The influence of flowmeters on rhinomanometry results and detection of nasal airflow asymmetry.

<b><br>Introduction:</b> Rhinomanometry is an otolaryngological diagnostic method used to determine airflow as a function of the pressure drop through the left and right nasal cavities. Airflow is measured using orifice flowmeters that attenuate the flow.</br> <b><br>Aim:</b> This paper describes the results of a study into the effects of flowmeter design on rhinomanometry results and detection of nasal airflow asymmetry.</br> <b><br>Material and methods:</b> Four flowmeters were examined using a 3D printed model of a human nose.</br> <b><br>Conclusions:</b> Each flowmeter interfered with the rhinomanometry results.</br>.

Development of a urinometer for automatic measurement of urine flow in catheterized patients.

Urinary flow measurement and colorimetry are vital medical indicators for critically ill patients in intensive care units. However, there is a clinical need for low-cost, continuous urinary flow monitoring devices that can automatically and in real-time measure urine flow. This need led to the development of a non-invasive device that is easy to use and does not require proprietary disposables. The device operates by detecting urine flow using an infrared barrier that returns an unequivocal pattern, and it is capable of measuring the volume of liquid in real-time, storing the history with a precise date, and returning alarms to detect critical trends. The device also has the ability to detect the color of urine, allowing for extended data and detecting problems in catheterized patients such as hematuria. The device is proposed as an automated clinical decision support system that utilizes the concept of the Internet of Medical Things. It works by using a LoRa communication method with the LoRaWAN protocol to maximize the distance to access points, reducing infrastructure costs in massive deployments. The device can send data wirelessly for remote monitoring and allows for the collection of data on a dashboard in a pseudonymous way. Tests conducted on the device using a gold standard medical grade infusion pump and fluid densities within the 1.005 g/ml to 1.030 g/ml urine density range showed that droplets were satisfactorily captured in the range of flows from less than 1 ml/h to 500 ml/h, which are acceptable ranges for urinary flow. Errors ranged below 15%, when compared to the values obtained by the hospital infusion pump used as gold standard. Such values are clinically adequate to detect changes in diuresis patterns, specially at low urine output ranges, related to renal disfunction. Additionally, tests carried out with different color patterns indicate that it detects different colors of urine with a precision in detecting RGB values <5%. In conclusion, the results suggest that the device can be useful in automatically monitoring diuresis and colorimetry in real-time, which can facilitate the work of nursing and provide automatic decision-making support to intensive care physicians.

Comparison of flowmeter (transit time flow measurement) values for graft flow in three different surgical methods for isolated coronary artery bypass surgery.

BACKGROUND: Graft patency is the most important factor in coronary artery bypass surgery. This study aimed to compare the relationship between three different surgical methods and transit time flow measurement (TTFM), which is used to detect technical problems in anastomoses performed during coronary artery bypass graft operations and to correct them if necessary. METHODS: A total of 110 patients undergoing isolated coronary artery bypass surgery were analysed. Of these patients, 48 were operated on by inducing cardiopulmonary arrest (group 1), 33 were operated on without inducing cardiac arrest (group 2) during cardiopulmonary bypass surgery, and 29 underwent surgery on the off-pump beating heart (group 3). TTFMs were performed on all the patients' grafts. Additional surgical intervention requirements, the need for intra-operative and postoperative inotropic support, and all postoperative follow-up data were compared. RESULTS: In total, 110 patients were measured for 301 grafts. Due to insufficient measurements performed on these patients, additional surgical intervention was performed on five grafts in group 1, five grafts in group 2, and seven grafts in group 3. These interventions enabled a normal flow rate to be achieved. The number of grafts that required revision was highest in group 3. There was no difference between the groups in terms of demographic data, EuroSCORE II, preoperative ejection fraction, postoperative complications and mortality rate. CONCLUSION: TTFM is important for detecting technical problems in grafts. We believe that all surgical methods can be applied more safely by controlling graft flow.

Usefulness of a Novel Vascular Access Management Method Using a Laser Blood Flowmeter.

INTRODUCTION: Various methods for vascular access (VA) management have been studied. We investigated the usefulness of a new, simple, and quantitative VA management method using the Pocket LDF® laser blood flowmeter (hereinafter "LDF") that noninvasively measures peripheral circulation flow. METHODS: Peripheral circulation flow was measured in 82 patients (43 men) on maintenance hemodialysis with an arteriovenous fistula (AVF). The shunt symmetry index (SSI) was calculated as peripheral circulation flow in the AVF limb divided by that in the non-AVF limb. SSI was used for microcirculation evaluation and also compared by AVF site. Patients undergoing vascular access interventional therapy (VAIVT) underwent ultrasound evaluation (Doppler ultrasonography) of the AVF and SSI measurement before and after VAIVT. SSI was compared between those who did and did not require VAIVT, and the cutoff value for SSI was determined by receiver operating characteristic curve (ROC) analysis. RESULTS: As many as 86% of the patients who were measured peripheral circulation flow had SSI <1.0, which indicates that AVF reduced peripheral circulation flow. All patients who underwent VAIVT showed a decrease in SSI to <1.0 after VAIVT, probably due to improvement of stenosis. SSI differed significantly between patients who did and did not require VAIVT (1.20 ± 0.49 vs. 0.65 ± 0.33, p < 0.001), which indicates that SSI is affected by the presence of stenosis in the proximal vein of the VA anastomosis. In patients with SSI ≥1.0, stenosis of the proximal vein of the AVF caused stasis of blood flow, resulting in increased peripheral blood flow. AVF site seems to have no impact on peripheral circulation flow. The SSI cutoff value for the screening of proximal vein stenosis was 1.06 (sensitivity: 0.69, specificity: 0.93, area under the curve: 0.81). CONCLUSION: Based on the ROC analysis, we recommend considering AVF ultrasound for SSI >1.06. Our results suggest the usefulness of the described VA management method using the LDF.

Calibration methods for flow rates down to 5 nL/min and validation methodology.

Improving the accuracy and enabling traceable measurements of volume, flow, and pressure in existing drug delivery devices and in-line sensors operating at very low flow rates is essential in several fields of activities and specially in medical applications. This can only be achieved through the development of new calibrationmethods and by expanding the existing metrological infrastructure to perform micro-flow and nano-flow measurements. In this paper, we will investigate new traceable techniques for measuring flow rate, from 5 nL/min to 1,500 nL/min and present the results of an inter-comparison between nine laboratories for the calibration of two different flow meters and a syringe pump.

Design and Implementation of an Ultrasonic Flowmeter Based on the Cross-Correlation Method.

Ultrasonic flowmeters play an important role in industrial production, aerospace and other fields. In this paper, a high-precision ultrasonic flowmeter based on the cross-correlation method is designed, and the commercial finite element software COMSOL Multiphysics 5.6 is used to simulate the propagation process of ultrasonic waves during flow measurement, and the implementation process of the cross-correlation algorithm is simulated by Python language. The flowmeter adopts the cross-correlation algorithm to improve the measurement accuracy of ultrasonic time of flight and adopts the method of combining FPGA and an embedded microprocessor to improve operation efficiency. In order to verify the performance of the flowmeter, we tested the flowmeter on the National Institute of Metrology and the self-built test platform, using the still water dragging method, the dynamic volume method and the field comparison method, respectively. The results show that the flowmeter has the ability to test the flow under the condition of high flow velocity (26 m/s) and a pipe diameter in the range of DN6~DN1600, that the absolute value of the relative indication error does not exceed 0.815% and that the repeatability does not exceed 0.150%. The designed ultrasonic flowmeter has high measurement accuracy, good repeatability, strong stability and a wide application range.

Automatic Classification of Audio Uroflowmetry with a Smartwatch.

Prior work has shown the classification of voiding dysfunctions from uroflowmeter data using machine learning. We present the use of smartwatch audio, collected through the UroSound platform, in order to automatically classify voiding signals as normal or abnormal, using classical machine learning techniques. We train several classification models using classical machine learning and report a maximal test accuracy of 86.16% using an ensemble method classifier. Clinical relevance- This classification task has the potential to be part of an essential toolkit for urology telemedicine. It is especially useful in areas that lack proper medical infrastructure but still host ubiquitous audio capture devices such as smartphones and smartwatches.

Fiber optofluidic Coriolis flowmeter based on a dual-antiresonant reflecting optical waveguide.

A microfiber optofluidic flowmeter based on the Coriolis principle and a dual-antiresonant reflecting optical waveguide (ARROW) is proposed and experimentally demonstrated. A hollow hole in a hollow-core fiber is fabricated as an optofluidic channel to move the liquid sample, which forms a dual-ARROW in the hollow-core fiber. Two sides of the hollow-core fiber are used as two adjacent Fabry-Perot resonators based on the refractive index modulation of a CO2 laser, which is used to investigate the vibration signals of the two resonators. The flow rate can be measured based on the Coriolis force by calculating the phase difference between the two ARROWs. The experimental results show that a flow rate sensitivity of 8.04 deg/(µl/s) can be achieved for ethanol solution. The proposed micro Coriolis fiber optic flowmeter can be used in various fields, such as food production, medicine, bioanalysis, etc.

Replication of the abnormal niacin response in first episode psychosis measured using laser Doppler flowmeter.

INTRODUCTION: Impaired sensitivity of the skin flush response to niacin is found in approximately 30% of patients with schizophrenia. Although the niacin response abnormality (NRA) may serve as a useful endophenotype for schizophrenia, few studies have directly replicated NRA in patients with first-episode psychosis (FEP). METHODS: In total, 204 patients with FEP, 16 with psychotic mood disorder (PMD), and 68 healthy controls (HC) were included. The log10 (EC50 ) values represent the concentration of methyl nicotinate required to elicit a half-maximal blood flow (MBF) response, and the MBF value was calculated. The NRA was defined as having log10 (EC50 ) molar value above the 90% and an MBF value below the 60% of those in the HC group. RESULTS: In total, 13.7% of the FEP, 12.5% of the PMD, and 7.4% of the HC group met the definition of NRA. Significant differences were found in the log10 (EC50 ) values between the FEP and HC groups (p = .014) and in the MBF between the FEP and PMD groups (p = .011). Patients with FEP and NRA had more severe negative symptoms than those with a normal niacin response. DISCUSSION: These data represent the NRA in patients with FEP, defining a small subgroup of patients with early-phase psychosis possessing a clinically significant phospholipid-signaling defect.

Microfluidic Thermal Flowmeters for Drug Injection Monitoring.

This paper presents a microfluidic thermal flowmeter for monitoring injection pumps, which is essential to ensure proper patient treatment and reduce medication errors that can lead to severe injury or death. The standard gravimetric method for flow-rate monitoring requires a great deal of preparation and laboratory equipment and is impractical in clinics. Therefore, an alternative to the standard method suitable for remote, small-scale, and frequent infusion-pump monitoring is in great demand. Here, we propose a miniaturized thermal flowmeter consisting of a silicon substrate, a platinum heater layer on a silicon dioxide thin-membrane, and a polymer microchannel to provide accurate flow-rate measurement. The present thermal flowmeter is fabricated by the micromachining and micromolding process and exhibits sensitivity, linearity, and uncertainty of 0.722 mW/(g/h), 98.7%, and (2.36 ± 0.80)%, respectively, in the flow-rate range of 0.5-2.5 g/h when the flowmeter is operated in the constant temperature mode with the channel width of 0.5 mm. The measurement range of flow rate can be easily adjusted by changing the cross-sectional microchannel dimension. The present miniaturized thermal flowmeter shows a high potential for infusion-pump calibration in clinical settings.

Freeflow: The novel portable uroflowmeter can help to realize practical urinary conditions at home.

OBJECTIVES: To evaluate the effectiveness of a novel portable urine flowmeter, Freeflow, for examining the actual state of urination at home. METHODS: Forty-three patients with benign prostatic hyperplasia used the Freeflow uroflowmeter in the hospital and at home without accumulating urine. We created a nomogram for each patient's urine volume and maximal urinary flow rate (Qmax). Furthermore, we investigated the actual state of each patient's urination. We also investigated the differences in the micturition status between daytime and nighttime. RESULTS: Of the 43 patients, 40 were able to provide the necessary data in the hospital, and all patients provided data measured at home. The trial period of the home assessment was 2-7 days. Regarding the average urine volume, no significant difference was observed between in-hospital and at-home patients; however, Qmax and mean flow rate (Qave) were significantly higher at home. The average coefficient of variation was very large. The relationship between daytime and nighttime was observed in 30 patients; urine volume increased significantly at nighttime; however, no significant difference was observed in Qmax and Qave. The nomogram for several days and a completed urinary diary helped to display daytime and nighttime urination characteristics. CONCLUSIONS: Freeflow, the newly developed uroflowmeter, enabled us to determine the fluctuations in the measurements recorded at home and the differences between daytime and nighttime. Thus, creating a nomogram for objectively examining nighttime urination status and utilizing a urination diary was found to be effective for providing correct diagnosis and treatment of lower urinary tract symptoms.

CFD Model of a Mechanical Oscillator Flowmeter.

Most of the studies on mechanical oscillator flowmeters were conducted in the '80s and '90s when computational fluid dynamics (CFD) was not a viable scientific tool in flow metrology. Still, many topics related to the application of mechanical oscillator flowmeters require further investigation. In the article, a numerical model of a mechanical oscillator flowmeter is developed with the commercial software ANSYS Fluent. The model is validated against experimental data obtained at a water calibration stand. The influence of the selected turbulence model, dynamic mesh method, as well as grid and time step size is studied. The model's qualitative behavior is correct, allowing investigation into the flowmeter operation in detail. It can provide a base for the improvement of the flowmeter's performance. Relative differences in the frequency of oscillations did not exceed 4% for a DN50 flowmeter in the flow rate range (2-40) m3/h.

Outcomes of Autogenous Radiocephalic Versus Brachiocephalic Arteriovenous Fistula Surgery Based on Transit-Time Flowmeter Assessment: A Retrospective Study.

BACKGROUND: Despite the better operative results of autogenous brachiocephalic arteriovenous fistula (BC-AVF), it is considered secondary to autogenous radiocephalic AVF (RC-AVF) failure. Here we compared the results of our multidisciplinary management protocol of BC-AVF versus RC-AVF. METHODS: A total of 194 matched patients who requested autogenous BC-AVF or RC-AVF surgery between 2017 and 2019 were included in this retrospective study. All patients strictly adhered to our departmental perioperative management protocol for AVF surgery, including vessel status monitoring, exercise with or without a tourniquet, intraoperative flow assessment, and antiplatelet and anticoagulant medications. AVF function and patient status data were acquired from the electronic medical records, and the final evaluation was made via outpatient department visit or phone call in October 2020. RESULTS: Patients who underwent elective BC-AVF or RC-AVF (n = 97 each) were included. The patient groups had similar preoperative clinical characteristics. Artery and vein sizes at the planned anastomosis site were larger in the BC-AVF group (P < 0.001). The mean intraoperative maximal flow rate was higher in the BC-AVF group (492.5 ± 186.9 mL/min) than in the RC-AVF group (307.3 ± 113.0 mL/min, P < 0.001). The simultaneously evaluated mean pulsatility index was 0.5 ± 0.2 in the BC-AVF group and 0.6 ± 0.2 in the RC-AVF group (P < 0.001). The median observation duration was 19.4 months (11.0‒31.3 months). The primary patency rate was higher in the BC-AVF group (88.7%) than in the RC-AVF group (62.9%, P < 0.001). Patency duration was similar between groups, and the primary patency maintenance duration was longer in the BC-AVF group. Three cases of cephalic arch stenosis were observed in the BC-AVF group, while no cases of arterial steal syndrome were observed during the indexed observation period. Mortality rates were 14.4% and 9.3% in the BC-AVF and RC-AVF groups, respectively (P = 0.267), and the cause of death did not differ significantly between groups. For mortality, the estimated hazard ratio of RC-AVF over BC-AVF was 0.47 (95% CI, 0.19‒1.17, P = 0.106) during the observation period. CONCLUSION: BC-AVF had good characteristics for hemodialysis without an increased risk of AVF related complications during a median 19-month observation period. BC-AVF did not feature high flow-related complications with the multimodal approach, including preoperative exercise, intraoperative flow assessment to guarantee an adequate flow rate, postoperative exercise, and medications.

Gingival blood flow before, during, and after clenching, measured by laser Doppler blood flowmeter: A pilot study.

INTRODUCTION: This study aimed to investigate the effects of the strong occlusal force on the hemodynamics of gingival microcirculation. METHODS: Eleven adult volunteers with healthy periodontium and normal occlusion participated in this study. Using a noncontact laser Doppler flowmeter placed at the attached gingiva and the interdental papilla of the maxillary first premolar, changes in gingival blood flow (GBF) were examined during and after clenching. RESULTS: When the strong occlusal pressure was applied on the maxillary first premolar by clenching, GBF in the attached gingiva on the buccal side decreased significantly compared with the resting GBF, with medians of 2.3 mL/min/100 g and 5.4 mL/min/100 g, respectively (P <0.05). After the release of the maximum clenching, GBF recovered immediately and transiently increased to a median of 2.4 mL/min/100 g, showing a significant difference to the resting GBF (P <0.05). In contrast, in the interdental papilla, no significant change in GBF was found by clenching. CONCLUSIONS: Ischemia of the buccal attached gingiva associated with strong clenching may be due to compression of the vascular network of the periodontal membrane. Through reactive hyperemia resulting from the release of clenching, it is possible not only that blood flow will be restored to the tissue but that the tissue itself may be damaged by the reperfusion. During active orthodontic treatment, it is suggested that occlusal management to prevent occlusal trauma is important to avoid detrimental effects on periodontal tissues.

Optimization of a Thermal Flow Meter for Failure Management of the Shunt in Pediatric Hydrocephalus Patients.

Hydrocephalus patients suffer from an abnormal buildup of cerebrospinal fluid (CSF) in their ventricles, and there is currently no known way to cure hydrocephalus. The most prevalent treatment for managing hydrocephalus is to implant a ventriculoperitoneal shunt, which diverts excess CSF out of the brain. However, shunts are prone to failure, resulting in vague symptoms. Our patient survey results found that the lack of specificity of symptoms complicates the management of hydrocephalus in the pediatric population. The consequences include persistent mental burden on caretakers and a significant amount of unnecessary utilization of emergency healthcare resources due to the false-positive judgement of shunt failure. In order to reliably monitor shunt failures for hydrocephalus patients and their caretakers, we propose an optimized design of the thermal flow meter for precise measurements of the CSF flow rate in the shunt. The design is an implantable device which slides onto the shunt and utilizes sinusoidal heating and temperature measurements to improve the signal-to-noise ratio of flow-rate measurements by orders of magnitude.Clinical Relevance- An implantable flow meter would be transformative to allow hydrocephalus patients to monitor their shunt function at home, resulting in reduced hospital visits, reduced exposure to radiation typically required to rule out shunt failure, and reduced caretaker anxiety.

Non-Singleton Type-3 Fuzzy Approach for Flowmeter Fault Detection: Experimental Study in a Gas Industry.

The main contribution of this paper is to develop a new flowmeter fault detection approach based on optimized non-singleton type-3 (NT3) fuzzy logic systems (FLSs). The introduced method is implemented on an experimental gas industry plant. The system is modeled by NT3FLSs, and the faults are detected by comparison of measured end estimated signals. In this scheme, the detecting performance depends on the estimation and modeling performance. The suggested NT3FLS is used because of the existence of a high level of measurement errors and uncertainties in this problem. The designed NT3FLS with uncertain footprint-of-uncertainty (FOU), fuzzy secondary memberships and adaptive non-singleton fuzzification results in a powerful tool for modeling signals immersed in noise and error. The level of non-singleton fuzzification and membership parameters are tuned by maximum correntropy (MC) unscented Kalman filter (KF), and the rule parameters are learned by correntropy KF (CKF) with fuzzy kernel size. The suggested learning algorithms can handle the non-Gaussian noises that are common in industrial applications. The various types of flowmeters are investigated, and the effect of common faults are examined. It is shown that the suggested approach can detect the various faults with good accuracy in comparison with conventional approaches.

A Rapid Prototyped Thermal Mass Flowmeter.

An innovative rapid prototyping technique for embedding microcomponents in PDMS replicas was developed and applied on a thermal mass flowmeter for closed loop micropump flowrate control. Crucial flowmeter design and thermal parameters were investigated with a 3-D fully coupled electro-thermal-fluidic model which was built in Comsol Multiphysics 5.2. The flowmeter was characterized for three distinct measuring configurations. For precise low flowrate applications, a sensor-heater-sensor flowmeter configuration with a constant heater temperature was found to be the most appropriate yielding the measuring range of 0 to 90 µL·min-1 and the sensitivity of 1.3 °C·µL-1·min in the lower flowrate range of 0 to 40 µL·min-1.

Validity of the Handheld Expiratory Flowmeter for COPD Screening in the Primary Care Setting of China.

Purpose: The use of simple and affordable screening tools for chronic obstructive pulmonary disease (COPD) is limited. We aimed to assess the validity of a handheld expiratory flowmeter (Vitalograph Ltd., COPD-6®, Ireland) for COPD screening in Chinese primary care settings. Methods: In our cross-sectional study, subjects were randomly selected in eight primary care settings. Tests with the handheld expiratory flowmeter and the conventional spirometry were sequentially performed on all participants. The correlation between the handheld expiratory flowmeter and the conventional spirometry was determined. Validity was determined by the area under the receiver operator characteristic curve (AUC) of the forced expiratory volume in one second (FEV1)/forced expiratory volume in six seconds (FEV6) that used to detect airway obstruction. The sensitivity, specificity, predictive values, and likelihood ratio were calculated according to different FEV1/FEV6 cut-off points. Results: A total of 229 subjects (15.4%) were diagnosed with airflow limitation by conventional spirometry. FEV1, FEV6, and FEV1/FEV6 measured by the handheld expiratory flowmeter were correlated with FEV1, FVC, and FEV1/FVC measured by the conventional spirometry (r=0.889, 0.835 and 0.647, p<0.001), respectively. AUC of the FEV1/FEV6 to determine airflow obstruction was 0.857 (95% CI: 0.826 to 0.888). No significant difference of AUC was observed between the symptomatic group and the asymptomatic group (AUC=0.869 vs 0.843, P=0.425). A similar phenomenon was found in the AUC of smokers and never-smokers (AUC=0.862 vs 0.840; P=0.515). The cut-off point for FEV1/FEV6 was 0.77 and the corresponding sensitivity and specificity were 71.2% and 89.8%, respectively. Conclusion: The handheld expiratory flowmeter might be used as a screening device for COPD in Chinese primary care settings.

A Four-Channel Low-Noise Readout IC for Air Flow Measurement Using Hot Wire Anemometer in 0.18 µm CMOS Technology.

Air flow measurements provide significant information required for understanding the characteristics of insect movement. This study proposes a four-channel low-noise readout integrated circuit (IC) in order to measure air flow (air velocity), which can be beneficial to insect biomimetic robot systems that have been studied recently. Instrumentation amplifiers (IAs) with low-noise characteristics in readout ICs are essential because the air flow of an insect's movement, which is electrically converted using a microelectromechanical systems (MEMS) sensor, generally produces a small signal. The fundamental architecture employed in the readout IC is a three op amp IA, and it accomplishes low-noise characteristics by chopping. Moreover, the readout IC has a four-channel input structure and implements an automatic offset calibration loop (AOCL) for input offset correction. The AOCL based on the binary search logic adjusts the output offset by controlling the input voltage bias generated by the R-2R digital-to-analog converter (DAC). The electrically converted air flow signal is amplified using a three op amp IA, which is passed through a low-pass filter (LPF) for ripple rejection that is generated by chopping, and converted to a digital code by a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC). Furthermore, the readout IC contains a low-dropout (LDO) regulator that enables the supply voltage to drive digital circuits, and a serial peripheral interface (SPI) for digital communication. The readout IC is designed with a 0.18 µm CMOS process and the current consumption is 1.886 mA at 3.3 V supply voltage. The IC has an active area of 6.78 mm2 and input-referred noise (IRN) characteristics of 95.4 nV/√Hz at 1 Hz.