EndoFLIP evaluation of the pylorus during minimal invasive Ivor-Levis esophagectomy.

BACKGROUND/AIMS: During esophagectomy for malignancy, the anterior and posterior branches of the vagus nerve are transected in order to achieve surgical radicality. This leads to loss of central nervous system-control of the pylorus which may lead to delayed gastric emptying. We aimed to investigate the feasibility of the EndoFLIP technique for assessment of pyloric biomechanical properties in patients undergoing esophagectomy. METHODS: A feasibility study in six patients undergoing surgery was conducted. EndoFLIP measurements were carried out preoperative (Pre-op), after surgical resection (Post-op) and following prophylactic balloon dilatation of the pylorus (Post-dil). By measuring the cross-sectional area and pressure of the pylorus the pyloric compliance and the incremental pressure-strain elastic modulus (Ep) were calculated. RESULTS: Placing the catheter in the pyloric region was successfully achieved in all six patients. No complications were observed. Resection of the esophagus increased the incremental pyloric elastic modulus (Ep) from 0.59 ± 0.18 kPa to 0.99 ± 0.34 kPa (p = 0.03). After dilatation, the Ep was reduced to 0.53 ± 0.23 kPa (p = 0.04), which was close to Pre-op (p = 0.62). The pyloric compliance showed a similar pattern as that found for Ep. CONCLUSION: The EndoFLIP system holds promise for assessment of biomechanics of the pyloric region in patients undergoing esophagectomy for cancer.

Pan-alimentary assessment of motility, luminal content, and structures: an MRI-based framework.

BACKGROUND: Gastrointestinal symptoms originating from different segments overlap and complicate diagnosis and treatment. In this study, we aimed to develop and test a pan-alimentary framework for the evaluation of gastrointestinal (GI) motility and different static endpoints based on magnetic resonance imaging (MRI) without contrast agents or bowel preparation. METHODS: Twenty healthy volunteers (55.6 ± 10.9 years, BMI 30.8 ± 9.2 kg/m2) underwent baseline and post-meal MRI scans at multiple time points. From the scans, the following were obtained: Gastric segmental volumes and motility, emptying half time (T50), small bowel volume and motility, colonic segmental volumes, and fecal water content. Questionnaires to assess GI symptoms were collected between and after MRI scans. KEY RESULTS: We observed an increase in stomach and small bowel volume immediately after meal intake from baseline values (p<.001 for the stomach and p=.05 for the small bowel). The volume increase of the stomach primarily involved the fundus (p<.001) in the earliest phase of digestion with a T50 of 92.1 ± 35.3 min. The intake of the meal immediately elicited a motility increase in the small bowel (p<.001). No differences in colonic fecal water content between baseline and 105 min were observed. CONCLUSION & INFERENCES: We developed a framework for a pan-alimentary assessment of GI endpoints and observed how different dynamic and static physiological endpoints responded to meal intake. All endpoints aligned with the current literature for individual gut segments, showing that a comprehensive model may unravel complex and incoherent gastrointestinal symptoms in patients.

Gastrocolic Reflex Is Delayed and Diminished in Adults with Type 1 Diabetes.

BACKGROUND: Constipation is a prevalent gastrointestinal complication in diabetes. The pathophysiology may include neural dysfunction and impaired gastrocolic reflex; however, investigation of the latter has been limited in diabetes. Using the wireless motility capsule, we investigated whether the gastrocolic reflex was impaired in adults with type 1 diabetes compared to healthy. METHODS: One hundred and four adults with type 1 diabetes underwent investigation with the wireless motility capsule and recorded sleep cycle, eating habits, and bowel movements in a diary. Colonic motility index, contraction amplitudes, time-to-peak, peak motility, and colonic transit time were investigated directly in response to a meal. Diagnosis of peripheral (nerve conduction) and autonomic (orthostatic hypotension) polyneuropathy was verified. RESULTS: In comparison with health, people with diabetes had at the time of ingestion decreased motility index and contraction amplitudes (p < 0.001), prolonged time-to-peak (p = 0.01), and borderline decreased peak motility (p = 0.06), which taken together indicate impaired coordination of the gastrocolic reflex. These features were most prominent in those with concomitant peripheral or autonomic neuropathy. Additionally, they were associated with prolonged colonic transit time (p > 0.01). CONCLUSIONS: In type 1 diabetes, the gastrocolic reflex was delayed and diminished and further associated with the presence of neuropathy and constipation. These results suggest that impaired reflex is part of the underlying pathogenesis in the development of constipation.

Long-term anorectal function in rectal cancer patients treated with chemoradiotherapy and endorectal brachytherapy.

AIM: The aim was to study anorectal function in long-term survivors after combined, curatively intended, chemoradiotherapy and endorectal brachytherapy for low rectal cancer. METHODS: This was a case-control design. We compared anorectal function by anal manometry, anal functional lumen imaging probe (EndoFLIP) and rectal bag distension in rectal cancer patients (RCPs) and healthy, normal subjects (NSs). Symptoms were assessed by the low anterior resection syndrome (LARS) and Wexner faecal incontinence scores. RESULTS: Thirteen RCPs (12 men, median age 68 years, range 52-92) after 60 Gy radiotherapy, 5 Gy endorectal brachytherapy and oral tegafur-uracil with complete clinical response (median time since treatment 2.8 years, range 2.2-5.6) were compared to 15 NSs (14 men, median age 64 years, range 47-75). RCPs had lower than normal anal resting pressure, 38.6 mmHg (range 8.8-67.7) versus 58.8 mmHg (25.7-105.2) (P < 0.003), and squeeze pressure, 117 mmHg (55.2-203) versus 188 mmHg (103-248) (P < 0.01). Squeeze-induced pressure increase recorded by EndoFLIP was also lower in RCPs (q > 7.56, P < 0.001) as was the anal canal resistance to increasing distension (q = 3.13, P < 0.05). No differences in median rectal volume at first sensation (72 [22-158] vs. 82 [36-190] ml, P = 0.4) or at urge to defaecate (107 [42-227] vs. 132 [59-334] ml, P = 0.2) were found. However, maximum tolerable rectal volume was lower in RCPs (145 [59-319] vs. 222 [106-447] ml, P < 0.02). The median (range) low anterior resection syndrome score was 27 (0-39) for RCPs and 7 (0-23) for NSs (P < 0.001), while the Wexner score was 0 (0-5) versus 0 (0-4) (P = 0.56). CONCLUSION: Radiotherapy combined with endorectal brachytherapy for rectal cancer causes long-term anorectal symptoms, impaired anal sphincter function and reduced rectal capacity.

Anal sphincter dysfunction in patients treated with primary radiotherapy for anal cancer: a study with the functional lumen imaging probe.

BACKGROUND: Sphincter-sparing radiotherapy or chemoradiation are standard treatments for patients with anal cancer. The ultimate treatment goal is full recovery from anal cancer with preserved anorectal function. Unfortunately, long-term survivors often suffer from severe anorectal symptoms. The aim of the present study was to characterize changes in anorectal physiology after radiotherapy for anal cancer. METHOD: We included 13 patients (10 women, age 63.4 ± 1.9) treated with radiotherapy or chemoradiation for anal cancer and 14 healthy volunteers (9 women, age 61.4 ± 1.5). Symptoms were assessed with scores for fecal incontinence and low anterior resection syndrome. Anorectal physiology was examined with anorectal manometry and the Functional Lumen Imaging Probe. RESULTS: Patients had a median Wexner fecal incontinence score of 5 (0-13) and a median LARS score of 29 (0-39). Compared to healthy volunteers, patients had lower mean (±SE) anal -resting (38 ± 5 vs. 71 ± 6, p < .001) and -squeeze pressures (76 ± 11 vs. 165 ± 15, p < .001). Patients also had lower anal yield pressure (15.5 ± 1.3 mmHg vs. 28.0 ± 2.0 mmHg, p < .001), higher distensibility, and lower resistance to flow (reduced resistance ratio of the anal canal during distension, q = 5.09, p < .001). No differences were found in median (range) rectal volumes at first sensation (70.5 (15-131) vs. 57 (18-132) ml, p > .4), urge (103 (54-176) vs. 90 (32-212), p > .6) or maximum tolerable volume (173 (86-413) vs. 119.5 (54-269) ml, p > .10). CONCLUSION: Patients treated with radiotherapy or chemoradiation for anal cancer have low anal resting and squeeze pressures as well as reduced resistance to distension and flow.

Prolonged-Release Oxycodone/Naloxone Improves Anal Sphincter Relaxation Compared to Oxycodone Plus Macrogol 3350.

BACKGROUND: Opioid analgesics inhibit anal sphincter function and contribute to opioid-induced bowel dysfunction (OIBD). However, it is unknown whether the inhibition can be reduced by opioid antagonism with prolonged-release (PR) naloxone and how this compares to laxative treatment. AIMS: To compare the effects of combined PR oxycodone/naloxone or PR oxycodone plus macrogol 3350 on anal sphincter function and gastrointestinal symptoms. METHODS: A randomized, double-blind, crossover trial was conducted in 20 healthy men. Participants were treated for 5 days with combined PR oxycodone/naloxone or PR oxycodone plus macrogol 3350. Resting anal pressure, anal canal distensibility, and relaxation of the internal sphincter to rectal distension were evaluated before treatment (baseline) and on day 5. The Patient Assessment of Constipation Symptom (PAC-SYM) questionnaire, stool frequency, and stool consistency were assessed daily. RESULTS: Both PR oxycodone/naloxone and PR oxycodone plus macrogol treatment decreased sphincter relaxation compared to baseline (- 27.5%; P < 0.001 and - 14.7%; P = 0.01). However, sphincter relaxation was increased after PR naloxone/oxycodone treatment compared to macrogol (difference = + 17.6%; P < 0.001). Resting anal pressure and anal canal distensibility did not differ between treatments. PAC-SYM abdominal symptoms score was lower during PR naloxone compared to macrogol (0.2 vs. 3.2; P = 0.002). The number of bowel movements was lower during PR naloxone versus macrogol (4.2 vs. 5.4; P = 0.035). CONCLUSION: Relaxation of the internal anal sphincter was significantly better after PR oxycodone/naloxone treatment compared to PR oxycodone plus macrogol 3350. These findings highlight that OIBD may require specific therapy against the complex, pan-intestinal effects of opioids.

Ravages of Diabetes on Gastrointestinal Sensory-Motor Function: Implications for Pathophysiology and Treatment.

Symptoms related to functional and sensory abnormalities are frequently encountered in patients with diabetes mellitus. Most symptoms are associated with impaired gastric and intestinal function. In this review, we discuss basic concepts of sensory-motor dysfunction and how they relate to clinical findings and gastrointestinal abnormalities that are commonly seen in diabetes. In addition, we review techniques that are available for investigating the autonomic nervous system, neuroimaging and neurophysiology of sensory-motor function. Such technological advances, while not readily available in the clinical setting, may facilitate stratification and individualization of therapy in diabetic patients in the future. Unraveling the structural, mechanical, and sensory remodeling in diabetes disease is based on a multidisciplinary approach that can bridge the knowledge from a variety of scientific disciplines. The final goal is to increase the understanding of the damage to GI structures and to sensory processing of symptoms, in order to assist clinicians with developing an optimal mechanics based treatment.

Distensibility and pain of the uterine cervix evaluated by novel techniques.

The article serves to review the literature on the human uterine cervix based on a new distension technology named functional luminal imaging probe. This technology was originally developed to study the biomechanical competence of the gastro-esophageal junction where it provides a geometric profile of the lumen during distension, which can be related to sensory data. We searched and reviewed publications on cervical distention from 2002. The functional luminal imaging probe technology has been used for studying the mechanical and mechano-sensory properties of the cervix in non-pregnant women. In early pregnant women and in term pregnant women, the technique provides geometric measurements from the whole cervical canal during distension, which changes dramatically during pregnancy. Furthermore, it has been demonstrated that the technique predicts the outcome of labor induction better than the Bishop score does. The functional luminal imaging probe technology has potential as a research tool as well as for clinical use in gynecology and obstetrics.

An image-based method to quantify biomechanical properties of the rectum in radiotherapy of prostate cancer.

BACKGROUND: Gastrointestinal morbidity after radiotherapy (RT) for prostate cancer may be related to the biomechanical properties of the rectum. In this study we present a magnetic resonance imaging (MRI)-based method to quantitate the thickness and elasticity of the rectal wall in prostate cancer patients treated with RT. MATERIAL AND METHODS: Four patients previously treated with RT for prostate cancer underwent an MRI session with stepwise rectal bag deflation (from a maximum tolerable volume to 0 ml, in 50 ml steps), with a probe inserted inside the bag to monitor the internal rectal pressure. MRIs were acquired using Dixon sequences (4 mm axial slice thickness) at each deflation step. Rectal walls were defined from the recto-sigmoid junction to 3 cm above the anal canal as the space between the inner and outer wall surfaces. The wall thickness was determined and biomechanical properties (strain and stress) were calculated from the pressure measurements and the MRI-segmented rectal walls. RESULTS: The integral rectal pressure varied for the maximum tolerable volume (range 150-250 ml) across patients and ranged from 1.3 to 4.0 kPa (SD = 1.2 kPa). Wall thickness was found to vary between patients and also across different rectum segments, with a mean (SD) thickness for the different segments at the 50 ml distension volume of 1.8-4.0 (0.6) mm. Stress showed larger variation than strain, with mean (SD) values for the different segments ranging between 1.5 and 7.0 (1.5) kPa. CONCLUSION: We have developed a method to quantify biomechanical properties of the rectal wall. The resulting rectal wall thickness, strain and stress differed between patients, as well as across different rectal wall sections. These findings could provide guidance in future predictive outcome modelling in order to better understand the rectal dose-volume response relationship.

Quantitative differences between primary and secondary peristaltic contractions of the esophagus.

BACKGROUND AND AIMS: Differences in contraction characteristics between primary and secondary peristalsis have only been scarcely studied. Recently new measures of contractile activity in the human esophagus were developed. The study aims were to use combined manometry and impedance planimetry [pressure-cross-sectional area (P-CSA)] recordings from healthy volunteers to examine esophageal peristalsis, and, furthermore, to investigate the effect of the motility enhancing drug erythromycin to study differential effects on the two types of contractions. METHODS: Sixteen healthy volunteers participated in the study [mean age 23 (range, 19-34) years, 6 females]. An esophageal probe with a bag for CSA measurement was positioned 10 cm above the lower esophageal sphincter. Bag volume was increased stepwise from 5 to 25 ml before and after intravenous infusion of 250 mg erythromycin. Swallow-evoked primary and distension-evoked secondary esophageal peristalsis were compared with regard to (1) pressure amplitude, (2) CSA amplitude, (3) preload tension (wall tension before an evoked contraction), (4) contractile tension, and (5) work outputs. RESULTS: Primary peristalsis induced more efficient contractions as the contraction amplitudes, work output and contractile tension were higher compared to secondary peristalsis (P < 0.001). Erythromycin induced change in CSA during distension-evoked secondary peristalsis (CSA before 212.9 ± 26.8 vs. after 180.5 ± 23.3, P < 0.05). The sensitivity to esophageal distension increased with the distending volume both before and during erythromycin. The sensitivity was not changed by erythromycin (P = 0.6). CONCLUSIONS: Esophageal primary peristaltic contractions were more forceful with longer duration, and higher work output compared to secondary peristalsis contractions. Erythromycin affected peristalsis only to a minor degree.

A comparison of function lumen imaging probe measurements of anal sphincter function in fecal incontinence.

BACKGROUND: The functional lumen imaging probe (FLIP) is a test of anal sphincter distensibility under evaluation by specialist centers. Two measurement protocols termed "stepwise" and "ramp" are used, risking a lack of standardization. This study aims to compare the performance of these protocols to establish if there are differences between them. METHODS: Patients with fecal incontinence were recruited and underwent measurement with both protocols at a tertiary pelvic floor referral unit. Differences in minimum diameter, FLIP bag pressure, and distensibility index (DI) at rest and during squeeze were calculated at various FLIP bag volumes. KEY RESULTS: Twenty patients (19 female, mean age 61 [range: 38-78]) were included. The resting minimum diameter at 30 and 40 mL bag volumes were less in the stepwise protocol (mean bias: -0.55 mm and -1.18 mm, p < 0.05) along with the DI at the same bag volumes (mean bias: -0.37 mm2/mmHg and -0.55 mm2/mmHg, p < 0.05). There was also a trend towards greater bag pressures at 30 mL (mean bias: +2.08 mmHg, p = 0.114) and 40 mL (mean bias: +2.81 mmHg, p = 0.129) volumes in the stepwise protocol. There were no differences between protocols in measurements of minimum diameter, maximum bag pressure, or DI during voluntary squeeze (p > 0.05). CONCLUSION AND INFERENCES: There are differences between the two commonly described FLIP measurement protocols at rest, although there are no differences in the assessment of squeeze function. Consensus agreement is required to agree the most appropriate FLIP measurement protocol in assessing anal sphincter function.

Evidence for stress-dependent mechanoreceptors linking intestinal biomechanics and sensory signal transduction.

Sensory nerve endings are widely distributed throughout the body. Neither the nature of the mechanosensitive channels nor the principal mechanical stimulus for these receptors is known. Afferents supplying the gastrointestinal tract responding to distension and contraction are responsible for co-ordinated reflex control, feeding behaviour and sensations, including pain. Different populations of intestinal afferent fibres follow different pathways to the CNS, have different terminal fields and possess different thresholds for activation that may reflect the extent to which mechanical forces are distributed and dissipated by non-neural structures in the bowel wall. In this study, we have characterized the stimulus-response function of afferent fibres innervating the rat jejunum, correlating luminal distensions in the bowel wall with the firing frequency of mesenteric afferent nerve bundles. Combining video imaging with intraluminal pressure recordings and utilizing a strain softening protocol, we have determined whether mechanoreceptors respond primarily to stress or strain. Multiunit afferent recordings were separated using spike discrimination software into low-threshold (LT) and high-threshold (HT) single units. For multifibre afferent recordings and both LT and HT single units, we observed a linear relationship between circumferential stress and mesenteric afferent discharge that was independent of distension-induced tissue softening, with correlation coefficients >0.9. A fivefold change in the rate of applied distension did not significantly alter the magnitude of the afferent response and the linearity of the stress-dependent mechanotransduction in both multifibre preparations and the LT and HT afferent fibres (P > 0.2). Thus, the firing characteristics of intestinal mechanoreceptors are linearly associated with the input in terms of mechanical stress.

A novel MRI-based three-dimensional model of stomach volume, surface area, and geometry in response to gastric filling and emptying.

BACKGROUND: Gastric motility and accommodation have a critical role in maintaining normal gastrointestinal homeostasis. Different modalities can be adopted to quantify those processes, that is, scintigraphy to measure emptying time and intragastric Barostat for accommodation assessment. However, magnetic resonance imaging (MRI) can assess the same parameters noninvasively without ionizing radiation. Our study aimed to develop a detailed three-dimensional (3D) MRI model of the stomach to describe gastric volumes, surface areas, wall tension distribution, and interobserver agreement. METHODS: Twelve healthy volunteers underwent an MRI protocol of six axial T2-weighted acquisitions. Each dataset was used to construct a 3D model of the stomach: First, the volumes of the whole stomach, gastric liquid, and air were segmented. After landmark placing, a raw 3D model was generated from segmentation data. Subsequently, irregularities were removed, and the model was divided into compartments. Finally, surface area and 3D geometry parameters (inverse curvatures) were extracted. The inverse curvatures were used as a proxy for wall tension distribution without measuring the intragastric pressure. KEY RESULTS: The model was able to describe changes in volume and surface geometry for each compartment with a distinct pattern in response to filling and emptying. The surface tension was distributed nonhomogeneously between compartments and showed dynamical changes at various time points. CONCLUSION & INFERENCES: The presented model offers a detailed tool for evaluating gastric volumes, surface geometry, and wall tension in response to filling and emptying and will provide insights into gastric emptying and accommodation in diseases such as diabetic gastroparesis.

Current and future perspectives on the utility of provocative tests of anal sphincter function: A state-of-the-art summary.

BACKGROUND: The maintenance of fecal continence depends upon coordinated interactions between the pelvic floor, anorectum, and anal sphincter complex orchestrated by central and peripheral neural activities. The current techniques to objectively measure anorectal function rely on fixed diameter catheters placed inside the anal canal with a rectal balloon to obtain measurements of anal resting and squeeze function, and rectal compliance. Until recently it had not been possible to measure the distensibility of the anal canal, or in other words its ability to resist opening against an increasing pressure, which has been proposed as the main determinant of a biological sphincter's function. Anal acoustic reflectometry (AAR) and the functional lumen imaging probe (FLIP) are two novel, provocative techniques that dynamically assess the anal sphincter complex under volume-controlled distension. In doing so, both provide information on the viscoelastic properties of the anal canal and offer new insights into its function. PURPOSE: This review details the current and potential future applications of AAR and FLIP and highlights the unanswered questions relevant to these new technologies.

Electrocardiography Assessment of Sympatico-Vagal Balance during Resting and Pain Using the Texas Instruments ADS1299.

Sympatico-vagal balance is essential for regulating cardiac electrophysiology and plays an important role in arrhythmogenic conditions. Various noninvasive methods, including electrocardiography (ECG), have been used for clinical assessment of the sympatico-vagal balance. This study aimed to use a custom-designed wearable device to record ECG and ECG-based cardiac function biomarkers to assess sympatico-vagal balance during tonic pain in healthy controls. Nineteen healthy volunteers were included for the ECG measurements using the custom-designed amplifier based on the Texas Instruments ADS1299. The ECG-based biomarkers of the sympatico-vagal balance, (including heart rate variability, deceleration capacity of the heart rate, and periodic repolarization dynamic), were calculated and compared between resting and pain conditions (tonic pain). The custom-designed device provided technically satisfactory ECG recordings. During exposure to tonic pain, the periodic repolarization dynamics increased significantly (p = 0.02), indicating enhancement of sympathetic nervous activity. This study showed that custom-designed wearable devices can potentially be useful in healthcare as a new telemetry technology. The ECG-based novel biomarkers, including periodic repolarization dynamic and deceleration capacity of heart rate, can be used to identify the cold pressor-induced activation of sympathetic and parasympathetic systems, making it useful for future studies on pain-evoked biomarkers.

MRI-Based Quantification of Pan-Alimentary Function and Motility in Subjects with Diabetes and Gastrointestinal Symptoms.

Background: Diabetes-induced gastrointestinal (GI) symptoms are common but difficult to correctly diagnose and manage. We used multi-segmental magnetic resonance imaging (MRI) to evaluate structural and functional GI parameters in diabetic patients and to study the association with their symptomatic presentation. Methods: Eighty-six participants (46 with diabetes and GI symptoms, 40 healthy controls) underwent baseline and post-meal MRI scans at multiple timepoints. Questionnaires were collected at inclusion and following the scans. Data were collected from the stomach, small bowel, and colon. Associations between symptoms and collected data were explored. Utilizing machine learning, we determined which features differentiated the two groups the most. Key Results: The patient group reported more symptoms at inclusion and during MRI scans. They showed 34% higher stomach volume at baseline, 40% larger small bowel volume, 30% smaller colon volume, and less small bowel motility postprandially. They also showed positive associations between gastric volume and satiety scores, gastric emptying time and reflux scores, and small bowel motility and constipation scores. No differences in gastric emptying were observed. Small bowel volume and motility were used as inputs to a classification tool that separated patients and controls with 76% accuracy. Conclusions: In this work, we studied structural and functional differences between patients with diabetes and GI symptoms and healthy controls and observed differences in stomach, small bowel, and colon volumes, as well as an adynamic small bowel in patients with diabetes and GI symptoms. Associations between recorded parameters and perceived symptoms were also explored and discussed.

Distension of the renal pelvis in kidney stone patients: sensory and biomechanical responses.

The pathogenesis of symptoms in urolithiasis is poorly understood. Traditionally increased endoluminal pressure is considered the main mechanism causing pain in the upper urinary tract but clinical data are sparse. The aim of the present study was to develop a new model related to mechanosensation in order to describe the geometric and mechanical properties of the renal pelvis in patients with kidney stone disease. Pressure measurement in the renal pelvis was done during CT-pyelography in 15 patients who underwent percutaneus nephrolithotomy. The sensory intensity was recorded at the thresholds for first sensation and for pain. 3D deformation and strain were calculated in five patients. The deformation of pelvis during distension was not uniform due to the complex geometry. The pelvis deformed to 113 ± 6% and 115 ± 11% in the longitudinal and circumferential directions, respectively. Endoluminal pressure in the renal pelvis corresponded positively to the sensory ratings but the referred pain area was diffuse located and varied in size. The present study provides a method for describing the mechanosensory properties and 3D deformation of the complex renal pelvis geometry. Although there was a relation between pressure and pain score, the non-homogenous spatial strain distribution suggests that the 3D biomechanical properties of the renal pelvis are not reflected by simple estimates of tension based on pressure and volume.

Surface deformation analysis of end-to-end stapled intestinal anastomosis.

BACKGROUND: Stapling devices for creating anastomosis in internal organs are commonly used during surgery. Despite the obvious advantages of shortened procedure duration and fewer complications to manual suturing, staple-line leakage during intestinal anastomosis likely relates to the interaction between the staples and the tissue and to the tissue mechanical properties. The authors studied the deformation pattern close to the anastomosis to learn more about the mechanism involved in leakage. METHODS: End-to-end anastomosis in pig small intestine was done using 21-mm circular staplers. Distension with pressure up to 100 cm H2O was done on the anastomosed segment. Surface markers were tracked using a microscope and a CCD camera. Circumferential and longitudinal strains were computed. RESULTS: The staples restricted the deformation both in circumferential and longitudinal directions and induced a heterogeneous strain distribution. Circumferential strains were bigger between the staples (range 0.5-1) than inside the staples (range 0-0.3). The longitudinal strain ranged from 0 to slightly negative between the staples, indicating longitudinal compression. The negative strains turned into positive strains with increasing distance from the anastomosis. Further away from the anastomosis the longitudinal strain was in the range 0.3 to 0.5. CONCLUSION: The surface strain field was heterogeneously close to the stapled anastomosis. The longitudinal compression between staples in the longitudinal direction during inflation may have a beneficial effect preventing leakage, a phenomenon that needs further studies. The method may be useful in the design and validation of new staplers.

Central neuronal transmission in response to tonic cold pain is modulated in people with type 1 diabetes and severe polyneuropathy.

AIMS: This study aimed to investigate cortical source activity and identify source generators in people with type 1 diabetes during rest and tonic cold pain. METHODS: Forty-eight participants with type 1 diabetes and neuropathy, and 21 healthy controls were investigated with electroencephalography (EEG) during 5-minutes resting and 2-minutes tonic cold pain (immersing the hand into water at 2 °C). EEG power was assessed in eight frequency bands, and EEG source generators were analyzed using standardized low-resolution electromagnetic tomography (sLORETA). RESULTS: Compared to resting EEG, cold pain EEG power differed in all bands in the diabetes group (all p < 0.001) and six bands in the controls (all p < 0.05). Source generator activity in the diabetes group was increased in delta, beta2, beta3, and gamma bands and decreased in alpha1 (all p < 0.006) with changes mainly seen in the frontal and limbic lobe. Compared to controls, people with diabetes had decreased source generator activity during cold pain in the beta2 and beta3 bands (all p < 0.05), mainly in the frontal lobe. CONCLUSIONS: Participants with type 1 diabetes had altered EEG power and source generator activity predominantly in the frontal and limbic lobe during tonic cold pain. The results may indicate modulated central transmission and neuronal impairment.