Manometric Sensors Research Articles

Development of portable gas sensing system for measuring gas emission concentration and diffusivity using commercial manometric sensors in gas exposed polymers: Application to pure gases, H2, He, N2, O2 and Ar

Low-cost gas sensing system to measure the emission concentration and diffusion coefficient of the gas emitted from specimens, which were exposed by gas under high pressure, was developed using the commercial manometric sensors. The gas emitted from two polymer specimens [low density polyethylene (LDPE) and nitrile butadiene rubber (NBR)] during desorption produced a measurable increase in pressure; this pressure was recorded by a portable data logger in the specimen container chamber. Thus, the molar concentration and diffusivity of the released gas were calculated via the ideal gas equation and diffusion analysis program. As results, gas sensor immediately responded without any chemical interaction and emitted gas weight per specimen weight up to 1400×10−6 with a controllable sensitivity/resolution. The performance test confirmed that our developed sensing technique had good reliability, adjustable measurable range and independence to fluctuations in temperature and pressure. Consequently, the developed simple sensing system was successfully used for the simultaneous real-time detection and transport characterizations for pure gases (H2, He, N2, O2 and Ar).

Comparison between the portable pressure measuring device and PicoPress® for garment pressure measurement on hypertrophic burn scar during compression therapy

PurposeThe current standard treatment for hypertrophic scars following burn injury is pressure garment therapy. The experimenters developed the novel portable pressure measuring device using silicon piezoresistive sensors. As PicoPress® is the most accurate (i.e., lowest variation and error) manometric sensor for pressure measurement, we sought to compare and examine the accuracy of the novel device regarding in vitro pressure measurements at the hypertrophic scar–pressure garment interface. MethodsThe novel device was designed to operate in non-corrosive media, such as air. The device can use up to six pressure sensing points and was developed to adjust the number of pressure sensors according to the size of the scar. Pressure measurements were acquired through a readout circuit consisting of an analog-to-digital converter, a microprocessor, and a Bluetooth transmission module for wireless data transmission to an external device. All signals were converted into mean pressure expressed in millimeters of mercury (mmHg). The mean pressure values measured by the sensors were compared to those obtained from PicoPress®. 55 garment pressures recordings were obtained from the sensors over this study conducted in 2018–February 2020. We then analyzed the test–retest reliability using the intraclass correlation coefficients (ICC). PicoPress® was also employed in the same pressure garments for obtaining similar measurements. A two way random effects model ICC with 95% confidence intervals was used to compare the mean pressure values obtained from the silicon piezoresistive sensors to the PicoPress® measurements. ResultsThe test–retest reliability of the pressure sensors was close to the acceptable level for clinical use regarding stationary interface pressure measurement (ICC = 0.99, 95% CI 0.990−0.997). The mean pressure obtained from the silicon piezoresistive pressure sensors showed an accordance with the measurements from PicoPress® (ICC = 0.97, 95% CI 0.947−0.985). ConclusionThe novel device may present a viable alternative to PicoPress® for garment pressure measurements. In addition, the novel device improves adaptability to the hypertrophic scar shape and size. Complementary characteristics such as wireless transmission to an external device may allow burn patients to continuously wear the device for real-time measurements during pressure garment therapy, thus improving existing devices including PicoPress®.

Propagation Characteristics of Fasting Duodeno-Jejunal Contractions in Healthy Controls Measured by Clustered Closely-spaced Manometric Sensors.

Background/AimsHigh-resolution methods have advanced esophageal and anorectal manometry interpretation but are incompletely established for intestinal manometry. We characterized normal fasting duodeno-jejunal manometry parameters not measurable by standard techniques using clustered closely-spaced recordings.MethodsTen fasting recordings were performed in 8 healthy controls using catheters with 3–4 gastrointestinal manometry clusters with 1–2 cm channel spacing. Migrating motor complex phase III characteristics were quantified. Spatial-temporal contour plots measured propagation direction and velocity of individual contractions. Coupling was defined by pressure peak continuity within clusters.ResultsTwenty-three phase III complexes (11 antral, 12 intestinal origin) with 157 (95% CI, 104–211) minute periodicities, 6.99 (6.25–7.74) minute durations, 10.92 (10.68–11.16) cycle/minute frequencies, 73.6 (67.7–79.5) mmHg maximal amplitudes, and 4.20 (3.18–5.22) cm/minute propagation velocities were recorded. Coupling of individual contractions was 39.1% (32.1–46.1); 63.0% (54.4–71.6) of contractions were antegrade and 32.8% (24.1–41.5) were retrograde. Individual phase III contractions propagated > 35 fold faster (2.48 cm/sec; 95% CI, 2.25–2.71) than complexes themselves. Phase III complexes beyond the proximal jejunum were longer in duration (P = 0.025) and had poorer contractile coupling (P = 0.025) than proximal complexes. Coupling was greater with 1 cm channel spacing vs 2 cm (P < 0.001).ConclusionsIntestinal manometry using clustered closely-spaced pressure ports characterizes novel antegrade and retrograde propagation and coupling properties which degrade in more distal jejunal segments. Coupling is greater with more closely-spaced recordings. Applying similar methods to dysmotility syndromes will define the relevance of these methods.

Interpreting manometric signals for propulsion in the gut

Propulsion of intestinal contents involves coordinated contractions and relaxations of the muscle controlled by polarised enteric neural reflex pathways. Due to the inaccessibility of the small and large bowel, obtaining detailed manometric measurements in the gut or visualizing the movement of digesta is difficult in vivo. Computational modelling that incorporates the complex interactions between gut content and wall contractility has the potential to explain the mechanisms behind propulsive motor patterns and aid the interpretation of manometric measurements. We present here a biomechanical computational model of coupled wall flexure and flow dynamics in a virtual segment of intestine. The model uses the smoothed particle hydrodynamics method which permits coupling of the fluid/solid motion and wall deformation in a natural way. Peristaltic waves of contraction and relaxation, similar to those observed in physiological experiments, were applied to the gut wall of the model. A catheter containing manometric sensors was also incorporated into the model to derive representative pressure readings. The sensitivity of the model to input parameters including wall stiffness, viscosity of content and degree of muscular contraction is also presented. The results show that there is a rapid rise in pressure of fluid content trapped between the catheter and the contracting wall. The peristaltic wave travels along the length of the virtual segment of intestine passing over each sensor. The bolus, formed by the peristaltic contraction, grows in size and longitudinal extent until the bolus size reaches steady state. The wall force and the peak fluid pressure both scale proportionally with the change in muscle length, indicating that manometric data provide a reliable means for measuring the strength of contractions. Changes in stiffness of the wall and viscosity of contents result in predictable changes in the parameters of peristalsis. The model can be thus applied to manometry measurements in real experimental conditions.

Influence of head rotation on upper esophageal sphincter pressure evaluated by high-resolution manometry system

Objectives This study aimed to quantify the effects of head rotation on upper esophageal sphincter (UES) pressure in healthy subjects using a novel high-resolution manometry (HRM) system. Study Design Prospective study. Setting Nagasaki University Hospital. Subjects and Methods Eighteen asymptomatic Japanese male adult volunteers were studied. A solid-state HRM was positioned to record resting UES pressure. After endoscopically confirming on which side of the pyriform sinus the manometric sensor was positioned within the hypopharynx, we measured the maximum and mean values of the resting UES pressure and the length of the zone of the UES along the esophagus with the patients in the following positions: 1) neutral and straightforward head position (NSF), 2) turning the head in the direction of the side in which the sensor was positioned (HSS), and 3) turning the head in the opposite direction of the side with sensor (HOS). Results The maximum and mean values of the resting UES pressure were statistically higher in HSS than in NSF ( P = 0.0001 and P < 0.0001, respectively), and were statistically lower in HOS than in NSF ( P < 0.0001 and P < 0.0001, respectively). The length of the zone of the UES was statistically shorter in HOS than in NSF ( P < 0.0001), but there was no significant difference in resting UES pressure along the esophagus between HSS and NSF ( P = 0.3024). Conclusion The present study provided us with physiological information regarding normal UES pressure in relation to head rotation. This data will be of aid to future clinical and investigative swallowing studies. Additionally, the current study provides evidence of the safety and usefulness of the head rotation maneuver for dysphagic patients.

Esophageal Pressure Topography Criteria Indicative of Incomplete Bolus Clearance: A Study Using High-Resolution Impedance Manometry

This study used high-resolution impedance manometry (HRIM) to determine pressure topography thresholds of peristaltic integrity predictive of incomplete esophageal bolus clearance. A total of 16 normal controls and 8 patients with dysphagia were studied using a solid-state HRIM assembly incorporating 36 manometric sensors and 12 impedance segments. Each of the 10 saline swallows in each study was dichotomously scored as either complete or incomplete bolus clearance by impedance criteria, and peristaltic integrity was evaluated using pressure topography isobaric contours ranging from 10 to 30 mm Hg in 5- mm Hg increments. Each isobaric contour plot was characterized by the location and length of breaks in the isobaric contour. All subjects had normal esophagogastric junction (EGJ) relaxation and none met the pressure topography criteria of hiatus hernia. In all, 70 (29%) of the 240 individual swallows had incomplete bolus clearance. In every case, an intact >or=20 mm Hg isobaric contour was associated with complete bolus clearance. The largest defect in the 20 and 30 mm Hg isobaric contours associated with complete bolus clearance measured 1.7 and 3.0 cm, respectively, in length, whereas the smallest defect predictive of incomplete bolus clearance measured 2.1 and 3.2 cm, respectively. In individuals with normal EGJ relaxation and morphology, peristaltic contractions with breaks <2 cm in the 20 mm Hg isobaric contour or <3 cm in the 30 mm Hg isobaric contour are associated with complete bolus clearance, and longer breaks predict incomplete bolus clearance.

An optic pharyngeal manometric sensor for deglutition analysis

A micro optic pharyngeal manometric sensor for deglutition analysis was constructed. The optical manometric sensor was composed of a fluid-sensitive and air-sensitive fiber-optic pressure sensor (extrinsic Fabry-Perot interferometric type) and a lateral pressure-sensitive attachment. The manometric sensor was circumferential type, and had a very small diameter (distal: 2.08 mm, mesial: 0.99 mm). The output current of the sensor was linearly related to the output of a conventional catheter-type solid-state pressure sensor over a range of -3.0 x 10(4) to 3.0 x 10(4) N/m(2). The time constants of responsiveness were 12.2 +/- 2.7 ms during rapid decompression and 32.1 +/- 1.6 ms after a rapid return to ambient pressure. The optical pharyngeal manometric sensor had similar response time characteristics as the naked optical sensor and the conventional solid-state sensor. During in vivo measurement, the waveform of the optical pharyngeal manometer output was almost similar to the waveform of the output of the conventional sensor. The optical manometer could sufficiently detect the lateral pressure and the suction pressure for bolus transit generated in the P-E segment.

Clinical Measurement of Pharyngeal Surface Electromyography

Background. Dysphagia diagnosis is limited by our inability to evaluate the underlying neuromuscular pathology of swallowing. A novel approach using pharyngeal surface electromyography (PsEMG) has been reported in the literature. Objective. Three exploratory projects were undertaken to provide data toward the validation of PsEMG as a clinical measure of pharyngeal physiology. The first evaluates laterality of electrode placement in the pharynx. The second and third evaluate PsEMG using a circumferential and unidirectional electrode, respectively, during swallowing maneuvers. Methods. In experiment 1, a catheter housing 3 manometric sensors and 1 bipolar PsEMG electrode was randomly inserted in each nares of 10 participants. Moving jaw radiographs were taken, and the PsEMG electrode was measured in millimeters from midline. In experiments 2 and 3, the catheter was placed in 22 and 40 research participants, respectively. Waveform characteristics were collected during swallowing maneuvers. The 2 experiments differed by type of electrode (circumferential, unidirectional) and swallowing maneuver (noneffortful and effortful swallow; noneffortful, effortful, and tongue-hold swallow). Results. Midline electrode placement occurred on 20% of trials with deviation of up to 14.7 mm on all other trials. Maneuver-specific differences in amplitude were not detected with PsEMG; unacceptable levels of intrasubject and intersubject variability were identified. Temporal relationships of PsEMG and pharyngeal manometric pressure appeared appropriate. The unidirectional electrode revealed a unique bimodal PsEMG pattern that may reflect sequential contraction of muscles of the posterior pharyngeal wall. Conclusions. The current PsEMG design and procedures do not validly measure pharyngeal muscle activity. Recommendations for improved methods are provided.

Timing of Pharyngeal and Upper Esophageal Sphincter Pressures as a Function of Normal and Effortful Swallowing in Young Healthy Adults

The effect of effortful swallow on pharyngeal pressure and UES relaxation onsets and durations was examined. Eighteen adults, nine males and nine females (mean age=27.9 yr), participated. Timing of pharyngeal pressure and onset and duration of UES relaxation were measured across ten trials of normal and ten trials of effortful swallows. Results revealed that manometric timing measurements are consistent across trials. The first and second statistical analyses investigated the pharyngeal pressure and UES relaxation onsets and durations, respectively. Both analyses identified a significant interaction of swallow type (i.e., effortful vs. normal) by manometric sensor location (p<0.05). Across normal and effortful swallows, UES relaxation preceded pharyngeal pressure onsets, yet the rate of change (or degree of delay) varied across the sensors. Furthermore, the effortful swallow elicited longer pharyngeal pressure and UES relaxation durations, yet the pressure duration measured in the upper pharynx was significantly longer than that measured lower in the pharynx. These findings offer insight as to the potential positive and negative influence of the effortful swallow on pharyngeal timing.

Adaptation of a manometric biosensor to measure glucose and lactose

A manometric sensor previously developed to measure urea was modified to measure glucose and lactose through enzymatic oxidation. Change in pressure in an enclosed cavity was correlated to the depletion of oxygen resulting from the enzymatic oxidation of glucose or lactose. The response of the sensor was linear and could be made adjustable over a large range by adjusting the amount of sample loaded into the fixed volume reactor. Because of the slow mutarotation of glucose, the oxidation of glucose was not allowed to proceed to completion. Therefore, the precision of the sensor (approximately 0.2 mM in a range from 0 to 5 mM) was limited by variations in the oxidation rate of glucose by glucose oxidase. Because the assay for lactose measured glucose subsequent to the hydrolysis of lactose by β-galactosidase, the same degree of precision was observed in lactose. Milk lactose, typically at concentrations of about 150 mM, was estimated using the lactose assay after first diluting the samples. For many fluids such as milk, the use of manometric sensors for oxidizable substrates may be preferable to optical and electrochemical methods because they are robust and suffer a low degree of optical and chemical interferences. Glucose and lactose are representative of many important oxidizable substrates, which may be determined in this manner, many of which do not suffer from limitations caused by mutarotation. In theory, detection limits less than 1 μM may be achieved using these methods.

An immersible manometric sensor for measurement of humidity and enzyme mediated changes in dissolved gas

An immersible manometric sensor was made by covering the gaseous cavity of a pressure transducer with a 1 μm controlled pore membrane. Transfer of gas across the membrane allowed the pressure transducer to record changes in humidity or dissolved gas when immersed in solution. By immersing the sensor in distilled water, atmospheric humidity could be estimated by the deficit of atmospheric vapor pressure from saturation. In another application of the sensor, CO 2 was monitored continuously. This was not possible in previous closed-reactor type manometric sensors, and may allow the new technology to be used in applications requiring continuous monitoring of a process or stream. By coupling the sensor with enzymes liberating or consuming dissolved gas, different chemicals could be estimated. Urea was estimated by first hydrolyzing it with urease and then measuring the resulting CO 2 gas in solution. Glucose was measured through its enzymatic oxidation by glucose oxidase. The sensitivity to urea over the range 0–2.5 mM was about 1.02 kPa/mM, and the standard error was 0.086 mM. Due to the lower solubility of oxygen, the sensitivity to glucose in a range from 0 to 10 μM was over 100 kPa/mM, with a standard error of only 0.76 μM. This sensitivity was not possible in closed-reactor type manometric sensors due to constraints of dimensioning the head space gas volume for reproducibility and effective mass transfer. The 90% rise times for the sensor ranged from about 1–60 min for the different applications. The dynamic characteristics of the device may be improved by using a membrane with greater porosity, higher rigidity and lower thickness, and by reducing the dimensions of the cavity volume in the sensor through integrated microfabrication of the membrane onto the transducer.

Antral axial forces postprandially and after erythromycin in organic and functional dysmotilities

Our aims were to measure antral axial forces in patients with suspected upper gut dysmotilities and to compare the number of antral contractions detected by an axial force catheter and by manometric sensors in the distal antrum and pylorus. Fifteen patients (2 men, 13 women; mean age 42 years) underwent studies for 3 hr fasting, 2 hr postprandially, and up to 60 min after intravenous erythromycin (3mg/kg). Seven patients had gastroparesis or chronic intestinal pseudoobstruction, five functional disease, and three subacute obstruction. Postprandially, the number of peaks detected by the two methods was not significantly different; however, after erythromycin, the axial catheter detected more contractions (P = 0.02). Erythromycin significantly increased the number of postprandial axial forces (from 1.2 +/- 0.3/min to 2.5 +/- 0.3/min, P < or = 0.01) in the whole group and in the organic dysmotility group (P = 0.01). Erythromycin significantly increases the number of axial forces in functional and organic upper gut dysmotilities, but the axial force catheter is not advantageous over manometry for postprandial measurements of antral motility.

Pharyngeal Solid-State Manometry Catheter Movement During Swallowing in Dysphagic and Nondysphagic Participants

The movements of the soft palate and the larynx are crucial in pharyngeal manometry because of the potential risk of manometry sensor dislocation. Twenty dysphagic patients and 20 nondysphagic volunteers were examined with simultaneous videoradiography and intraluminal pharyngeal solid-state manometry. The movements of the manometric sensors were analyzed from lateral videorecording. Two different types of catheter movement were found. The sensor in the upper esophageal sphincter (UES) could either be lifted cranially during the closure of the soft palate (type 1) or stay unaltered in the sphincter until the beginning of the laryngeal elevation and then follow the sphincter cranially during laryngeal elevation with no previous response to soft palate closure (type 2). Type 1 movement was found in eight of 20 patients but in only one of the 20 volunteers. The resting pressure of the upper esophageal sphincter was significantly higher in type 2 (P = 0.004). Nineteen of the 20 patients with a high resting pressure of the UES (83+ mm Hg) were found to have the type 2 movement. High resting pressure in the UES permitted the sphincter to grasp the manometry catheter and caused the sensor to follow the cranial movement during laryngeal elevation. Sensor movement is important during pharyngeal manometry, and sensor dislocation out of the sphincter can be misinterpreted as sphincter relaxation. Simultaneous videoradiography provides control of sensor positioning and allows for correction.

An Experimental Manometric Study Simulating Upper Esophageal Sphincter Narrowing

Elevated intrabolus pressure above a pharyngeal narrowing has been postulated as an important finding in patients with cricopharyngeal bars. To elucidate the significance of intrabolus pressure around lumen narrowings in the pharynx, intraluminal pressure characteristics were evaluated in a laboratory model simulating upper esophageal sphincter narrowing. Intraluminal solid-state manometry was performed in an experimental model in which variable narrowing was created in an expandable balloon simulating the pharyngeal walls. Intrabolus pressure was dependent on the position of the manometric sensor, degree of lumen narrowing, bolus volume, flow rate, and fluid viscosity. Elevated intrabolus pressure is an important finding. Intrabolus pressure is dependent on many parameters, and hence, is difficult to evaluate. If results found with this model hold true in patients, manometric sensor positioning is crucial, and concurrent fluoroscopy is highly recommended to achieve a standardized manometric technique in pharyngeal manometry.

Perendoscopic manometry of the distal ileum and ileocecal junction in humans

Previous manometric studies of the ileocolonic junction were performed without assessing the precise spatial relationship between recording sensors and ileocolonic junction. In the present study, the motor activity of the ileocolonic junction was recorded using manometric sensors localized under direct colonoscopic control in 11 patients (4 men, 7 women; mean age, 55 years) referred for hematochezia with normal stool frequency. No medications were administered before and during endoscopy. A perfused catheter (OD 1.7 mm, with three side holes 4 mm apart and marked by evenly spaced black rings in the distal 6 cm) was passed through the biopsy channel of the endoscope and advanced through the ileocolonic junction and 6 cm into the ileum. The catheter was then withdrawn into the cecum by 1-cm steps, and motor activity was recorded for 4–6 minutes at each station. A single catheter taped to the endoscope continuously recorded cecal pressure. An ileocecal pressure gradient could not be identified in the majority of subjects; individual values ranged from −8 to +4 mm Hg, and gradients were maintained over the entire length of the ileum. In the distal ileum, tonic and phasic pressure waves were detected. Tonic variations were present for 70.1% of the recording time, either alone (44%) or together with phasic waves (56%). Phasic waves were present for 10.3% of the recording time and, according to their duration, were subdivided into those compatible with the rate of ileal slow waves and prolonged waves not compatible with the rate of ileal slow waves. Regular phasic waves could be either isolated or in clusters; prolonged waves were always isolated. A similar proportion of regular (27.9%) and prolonged (31.2%) phasic waves propagated aborally along the ileum or from ileum to cecum. Clusters presented an average of 8.7 ± 0.6 peaks/min, and 44% of them propagated aborally. The manometric characteristics did not vary between the segments 5-3 cm and 2-0 cm proximal to the ileocecal junction. In conclusion, a powerful ileocecal sphincter was not detected at the human ileocecal junction, and motor activity of the distal ileum was characterized by tonic changes and rapid phasic contractions.

The fibre Fabry Perot sensor. A long-term manometry sensor for quantitative intraluminal pressure measurement of the gastrointestinal tract

Sensor dislocation of water perfused side-hole manometry catheters during longer periods of examination, as well as heavy expenditure on equipment and personal, are disadvantages of perfusion manometry. Such catheters have contributed substantially to the attempt to become independent of water as a transmitter medium in manometric pressure sensors for the upper gastrointestinal tract. Using the principle of the mirror interferometer of Fabry and Perot, we have developed and manufactured a fibre-optic Fabry Perot Sensor (FFP) which records local asymmetric pressure with constant sensitivity over the sensor surface area of 40 mm length. The FFP signal was compared with the pressure measured with a conventional four-side-hole perfusion catheter. The signal corresponding to long-term basal pressure of the lower oesophageal sphincter (LOS) varied over a normal range, and the signal presenting the pressure in the tubular oesophagus had a normal range determined from 15 healthy volunteers. Due to the phase modulation of its laser, the FFP is nearly independent of substantial artefacts.

A manometric pressure sensor with an adjustable measurement range

A manometric pressure sensor with an adjustable measurement range

Determinants of upper esophageal sphincter pressure in dogs

Chronic experiments were done on six dogs fitted with EMG electrodes on pharyngeal and esophageal musculature. Electromyographic activity of the cricopharyngeus was recorded in awake and sedated animals with and without manometric recordings as well as during esophageal distension. Intraluminal upper esophageal sphincter (UES) pressure had two distinct components; active contraction accompanied by cricopharyngeal EMG activity and passive elasticity that persisted in the absence of EMG activity. Between swallows, the cricopharyngeal EMG activity patterns observed were of either tonic activity, no activity, or phasic activity with inspiratory bursts. The activity level was markedly affected by anesthesia, phonating, whining, panting, level of alertness, or changes in head posture. A brisk UES contraction was elicited in response to passage of the manometric assembly and to intraesophageal balloon distension. Persistent EMG augmentation after stationing of the manometric sensor suggested that intraluminal manometry tends to exaggerate resting sphincter pressure. We conclude that electrical activity of the cricopharyngeus, and by inference UES pressure, is markedly affected by many variables that are difficult to control during clinical or experimental determinations of UES pressure.