

Ether anesthesia increased gastric motility and inhibited small intestinal motility, while enflurane anesthesia had only minor effects on gastrointestinal motility. Abdominal surgery inhibited gastric, small intestinal, and colonic motility, and a detailed analysis of gastrointestinal motility in our postoperative ileus model is given.

CONCLUSIONS

We established a model to record gastric, small intestinal, and colonic motility in awake rats postoperatively. We could demonstrate that enflurane anesthesia had little effect on gastrointestinal motility, while laparotomy and short manipulation of the cecum produced a prolonged inhibition of gastrointestinal motility. Our model could be used to investigate postoperative ileus, particularly of the colon, in awake rats.

Canine intestinal myoelectric activity after open versus laparoscopically assisted right hemicolectomy

BACKGROUND

It is a common belief that a laparoscopic procedure results in a shorter duration of postoperative ileus compared with the equivalent open procedure. This study was undertaken to determine whether laparoscopically assisted right hemicolectomy in the dog results in a shorter duration of ileus compared with open right hemicolectomy.

METHODS

Eight bipolar serosal electrodes (4 on the small bowel, 4 on the left colon) were implanted in each dog (n = 10). Three weeks after electrode implantation baseline recording was made for 5 days; then 5 dogs underwent laparoscopically assisted right hemicolectomy and 5 underwent open right hemicolectomy. Myoelectric activity was recorded continuously for 72 hours postoperatively. Tracings were analyzed for the time of reappearance, duration, migration velocity, and cycle length of phase 2, phase 3, and the migrating colonic complex. The criteria used for the resolution of postoperative ileus were the return of phase 2, phase 3, and the migrating colonic complex.

RESULTS

All dogs had temporary loss of organized myoelectric activity postoperatively. The mean reappearance time (minutes +/- standard deviation) for phase 3 was 857 +/- 574 versus 761 +/- 600; the phase 2 reappearance time was 1,845 +/- 610 versus 1,590 +/- 668; and the migrating colonic complex reappearance time was 534 +/- 365 versus 572 +/- 552, open versus laparoscopically assisted right hemicolectomy, respectively. The times were not different (Wilcoxon rank sum test, P > 0.05). The time required for phase 3, phase 2, and the migrating colonic complex to attain preoperative configuration also was not different between the open and laparoscopically assisted group.

CONCLUSION

Myoelectric resolution of postoperative ileus did not occur earlier in the dog undergoing laparoscopically assisted right hemicolectomy compared to the dog undergoing open right hemicolectomy. This data does not support the hypothesis that a laparoscopically assisted colectomy results in a shorter duration of postoperative ileus than the equivalent open procedure.

Electrogastroenterographic examination of 22 patients before and after cholecystectomy

The object of this study was to define the pattern of gastrointestinal myoelectrical activity before and after cholecystectomy. After surgery, on the first postoperative day, the mean and maximal activities of the gastrointestinal tracts decreased significantly, but there was no significant change in the pattern and the duration of the nonreactive period. A dyskinetic effect and/or weakness of electrical activity was observed in all patients before operation, and the same pattern persisted after operation for one month. This suggests the future onset of the so-called postcholecystectomy syndrome, which may result from the fundamental pathological effect of gallstones.

Gastrointestinal recovery following laparoscopic vs open colon surgery

BACKGROUND

We prospectively studied the recovery of gastrointestinal motility in patients undergoing laparoscopic (LAP, n = 7) or open (OPEN, n = 7) colon resections.

METHODS

At operation, bipolar recording electrodes were placed on the proximal and distal antrum, the proximal site of the colonic anastomosis, and the rectosigmoid for postoperative myoelectric recordings.

RESULTS

Shorter postoperative hospitalization and earlier resumption of a regular diet of the LAP group just barely failed to achieve significant differences when compared with the OPEN group (p = 0.091, p = 0.050, respectively). There were no differences between groups for slow wave frequency, amplitude, or dysrhythmias in the antrum, nor for return of discrete (DERA) and continuous (CERA) electrical response activity in the colon. Percentage of slow waves with spike activity tended to increase with passage of time postoperatively in both groups. There was a significant difference between POD 3 and 7+ in the LAP group (p < 0.05). However, there were no significant differences in the percentage of slow waves with spike activities between groups on any postoperative day.

CONCLUSIONS

The potential benefits of using a laparoscopic approach to colon resection are not clearly confirmed by these data. While such an approach may possibly result in shorter hospitalization, it appears to offer at best only modest increases in the rapidity of recovery of gastrointestinal function.

Gastric myoelectric activity changes following open abdominal surgery in humans

We examined the postoperative changes in fasting gastric myoelectric activity in 11 patients undergoing nongastric surgery (colon surgery) via celiotomy. Recordings were performed on postoperative days (POD) 1, 2, 3, 5, and 7+ (7-35) for 1-1.5 hr after overnight fasting. Patients had placement of bipolar seromuscular recording electrodes on the proximal (N = 9) and distal (N = 11) antrum at the time of surgery. Data were analyzed visually and analysis of variance or tests of proportion were used for statistical analysis. Although there was a trend of decreasing slow wave frequency from POD 1 to 7+ in the proximal and distal antrum, no significant differences were observed in slow wave amplitude or in the percentage of slow waves with spike activity between postoperative day. In a few of the patients, several types of gastric dysrhythmias were infrequently observed. We conclude that certain parameters of fasting gastric myoelectric activity do not change sufficiently following open abdominal surgery to adequately reflect clinical recovery from postoperative ileus.

Recovery of gastrointestinal motility following open versus laparoscopic colon resection in dogs

The recovery of gastrointestinal motility was compared in dogs undergoing either laparoscopic or open sigmoidectomy. During surgery, bipolar recording electrodes were placed on the proximal and distal antrum, mid- and distal colon, and the rectum. Fasting myoelectric data were recorded postoperatively. Scintigraphic gastric emptying studies employing a solid test meal were performed before and after [postoperative day (POD) 2] operation. Ten radiopaque markers were given just before operation and retained markers were counted daily by abdominal x-ray. Gastric emptying on POD 2 was significantly delayed in the open group at 120 min compared with preoperative studies for the open group and compared with the laparoscopic group on POD 2 (P < 0.05 and P < 0.01, respectively). A significant difference in the number of retained markers was observed between the groups on POD 4 (P < 0.05). There were no significant differences in slow-wave frequency, presence of dysrhythmias in the proximal and distal antrum, or presence of either discrete or continuous electrical response activity in the colon and rectum between groups on any days. We conclude that using a laparoscopic approach results in more rapid recovery of fed-state gastrointestinal motility following colon resection. These data also suggest that myoelectric activity alone is not a sensitive enough parameter to detect these differences in recovery in this animal model.

Gastrointestinal motility and disease in large animals

An understanding of the relationship between gastrointestinal (GI) motility and disease is imperative for the proper treatment of large animal patients, especially as new therapeutic agents become available. However, the abundance of information that has become available in the last 2 decades makes gaining this understanding a formidable task. This article summarizes the changes in GI motility caused by some common diseases and conditions encountered in large animal practice, such as GI obstruction, postoperative ileus, resection and anastomosis, diarrhea, endotoxemia, GI parasitism, hypocalcemia, and pregnancy.

Characterization of distal colonic motility in early postoperative period and effect of colonic anastomosis

Under standardized conditions, the manometric motility of the distal colon following rectosigmoid anastomosis (N = 11, median age 70 years, range 47-80), was compared to that following laparotomies not involving colonic anastomosis (N = 9, 56 years, 32-65). Microtransducer probes were inserted peroperatively and colonic activity recorded continuously (median 96 hr, range 48-109 anastomotic and 75 hr, range 46-107 control group) employing an ambulatory system. Quantitative indices of motility were calculated with an automated analysis program. Total postoperative analgesic doses and duration of surgery were similar in both groups. The first return in the anastomotic group of isolated waveforms [median 1.8 hr, interquartile range (IQR) 1-3] and propagated waves (92 hr, 79-100), was comparable to the control group (4 hr, 1.8-7, and 73 hr, 72-101, respectively). Motor complexes, characterized by bursts of regular contractile activity at 3-5 cpm, returned faster in the control group (3 hr, 2-24 vs 24 hr, 19-30, P < 0.05). Motility index was significantly depressed during the first 72 hr following surgery in the anastomotic group compared to controls (P < 0.001). Flatus was passed at a median of 72 hr (IQR 45-79) in the control and 94 hr (81-105) in the anastomotic group (P = 0.05). The presence of a left-sided colonic anastomosis has a major inhibitory effect on distal colonic motility, compared to nonanastomotic surgery of similar severity, in the early postoperative period.

Small bowel motility following major intra-abdominal surgery: the effects of opiates and rectal cisapride

BACKGROUND/AIMS

Human small bowel motility is altered after laparotomy. Opiate analgesia is a possible cause of these alterations, and cisapride is a potential therapy.

METHODS

Continuous proximal small bowel manometry was performed for up to 92 hours in 23 patients after major intra-abdominal surgery. They were treated with rectal cisapride (30 mg three times daily) or placebo until the clinical resolution of ileus. Small bowel manometry was performed for 30 hours in 5 volunteers receiving 1 mg/kg meperidine over 3 hours.

RESULTS

Phase III activity was present within 3 hours of the end of surgery in all patients. Initially, the migrating motor complex (MMC) period was markedly reduced (mean, 22 minutes) but gradually increased. Phase II activity was absent until a median of 40 hours had elapsed. Phase III contractile amplitude was markedly attenuated in the jejunum, in contrast to that in the duodenum, presumably as a result of dilatation and/or altered tone, increasing to normal by 72 hours. In the volunteer group, although the MMC period was reduced by meperidine, it remained significantly greater than that of the placebo patient group for approximately 48 hours and phase II was reduced but not eliminated. Cisapride induced some changes in motor activity but did not accelerate the recovery of normal motility. Clinical outcome, assessed by the return of bowel sounds and passage of flatus, was accelerated by cisapride, but the trend was not significant (P = 0.11).

CONCLUSIONS

This is the first published study using prolonged manometry to show the gradual evolution of small bowel motor activity after major intra-abdominal surgery. The findings suggest that surgery decreases the MMC period to the equivalent of the absolute refractory period, thereby eliminating phase II, which returns as the MMC period lengthens. Cisapride, at the dosage given, confers only modest benefit.

Does disorder of gastrointestinal motility affect food intake in the post-surgical patient?

In summary, POI is a predictable event with actual return of bowel function preceding clinically detectable signs of function by at least 24 h. All parts of the gastrointestinal tract are affected, but small-intestinal function returns first, probably as early as 4-8 h after surgery in many cases. The timing of restarting feeding could be earlier than current practice would suggest, and because of the more rapid recovery of small-intestinal function it could be argued that post-pyloric feeding, at least in the first 24-48 h, may be preferable. While a policy of refeeding only when bowel function is clinically detectable is acceptable for many patients, there are certainly some who would benefit from feeding at an earlier stage. Parenteral feeding is expensive and a greater knowledge of the mechanisms underlying POI may lead clinicians to different and perhaps more appropriate methods of management.

Pathophysiology of small intestinal motility

Only in the last few years have we begun to understand the effects of surgical procedures on contractile activity of the small intestine. Although most patients readily adapt to the procedures that are performed, operations such as small intestinal transplantation make it imperative that we pursue a more thorough understanding of the effects of surgery on the motility of the small intestine.

Measurement of electrical activity of the human small intestine using surface electrodes

Electrical activity of the human small intestine is usually measured by implanted or intraluminal electrodes. The application of these invasive techniques is, however, very limited. In this paper, a noninvasive technique is introduced to measure electrical activity of the small intestine by placing electrodes on the abdominal skin over the small intestine. Surface recordings were obtained in ten healthy volunteers, three patients with total gastrectomy and five patients with gastroparesis (a slight degree of paralysis of the mucosal coat of the stomach) with implanted electrodes on the serosa of the duodenum. An omnipresent 9-12 cpm electrical activity was observed in all surface recordings. Our findings from the surface electrodes were consistent with those reported in the literature via implanted or intubated electrodes. It is concluded that the technique described in this paper provides a noninvasive way to measure electrical activity of the small intestine. It may have potential application in medical research and clinical diagnosis.

Physiology and pathophysiology of colonic motor activity (2)

The basic motor function of the colon is to mix and knead its contents, propel them slowly in the caudad direction, hold them in the distal colon until defecation, and provide a strong propulsive force during defecation. Infrequently, it also produces mass movements in the proximal colon. These motor functions are achieved in most species by three different types of contractions: the individual phasic contractions that include the short- and long-duration contractions, organized groups of contractions that include the migrating and nonmigrating motor complexes, and special propulsive contractions (giant migrating contractions). The spatial and temporal patterns of all of these contractions are controlled by myogenic, neural, and chemical control mechanisms. The individual phasic contractions are highly disorganized in time and space in the colon. For this reason, they are effective in mixing and kneading and slow distal propulsion. The underlying cause of the disorganization of short duration contractions is the irregularity in the frequency and waveshape of colonic electrical control activity and its phase unlocking throughout the colon. The individual contractions in many species occur in cyclic bursts called contractile states. At least in some species, these contractile states exhibit mostly caudad and sometimes orad migration. However, there are also nonmigrating or randomly migrating contractile states in the colon. These two patterns of contractile states are called colonic migrating motor complexes and colonic nonmigrating motor complexes, respectively. The giant migrating contractions provide the strong propulsive force for defecation and mass movements. The neural control of colonic contractions is organized at three levels--enteric, autonomic, and central. The enteric nervous system contains cholinergic and peptidergic neurons and plays a major role in the control of colonic contractions. The autonomic nerves, the vagi, pelvic, lumbar colonic, hypogastric, and splanchnic nerves, seem to continuously monitor the state of the colon and provide a modulatory input when necessary. These nerves play a major role in the reflexive control of colonic motor function. The voluntary input from the central nervous system coordinates the motor activity of the colon, rectum, anal canal and sphincters for orderly evacuation of feces during defecation. The role of acetylcholine, nonadrenaline, and the yet to be completely identified nonadrenergic, noncholinergic neurotransmitter, possibly VIP, in the control of contractions is fairly well established. Besides these, there are several other peptides and chemicals that are localized in the colonic wall; their physiological roles remain unknown. Colonic motor activity has been studied in several disease states. The findings have not always been consistent.(ABSTRACT TRUNCATED AT 400 WORDS)