51
|
Alighaleh S, Angeli TR, Sathar S, O'Grady G, Cheng LK, Paskaranandavadivel N. Design and application of a novel gastric pacemaker. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2017:2181-2184. [PMID: 29060329 DOI: 10.1109/embc.2017.8037287] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Omnipresent bioelectrical events known as slow waves are responsible for coordinating motility in the gastrointestinal tract. Functional motility diseases, such as gastroparesis, are associated with slow wave dysrhythmias. Electrical stimulation is a potential therapy to correct abnormal slow wave patterns. We present the design and application of a new gastric pacemaker. Real-time changes to the stimulation parameters such as period, amplitude and pulse width were applied using a graphical user interface, which communicated with the microcontroller to deliver the stimulus. The new pacemaker allows the voltage, delivered current and resistance between pacing electrodes to be continuously monitored. The pacing device was applied experimentally and was able to modulate and entrain gastric slow wave activity. After the onset of pacing, the direction of slow wave propagation was altered. Furthermore, the mean velocity and amplitude of slow wave activity increased from 4.7±1.5 to 5.4±1.3 mm/s, and from 1.1±1.1 to 1.7±0.9 mV, respectively. A simplified bidomain electrical model was used to simulate the recorded stimulus artifact. The model illustrated a new approach to evaluate if the stimulus has been delivered to the gastric tissue. The new pacing device and model will be used to investigate the mechanisms that allow pacing to entrain slow wave activity.
Collapse
|
52
|
Milne TGE, Jaung R, O'Grady G, Bissett IP. Nonsteroidal anti-inflammatory drugs reduce the time to recovery of gut function after elective colorectal surgery: a systematic review and meta-analysis. Colorectal Dis 2018; 20:O190-O198. [PMID: 29781564 DOI: 10.1111/codi.14268] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 04/30/2018] [Indexed: 12/15/2022]
Abstract
AIM Postoperative ileus causes significant patient morbidity after abdominal surgery. Some evidence suggests nonsteroidal anti-inflammatory drugs (NSAIDs) may reduce time to gut recovery, but there has not been a meta-analysis to assess their efficacy. This systematic review and meta-analysis aimed to determine the benefit of NSAIDs for recovery of postoperative gut function in patients undergoing elective colorectal surgery. METHOD MEDLINE, EMBASE, CENTRAL and reference lists were searched with no date or language restrictions. Randomized controlled trials comparing the use of NSAIDs with placebo in the perioperative or postoperative period were identified. Included studies reported outcomes relevant to gut function: time to pass flatus or stool and time to tolerate an oral diet. The mean difference in time from surgery until passage of flatus, stool and tolerance of diet were meta-analysed using a random-effects model in RevMan 5.3. RESULTS This study identified 992 relevant articles. Five randomized controlled trials on patients undergoing elective colorectal surgery met our inclusion criteria and were meta-analysed. Compared with placebo, NSAIDs significantly improved the time to pass flatus (mean difference -9.44 h, 95% CI: -17.22, -1.65, I2 = 70%, P = 0.02), time to pass stool (mean difference -12.09 h, 95% CI: -17.16, -7.02, I2 = 0%, P < 0.001) and time to tolerate a diet (mean difference -11.95 h, 95% CI: -18.66, -5.24, I2 = 0%, P < 0.001). CONCLUSION NSAIDs significantly improve time to gut recovery after elective colorectal surgery. Current evidence is not adequate to identify whether selective or nonselective drugs should be recommended. Further high-power studies using selective drugs are required.
Collapse
|
53
|
Angeli TR, O'Grady G, Vather R, Bissett IP, Cheng LK. Intra-operative high-resolution mapping of slow wave propagation in the human jejunum: Feasibility and initial results. Neurogastroenterol Motil 2018; 30:e13310. [PMID: 29493080 DOI: 10.1111/nmo.13310] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/11/2018] [Indexed: 02/08/2023]
Abstract
BACKGROUND Bioelectrical slow waves are a coordinating mechanism of small intestine motility, but extracellular human studies have been restricted to a limited number of sparse electrode recordings. High-resolution (HR) mapping has offered substantial insights into spatiotemporal intestinal slow wave dynamics, but has been limited to animal studies to date. This study aimed to translate intra-operative HR mapping to define pacemaking and conduction profiles in the human small intestine. METHODS Immediately following laparotomy, flexible-printed-circuit arrays were applied around the serosa of the proximal jejunum (128-256 electrodes; 4-5.2 mm spacing; 28-59 cm2 ). Slow wave propagation patterns were mapped, and frequencies, amplitudes, downstroke widths, and velocities were calculated. Pacemaking and propagation patterns were defined. KEY RESULTS Analysis comprised nine patients with mean recording duration of 7.6 ± 2.8 minutes. Slow waves occurred at a frequency of 9.8 ± 0.4 cpm, amplitude 0.3 ± 0.04 mV, downstroke width 0.5 ± 0.1 seconds, and with faster circumferential velocity than longitudinal (10.1 ± 0.8 vs 9.0 ± 0.7 mm/s; P = .001). Focal pacemakers were identified and mapped (n = 4; mean frequency 9.9 ± 0.2 cpm). Disordered slow wave propagation was observed, including wavefront collisions, conduction blocks, and breakout and entrainment of pacemakers. CONCLUSIONS & INFERENCES This study introduces HR mapping of human intestinal slow waves, and provides first descriptions of intestinal pacemaker sites and velocity anisotropy. Future translation to other intestinal regions, disease states, and postsurgical dysmotility holds potential for improving the basic and clinical understanding of small intestine pathophysiology.
Collapse
|
54
|
Vather R, O'Grady G, Lin AY, Du P, Wells CI, Rowbotham D, Arkwright J, Cheng LK, Dinning PG, Bissett IP. Hyperactive cyclic motor activity in the distal colon after colonic surgery as defined by high-resolution colonic manometry. Br J Surg 2018; 105:907-917. [PMID: 29656582 DOI: 10.1002/bjs.10808] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Revised: 10/18/2017] [Accepted: 11/21/2017] [Indexed: 01/10/2023]
Abstract
BACKGROUND Recovery after colonic surgery is invariably delayed by disturbed gut motility. It is commonly assumed that colonic motility becomes quiescent after surgery, but this hypothesis has not been evaluated rigorously. This study quantified colonic motility through the early postoperative period using high-resolution colonic manometry. METHODS Fibre-optic colonic manometry was performed continuously before, during and after surgery in the left colon and rectum of patients undergoing right hemicolectomy, and in healthy controls. Motor events were characterized by pattern, frequency, direction, velocity, amplitude and distance propagated. RESULTS Eight patients undergoing hemicolectomy and nine healthy controls were included in the study. Colonic motility became markedly hyperactive in all operated patients, consistently dominated by cyclic motor patterns. Onset of cyclic motor patterns began to a minor extent before operation, occurring with increasing intensity nearer the time of surgery; the mean(s.d.) active duration was 12(7) per cent over 3 h before operation and 43(17) per cent within 1 h before surgery (P = 0.024); in fasted controls it was 2(4) per cent (P < 0·001). After surgery, cyclic motor patterns increased markedly in extent and intensity, becoming nearly continuous (active duration 94(13) per cent; P < 0·001), with peak frequency 2-4 cycles per min in the sigmoid colon. This postoperative cyclic pattern was substantially more prominent than in non-operative controls, including in the fed state (active duration 27(20) per cent; P < 0·001), and also showed higher antegrade velocity (P < 0·001). CONCLUSION Distal gut motility becomes markedly hyperactive with colonic surgery, dominated by cyclic motor patterns. This hyperactivity likely represents a novel pathophysiological aspect of the surgical stress response. Hyperactive motility may contribute to gut dysfunction after surgery, potentially offering a new therapeutic target to enhance recovery.
Collapse
|
55
|
Lin AY, Dinning PG, Milne T, Bissett IP, O'Grady G. The "rectosigmoid brake": Review of an emerging neuromodulation target for colorectal functional disorders. Clin Exp Pharmacol Physiol 2018; 44:719-728. [PMID: 28419527 DOI: 10.1111/1440-1681.12760] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/09/2017] [Accepted: 03/27/2017] [Indexed: 12/11/2022]
Abstract
The regulation of gastrointestinal motility encompasses several overlapping mechanisms including highly regulated and coordinated neurohormonal circuits. Various feedback mechanisms or "brakes" have been proposed. While duodenal, jejunal, and ileal brakes are well described, a putative distal colonic brake is less well defined. Despite the high prevalence of colonic motility disorders, there is little knowledge of colonic motility owing to difficulties with organ access and technical difficulties in recording detailed motor patterns along its entire length. The motility of the colon is not under voluntary control. A wide range of motor patterns is seen, with long intervals of intestinal quiescence between them. In addition, the use of traditional manometric catheters to record contractile activity of the colon has been limited by the low number of widely spaced sensors, which has resulted in the misinterpretation of colonic motor patterns. The recent advent of high-resolution (HR) manometry is revolutionising the understanding of gastrointestinal motor patterns. It has now been observed that the most common motor patterns in the colon are repetitive two to six cycles per minute (cpm) propagating events in the distal colon. These motor patterns are prominent soon after a meal, originate most frequently in the rectosigmoid region, and travel in the retrograde direction. The distal prominence and the origin of these motor patterns raise the possibility of them serving as a braking mechanism, or the "rectosigmoid brake," to limit rectal filling. This review aims to describe what is known about the "rectosigmoid brake," including its physiological and clinical significance and potential therapeutic applications.
Collapse
|
56
|
Milne TGE, Vather R, O'Grady G, Miquel J, Biondo S, Bissett I. Gastrografin may reduce time to oral diet in prolonged post-operative ileus: a pooled analysis of two randomized trials. ANZ J Surg 2018; 88. [PMID: 29510463 DOI: 10.1111/ans.14443] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 01/09/2018] [Accepted: 01/13/2018] [Indexed: 11/27/2022]
Abstract
BACKGROUND Gastrografin has been suggested as a rescue therapy for prolonged post-operative ileus (PPOI) but trial data has been inconclusive. This study aimed to determine the benefit of gastrografin use in patients with PPOI by pooling the results of two recent randomized controlled trials assessing the efficacy of gastrografin compared to placebo given at time of PPOI diagnosis. METHODS Anonymized, individual patient data from patients undergoing elective bowel resection for any indication were included, stoma closure was excluded. The primary outcome was duration of PPOI. Secondary outcomes were time to tolerate oral diet, passage of flatus/stool, requirement and duration of nasogastric tube, length of post-operative stay and rate of post-operative complications. RESULTS Individual patient data were pooled for analysis (53 gastrografin, 55 placebo). Gastrografin trended towards a reduction in PPOI duration compared to placebo, respectively, median 96 h (interquartile range, IQR, 78 h) versus median 120 h (IQR, 84 h), however, this result was non-significant (P = 0.11). In addition, no significant difference was detected between the two groups for time to passage of flatus/stool (P = 0.36) and overall length of stay (P = 0.35). Gastrografin conferred a significantly faster time to tolerate an oral diet compared to placebo (median 84 h versus median 107 h, P = 0.04). There was no difference in post-operative complications between the two interventions (P > 0.05). CONCLUSION Gastrografin did not significantly reduce PPOI duration or length of stay after abdominal surgery, but did reduce time to tolerate a solid diet. Further studies are required to clarify the role of gastrografin in PPOI.
Collapse
|
57
|
Angeli TR, O'Grady G. Challenges in defining, diagnosing, and treating diabetic gastroparesis. J Diabetes Complications 2018; 32:127-128. [PMID: 29198995 DOI: 10.1016/j.jdiacomp.2017.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 11/12/2017] [Indexed: 12/11/2022]
|
58
|
Du P, Calder S, Angeli TR, Sathar S, Paskaranandavadivel N, O'Grady G, Cheng LK. Progress in Mathematical Modeling of Gastrointestinal Slow Wave Abnormalities. Front Physiol 2018; 8:1136. [PMID: 29379448 PMCID: PMC5775268 DOI: 10.3389/fphys.2017.01136] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/22/2017] [Indexed: 12/19/2022] Open
Abstract
Gastrointestinal (GI) motility is regulated in part by electrophysiological events called slow waves, which are generated by the interstitial cells of Cajal (ICC). Slow waves propagate by a process of "entrainment," which occurs over a decreasing gradient of intrinsic frequencies in the antegrade direction across much of the GI tract. Abnormal initiation and conduction of slow waves have been demonstrated in, and linked to, a number of GI motility disorders. A range of mathematical models have been developed to study abnormal slow waves and applied to propose novel methods for non-invasive detection and therapy. This review provides a general outline of GI slow wave abnormalities and their recent classification using multi-electrode (high-resolution) mapping methods, with a particular emphasis on the spatial patterns of these abnormal activities. The recently-developed mathematical models are introduced in order of their biophysical scale from cellular to whole-organ levels. The modeling techniques, main findings from the simulations, and potential future directions arising from notable studies are discussed.
Collapse
|
59
|
Wang THH, Du P, Angeli TR, Paskaranandavadivel N, Erickson JC, Abell TL, Cheng LK, O'Grady G. Relationships between gastric slow wave frequency, velocity, and extracellular amplitude studied by a joint experimental-theoretical approach. Neurogastroenterol Motil 2018; 30. [PMID: 28695661 DOI: 10.1111/nmo.13152] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 06/08/2017] [Indexed: 02/08/2023]
Abstract
BACKGROUND Gastric slow wave dysrhythmias are accompanied by deviations in frequency, velocity, and extracellular amplitude, but the inherent association between these parameters in normal activity still requires clarification. This study quantified these associations using a joint experimental-theoretical approach. METHODS Gastric pacing was conducted in pigs with simultaneous high-resolution slow wave mapping (32-256 electrodes; 4-7.6 mm spacing). Relationships between period, velocity, and amplitude were quantified and correlated for each wavefront. Human data from two existing mapping control cohorts were analyzed to extract and correlate these same parameters. A validated biophysically based ICC model was also applied in silico to quantify velocity-period relationships during entrainment simulations and velocity-amplitude relationships from membrane potential equations. KEY RESULTS Porcine pacing studies identified positive correlations for velocity-period (0.13 mm s-1 per 1 s, r2 =.63, P<.001) and amplitude-velocity (74 μV per 1 mm s-1 , r2 =.21, P=.002). In humans, positive correlations were also quantified for velocity-period (corpus: 0.11 mm s-1 per 1 s, r2 =.16, P<.001; antrum: 0.23 mm s-1 per 1 s, r2 =.55; P<.001), and amplitude-velocity (94 μV per 1 mm s-1 , r2 =.56; P<.001). Entrainment simulations matched the experimental velocity-period relationships and demonstrated dependence on the slow wave recovery phase. Simulated membrane potential relationships were close to these experimental results (100 μV per 1 mm s-1 ). CONCLUSIONS AND INFERENCES These data quantify the relationships between slow wave frequency, velocity, and extracellular amplitude. The results from both human and porcine studies were in keeping with biophysical models, demonstrating concordance with ICC biophysics. These relationships are important in the regulation of gastric motility and will help to guide interpretations of dysrhythmias.
Collapse
|
60
|
Krohn B, Sathar S, Rohrle O, Vanderwinden JM, O'Grady G, Cheng LK. A framework for simulating gastric electrical propagation in confocal microscopy derived geometries. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:4215-4218. [PMID: 29060827 DOI: 10.1109/embc.2017.8037786] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Interstitial Cells of Cajal (ICC) initiate and actively propagate electrical events in the gastrointestinal tract known as slow-waves. The slow-waves coordinate the contraction of the gastrointestinal tract necessary for breakdown and mixing of ingested food. Degradation of the ICC numbers has been linked to several gastrointestinal motility disorders. However, limitations in imaging techniques and techniques for the quantification of ICC network structure have hindered our understanding of these disorders. We evaluated different machine learning techniques to segment ICC networks imaged using confocal microscopy. The accuracy the segmented networks were then quantified and compared using numerical metrics. Structurally realistic finite element meshes were constructed and used to simulate the propagation of electrical activation over the tissue blocks. The presented framework provides a system to quantify the structure and function of an ICC tissue sample. These methods are also applicable to other biological tissues and networks.
Collapse
|
61
|
Paskaranandavadivel N, Cheng LK, Du P, Rogers JM, O'Grady G. High-resolution mapping of gastric slow-wave recovery profiles: biophysical model, methodology, and demonstration of applications. Am J Physiol Gastrointest Liver Physiol 2017; 313:G265-G276. [PMID: 28546283 DOI: 10.1152/ajpgi.00127.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 05/24/2017] [Accepted: 05/24/2017] [Indexed: 01/31/2023]
Abstract
Slow waves play a central role in coordinating gastric motor activity. High-resolution mapping of extracellular potentials from the stomach provides spatiotemporal detail on normal and dysrhythmic slow-wave patterns. All mapping studies to date have focused exclusively on tissue activation; however, the recovery phase contains vital information on repolarization heterogeneity, the excitable gap, and refractory tail interactions but has not been investigated. Here, we report a method to identify the recovery phase in slow-wave mapping data. We first developed a mathematical model of unipolar extracellular potentials that result from slow-wave propagation. These simulations showed that tissue repolarization in such a signal is defined by the steepest upstroke beyond the activation phase (activation was defined by accepted convention as the steepest downstroke). Next, we mapped slow-wave propagation in anesthetized pigs by recording unipolar extracellular potentials from a high-resolution array of electrodes on the serosal surface. Following the simulation result, a wavelet transform technique was applied to detect repolarization in each signal by finding the maximum positive slope beyond activation. Activation-recovery (ARi) and recovery-activation (RAi) intervals were then computed. We hypothesized that these measurements of recovery profile would differ for slow waves recorded during normal and spatially dysrhythmic propagation. We found that the ARi of normal activity was greater than dysrhythmic activity (5.1 ± 0.8 vs. 3.8 ± 0.7 s; P < 0.05), whereas RAi was lower (9.7 ± 1.3 vs. 12.2 ± 2.5 s; P < 0.05). During normal propagation, RAi and ARi were linearly related with negative unit slope indicating entrainment of the entire mapped region. This relationship was weakened during dysrhythmia (slope: -0.96 ± 0.2 vs -0.71 ± 0.3; P < 0.05).NEW & NOTEWORTHY The theoretical basis of the extracellular gastric slow-wave recovery phase was defined using mathematical modeling. A novel technique utilizing the wavelet transform was developed and validated to detect the extracellular slow-wave recovery phase. In dysrhythmic wavefronts, the activation-to-recovery interval (ARi) was shorter and recovery-to-activation interval (RAi) was longer compared with normal wavefronts. During normal activation, RAi vs. ARi had a slope of -1, whereas the weakening of the slope indicated a dysrhythmic propagation.
Collapse
|
62
|
Keane C, Wells C, O'Grady G, Bissett IP. Defining low anterior resection syndrome: a systematic review of the literature. Colorectal Dis 2017; 19:713-722. [PMID: 28612460 DOI: 10.1111/codi.13767] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 03/29/2017] [Indexed: 12/13/2022]
Abstract
AIM There is increasing awareness of the poor functional outcome suffered by many patients after sphincter-preserving rectal resection, termed 'low anterior resection syndrome' (LARS). There is no consensus definition of LARS and varying instruments have been employed to measure functional outcome, complicating research into prevalence, contributing factors and potential therapies. We therefore aimed to describe the instruments and outcome measures used in studies of bowel dysfunction after low anterior resection and identify major themes used in the assessment of LARS. METHOD A systematic review of the literature was performed for studies published between 1986 and 2016. The instruments and outcome measures used to report bowel function after low anterior resection were extracted and their frequency of use calculated. RESULTS The search revealed 128 eligible studies. These employed 18 instruments, over 30 symptoms, and follow-up time periods from 4 weeks to 14.6 years. The most frequent follow-up period was 12 months (48%). The most frequently reported outcomes were incontinence (97%), stool frequency (80%), urgency (67%), evacuatory dysfunction (47%), gas-stool discrimination (34%) and a measure of quality of life (80%). Faecal incontinence scoring systems were used frequently. The LARS score and the Bowel Function Instrument (BFI) were used in only nine studies. CONCLUSION LARS is common, but there is substantial variation in the reporting of functional outcomes after low anterior resection. Most studies have focused on incontinence, omitting other symptoms that correlate with patients' quality of life. To improve and standardize research into LARS, a consensus definition should be developed, and these findings should inform this goal.
Collapse
|
63
|
Du P, O'Grady G, Cheng LK. A theoretical analysis of anatomical and functional intestinal slow wave re-entry. J Theor Biol 2017; 425:72-79. [DOI: 10.1016/j.jtbi.2017.04.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Revised: 04/19/2017] [Accepted: 04/21/2017] [Indexed: 12/26/2022]
|
64
|
Paskaranandavadivel N, Angeli T, Stocker A, McElmurray L, O'Grady G, Abell T, Cheng LK. Ambulatory gastric mucosal slow wave recording for chronic experimental studies. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2017; 2017:755-758. [PMID: 29059982 DOI: 10.1109/embc.2017.8036934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Dysrhythmic bioelectric slow wave activity have been implicated in major functional motility disorders such as gastroparesis and chronic unexplained nausea and vomiting, but its correlation to symptoms is still unclear. For patients with severe gastroparesis, high-frequency gastric stimulation is offered as a therapy in some centers. Temporary gastric electrical stimulation has also been proposed an approach to screen patients who would benefit from the implantation of a permanent stimulator. In this study we introduced novel methods for recording slow wave activity from the gastric mucosa during the entire temporary stimulation phase of 5 days, in 3 patients. An ambulatory recording system was applied to record 3 channels of mucosal slow wave activity, as well as three axis accelerometer data to monitor when the patient was mobile. Techniques were developed to detect large movements and these time periods were excluded from analyses of mucosal slow waves. The frequency and amplitude of the slow waves was calculated in a 5 min segment, with 75% overlap, for the entire duration. In feasibility studies, the slow wave frequency and amplitude for the patients were 3.0±0.96 cpm and 1.43±1.75 mV. Large variations in slow wave amplitude were seen in comparsion to slow wave frequency, which were concordant with previous studies. The use of the ambulatory system will allow for investigation of pathophysiology, correlation of electrophysiology data to patient symptoms and to determine the effects of post-prandial and noctural slow wave patterns. We anticipate that future use of slow wave information alongside patient symptoms may allow improved selection of patients for stimulaton techniques.
Collapse
|
65
|
Paskaranandavadivel N, Alighaleh S, O'Grady G, Cheng LK. Suppression of ventilation artifacts for gastrointestinal slow wave recordings. 2017 39TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC) 2017; 2017:2769-2772. [PMID: 29060472 DOI: 10.1109/embc.2017.8037431] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
66
|
Al-Mozany N, Wright C, O'Grady G, Young CJ, Solomon MJ. Barriers to the management of obstructed defaecation according to colorectal surgeons. Colorectal Dis 2017; 19:649-655. [PMID: 28319316 DOI: 10.1111/codi.13665] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 10/17/2016] [Indexed: 12/13/2022]
Abstract
AIM Obstructed defaecation (OD) has a high prevalence and high disease impact; however, patients often experience suboptimal management. This problem reflects the complex pathophysiology of OD as well as health service delivery factors. This study aimed to identify the factors that act as a barrier to effective management of OD as perceived by specialist colorectal surgeons treating this disorder. METHOD A postal questionnaire was administered to a bi-national sampling of colorectal specialists in Australia and New Zealand who were registered with their specialty society. Questions addressed variables relevant in OD management, including clinical access, decision-making, patient factors and surgeon experience and perceptions, and used Likert scales. Statistical analyses compared surgeon practice variables. RESULTS The response rate was 68.5% (n = 113). Most surgeons managed OD (94%), and preferred to treat OD patients themselves (87%); however, 33% of these respondents were dissatisfied with their management, 46% felt they lacked management expertise and 33% stated they had inadequate expertise in OD investigations. Clinical investigation services were more limited in private than public practice, and many surgeons lacked access to biofeedback (31%). Other barriers included heterogeneity in decision-making by surgeon age and practice location (P < 0.05), dual pathologies (e.g. irritable bowel syndrome) and psychological factors, and limited uptake of multidisciplinary services and standardized (Rome) diagnostic criteria. CONCLUSION Barriers to OD management include surgeon-specific factors, patient-specific factors and healthcare access factors. Increased utilization of pelvic floor and multidisciplinary services, increased training and standardization of OD investigations and improved access to specialist investigations and allied-health management services could improve outcomes for OD.
Collapse
|
67
|
Jaung R, Robertson J, O'Grady G, Milne T, Rowbotham D, Bissett IP. Limited evidence of abnormal intra-colonic pressure profiles in diverticular disease - a systematic review. Colorectal Dis 2017; 19:O168-O176. [PMID: 28436177 DOI: 10.1111/codi.13692] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 01/30/2017] [Indexed: 12/17/2022]
Abstract
AIM Abnormal colonic pressure profiles and high intraluminal pressures are postulated to contribute to the formation of sigmoid colon diverticulosis and the pathophysiology of diverticular disease. This study aimed to review evidence for abnormal colonic pressure profiles in diverticulosis. METHOD All published studies investigating colonic pressure in patients with diverticulosis were searched in three databases (Medline, Embase, Scopus). No language restrictions were applied. Any manometry studies in which patients with diverticulosis were compared with controls were included. The Newcastle-Ottawa Quality Assessment Scale (NOS) for case-control studies was used as a measure of risk of bias. A cut-off of five or more points on the NOS (fair quality in terms of risk of bias) was chosen for inclusion in the meta-analysis. RESULTS Ten studies (published 1962-2005) met the inclusion criteria. The studies followed a wide variety of protocols and all used low-resolution manometry (sensor spacing range 7.5-15 cm). Six studies compared intra-sigmoid pressure, with five of six showing higher pressure in diverticulosis vs controls, but only two reached statistical significance. A meta-analysis was not performed as only two studies were above the cut-off and these did not have comparable outcomes. CONCLUSION This systematic review of manometry data shows that evidence for abnormal pressure in the sigmoid colon in patients with diverticulosis is weak. Existing studies utilized inconsistent methodology, showed heterogeneous results and are of limited quality. Higher quality studies using modern manometric techniques and standardized reporting methods are needed to clarify the role of colonic pressure in diverticulosis.
Collapse
|
68
|
Angeli TR, Du P, Paskaranandavadivel N, Sathar S, Hall A, Asirvatham SJ, Farrugia G, Windsor JA, Cheng LK, O'Grady G. High-resolution electrical mapping of porcine gastric slow-wave propagation from the mucosal surface. Neurogastroenterol Motil 2017; 29:10.1111/nmo.13010. [PMID: 28035728 PMCID: PMC5393964 DOI: 10.1111/nmo.13010] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 11/19/2016] [Indexed: 12/12/2022]
Abstract
BACKGROUND Gastric motility is coordinated by bioelectrical slow waves, and gastric dysrhythmias are reported in motility disorders. High-resolution (HR) mapping has advanced the accurate assessment of gastric dysrhythmias, offering promise as a diagnostic technique. However, HR mapping has been restricted to invasive surgical serosal access. This study investigates the feasibility of HR mapping from the gastric mucosal surface. METHODS Experiments were conducted in vivo in 14 weaner pigs. Reference serosal recordings were performed with flexible-printed-circuit (FPC) arrays (128-192 electrodes). Mucosal recordings were performed by two methods: (i) FPC array aligned directly opposite the serosal array, and (ii) cardiac mapping catheter modified for gastric mucosal recordings. Slow-wave propagation and morphology characteristics were quantified and compared between simultaneous serosal and mucosal recordings. KEY RESULTS Slow-wave activity was consistently recorded from the mucosal surface from both electrode arrays. Mucosally recorded slow-wave propagation was consistent with reference serosal activation pattern, frequency (P≥.3), and velocity (P≥.4). However, mucosally recorded slow-wave morphology exhibited reduced amplitude (65-72% reduced, P<.001) and wider downstroke width (18-31% wider, P≤.02), compared to serosal data. Dysrhythmias were successfully mapped and classified from the mucosal surface, accorded with serosal data, and were consistent with known dysrhythmic mechanisms in the porcine model. CONCLUSIONS & INFERENCES High-resolution gastric electrical mapping was achieved from the mucosal surface, and demonstrated consistent propagation characteristics with serosal data. However, mucosal signal morphology was attenuated, demonstrating necessity for optimized electrode designs and analytical algorithms. This study demonstrates feasibility of endoscopic HR mapping, providing a foundation for advancement of minimally invasive spatiotemporal gastric mapping as a clinical and scientific tool.
Collapse
|
69
|
Lin AY, Du P, Dinning PG, Arkwright JW, Kamp JP, Cheng LK, Bissett IP, O'Grady G. High-resolution anatomic correlation of cyclic motor patterns in the human colon: Evidence of a rectosigmoid brake. Am J Physiol Gastrointest Liver Physiol 2017; 312:G508-G515. [PMID: 28336544 PMCID: PMC5451563 DOI: 10.1152/ajpgi.00021.2017] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/27/2017] [Accepted: 03/13/2017] [Indexed: 01/31/2023]
Abstract
Colonic cyclic motor patterns (CMPs) have been hypothesized to act as a brake to limit rectal filling. However, the spatiotemporal profile of CMPs, including anatomic origins and distributions, remains unclear. This study characterized colonic CMPs using high-resolution (HR) manometry (72 sensors, 1-cm resolution) and their relationship with proximal antegrade propagating events. Nine healthy volunteers were recruited. Recordings were performed over 4 h, with a 700-kcal meal given after 2 h. Propagating events were visually identified and analyzed by pattern, origin, amplitude, extent of propagation, velocity, and duration. Manometric data were normalized using anatomic landmarks identified on abdominal radiographs. These were mapped over a three-dimensional anatomic model. CMPs comprised a majority of detected propagating events. Most occurred postprandially and were retrograde propagating events (84.9 ± 26.0 retrograde vs. 14.3 ± 11.8 antegrade events/2 h, P = 0.004). The dominant sites of initiation for retrograde CMPs were in the rectosigmoid region, with patterns proximally propagating by a mean distance of 12.4 ± 0.3 cm. There were significant differences in the characteristics of CMPs depending on the direction of travel and site of initiation. Association analysis showed that proximal antegrade propagating events occurred independently of CMPs. This study accurately characterized CMPs with anatomic correlation. CMPs were unlikely to be triggered by proximal antegrade propagating events in our study context. However, the distal origin and prominence of retrograde CMPs could still act as a mechanism to limit rectal filling and support the theory of a "rectosigmoid brake."NEW & NOTEWORTHY Retrograde cyclic motor patterns (CMPs) are the dominant motor patterns in a healthy prepared human colon. The major sites of initiation are in the rectosigmoid region, with retrograde propagation, supporting the idea of a "rectosigmoid brake." A significant increase in the number of CMPs is seen after a meal. In our study context, the majority of CMPs occurred independent of proximal propagating events, suggesting that CMPs are primarily controlled by external innervation.
Collapse
|
70
|
Wells CI, Robertson JP, O'Grady G, Bissett IP. Response to Re: Trends in publication of general surgical research in New Zealand, 1996-2015. ANZ J Surg 2017; 87:317. [PMID: 28371033 DOI: 10.1111/ans.13923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 01/10/2017] [Indexed: 11/27/2022]
|
71
|
Du P, O'Grady G, Paskaranandavadivel N, Tang SJ, Abell T, Cheng LK. Reply. Exp Physiol 2017; 102:135. [DOI: 10.1113/ep086141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
72
|
O'Grady G, Barnett T, Thomson N. Intraparotid lymphadenitis caused by Haemophilus aphrophilus. Otolaryngol Head Neck Surg 2016; 136:S54-5. [PMID: 17398343 DOI: 10.1016/j.otohns.2007.01.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2006] [Accepted: 01/26/2007] [Indexed: 11/26/2022]
|
73
|
Yuan L, O'Grady G, Milne T, Jaung R, Vather R, Bissett IP. Prospective comparison of return of bowel function after left versus right colectomy. ANZ J Surg 2016; 88:E242-E247. [PMID: 27806440 DOI: 10.1111/ans.13823] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/20/2016] [Accepted: 09/22/2016] [Indexed: 12/18/2022]
Abstract
BACKGROUND Passage of flatus and stool represents a key milestone in recovery after colonic resections. Colorectal surgeons may hold varied expectations regarding recovery rates after left- versus right-sided colectomies, but there is currently little evidence to inform post-operative care. This study prospectively compared gut function recovery after left- versus right-sided resections. METHODS Prospective data were analysed from 94 consecutive patients undergoing elective colorectal resections with primary anastomosis at Auckland City Hospital. Patients having ileostomies were excluded. Primary analysis compared time to first bowel motion between left- versus right-sided resections, excluding patients who developed prolonged post-operative ileus, while secondary analyses compared length of stay, rates of prolonged ileus and other complications. RESULTS Analysis included 42 patients with left-sided and 52 with right-sided resections. No significant differences were observed for complications (P = 0.1), length of stay (P = 0.9) or development of prolonged ileus (P = 0.2). Rate of return of bowel function was faster in patients after left-sided resections (median 2.5 versus 4 days; P = 0.03 by Log-rank (Mantel-Cox) test), when patients with prolonged post-operative ileus were excluded. An association was also identified between length of bowel resected and time to recovery of bowel function for right-sided (P = 0.02) but not left-sided resections (P = 0.9). CONCLUSION This study shows that for patients who do not progress to prolonged ileus, those with left-sided resections experience faster return of bowel function when compared with those having right-sided resections. The reason for this finding is currently unknown and deserves further attention.
Collapse
|
74
|
Berry R, Miyagawa T, Paskaranandavadivel N, Du P, Angeli TR, Trew ML, Windsor JA, Imai Y, O'Grady G, Cheng LK. Functional physiology of the human terminal antrum defined by high-resolution electrical mapping and computational modeling. Am J Physiol Gastrointest Liver Physiol 2016; 311:G895-G902. [PMID: 27659422 PMCID: PMC5130547 DOI: 10.1152/ajpgi.00255.2016] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 09/14/2016] [Indexed: 01/31/2023]
Abstract
High-resolution (HR) mapping has been used to study gastric slow-wave activation; however, the specific characteristics of antral electrophysiology remain poorly defined. This study applied HR mapping and computational modeling to define functional human antral physiology. HR mapping was performed in 10 subjects using flexible electrode arrays (128-192 electrodes; 16-24 cm2) arranged from the pylorus to mid-corpus. Anatomical registration was by photographs and anatomical landmarks. Slow-wave parameters were computed, and resultant data were incorporated into a computational fluid dynamics (CFD) model of gastric flow to calculate impact on gastric mixing. In all subjects, extracellular mapping demonstrated normal aboral slow-wave propagation and a region of increased amplitude and velocity in the prepyloric antrum. On average, the high-velocity region commenced 28 mm proximal to the pylorus, and activation ceased 6 mm from the pylorus. Within this region, velocity increased 0.2 mm/s per mm of tissue, from the mean 3.3 ± 0.1 mm/s to 7.5 ± 0.6 mm/s (P < 0.001), and extracellular amplitude increased from 1.5 ± 0.1 mV to 2.5 ± 0.1 mV (P < 0.001). CFD modeling using representative parameters quantified a marked increase in antral recirculation, resulting in an enhanced gastric mixing, due to the accelerating terminal antral contraction. The extent of gastric mixing increased almost linearly with the maximal velocity of the contraction. In conclusion, the human terminal antral contraction is controlled by a short region of rapid high-amplitude slow-wave activity. Distal antral wave acceleration plays a major role in antral flow and mixing, increasing particle strain and trituration.
Collapse
|
75
|
Wells CI, Robertson JP, O'Grady G, Bissett IP. Trends in publication of general surgical research in New Zealand, 1996-2015. ANZ J Surg 2016; 87:76-79. [PMID: 27804200 DOI: 10.1111/ans.13821] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/21/2016] [Accepted: 09/22/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND Recent analyses of the surgical literature have suggested a general trend towards increasing numbers of published articles and an improved quality of evidence produced. The aim of this bibliometric analysis was to identify trends in the publication of general surgical research in New Zealand from 1996 to 2015. METHODS Ovid MEDLINE was searched for general surgical publications by New Zealand authors. Two investigators screened results, and a range of data were collected for included articles. Descriptive statistics were used to summarize data and identify significant trends. RESULTS A total of 601 articles were identified, with a progressive increase in the number of publications from 1996 to 2015. Randomized trials and systematic reviews accounted for 33 and 97 publications, respectively. The median number of authors per paper rose from 3.0 to 5.0 (P < 0.001). There was an exponential increase in the publication of randomized trials (P = 0.001) and systematic reviews (P < 0.001), while publication of basic science articles remained relatively steady (P = 0.22). The median impact factor for published articles increased from 1.5 to 2.6, which was equivalent to organic growth of the journal impact factors over the 20-year period. CONCLUSION The quality and quantity of surgical research in New Zealand has substantially increased over the past two decades. These results reflect the successful growth of a culture of academic surgery and the ongoing support of partner organizations.
Collapse
|