Intestinal Motility Index Research Articles

Photoacoustic Imaging as a Novel Non-invasive Biomarker to Assess Intestinal Tissue Oxygenation and Motility in Neonatal Rats

BackgroundWithin the premature infant intestine, oxygenation and motility play key physiological roles in healthy development and disease such as necrotizing enterocolitis. To date, there are limited techniques to reliably assess these physiological functions that are also clinically feasible for critically ill infants. To address this clinical need, we hypothesized that photoacoustic imaging (PAI) can provide non-invasive assessment of intestinal tissue oxygenation and motility to characterize intestinal physiology and health. MethodsUltrasound and photoacoustic images were acquired in 2-day and 4-day old neonatal rats. For PAI assessment of intestinal tissue oxygenation, an inspired gas challenge was performed using hypoxic, normoxic, and hyperoxic inspired oxygen (FiO2). For intestinal motility, oral administration of ICG contrast agent was used to compare control animals to an experimental model of loperamide-induced intestinal motility inhibition. ResultsPAI demonstrated progressive increases in oxygen saturation (sO2) as FiO2 increased, while the pattern of oxygen localization remained relatively consistent in both 2-day and 4-day old neonatal rats. Analysis of intraluminal ICG contrast enhanced PAI images yielded a map of the motility index in control and loperamide treated rats. From PAI analysis, loperamide significantly inhibited intestinal motility, with a 32.6% decrease in intestinal motility index scores in 4-day old rats. ConclusionThese data establish the feasibility and application of PAI to non-invasively and quantitatively measure intestinal tissue oxygenation and motility. This proof-of-concept study is an important first step in developing and optimizing photoacoustic imaging to provide valuable insight into intestinal health and disease to improve the care of premature infants.

Utility of Octreotide in Advancing Enteral Feeds in Children with Chronic Intestinal Pseudo-Obstruction.

Chronic intestinal pseudo-obstruction (CIPO) is a challenging disorder with high morbidity and mortality due to limited effective therapies that improve enteral tolerance. We aimed to present our experience using octreotide in children with CIPO and evaluate factors predicting therapy response. The study population included total parenteral nutrition (TPN)-dependent children with CIPO receiving octreotide at a tertiary care center. Octreotide response was defined as an enteral feeding increase of ≥10cc/kg/day. A total of 16 children were included (median age 5 years, range 1-18; 88% female). We observed an overall feed increase in 11/16 (69%) subjects and 7/16 (44%) were considered responders: three tolerated >65cc/kg/day (discontinued TPN), one tolerated >30cc/kg/day (decreased TPN) and three patients tolerated 10-12cc/kg/day. We found an association between therapeutic octreotide response and both the presence of octreotide-induced intestinal phase III of the migrating motor complex (MMC) as well as a higher median increase in intestinal motility index after octreotide challenge during the antroduodenal manometry (p=0.03 and <0.01, respectively). We did not find an association between octreotide response and age, presence of ileostomy, and colonic manometry testing parameters. Side effects were observed in four patients: an allergic reaction and hyperglycemia requiring octreotide discontinuation, hypertension that responded to dose reduction, and cholecystitis (gallstones) with octreotide successfully restarted after cholecystectomy. Octreotide is safe and effective in improving enteral tolerance in TPN-dependent children with CIPO and the antroduodenal manometry may be helpful in predicting octreotide response. Prospective studies are needed to evaluate the safety and efficacy of octreotide in children with CIPO.

Combined Method for Reduction of High Frequency Interferences in Surface Electroenterogram (EEnG)

Surface electroenterogram (EEnG) recording is a novel technique for monitoring intestinal motility non-invasively. However, surface EEnG recordings are contaminated by cardiac activity, the respiratory artefact, movement artefacts and other types of interference. The goal of this work is to remove electrocardiogram (ECG) interference and movement artefacts from surface EEnG by means of a combined method of empirical mode decomposition and independent component analysis. For this purpose, 11 recording sessions were conducted on animal models. In order to quantify the effectiveness of the proposed method, several parameters were calculated from each session: signal-to-ECG interference ratio (S/I), energy over 2 Hz (EF2) which quantifies the intestinal motility index of external EEnG recording and the variation of EF2. The proposed method removes both ECG interference and movement artefacts from surface EEnG, obtaining a significantly higher S/I ratio and considerably reducing the non-physiological variation of EF2. Furthermore, after applying the combined method, the correlation coefficient between internal recording EF2 and surface recording EF2 rises significantly. The proposed method could therefore be a useful tool to reduce high frequency interference in EEnG recording and to provide more robust non-invasive intestinal motility indexes.

The detection of intestinal spike activity on surface electroenterograms

Myoelectrical recording could provide an alternative technique for assessing intestinal motility, which is a topic of great interest in gastroenterology since many gastrointestinal disorders are associated with intestinal dysmotility. The pacemaker activity (slow wave, SW) of the electroenterogram (EEnG) has been detected in abdominal surface recordings, although the activity related to bowel contractions (spike bursts, SB) has to date only been detected in experimental models with artificially favored electrical conductivity. The aim of the present work was to assess the possibility of detecting SB activity in abdominal surface recordings under physiological conditions. For this purpose, 11 recording sessions of simultaneous internal and external myolectrical signals were conducted on conscious dogs. Signal analysis was carried out in the spectral domain. The results show that in periods of intestinal contractile activity, high-frequency components of EEnG signals can be detected on the abdominal surface in addition to SW activity. The energy between 2 and 20 Hz of the surface myoelectrical recording presented good correlation with the internal intestinal motility index (0.64 ± 0.10 for channel 1 and 0.57 ± 0.11 for channel 2). This suggests that SB activity can also be detected in canine surface EEnG recording.

Thoracic epidural anesthesia improves the gastric microcirculation during experimental gastric tube formation

Background Gastric tube formation is a surgical technique to reestablish the continuity of the gastrointestinal tract after esophagectomy. Our aims were to study the microcirculatory consequences of experimental gastric tube formation and characterize the effects of thoracic epidural anesthesia (TEA) during this condition. Methods The experiments were performed on mongrel dogs anesthetized with pentobarbital. The stomach was prepared for replacement according to the method of Akiyama, and TEA was induced with bupivacaine (1 mg/kg). Macrohemodynamics, intramucosal pH, and gastric motility changes were monitored, and intravital video-microscopy with orthogonal polarization spectral imaging technique was used to observe the gastric microcirculation. Results The gastric pull-up induced a significant decrease in intramucosal pH. The functional capillary density of the mucosa or subserosa did not change; the red blood cell velocity in the capillaries of the upper part of the gastric tube was decreased in the mucosa, as well as on the serosal side. After epidural anesthesia the red blood cell velocity returned to the baseline, and the gastric and intestinal motility index was significantly increased. Conclusions TEA significantly improves the microcirculation of the distal portion of the gastric tube and increases the intestinal and gastric motility after gastric pull-up. The procedure is favorable and should be recommended during reconstructive esophageal surgery.

Glucagon-like peptide-1 (GLP-1) strongly affects duodeno-cecal transit time, but only weakly small intestinal motility index in humans

Glucagon-like peptide-1 (GLP-1) strongly affects duodeno-cecal transit time, but only weakly small intestinal motility index in humans

Effect of enteric pacing on intestinal motility and hormone secretion in dogs with short bowel

The present study was designed to examine the role of electrode position during retrograde pacing in dogs with short bowel syndrome and unsevered intact duodenum. In nine beagle dogs a subtotal resection of the small bowel and jejunoileostomy was performed. In five of these dogs, an isolated blind loop (jejunum) with preserved mesenteric connections was left in situ as an additional place for a stimulation electrode. Small intestinal motility and plasma levels of insulin, glucagon, gastrin, somatostatin, and glucose were examined during pacing of the residual jejunum or the isolated loop, respectively, compared with control experiments in the same dogs without pacing. During pacing of the loop a significant (P < 0.05−0.01) decrease in the postprandial small intestinal motility index was observed combined with a significant (P < 0.05) increase in plasma insulin levels, whereas the postprandial increase in glucagon, somatostatin, gastrin, and glucose levels was not different from that in controls. In contrast, pacing of the jejunum increased postprandial small intestinal motility index (≤ 68%), whereas the levels of the four hormones and plasma glucose were not different from those in controls. The data suggest that in dogs with intact duodenum, pacing on an excluded loop is required to obtain the desired effect of reduced intestinal motility and improved anabolic pancreatic hormone secretion.