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

A novel pilot study to evaluate the efficacy and safety of a wireless patch system in patients with chronic nausea and vomiting

BACKGROUND

Gastric sensorimotor disorders (functional dyspepsia [FD] and gastroparesis [GP]) are prevalent and burdensome. Prolonged ambulatory recording using a wireless patch may provide novel information in these patients.

METHODS

Consecutive adult patients (age ≥ 18 years) referred for gastric emptying scintigraphy (GES) were eligible for study inclusion. Patients were excluded if they had prior foregut surgery; were taking opioids or other medications known to affect gastric emptying; had a HgbA1C > 10; or were recently hospitalized. Three wireless motility patches were applied to the skin prior to GES. Patients wore the patches for 6 days while recording meals, symptoms, and bowel movements using an iPhone app.

KEY RESULTS

Twenty-three consecutive adults (87% women; mean age = 43.9 years; mean BMI = 26.7 kg/m2) were enrolled. A gastric histogram revealed three levels of gastric myoelectric activity: weak, moderate, and strong. Patients with delayed gastric emptying at 4 h had weak gastric myoelectrical activity. Patients with nausea and vomiting had strong intestinal activity. Those with FD had weak gastric and intestinal myoelectric activity, and a weak meal response in the stomach, intestine, and colon compared to those with nausea alone or vomiting alone.

CONCLUSIONS AND INFERENCES

Patients with FD, and those with delayed gastric emptying, had unique gastrointestinal myoelectrical activity patterns. Reduced postprandial pan-intestinal myoelectric activity may explain the symptoms of FD in some patients. Recording gastrointestinal activity over a prolonged period in the outpatient setting has the potential to identify unique pathophysiologic patterns and meal-related activity that distinguishes patients with distinct gastric sensorimotor disease states.

Perioperative Gastrointestinal Myoelectric Activity Measurement Using Wireless External Patches

BACKGROUND

Stomach, small intestine, and colon have distinct patterns of contraction related to their function to mix and propel enteric contents. In this study, we aim to measure gut myoelectric activity in the perioperative course using external patches in an animal model.

METHODS

Four external patches were placed on the abdominal skin of female Yucatan pigs to record gastrointestinal myoelectric signals for 3 to 5 d. Pigs subsequently underwent anesthesia and placement of internal electrodes on stomach, small intestine, and colon. Signals were collected by a wireless transmitter. Frequencies associated with peristalsis were analyzed for both systems for 6 d postoperatively.

RESULTS

In awake pigs, we found frequency peaks in several ranges, from 4 to 6.5 cycles per minute (CPM), 8 to 11 CPM, and 14 to 18 CPM, which were comparable between subjects and concordant between internal and external recordings. The possible effect of anesthesia during the 1 or 2 h before surgical manipulation was observed as a 59% (±36%) decrease in overall myoelectric activity compared to the immediate time before anesthesia. The myoelectrical activity recovered quickly postoperatively. Comparing the absolute postsurgery activity levels to the baseline for each pig revealed higher overall activity after surgery by a factor of 1.69 ± 0.3.

CONCLUSIONS

External patch measurements correlated with internal electrode recordings. Anesthesia and surgery impacted gastrointestinal myoelectric activity. Recordings demonstrated a rebound phenomenon in myoelectric activity in the postoperative period. The ability to monitor gastrointestinal tract myoelectric activity noninvasively over multiple days could be a useful tool in diagnosing gastrointestinal motility disorders.

Abdominal massage to prevent ileus after colorectal surgery. A single-center, prospective, randomized clinical trial: the MATRAC Trial

BACKGROUND

There is scarce literature on the effect of mechanical abdominal massage on the duration of ileus after colectomy, particularly in the era of enhanced recovery after surgery (ERAS). The aim of this study was to determine whether abdominal massage after colorectal surgery with anastomosis and no stoma helps toward a faster return of intestinal transit.

METHODS

This study was a superiority trial and designed as a prospective open-label, single-center, randomized controlled clinical trial with two parallel groups. Patients scheduled to undergo intestinal resection and follow an ERAS protocol were randomly assigned to either the standard ERAS group or the ERAS plus massage group. The primary endpoint was the return of intestinal transit, defined as the first passage of flatus following the operation. Secondary endpoints included time of the first bowel motion, maximal pain, 30 day complications, complications due to massage, anxiety score given by the Hospital Anxiety and Depression (HAD) questionnaire, and quality of life assessed by the EQ-5D-3L questionnaire.

RESULTS

Between July 2020 and June 2021, 36 patients were randomly assigned to the ERAS group or the ERAS plus massage group (n = 19). Patients characteristics were comparable. There was no significant difference in time to passage of the first flatus between the ERAS group and the ERAS plus abdominal massage group (1065 versus 1389 min, p = 0.274). No statistically significant intergroup difference was noted for the secondary endpoints.

CONCLUSION

Our study, despite its limitations, failed to demonstrate any advantage of abdominal massage to prevent or even reduce symptoms of postoperative ileus after colorectal surgery.

TRIAL REGISTRATION NUMBER

38RC20.021.

Validation of body surface colonic mapping (BSCM) against high resolution colonic manometry for evaluation of colonic motility

Abnormal cyclic motor pattern (CMP) activity is implicated in colonic dysfunction, but the only tool to evaluate CMP activity, high-resolution colonic manometry (HRCM), remains expensive and not widely accessible. This study aimed to validate body surface colonic mapping (BSCM) through direct correlation with HRCM. Synchronous meal-test recordings were performed in asymptomatic participants with intact colons. A signal processing method for BSCM was developed to detect CMPs. Quantitative temporal analysis was performed comparing the meal responses and motility indices (MI). Spatial heat maps were also compared. Post-study questionnaires evaluated participants' preference and comfort/distress experienced from either test. 11 participants were recruited and 7 had successful synchronous recordings (5 females/2 males; median age: 50 years [range 38-63]). The best-correlating MI temporal analyses achieved a high degree of agreement (median Pearson correlation coefficient (Rp) value: 0.69; range 0.47-0.77). HRCM and BSCM meal response start and end times (Rp = 0.998 and 0.83; both p < 0.05) and durations (Rp = 0.85; p = 0.03) were similar. Heat maps demonstrated good spatial agreement. BSCM is the first non-invasive method to be validated by demonstrating a direct spatio-temporal correlation to manometry in evaluating colonic motility.

Gastrointestinal Myoelectric Measurements via Simultaneous External and Internal Electrodes in Pigs

INTRODUCTION

Currently, there is no accurate noninvasive measurement system to diagnose gastrointestinal (GI) motility disorders. Wireless skin patches have been introduced to provide an accurate noninvasive measurement of GI myoelectric activity which is essential for developing neuro-stimulation devices to treat GI motility disorders. The aim of this study is to compare the external and internal electrical signal measurements in ambulatory pigs.

METHODS

Yucatan pigs underwent placement of internal electrodes on the stomach, small intestine, and colon. Wires were brought through the abdominal wall. Signals were collected by a wireless receptor. Four external patches were placed on the abdominal skin to record the signals simultaneously. Pigs were kept for 6 d while the sensors were continuously recording the data from both systems.

RESULTS

Internal sensors detected rich signals from each organ. The stomach had a dominant frequency that ranged from 4 to 4.5 cpm, with occasional higher frequencies at 2, 3 and 4 times that. Small intestine signals had their primary energy in the 12-15 cpm range. Colon signals primarily displayed a dominant broad peak in the 4-6 cpm region. External skin patches detected a substantial fraction of the activities measured by the internal electrodes. A clear congruence in the frequency spectrum was observed between the internal and external readings.

CONCLUSIONS

Internally measured myoelectrical signals confirmed different patterns of rhythmic activity of the stomach, small intestine, and colon. Skin patches provided GI myoelectric measurement with a range of frequencies that could be useful in the diagnosis and treatment of motility disorders.

OUP accepted manuscript

Background

Wearable devices have been proposed as a novel method for monitoring patients after surgery to track recovery, identify complications early, and improve surgical safety. Previous studies have used a heterogeneous range of devices, methods, and analyses. This review aimed to examine current methods and wearable devices used for monitoring after abdominal surgery and identify knowledge gaps requiring further investigation.

Methods

A scoping review was conducted given the heterogeneous nature of the evidence. MEDLINE, EMBASE, and Scopus databases were systematically searched. Studies of wearable devices for monitoring of adult patients within 30 days after abdominal surgery were eligible for inclusion.

Results

A total of 78 articles from 65 study cohorts, with 5153 patients were included. Thirty-one different wearable devices were used to measure vital signs, physiological measurements, or physical activity. The duration of postoperative wearable device use ranged from 15 h to 3 months after surgery. Studies mostly focused on physical activity metrics (71.8 per cent). Continuous vital sign measurement and physical activity tracking both showed promise for detecting postoperative complications earlier than usual care, but conclusions were limited by poor device precision, adherence, occurrence of false alarms, data transmission problems, and retrospective data analysis. Devices were generally well accepted by patients, with high levels of acceptance, comfort, and safety.

Conclusion

Wearable technology has not yet realized its potential to improve postoperative monitoring. Further work is needed to overcome technical limitations, improve precision, and reduce false alarms. Prospective assessment of efficacy, using an intention-to-treat approach should be the focus of further studies.

Post-operative ileus: definitions, mechanisms and controversies

Post-operative ileus (POI) is a syndrome of impaired gastrointestinal transit which occurs following abdominal surgery. There are few effective targeted therapies for ileus, and research has been limited by inconsistent definitions and an incomplete understanding of the underlying pathophysiology. Despite considerable effort, there remains no widely-adopted definition of ileus, and recent work has identified variation in outcome reporting is a major source of heterogeneity in clinical trials. Outcomes should be clearly-defined, clinically-relevant, and reflective of the underlying biology, impacts on hospital resources and quality of life. Further collaborative efforts will be needed to develop consensus definitions and a core outcome set for postoperative gastrointestinal recovery. Investigation into the pathophysiology of POI has been hindered by use of low-resolution techniques and difficulties linking cellular mechanisms to dysmotility patterns and clinical symptoms. Recent evidence has suggested the common assumption of post-operative GI paralysis is incorrect, and that the distal colon becomes hyperactive following surgery. The post-operative inflammatory response is important in the pathophysiology of ileus, but the time course of this in humans remains unclear, with the majority of evidence coming from animal models. Future work should investigate dysmotility patterns underlying ileus, and identify biomarkers which may be used to diagnose, monitor and stratify patients with ileus.

Pilot Validation of a New Wireless Patch System as an Ambulatory, Noninvasive Tool That Measures Gut Myoelectrical Signals: Physiologic and Disease Correlations

BACKGROUND AND AIMS

Limited means exist to assess gastrointestinal activity in a noninvasive, objective way that is highly predictive of underlying motility disorders. The aim of this paper is to demonstrate the feasibility of recording myoelectric gastrointestinal activity by cutaneous patches and to correlate myoelectric signals with gastrointestinal function in various clinical settings.

METHODS

A novel wireless patch system (WPS) (G-Tech Medical) that acquires gastrointestinal myoelectrical signals was placed on the patients' anterior abdomens. 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

The inherent reproducibility of the WPS measurement technique itself and from the underlying gut activity, coupled with source validation and sensitivity to changes in gut activity in several physiologic and pathologic states, demonstrates its feasibility, safety, and performance in clinical settings.

CONCLUSIONS

The novel WPS technology, measuring myoelectric intestinal activity noninvasively and continuously over multiple days, is feasible in a wide range of clinical settings, highlighting its promise in the diagnosis and management of motility disorders. Further research is required for more extensive validation and to determine how best to employ this information to optimize patient care.

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.