Vaginal pressure sensor measurement during maximal voluntary pelvic floor contraction correlates with vaginal birth and pelvic organ prolapse-A pilot study.

AIMS: To measure the force applied along the anterior and posterior vaginal walls in a cohort of 46 patients measured by a fiber-optic pressure sensor and determine if this correlates with vaginal parity and pelvic organ prolapse (POP). METHODS: An intravaginal fiber-optic sensor measured pressure at nine locations along the anterior and posterior vaginal walls during a maximal voluntary pelvic floor muscle contraction (MVC). An automated probe dilation cycle measured the tissue resistance incorporating the vagina and surrounding anatomy. MVC and resting tissue resistance (RTR) were assessed between subjects grouped by the number of vaginal births and prolapse stage. RESULTS: A previous vaginal birth was associated with a significant threefold decrease in the overall anterior pressure measurement during MVC. Decreased anterior pressure measurements were observed at Sensors 1 and 3 (distal vagina) and, posteriorly at Sensors 4-6 (midvagina). Women with Stage 2 posterior prolapse exhibited a decreased MVC pressure in the midvagina than those with Stage 0/1. In this pilot study, there was no difference in the vaginal wall RTR according to previous vaginal birth or stage of prolapse. CONCLUSION: This pilot study found that a decrease in vaginal pressure measured during MVC is associated with vaginal birth and with posterior POP. Greater sample size is required to assess the role of resting tissue pressure measurement.

ManoMap: an automated system for characterization of colonic propagating contractions recorded by high-resolution manometry.

RATIONALE: Colonic high-resolution manometry (cHRM) is an emerging clinical tool for defining colonic function in health and disease. Current analysis methods are conducted manually, thus being inefficient and open to interpretation bias. OBJECTIVE: The main objective of the study was to build an automated system to identify propagating contractions and compare the performance to manual marking analysis. METHODS: cHRM recordings were performed on 5 healthy subjects, 3 subjects with diarrhea-predominant irritable bowel syndrome, and 3 subjects with slow transit constipation. Two experts manually identified propagating contractions, from five randomly selected 10-min segments from each of the 11 subjects (72 channels per dataset, total duration 550 min). An automated signal processing and detection platform was developed to compare its effectiveness to manually identified propagating contractions. In the algorithm, individual pressure events over a threshold were identified and were then grouped into a propagating contraction. The detection platform allowed user-selectable thresholds, and a range of pressure thresholds was evaluated (2 to 20 mmHg). KEY RESULTS: The automated system was found to be reliable and accurate for analyzing cHRM with a threshold of 15 mmHg, resulting in a positive predictive value of 75%. For 5-h cHRM recordings, the automated method takes 22 ± 2 s for analysis, while manual identification would take many hours. CONCLUSIONS: An automated framework was developed to filter, detect, quantify, and visualize propagating contractions in cHRM recordings in an efficient manner that is reliable and consistent.

Altered colonic motility is associated with low anterior resection syndrome.

AIM: Patients frequently suffer from low anterior resection syndrome (LARS) after distal colorectal resection. The pathophysiology of LARS has not been clearly elucidated. We hypothesized that rectosigmoid resection could impair motility patterns in the distal colon, such as the rectosigmoid brake, which contribute to control of stool form and frequency. METHOD: High-resolution colonic manometry was performed in patients who had previously undergone distal colorectal resection (mean 6.8 years after resection) and non-operative controls before and after a standardized meal. Symptoms were assessed using the LARS score. Propagating contractions were compared between patients with and without LARS, and controls. RESULTS: Data were analysed from 23 patients (11 no-LARS; 12 LARS) and nine controls. All groups demonstrated a significant meal response. LARS patients had fewer post-prandial antegrade propagating contractions than controls (P = 0.028), and fewer retrograde propagating contractions both pre- (P = 0.005) and post-prandially (P = 0.004). Post-prandially, the LARS group had a significantly lower percentage of propagating contractions that met the criteria for the cyclic motor pattern compared to the control group (26% vs. 58%; P = 0.009). There were significant differences in antegrade and retrograde amplitude (P = 0.049; P = 0.018) and distance of propagation (P = 0.003; P = 0.002) post-prandially between LARS patients and controls. CONCLUSION: Rectosigmoid resection alters the meal response following anterior resection, including impairment of the rectosigmoid brake cyclic motor pattern. These findings help to quantify the impaired functional motility after rectosigmoid resection and offer new insights into the mechanisms of LARS.

Novel insight into pressurization of the male and female urethra through application of a multi-channel fibre-optic pressure transducer: Proof of concept and validation.

PURPOSE: To confirm feasibility of recording pressure along the length of the urethra using a multi-sensor fibre-optic pressure catheter; to identify the spatial and temporal features of changes in pressure along the urethra at sites related to specific striated pelvic floor muscles; and to investigate the relationship between urethral pressures and activation of individual pelvic floor muscles estimated from ultrasound imaging. MATERIALS AND METHODS: Proof-of-concept study including one male (47 years old) and one female (33 years old). A multi-sensor fibre optic pressure catheter (10 mm sensor separation) was inserted into the urethra. Pressure data were recorded simultaneously with trans-perineal ultrasound imaging measures of pelvic floor muscle activity during sub-maximal and maximal voluntary contractions and evoked coughs. RESULTS: Pressure changes along the urethra were recorded in all tasks in both participants. Face validity of interpretation of pressure measures with respect to individual muscles was supported by correlation with ultrasound-measured displacements induced by the relevant muscles. Onset of pressure increase occurred in a distal to proximal sequence in the urethra of the male but not the female during voluntary contraction. Peak urethral pressures varied in location, timing and amplitude between tasks. Evoked cough induced in the greatest urethral pressure increase across all tasks for both participants. CONCLUSIONS: The high spatial resolution pressure catheter provide viable and valid recordings of urethral pressure in a male and female. Data provide preliminary evidence of sex differences in spatial and temporal distribution of urethral pressure changes.

Distinct patterns of myogenic motor activity identified in isolated human distal colon with high-resolution manometry.

BACKGROUND: Colonic high-resolution manometry (HRM) has been used to reveal discrete, propagating colonic motor patterns. To help determine mechanisms underlying these patterns, we used HRM to record contractile activity in human distal colon ex vivo. METHODS: Surgically excised segments of descending (n = 30) or sigmoid colon (n = 4) were immersed in oxygenated Krebs solution at 36°C (n = 34; 16 female; 67.6 ± 12.4 years; length: 24.7 ± 3.5 cm). Contractility was recorded by HRM catheters. After 30 minutes of baseline recording, 0.3 mM lidocaine and/or 1 mM hexamethonium were applied. Ascending neural pathways were activated by electrical field stimulation (EFS; 10 Hz, 0.5 ms, 50 V, 5-s duration) applied to the anal end before and after drug application. RESULTS: Spontaneous propagating contractions were recorded in all specimens (0.1-1.5 cycles/minute). Most contractions occurred synchronously across all recording sites. In five specimens, rhythmic antegrade contractions propagated across the full length of the preparation. EFS evoked local contractions at the site of stimulation (latency: 5.5 ± 2.4 seconds) with greater amplitude than spontaneous contractions (EFS; 29.3 ± 26.9 vs 12.1 ± 14.8 mm Hg; P = .02). Synchronous or retrograde propagating motor patterns followed EFS; 71% spanned the entire preparation length. Hexamethonium and lidocaine modestly and only temporarily inhibited spontaneous contractions, whereas TTX increased the frequency of contractile activity while inhibiting EFS-evoked contractions. CONCLUSIONS AND INFERENCES: Our study suggests that the propagated contractions recorded in the organ bath have a myogenic origin which can be regulated by neural input. Once activated at a local site, the contractions do not require the propulsion of fecal content to sustain long-distance propagation.

Manometric demonstration of duodenal/jejunal motor function consistent with the duodenal brake mechanism.

BACKGROUND: High-resolution manometric studies below the stomach are rare due to technical limitations of traditional manometry catheters. Consequently, specific motor patterns and their impact on gastric and small bowel function are not well understood. High-resolution manometry was used to record fed-state motor patterns in the antro-jejunal segment and relate these to fasting motor function. METHODS: Antro-jejunal pressures were monitored in 15 healthy females using fiber-optic manometry (72 sensors at 1 cm intervals) before and after a high-nutrient drink. KEY RESULTS: Postprandial motility showed a previously unreported transition point 18.8 cm (range 13-28 cm) beyond the antro-pyloric junction. Distal to the transition, a zone of non-propagating, repetitive pressure events (11.5 ± 0.5 cpm) were dominant in the fed state. We have named this activity, the duodeno-jejunal complex (DJC). Continuous DJC activity predominated, but nine subjects also exhibited intermittent clusters of DJC activity, 7.4 ± 4.9/h, lasting 1.4 ± 0.55 minutes, and 3.8 ± 1.2 minutes apart. DJC activity was less prevalent during fasting (3.6 ± 3.3/h; P = .04). 78% of fed and fasting state propagating antro-duodenal pressure events terminated proximally or at the transition point and were closely associated with DJC clusters. CONCLUSIONS AND INFERENCES: High-resolution duodeno-jejunal manometry revealed a previously unrecognized transition point and associated motor pattern extending into the jejunum, consistent with the duodenal brake previously identified fluoroscopically. Timing suggests DJC activity is driven by chyme stimulating duodenal mucosal chemosensors. These findings indicate that the duodenum and proximal jejunum consists of two major functional motor regions.

Neural motor complexes propagate continuously along the full length of mouse small intestine and colon.

Cyclical propagating waves of muscle contraction have been recorded in isolated small intestine or colon, referred to here as motor complexes (MCs). Small intestinal and colonic MCs are neurogenic, occur at similar frequencies, and propagate orally or aborally. Whether they can be coordinated between the different gut regions is unclear. Motor behavior of whole length mouse intestines, from duodenum to terminal rectum, was recorded by intraluminal multisensor catheter. Small intestinal MCs were recorded in 27/30 preparations, and colonic MCs were recorded in all preparations (n = 30) with similar frequencies (0.54 ± 0.03 and 0.58 ± 0.02 counts/min, respectively). MCs propagated across the ileo-colonic junction in 10/30 preparations, forming "full intestine" MCs. The cholinesterase inhibitor physostigmine increased the probability of a full intestine MC but had no significant effect on frequency, speed, or direction. Nitric oxide synthesis blockade by Nω-nitro-l-arginine, after physostigmine, increased MC frequency in small intestine only. Hyoscine-resistant MCs were recorded in the colon but not small intestine (n = 5). All MCs were abolished by hexamethonium (n = 18) or tetrodotoxin (n = 2). The enteric neural mechanism required for motor complexes is present along the full length of both the small and large intestine. In some cases, colonic MCs can be initiated in the distal colon and propagate through the ileo-colonic junction, all the way to duodenum. In conclusion, the ileo-colonic junction provides functional neural continuity for propagating motor activity that originates in the small or large intestine.NEW & NOTEWORTHY Intraluminal manometric recordings revealed motor complexes can propagate antegradely or retrogradely across the ileo-colonic junction, spanning the entire small and large intestines. The fundamental enteric neural mechanism(s) underlying cyclic motor complexes exists throughout the length of the small and large intestine.

Roles of three distinct neurogenic motor patterns during pellet propulsion in guinea-pig distal colon.

KEY POINTS: Enteric neural circuits enable isolated preparations of guinea-pig distal colon to propel solid and fluid contents by a self-sustaining neuromechanical loop process. In addition there are at least three neural mechanisms which are not directly involved in propulsion: cyclic motor complexes, transient neural events and distal colon migrating motor complexes. In excised guinea-pig colon we simultaneously recorded high resolution manometry, video-imaging of colonic wall movements and electrophysiological recordings from smooth muscle, which enabled us to identify mechanisms that underlie the propulsion of colonic content. The results show that the intermittent propulsion during emptying of the multiple natural faecal pellets is due to the intermittent activation of cyclic motor complexes and this is facilitated by transient neural events. Loss or dysfunction of these activities is likely to underlie disordered gastrointestinal transit. ABSTRACT: It is well known that there are different patterns of electrical activity in smooth muscle cells along different regions of the gastrointestinal tract. These different patterns can be generated by myogenic and/or neurogenic mechanisms. However, what patterns of electrical activity underlie the propulsion of natural faecal content remains unknown, particularly along the large intestine, where large quantities of water are reabsorbed and semi-solid faeces form. In this study, we developed a novel approach which enables for the first time the simultaneous recording of high resolution intraluminal manometry, electrophysiology from the smooth muscle, and spatio-temporal video imaging of colonic wall movements. Using this approach we were able to reveal the nature of enteric neuromuscular transmission and patterns of motor activity responsible for the movement of content. Three distinct neurogenic patterns of electrical activity were recorded even in the absence of propulsive movement. These were the cyclic motor complexes (CMCs), the transient neural events (TNEs) and the slowly propagating distal colonic migrating motor complexes (DCMMCs). We present evidence that the initiation of pellet propulsion is due to a cyclic motor complex (CMC) occurring oral to the pellet. Furthermore, we discovered that the intermittent propulsion of natural faecal pellets is generated by intermittent activation of CMCs; and this propulsion is facilitated by hexamethonium-sensitive TNEs. However, TNEs were not required for propulsion. The findings reveal the patterns of electrical activity that underlie propulsion of natural colonic content and demonstrate that propulsion is generated by a complex interplay between distinct enteric neural circuits.

Development and feasibility of an ambulatory acquisition system for fiber-optic high-resolution colonic manometry.

BACKGROUND: High-resolution colonic manometry is an emerging technique that has provided new insights into the pathophysiology of functional colorectal diseases. Prior studies have been limited by bulky, non-ambulatory acquisition systems, which have prevented mobilization during prolonged recordings. METHODS: A novel ambulatory acquisition system for fiber-optic high-resolution colonic manometry was developed. Benchtop validation against a standard non-ambulatory system was performed using standardized calibration metrics. Clinical feasibility studies were conducted in three patients undergoing right hemicolectomy. RESULTS: Pressure profiles obtained from benchtop testing were near-identical using the ambulatory and the non-ambulatory systems. Clinical studies successfully demonstrated ambulatory data capture with patients freely mobilizing postoperatively during continuous recordings of >60 hours. The occurrence (P = .56), amplitude (P = .65), velocity (P = .10), and extent (P = .12) of colonic motor patterns were similar to those obtained in non-ambulatory studies. CONCLUSIONS: A novel ambulatory system for high-resolution colonic manometry has been developed and validated. This technique will facilitate prolonged ambulatory recordings of colonic motor activity, assisting with investigations into the role of colonic motility in disease states.

A fiber-optic sensor-based device for the measurement of vaginal integrity in women.

AIMS: Pelvic floor disorders (PFDs) in women are a major public health concern. Current clinical methods for assessing PFDs are either subjective or confounded by interference from intra-abdominal pressure (IAP). This study introduces an intravaginal probe that can determine distributed vaginal pressure during voluntary exercises and measures the degree of vaginal tissue support independent of IAP fluctuations. METHODS: An intravaginal probe was fabricated with 18 independent fiber-optic pressure transducers positioned along its upper and lower blades. Continuous pressure measurement along the anterior and posterior vaginal walls during the automated expansion of the probe enabled the resistance of the tissue to be evaluated as a function of displacement, in a manner reflecting the elastic modulus of the tissue. After validation in a simulated vaginal phantom, in vivo measurements were conducted in the relaxed state and during a series of voluntary exercises to gauge the utility of the device in women. RESULTS: The probe reliably detected variations in the composition of sub-surface material in the vaginal phantom. During in-vivo measurements the probe detected distributed tissue elasticity in the absence of IAP change. In addition, the distribution of pressure along both anterior and posterior vaginal walls during cough, Valsalva and pelvic floor contraction was clearly resolved with a large variation observed between subjects. CONCLUSIONS: Our data highlight the potential for the probe to assess the integrity of the vagina wall and support structures as an integrated functional unit. Further in vivo trials are needed to correlate data with clinical findings to assist in the assessment of PFDs.

Optical flow sensor for continuous invasive measurement of blood flow velocity.

Continuous monitoring of intrapulse measurement of blood flow in humans is currently not achievable with clinically available instruments. In this paper, we demonstrate a method of measuring the instantaneous variations in flow during pulsatile blood flow with an optical flow sensor comprising a fiber Bragg grating sensor and illumination from a 565 nm Light-Emitting-Diode. The LED illumination heats the blood and fluctuations in temperature, due to variations in flow, are detected by the fiber sensor. A set of experiments at different flow rates (20 to 900 mL/min) are performed in a simulated cardiac circulation setup with pulsatile flow. Data are compared with an in-line time of flight ultrasound flow sensor. Our results show that the optical and ultrasonic signals correlate with Pearson coefficients ranging from -0.83 to -0.98, dependent on the pulsatile frequency. Average flow determined by ultrasound and the optical fiber sensor showed a parabolic relationship with R2 = 0.99. An abrupt step change in flow induced by occlusion and release of the circuit tubing demonstrated that the optical fiber and ultrasound sensor had similar response. The method described is capable of intrapulse blood flow measurement under pulsatile flow conditions, with potential applications in medicine where continuous blood flow sensing is desired.

Effect of electrode separation on high-resolution impedance manometry catheters for ex vivo animal experiments.

BACKGROUND: High-resolution impedance manometry (HRIM) catheters are used for esophageal reflux and bolus transit studies. Usually, these catheters have electrodes spaced at 20 mm intervals that are used for measuring electrical impedance between the consecutive electrodes and pressure sensors with 10 mm separation. Electrical impedance is a distributed measurement between the electrodes, unlike the point measurement of pressure sensors. Thus, the electrode separations affect the overall spatiotemporal resolution of the measurement. METHODS: A 3D model of the gastrointestinal tract, in which bolus shape and size can be modified, was used to simulate the admittance signal response of an intraluminal impedance catheter with 10 and 20 mm electrode separation to study the distributed sensitivity in the lumen to gain insight on the impedance measurement. In addition, experiments on sections of rabbit proximal colon were conducted with two catheters with electrode separations of 10 and 20 mm to compare the experimental data with the simulated data. KEY RESULTS: Reducing electrode spacing from 20 to 10 mm increased sensitivity to diameter change by a factor of ten. Admittance and diameter correlated strongly during a myogenic contraction with a Pearson's Correlation Coefficient of 0.86 for the custom catheter, in comparison with 0.56 for the commercial HRIM catheter. CONCLUSIONS: Ten millimeter electrode separation has a better spatiotemporal resolution, and unlike 20 mm electrode separation is able to identify myogenic contractions. Based on the numerical and experimental data, closer electrode separation should be considered for improved spatial resolution.

Identification of multiple distinct neurogenic motor patterns that can occur simultaneously in the guinea pig distal colon.

In the guinea pig distal colon, nonpropulsive neurally mediated motor patterns have been observed in different experimental conditions. Isolated segments of guinea pig distal colon were used to investigate these neural mechanisms by simultaneously recording wall motion, intraluminal pressure, and smooth muscle electrical activity in different conditions of constant distension and in response to pharmacological agents. Three distinct neurally dependent motor patterns were identified: transient neural events (TNEs), cyclic motor complexes (CMC), and distal colon migrating motor complexes (DCMMC). These could occur simultaneously and were distinguished by their electrophysiological, mechanical, and pharmacological features. TNEs occurred at irregular intervals of ~3s, with bursts of action potentials at 9 Hz. They propagated orally at 12 cm/s via assemblies of ascending cholinergic interneurons that activated final excitatory and inhibitory motor neurons, apparently without involvement of stretch-sensitive intrinsic primary afferent neurons. CMCs occurred during maintained distension and consisted of clusters of closely spaced TNEs, which fused to cause high-frequency action potential firing at 7 Hz lasting ~10 s. They generated periodic pressure peaks mediated by stretch-sensitive intrinsic primary afferent neurons and by cholinergic interneurons. DCMMCs were generated by ongoing activity in excitatory motor neurons without apparent involvement of stretch-sensitive neurons, cholinergic interneurons, or inhibitory motor neurons. In conclusion, we have identified three distinct motor patterns that can occur concurrently in the isolated guinea pig distal colon. The mechanisms underlying the generation of these neural patterns likely involve recruitment of different populations of enteric neurons with distinct temporal activation properties.

Monitoring the Effect of Contact Pressure on Bioimpedance Measurements.

This paper presents preliminary results on the effect of contact pressure on bioimpedance measurements in an excised section of human colon tissue. The impedance measurements were performed with a small diameter probe suitable for in-vivo use, which is capable of measuring contact force. Force measurements are performed by fiber optic sensor which consisted of a Fiber Bragg Grating. The obtained results highlight the importance on limiting the applied pressure during bioimpedance measurements.

Design, Construction and Validation of an Electrical Impedance Probe with Contact Force and Temperature Sensors Suitable for in-vivo Measurements.

Bioimpedance spectroscopy measurements can be used for tissue characterization. These measurements can be performed in soft tissues by direct contact of a non-invasive probe consisting of two or four electrodes. The amount of force applied by users can be quite different, and the measurements can vary as a result. To compensate for this, we have built an electrical impedance probe (diameter 3.2 mm) with fibre optic contact-force and temperature sensors built in it. The different sensors of the probe were tested individually. The errors in magnitude and phase angle of the probe are <0.9% and <4°, respectively, for a 0.9% NaCl solution. The linear dynamic range of the force sensor was from 0 to 100 grams. An ex-vivo experiment on a section of proximal colon from a guinea-pig was performed. Twenty bioimpedance measurements were taken in a frequency range of 5 kHz to 1 MHz, while simultaneously recording the force applied. For an increase in contact pressure applied to tissue from 0 to 15.4 kPa, the maximum change in resistivity was 33% at 5 kHz and the minimum was 6.6% at 142 kHz. The probe is small enough to be introduced via the instrument port of an endoscope.

Ovine multiparity is associated with diminished vaginal muscularis, increased elastic fibres and vaginal wall weakness: implication for pelvic organ prolapse.

Pelvic Organ Prolapse (POP) is a major clinical burden affecting 25% of women, with vaginal delivery a major contributing factor. We hypothesised that increasing parity weakens the vagina by altering the extracellular matrix proteins and smooth muscle thereby leading to POP vulnerability. We used a modified POP-quantification (POP-Q) system and a novel pressure sensor to measure vaginal wall weakness in nulliparous, primiparous and multiparous ewes. These measurements were correlated with histological, biochemical and biomechanical properties of the ovine vagina. Primiparous and multiparous ewes had greater displacement of vaginal tissue compared to nulliparous at points Aa, Ap and Ba and lower pressure sensor measurements at points equivalent to Ap and Ba. Vaginal wall muscularis of multiparous ewes was thinner than nulliparous and had greater elastic fibre content. Collagen content was lower in primiparous than nulliparous ewes, but collagen organisation did not differ. Biomechanically, multiparous vaginal tissue was weaker and less stiff than nulliparous. Parity had a significant impact on the structure and function of the ovine vaginal wall, as the multiparous vaginal wall was weaker and had a thinner muscularis than nulliparous ewes. This correlated with "POP-Q" and pressure sensor measurements showing greater tissue laxity in multiparous compared to nulliparous ewes.

High-resolution anatomic correlation of cyclic motor patterns in the human colon: Evidence of a rectosigmoid brake.

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.

A high-resolution tape sensor improves the accuracy of applied pressure profiles during lower-leg bandaging - results from a study using a fibre-optic sensing tape.

Compression bandaging is a mainstay practice in the treatment of conditions such as chronic wounds and lymphoedema. However, the ability of practitioners to measure bandage application to a desired pressure profile is difficult because of sensor limitations. We have used a novel fibre-optic-based, high-resolution sub-bandage pressure monitor to measure adherence to a target pressure gradient during compression bandaging. Participants of various experience (n = 46) were asked to bandage a lower-leg manikin to a gradient of 40 (ankle) to 20 mmHg (proximal calf) in both a blinded trial and subsequently with sensor feedback. Mean pressures across all sensors for both the blind and sensor-guided trials approximated a target mean of 30 mmHg. However, the mean gradient achieved in the blinded trial showed an inverse pressure gradient to the target with a high-pressure region at the mid-calf (44 ± 19 mmHg). Correlation to the target gradient improved from R2 = 0·62 during the blind trial to 0·93 using sensor feedback, with a gradient that closely approximated the target. This demonstrates the use of high-resolution sub-bandage pressure sensing in improving the ability of practitioners to achieve a target pressure gradient in compression bandaging for clinical use and training.

Vaginal wall weakness in parous ewes: a potential preclinical model of pelvic organ prolapse.

INTRODUCTION AND HYPOTHESIS: Ewes develop pelvic organ prolapse (POP) and may be a suitable model for preclinical studies evaluating cell-based therapies for POP. The aim of this study was to establish a clinical score of vaginal weakness and to compare POP Quantification System (POP-Q) values in conscious nulliparous and parous ewes and determine whether ewes are a suitable POP model. METHODS: Ewes (n = 114) were examined while conscious, without sedation, and standing in a V conveyer by adapting the human POP-Q measurement. Ovine POP was defined as descent to the introitus from POP-Q points Aa 3 cm above the introitus on the anterior wall, Ap 3 cm above the introitus on the posterior wall, or increased Ba anterior wall descent above the urethra (≥0). A test-retest showed good inter- and intrarater reliability. RESULTS: There was no evidence of tissue mobility at Aa, Ap, Ba (all -3 cm) in nulliparous ewes (n = 14). In contrast, multiparous ewes had a median of -1 and interquartile range (IQR) (-2 to 0) for Aa, [0 (-1 to 0)] for Ap and [0 (-2.75 to 0)] for Ba (n = 33; P < 0.0001 in comparison with nulliparous) ewes. Ovine vaginal displacement was seen in 50.9 % of parous ewes and was strongly associated with parity (P = 0.003). CONCLUSIONS: A modified POP-Q in conscious ewes was established showing that the vaginal wall of parous animals has similar regions of weakness as do women and may be similarly related to parity. Ewes appear to be a representative preclinical model of human vaginal prolapse.

Real-time measurement of the vaginal pressure profile using an optical-fiber-based instrumented speculum.

Pelvic organ prolapse (POP) occurs when changes to the pelvic organ support structures cause descent or herniation of the pelvic organs into the vagina. Clinical evaluation of POP is a series of manual measurements known as the pelvic organ prolapse quantification (POP-Q) score. However, it fails to identify the mechanism causing POP and relies on the skills of the practitioner. We report on a modified vaginal speculum incorporating a double-helix fiber-Bragg grating structure for distributed pressure measurements along the length of the vagina and include preliminary data in an ovine model of prolapse. Vaginal pressure profiles were recorded at 10 Hz as the speculum was dilated incrementally up to 20 mm. At 10-mm dilation, nulliparous sheep showed higher mean pressures ( 102 ± 46 ?? mmHg ) than parous sheep ( 39 ± 23 ?? mmHg ) ( P = 0.02 ), attributable largely to the proximal (cervical) end of the vagina. In addition to overall pressure variations, we observed a difference in the distribution of pressure that related to POP-Q measurements adapted for the ovine anatomy, showing increased tissue laxity in the upper anterior vagina for parous ewes. We demonstrate the utility of the fiber-optic instrumented speculum for rapid distributed measurement of vaginal support.