Standard Pressure Transducer Research Articles

Accuracy of arthroscopic fluid pump systems in shoulder surgery: a comparison of 3 different pump systems

Extra-articular fluid extravasation is a known complication during shoulder arthroscopy. The risk and amount of extravasation to a large degree is dependent on the fluid pressure delivered to the surgical site. Accurate measurement, knowledge, and control of the pressure delivered is thus important to surgeons, anesthetists, and the patient. The purpose of this study was to compare the pressure measurement accuracy of 3 arthroscopic fluid pumps, with 2 of them having 2 different settings. Twenty-five patients (n = 5 per group) undergoing shoulder arthroscopy were selected. Three different arthroscopic fluid pumps (ConMed 24K, Stryker Crossflow, Arthrex Dual Wave) were tested in 5 different operational settings (Stryker, standard and dynamic mode; ConMed, with and without TIPS; Arthrex Dual Wave). In each operation, the set pump pressures and the subsequently delivered intra-articular surgical site fluid pressures were measured by a spinal needle connected to an anesthetic standard pressure transducer attached to the anesthetic machine. Independent measures of the surgical site pressures were obtained before multiple portals were created or extravasation had occurred. Measurements were taken at the beginning of surgery. Measurements of the mean intra-articular pressure were found to not be significantly different from the set pressure for the ConMed 24K with TIPS (0.98 ± 0.02-fold) and Stryker Crossflow in standard mode (0.98 ± 0.02-fold). However, actual pressure was significantly greater than the set pressure for the ConMed 24K without TIPS (by 1.30 ± 0.13-fold), Stryker Crossflow in dynamic mode (by 1.82 ± 0.08-fold), and Arthrex Dual Wave (by 2.19 ± 0.06-fold). Independently measured intra-articular pressure can be more than double the set pressure for some arthroscopic pumps. Measuring intra-articular pressure can thus aid in adjusting the set pressure. This could minimize the risk of intraoperative complications.

Peripheral Venous Pressure to Predict Congestive Heart Failure Readmission

Introduction Acute decompensated heart failure (ADHF) readmission rates are high and act as a burden to both the patient and the healthcare system. Non-invasive measures of hemodynamic status are limited in accuracy, leading to patients being discharged with residual congestion and a higher likelihood of subsequent readmission for ADHF. Peripheral venous pressure (PVP) measurement involves transducing a peripheral intravenous (PIV) catheter and may serve as a minimally invasive method of determining hemodynamic status in patients with ADHF. PVP measurements have been shown to correlate with CVP measurements in heart failure patients, but the clinical relevance of this has not yet been established. We sought to examine if PVP measurements may predict heart failure readmission. Methods A prospective feasibility study was conducted from July to December 2018. Patients admitted with ADHF were enrolled on day-of-discharge. Using a standard pressure transducer leveled to the phlebostatic access, measurement of PVP was performed at the bedside using a previously-inserted PIV. The electronic medical record was reviewed for subsequent readmissions. The primary end-point was readmission at 30 days post-discharge. Results 29 patients were enrolled. The mean age of participants was 65.6 +/- 10.8 years. 66% of patients were male and 55% of patients were black. 72% of patients had a reduced ejection fraction (EF) and 28% had a preserved EF. At the time of discharge, the mean PVP was 11.6 +/- 4.9 mmHg. 5 patients (17%) were readmitted within 30 days. Mean PVP for those readmitted was 12.0 +/- 2.1 mmHg vs 11.5 +/- 5.3 mmHg for those without readmission (difference of the means 0.5 mmHg, p= 0.86). PVP was not significantly impacted by whether a 22-gauge or 20-gauge PIV was used (difference of means 2.3 mmHg, p= 0.51). Waveform analysis on a subset of patients showed lower PVP in those with a sinusoidal waveform as opposed to a flatline or static waveform (12.8 vs. 17.4 mmHg, p=0.32). Conclusion In this small feasibility study, few patients were readmitted for heart failure in 30 days. PVP was similar among the 5 patients readmitted with ADHF. PVP measurement was readily obtainable and PVP was not significantly impacted by PIV gauge. Further study of this clinical application to PVP measurement is warranted.

Application of shock tube in calibrating dynamic pressure transducers

The step pressure generated by shock tube was used for calibration of dynamic pressure transducers. First, the performance of the shock tube based calibration installation was theoretically predicted. The influence of Mach number to the step pressure and the duration of the step pressure plateau was analyzed by numerical calculation. Second, the performance of the calibration installation was tested, whose result showed that the minimum and maximum value of the step pressure generated by the calibration installation was 9.60kPa and 1.101MPa, respectively, the maximum value of the rise time of the step pressure was 0.7μs, the minimum value of the duration of the step pressure plateau was 4.14ms, the fluctuation of the step pressure plateau was better than ±2%, and the maximum value of the 2nd order expand uncertainty of the step pressure was 3.52%. The test result verified that the calibration installation met the requirements of the previous design and correlative verification regulations. Last, the sensitivity and syntonic frequency of standard pressure transducers were tested by the calibration installation. The result was in accord with the factory technical parameters.

Reasons For The Experimental Research Of Gas Outflows Based On The Signals Of Weak Interactions Between The Tested Model Of The Gas Pipeline, And Tested Equalizer

Abstract This article applies diagnosing issues outflows of gas pipelines using specialized research equipment - equalizers. Variant with only two measuring devices (equalizers), arranged on the inlet and outlet of the pipeline, and the standard pressure transducers and flow rate were considered. The signals from the system and research equipment (equalizers) are the basis for the development of new method to test outflow of gas pipeline, which is based on the quotient of the power spectral density of signals generated by the equalizer (diagnoser) and signals measured using standard pressure transducers and flow rate. Possible use to analysis the signals power will allow go from signal diagnostic for more effective parametric diagnostic.

Dialysis Access Flow Phenomenon Demonstrated via an Internal Jugular Central Venous Catheter Uniquely Positioned within a Superior Vena Cava Stenosis

Dialysis Access Flow Phenomenon Demonstrated <i>via</i> an Internal Jugular Central Venous Catheter Uniquely Positioned within a Superior Vena Cava Stenosis

Unsteady pressure measurement instrumentation using anodized-aluminium PSP applied in a transonic wind tunnel

The objective of this work is to demonstrate the feasibility of pressure measurement instrumentation using anodized-aluminium pressure-sensitive paint (or AA-PSP) for application in unsteady flows. An anodized procedure was applied to an aluminium tape that can be easily placed on a model even when it is mounted in a wind tunnel. The response time of the PSP coating is assessed using a calibration rig that generates fast pressure steps or sinusoidal pressure fluctuations up to 1 kHz. A pointwise measurement system made with a Cassegrain telescope and a photomultiplier tube was designed to collect the PSP luminescence. The spot displacement on the model surface was carried out by using a 3D moving bench. A camera is used to identify the spot position according to the model geometry. An application in a wind tunnel was performed on a forced shock wave oscillation test, generating amplitude variations up to 25 kPa. The calibration problem due to non-uniformity of the anodized properties did not allow quantitative data processing of pressure levels. Nevertheless frequency analysis demonstrates that the coating is able to follow the pressure fluctuations, as shown by comparison with standard pressure transducers.

The On-Line Pressure Vessel Rheometer for Concentrated Coal Slurries

At present, there are no commercially available rheometers that can make on-line measurements of the rheological types of settling particulate slurries. To accomplish this measurement, a pressure vessel rheometer has been developed for on-line rheological measurements of concentrated suspensions. This rheometer is simple in construction and uses standard pressure transducers and flow valves to make all necessary measurements of slurry flow through a calibrated tube. This simple design is made possible by the use of a sealed vessel to receive the slurry sample, which provides a means both for measuring the flowrate by monitoring the pressure and for smoothly varying the flowrate so that a complete rheological curve can be determined. Using this instrument, flow curves of two different coal slurries were determined. The first coal slurry sample consisted of coal ground to pass 106 µm and was suspended at a concentration of 52 wt % solids. The second sample consisted of coal ground to pass 850 µm, and was suspended at a concentration of 58 wt % solids. Results obtained from the pressure vessel rheometer showed that the behavior of the coal slurry with −106 µm material was pseudoplastic with yield type flow, and the flow type of the sample with −850 µm coal was represented by the Bingham plastic model.

Step response of pressure-sensitive paints

An experimental and analytical characterization of the response of three typical pressure-sensitive paint (PSP) formulations to a step change in pressure is presented. The three PSP formulations tested have all been previously used in wind-tunnel experiments and have been shown to have acceptable aerodynamic surface properties and mechanical durability. The time response of the PSP coatings is dependent on the diffusion of oxygen through the PSP binder material with typical time constants ranging from 0.05 to 2.5 s. The PSP response is best characterized by a two-term exponential decay function representing a complex first-order dynamic system. In contrast, a standard pressure transducer responds as a second-order dynamic system. The two-exponential curvefit provides a convenient way to compare the time response of different PSP formulations. A mass diffusion model of the PSP response is also presented that is capable of predicting the time response of PSP layers. Nomenclature Aj = constant in mass diffusion solution, Eq. (7) a = binder layer thickness B = constant in two-exponential curvefit, Eq. (10) Ci, C2 = constants in two-exponential curvefit, Eq. (10) Dm = mass diffusivity, Eq. (5) /i, /2 = functional relationships / = light intensity N, n = mass concentration in the binder layer P = pressure R = calibration constant, Eq. (1) S = calibration constant, Eq. (1) x = distant above the substrate e}, e2 = exponential decay terms, Eq. (10) X = wavelength A./ = eigenvalues in mass diffusion solution, Eq. (7) a = Henry's constant, Eq. (2) TI , T2 = time constants, Eq. (10) r = time constant, Eq. (8) Subscripts

Bladder pressure monitoring significantly enhances care of infants with abdominal wall defects: A prospective clinical study

Increased intraabdominal pressure (IAP) has been demonstrated to cause intestinal and renal ischemia in both animals and humans. Neonates undergoing closure of anterior abdominal wall defects are at risk for these complications from markedly increased IAP, which are putatively responsible for a 13% to 20% mortality. In an effort to decrease morbidity and mortality we performed a 4-year prospective clinical study to determine if monitoring IAP using bladder pressure (BdP) measurements would significantly improve perioperative care in infants with abdominal wall defects. Forty-two consecutive infants with gastroschisis (28) and omphalocele (14) were prospectively studied. Intraoperative and serial postoperative measurements of BdP were obtained from an indwelling bladder catheter using a standard pressure transducer. Methods of initial closure, as well as manipulations in sedation, paralysis, and silo reduction, were selected to keep BdP < 20 mm Hg. Bladder pressure monitoring significantly altered the management of 64% of our patients, particularly those with gastroschisis (74%). Thirteen patients with gastroschisis underwent staged closure; in 7 (54%) this decision was based on high BdP even though bowel reduction was mechanically possible. Elevated BdP influenced the closure method and timing of silo reductions in 5 of 14 (42%) infants with omphalocele. There were no episodes of renal failure or refractory oliguria. There were three patients in a single cluster who developed uncomplicated, nonsurgical necrotizing enterocolitis late in their respective courses. One patient whose bowel was placed in a silo had severe hypotension associated with group B streptococcal sepsis and subsequently developed necrotic bowel despite low BdP.(ABSTRACT TRUNCATED AT 250 WORDS)

Computerized blood pressure and heart rate recording system interfaces standard chart recorder with any micro-computer

The designed inexpensive blood pressure recording system (BPRS) gives any micro-computer direct on-line blood pressure and heart rate recording capability that will save research time and increase the accuracy of collected data. The data is automatically stored in a file compatible with most graphic and statistical processing software. In vitro testing, over a range of 0–200 mmHg and 0–360 beats per minute showed a 0.999 intraclass correlation. In vivo testing of the BPRS used anaesthetized rats whereby their systolic and diastolic pressures were measured simultaneously with heart rate. The blood pressures and heart rate data, measured by the BPRS demonstrated excellent stability, sensitivity and accuracy when compared to those measured by standard pressure transducers in conjunction with a Grass polygraph and a sphygmomanometer.

Disposable system for intraventricular pressure measurement and CSF drainage. Technical note.

✓ A simple disposable system for controlled cerebrospinal fluid drainage and monitoring of ventricular fluid pressure is described. The unit is connected between the patient's external ventriculostomy and a standard pressure transducer. This drainage system is easily assembled, incorporates an adjustable mechanism for releasing pressure, provides a continuous record of ventricular fluid pressure, and permits hourly measurement of CSF drainage. The pressure recording is continued even when the ventricular fluid pressure falls below a predetermined maximal value.