Real-time Pressure Monitoring Research Articles

A pressure measurement method based on profiling elastic press roller

A novel method was introduced based on a type of profiling elastic press roller to solve the problem that soil compaction pressure is difficult to monitor in real time. The pressure real-time values were acquired through the measurement of the profiling elastic press roller’s eccentricity. In order to evaluate the relationship between the profiling elastic press roller’s eccentricity and the pressure, the study was conducted in an indoor soil bin, in July 2015. Three experimental treatments with soil volumetric moisture content 14.9%, 22.7% and 29.7%, were used in clay soils. The relationship between the profiling elastic press roller’s eccentricity and soil cone index, and the relationship between the static pressure and soil cone index, were investigated. With the equivalent relationship of the cone index, the data was curve fitted and the model equation was established between eccentricity and pressure, in the topsoil layer in which the depth is 0–0.1m. The correlation coefficient values (R2) of the model equation all reached 0.99 at three experimental treatments, indicating the high degree of correlation. In order to evaluate the pressure measurement method, the validation experiments were conducted. The relationship was compared between the cone index predicted from the press roller measurements and the cone index measured from the manual measurements. The results showed that the dots of scatter diagram are all concentrated around the 1:1 ratio line, with high R2 values, at three volumetric moisture contents. These experiments indicate that the predictions were very consistent with the manual measurements, indicating the pressure measurement method based on the profiling elastic press roller can be used into real-time pressure monitoring.

Utilizing real-time pressure and tissue oxygenation monitoring to assess the adequacy of hinge craniotomy

Abstract Hinge craniotomy has been described as a feasible option for certain patients in need of decompression as a result of a mass lesion. The technique of hinging the bone flap alleviates the need to return to the operating room for cranioplasty as is the case with a traditional decompressive craniectomy. Intracranial pressure and brain tissue oxygenation monitoring can be utilized for intraoperative guidance to assess adequacy of hinge craniotomy. We report a case where intraoperative monitoring helped guide surgical decision making for a 23 year old male patient with a left traumatic subdural hematoma. The patient had a Licox monitor placed in the right frontal region, showing elevated intracranial pressure and decreased brain tissue oxygenation. The patient underwent hinge craniotomy, which initially lowered his intracranial pressure from 54 to 11 cm H 2 O and allowed his brain tissue oxygenation to rise to a normal value of 20.5 mm Hg. However, upon closure of the skin, the patient's intracranial pressure increased to 24 cm H 2 O and brain tissue oxygenation decreased to 7.8 mm Hg. As a result, the patient underwent decompressive craniectomy and the intracranial pressure and brain tissue oxygenation values normalized postoperatively. Intracranial pressure and brain tissue oxygenation can be helpful intraoperative guides in determining whether hinge craniotomy is adequate.

Intelligent-Completion Installations in the Santos Basin Presalt Cluster

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 174725, “Road to Success and Lessons Learned in Intelligent-Completion Installations at the Santos Basin Presalt Cluster,” by E. Schnitzler, D.A. Silva Filho, F.H. Marques, F.K. Delbim, K.L. Vello, L.F. Goncalez, and T.C. Fonseca, Petrobras, prepared for the 2015 SPE Annual Technical Conference and Exhibition, Houston, 28-30 September. The paper has not been peer reviewed. This paper presents information regarding the installation of intelligent-well completions (IWCs) in the Lula and SapinhoÁ fields of the Santos basin presalt cluster (SBPSC). The technology is intended to improve reservoir-management capability by using remotely operated flow-control valves and real-time pressure and temperature monitoring for each perforated interval, corresponding to different reservoir zones. The benefits are obtained at the expense of additional challenges for well engineering because well-completion design becomes more complex and overall associated risks increase. Introduction The area known as the presalt cluster in the Santos basin is located in ultradeep waters, between 1900 and 2400 m, approximately 290 km from Rio de Janeiro in southeast Brazil. Fig. 1 shows the main blocks of the presalt cluster currently in the appraisal-plan or production-development phases. The first areas selected for production development were Tupi (BM-S-11 Block) and GuarÁ (BM-S-9 block), which now are known as the Lula and SapinhoÁ fields. Initially, extended well tests were performed in these areas to gather information and test some of the technologies that would be applied on further developments. Later, a production pilot project was initiated in Lula field by the deployment of a production system with a total of nine wells (six producers and three injectors). Since then, new production systems are being deployed continually in the Lula and SapinhoÁ fields. Since the SBPSC initial phases, IWC was considered one of the more appropriate designs for production-development projects in the field. This technology is expected not only to improve reservoir management but also to provide better capabilities to deal with reservoir uncertainties, which is imperative in carbonate reservoirs. Intelligent-Completion Systems Internal risk-analysis assessments before the first production-development project supported the decision to use a two-zone hydraulic system to actuate the inflow-control valves (ICVs). The choice was based on the advice of specialists who considered it to be the simplest and most reliable system in the long term and recognized that it is a field-proven solution. On the other hand, wet trees designed for SBPSC projects contain a multiplex control system, which adds additional integration issues to be addressed during the planning phases.

Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro.

Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5cm tissue depth with 660nm irradiation and 1cm tissue depth with 980nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging.

Lessons Learnt from Measurements of Vertical Pressure at a Top Coal Mining Face at Datong Tashan Mines, China

Mining mechanics usually refers to the movement of overburden rocks and stress redistribution induced by mining effects, especially during the evolution of abutment pressure at a mining face (Xie et al. 2011). The characteristic of the stress field at a mining face serves as an important foundation for achieving roof safety and preventing excess gas (Suchowerska et al. 2013; Yang et al. 2011a). The mining effect may cause coal rocks to fracture, causing coal methane to escape from the fractured rock into the mining face, resulting in the exceedance of safety limits for gas. This is especially relevant under intensive mining conditions (Yang et al. 2011b; Li et al. 2006; Wang et al. 2012). Therefore, the study of mining mechanics is of great importance in achieving the safe and efficient coal mining. Many specific studies have been conducted to investigate stress redistribution, strata deformation, strata failure and fluid flow of coal seams (Islam and Shinjo 2009; Yang et al. 2014). However, these studies only focused on mining mechanics induced by mining advances, and neglected local mining effects, such as coal caving processes used for top coal caving method. In this manuscript, a field test and analytical analysis were conducted. A combination of global and local mining mechanics was consequently proposed for the top coal caving. Based on the real-time pressure monitoring of single props and hydraulic supports at a top coal mining face, intensive factors of pressure were adopted to provide a quantitative description of the mining mechanics.

Hydrocarbon reservoirs characterization by co-interpretation of pressure and flow rate data of the multi-rate well testing

Abstract Pressure transient behavior is among the most important information for characterizing a reservoir, forecasting its future performance, and designing an appropriate recovery scheme. Although a continuous real-time monitoring of reservoir bottom-hole pressure has become a routine task in intelligent wells, complete extraction of the potential information from these valuable sources of data may not be achieved by using traditional interpretation methods. Deconvolution transforms the pressure transient data related to the wells with variable production rates into an equivalent constant rate pressure data with duration equal to the whole duration of the multi-rate test i.e., unit step response. This technique can reveal high valuable information over a distance from the wellbore which may be several orders of magnitude greater than the radius of investigation of individual flow periods. In the present study, a robust and practical deconvolution methodology is developed for extracting the unit step response (USR) from synthetic, noisy and incomplete pressure transient histories pertaining to multi-rate data. Our proposed scheme calculates the USR from those multi-rate well testing data which may contain high levels of noises in both the flow rate and pressure data. A coupled wavelet transform/superposition theorem is the basis of the proposed method. The algorithm has shown an excellent performance for revealing reservoir/boundary models and their associated parameters.

A chest drainage system with a real-time pressure monitoring device.

Tube thoracostomy is a common procedure. A chest bottle may be used to both collect fluids and monitor the recovery of the chest condition. The presence of the "tidaling phenomenon" in the bottle can be reflective of the extent of patient's recovery. However, current practice essentially depends on gross observation of the bottle. The device used here is designed for a real-time monitoring of change in pleural pressure to allow clinicians to objectively determine when the lung has recovered, which is crucially important in order to judge when to remove the chest tube. The device is made of a pressure sensor with an operating range between -100 to +100 cmH2O and an amplifying using the "Wheatstone bridge" concept. Recording and analysis was performed with LABview software. The data can be shown in real-time on screen and also be checked retrospectively. The device was connected to the second part of a three-bottle drain system by a three-way connector. The test animals were two 40-kg pigs. We used a thoracoscopic procedure to create an artificial lung laceration with endoscopic scissors. Active air leaks could result in vigorous tidaling phenomenon up to 20 cmH2O. In the absence of gross tidaling phenomenon, the pressure changes were around 0.25 cmH2O. This real-time pleural pressure monitoring device can help clinicians objectively judge the extent of recovery of the chest condition. It can be used as an effective adjunct with the current chest drain system.

Optimization of Intrabone Delivery of Hematopoietic Progenitor Cells in a Swine Model Using Cell Radiolabeling with [89]zirconium

Intrabone (IB) hematopoietic cell transplantation (HCT) of umbilical cord blood in humans remains experimental and the technique has not been optimized. It is unknown whether hematopoietic progenitor cells (HPCs) injected IB are initially retained in the marrow or rapidly enter into the venous circulation before homing to the marrow. To develop an IB-injection technique that maximizes HPC marrow-retention, we tracked radiolabeled human HPCs following IB-injection into swine. We developed a method to radionuclide-label HPCs using a long-lived positron emitter (89) Zr and protamine sulfate that resulted in cellular-retention of low-dose radioactivity. This approach achieved radioactivity levels sufficient for detection by positron emission tomography with both high sensitivity and spatial resolution when fused with computed tomography. We found that conditions utilized in pilot IB-HCT clinical trials conducted by others led to both rapid drainage into the central venous circulation and cellular extravasation into surrounding muscle and soft tissues. By optimizing the needle design, using continuous real-time intra-marrow pressure monitoring, and by reducing the infusion-volume and infusion-rate, we overcame this limitation and achieved high retention of HPCs in the marrow. This method of IB cellular delivery is readily applicable in the clinic and could be utilized in future investigational IB-HCT trials aimed at maximizing marrow retention of HPCs.

Continuous wireless pressure monitoring and mapping with ultra-small passive sensors for health monitoring and critical care.

Continuous monitoring of internal physiological parameters is essential for critical care patients, but currently can only be practically achieved via tethered solutions. Here we report a wireless, real-time pressure monitoring system with passive, flexible, millimetre-scale sensors, scaled down to unprecedented dimensions of 1 × 1 × 0.1 cubic millimeters. This level of dimensional scaling is enabled by novel sensor design and detection schemes, which overcome the operating frequency limits of traditional strategies and exhibit insensitivity to lossy tissue environments. We demonstrate the use of this system to capture human pulse waveforms wirelessly in real time as well as to monitor in vivo intracranial pressure continuously in proof-of-concept mice studies using sensors down to 2.5 × 2.5 × 0.1 cubic millimeters. We further introduce printable wireless sensor arrays and show their use in real-time spatial pressure mapping. Looking forward, this technology has broader applications in continuous wireless monitoring of multiple physiological parameters for biomedical research and patient care.

Real time interior water and thermal monitoring of fuel cell with micro 3-in-1 sensor

The operating temperature and internal water accumulation influence the fuel cell performance significantly, and various regions inside the fuel cell still have non-uniformity. At present, only external, invasive, theoretical and simulation methods are available. The real information inside the fuel cell cannot be known instantly.This study used micro-electro-mechanical systems (MEMS) technology to develop a temperature, pressure and flow 3-in-1 micro sensor. First, the PI foil (Polyimide foil, 50 μm thick) was used to develop a 3-in-1 micro sensor, and then the 3-in-1 micro sensor was embedded in the low-temperature fuel cell for real-time microscopic monitoring of internal temperature, pressure and flow of fuel cell.In terms of temperature inside the fuel cell, as the upstream and midstream formed heat can be carried away by sufficient gas at the inlet, and the downstream reaction is violent, the downstream temperature is higher than upstream and midstream temperatures. In terms of pressure, in long-term observation, the internal pressure fluctuates, the pressure increases momently and reverts at some time points. This is possibly due to the removal of accumulated water from the flow channel. In terms of flow, the flow supplied by flow controller is higher than the upstream and downstream micro flow sensors, and the difference matches the gas leakage value.

Pulmonary artery catheter

Since its inception, the pulmonary artery catheter has enjoyed widespread use in both medical and surgical critically ill patients. It has also endured criticism and skepticism about its benefit in these patient populations. By providing information such as cardiac output, mixed venous oxygen saturation, and intracardiac pressures, the pulmonary artery catheter may improve care of the most complex critically ill patients in the intensive care unit and the operating room. With its ability to transduce pressures through multiple ports, one of the primary clinical uses for pulmonary artery catheters is real-time intracardiac pressure monitoring. Correct interpretation of the waveforms is essential to confirming correct placement of the catheter to ensure accurate data are recorded. Major complications related to catheter placement are infrequent, but misinterpretation of monitored data is not uncommon and has led many to question the utility of the pulmonary artery catheter. The evidence to date suggests that the use of the catheter does not change mortality in many critically ill patients and may expose these patients to a higher rate of complications. However, additional clinical trials are needed, particularly in the most complex critically ill patients, who have generally been excluded from many of the research trials performed to date.

Enhanced sensitivity of piezoelectric pressure sensor with microstructured polydimethylsiloxane layer

Highly sensitive detection tools that measure pressure and force are essential in palpation as well as real-time pressure monitoring in biomedical applications. So far, measurement has mainly been done by force sensing resistors and field effect transistor (FET) sensors for monitoring biological pressure and force sensing. We report a pressure sensor by the combination of a piezoelectric sensor layer integrated with a microstructured Polydimethylsiloxane (μ-PDMS) layer. We propose an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source that is used in FET sensors, by incorporating a microstructured PDMS layer in a piezoelectric sensor. By measuring the directly induced electrical charge from the microstructure-enhanced piezoelectric signal, we observed a 3-fold increased sensitivity in a signal response. Both fast signal relaxation from force removal and wide dynamic range from 0.23 to 10 kPa illustrate the good feasibility of the thin film piezoelectric sensor for mimicking human skin.

A Straightforward Design and Implementation of Real Time Pressure Monitoring System in Water Pipe

This paper reports the development of a real time system for pressure monitoring inside water pipe. In water supply industry it is valuable to know the water pressure inside the pipe. Thus the system created consisting hardware parts in compact form along with software in laptop for high mobility. In the hardware part, pressure gauge is chosen as sensor, and a conversion of the data into frequency is decided for better communication with the computer. The process in the software includes data captures, conversion, and display using visual basic MSviewer.

A Frequency-domain Diagnosis Tool for Early Leakage Detection at Geologic Carbon Sequestration Sites

Abstract Carbon capture, utilization, and sequestration have the potential to enable deep reductions in global carbon emissions if high storage efficiency can be achieved. A major hurdle to industrial-scale implementation of geological carbon sequestration (GCS) projects is the potential migration of fluids from the storage formations and the resulting legal and financial liabilities. The capability to accurately identify pathways by which stored CO2 could leak, has leaked, or is leaking from the targeted storage zone is thus of paramount importance to site licensees and regulators. Many monitoring, verification, and accounting (MVA) techniques have been devised over the years, however, pressure-based leakage detection remains one of the most sensitive and cost-effective technique for early detection of fluid migration from storage formations. It has consistently received the highest score in terms of benefit/cost ratio and it provides the greatest potential for leakage detection with broad areal coverage. Although much has been done in the area of forward modeling of leakage scenarios, the more challenging problems of pressure inversion for leakage detection, monitoring network design, and applications to operational GCS monitoring deserve more attention. Given the advent of permanent downhole gauges, which are real-time pressure and temperature monitoring systems installed at the bottom hole of reservoir wells, a salient question is how to leverage these infrastructure investments to reduce GCS risks caused by leakage from storage formations. Traditional well testing techniques impose constant injection rates and have been mainly applied to inferring reservoir formation properties. In contrast, the harmonic pulse testing (HPT) technique employed by this study induces sinusoidal flows into the reservoir through a pulser well, and pressure oscillations are collected at one or more observation wells. In this sense, HPT bears similarity to many geophysical techniques. The main difference is its low cost. By systematically varying pulsing frequencies, HPT can stimulate larger reservoir volumes than the conventional well testing techniques do and generate more useful information. Leakage will cause different pressure

First human use of a novel epicardial access needle embedded with a real time pressure/frequency monitoring of thoracic structures to facilitate epicardial access

Introduction: Epicardial (epi) ablation represents an adjunctive strategy for the treatment of challenging arrhythmias. Major complications may occur during epi access since the may inadvertently puncture the right ventricle (RV), the pleural space or the lung. We sought to evaluate if a new access epi reduce the risk for RV puncture and complications. Methods: 7 consecutive pts with epi arrhythmias (6 ventricular, 1 supraventricular) were enrolled. Epi access with a novel needle embedded with a tip sensor able to record beat-to-beat pressure waveform was utilized. Successful epi access was confirmed by fluoroscopy, contrast injection and visualization of the guidewire looping around the epi border of the heart. In 4 cases the epi access was obtained by an expert operator, while in 3 cases the access was obtained by a less experienced operator. Results: Successful epi access was obtained in all cases. No acute and delayed complications occurred. Mean Pericardial pressure/pulsation was 3.5±1.3 mmHg while mean RV pressure was 15±4 mmHg (p=0.001). Pressure monitoring identified pericardial wire access position in 75% of the attempts and was able to identify RV puncture in 100% of the cases. 3 false negative readings were recorded, where the guidewire was within the pericardial space while the tip pressure was indicating differently. Unintended RV puncture occurred in 50% of the cases (always detected). Unintended RV puncture occurred more often in the less experienced operator (6 times vs 2 times, P<0.05). ![Figure][1] Conclusion: Real time pressure monitoring identifies successful pericardial access and RV perforation. This information would be important to facilitate epi access to less experienced operators [1]: pending:yes

Research on simulation and experiment of noninvasive intracranial pressure monitoring based on acoustoelasticity effects

The real-time monitoring of intracranial pressure (ICP) is very important for craniocerebrally critically ill patients, but it is very difficult to realize long-time monitoring for the traditional invasive method, which very easily infects patients. Many noninvasive methods have emerged, but these have not been able to monitor ICP for long periods in real time, and they are not ready for clinical application. In order to realize long-time, online, real-time, noninvasive monitoring for ICP, a new method based on acoustoelasticity of ultrasound is herein proposed. Experimental models were devised to research the new method for experiment and simulation. Polymethyl methacrylate and hydrogel were adopted for the experiment, and their mechanical properties were very close to the real brain. A numerical solution for acoustoelasticity theory was acquired by simulating calculation based on a finite-element method. This was compared to the experimental value. The results showed a consistent match between theoretical solution and experimental value, with maximum error at most 5%. Thus, the effectiveness of the new method was verified. Theoretical and practical foundation is provided for this new method, and it could be used for animal experimentation or clinical testing in further research.

Simplified negative pressure wound therapy: clinical evaluation of an ultraportable, no‐canister system

The aim of this study was to evaluate a prototype negative pressure wound therapy (NPWT) system that has been developed to simplify NPWT for wounds at the lower end of the acuity scale. The new device has a single preset pressure of −80 mmHg, is single use and operates without an exudate canister. The disposable NPWT system (PICO™) was tested in a prospective, non‐comparative, multicentre clinical trial to assess device functionality and clinical acceptance. Twenty patients were recruited for a maximum treatment period of 14 days. The NPWT devices were fitted with data log chips to enable longitudinal assessment of negative pressure and leak rates during therapy. Sixteen (80%) patients had closed surgical wounds, two (10%) patients had traumatic wounds and two (10%) patients received meshed split thickness skin grafts. The mean study duration was 10·7 days (range: 5–14 days) and the mean dressing wear time per individual patient was 4·6 days (range: 2–11). Fifty‐five percent of wounds had closed by the end of the 14‐day study or earlier, with a further 40% of wounds progressing to closure. Real‐time pressure monitoring showed continuous delivery of NPWT. Three cases are discussed representing different wound locations and different patient factors that can increase the risk of post‐surgical complications. Clinical studies of the disposable NPWT system confirmed the ability of the simplified single‐use device to function consistently over the expected wear time. The anticipated reduced costs, ease of use and increased mobility of patients using this system may enable NPWT benefits to be available to a greater proportion of patients.

On the implementation of an automated acoustic output optimization algorithm for subharmonic aided pressure estimation

Incident acoustic output (IAO) dependent subharmonic signal amplitudes from ultrasound contrast agents can be categorized into occurrence, growth or saturation stages. Subharmonic aided pressure estimation (SHAPE) is a technique that utilizes growth stage subharmonic signal amplitudes for hydrostatic pressure estimation. In this study, we developed an automated IAO optimization algorithm to identify the IAO level eliciting growth stage subharmonic signals and also studied the effect of pulse length on SHAPE. This approach may help eliminate the problems of acquiring and analyzing the data offline at all IAO levels as was done in previous studies and thus, pave the way for real-time clinical pressure monitoring applications. The IAO optimization algorithm was implemented on a Logiq 9 (GE Healthcare, Milwaukee, WI) scanner interfaced with a computer. The optimization algorithm stepped the ultrasound scanner from 0% to 100% IAO. A logistic equation fitting function was applied with the criterion of minimum least squared error between the fitted subharmonic amplitudes and the measured subharmonic amplitudes as a function of the IAO levels and the optimum IAO level was chosen corresponding to the inflection point calculated from the fitted data. The efficacy of the optimum IAO level was investigated for in vivo SHAPE to monitor portal vein (PV) pressures in 5 canines and was compared with the performance of IAO levels, below and above the optimum IAO level, for 4, 8 and 16 transmit cycles. The canines received a continuous infusion of Sonazoid microbubbles (1.5μl/kg/min; GE Healthcare, Oslo, Norway). PV pressures were obtained using a surgically introduced pressure catheter (Millar Instruments, Inc., Houston, TX) and were recorded before and after increasing PV pressures. The experiments showed that optimum IAO levels for SHAPE in the canines ranged from 6% to 40%. The best correlation between changes in PV pressures and in subharmonic amplitudes (r=−0.76; p=0.24), and between the absolute PV pressures and the subharmonic amplitudes (r=−0.89; p<0.01) were obtained for the optimized IAO and 4 transmit cycles. Only for the optimized IAO and 4 transmit cycles did the subharmonic amplitudes differ significantly (p<0.01) before and after increasing PV pressures. A new algorithm to identify optimum IAO levels for SHAPE has been developed and validated with the best results being obtained for 4 transmit cycles. The work presented in this study may pave the way for real-time clinical applications of estimating pressures using the subharmonic signals from ultrasound contrast agents.

Electrofluidic pressure sensor embedded microfluidic device: a study of endothelial cells under hydrostatic pressure and shear stress combinations

Various microfluidic cell culture devices have been developed for in vitro cell studies because of their capabilities to reconstitute in vivo microenvironments. However, controlling flows in microfluidic devices is not straightforward due to the wide varieties of fluidic properties of biological samples. Currently, flow observations mainly depend on optical imaging and macro scale transducers, which usually require sophisticated instrumentation and are difficult to scale up. Without real time monitoring, the control of flows can only rely on theoretical calculations and numerical simulations. Consequently, these devices have difficulty in being broadly exploited in biological research. This paper reports a microfluidic device with embedded pressure sensors constructed using electrofluidic circuits, which are electrical circuits built by fluidic channels filled with ionic liquid. A microfluidic device culturing endothelial cells under various shear stress and hydrostatic pressure combinations is developed to demonstrate this concept. The device combines the concepts of electrofluidic circuits for pressure sensing, and an equivalent circuit model to design the cell culture channels. In the experiments, human umbilical vein endothelial cells (HUVECs) are cultured in the device with a continuous medium perfusion, which provides the combinatory mechanical stimulations, while the hydrostatic pressures are monitored in real time to ensure the desired culture conditions. The experimental results demonstrate the importance of real time pressure monitoring, and how both mechanical stimulations affect the HUVEC culture. This developed microfluidic device is simple, robust, and can be easily scaled up for high-throughput experiments. Furthermore, the device provides a practical platform for an in vitro cell culture under well-controlled and dynamic microenvironments.

Decreased Incidence of Pneumothorax in VLBW Infants After Increased Monitoring of Tidal Volumes

Pneumothorax is common in very low birth weight (VLBW) infants. In our NICU, we noted an above average incidence of pneumothorax compared with similar NICUs based on Vermont Oxford Network benchmarking. The quality improvement project was designed to decrease the incidence of pneumothorax in VLBW infants in a tertiary care NICU. The project was divided into 2 periods. During period 1, all VLBW infants were followed for 6 months for the presence of pneumothorax. A multidisciplinary team met regularly to review cases of pneumothorax and identify potential causes. High tidal volumes (VT) (>6 mL/kg) were noted around the time of occurrence of pneumothorax. Guidelines were developed for improved monitoring and rapid feedback of VT and peak inspiratory pressure between nursing staff and clinicians. During period 2, these guidelines were implemented and VLBW infants were again followed for 6 months. The incidence of pneumothorax was tracked. Run charts were used to monitor changes. The incidence of pneumothorax in VLBW infants decreased from 10.4% to 2.6% after the intervention (P = .04). By using process control, a reduction in pneumothorax was achieved in period 2. Increased vigilance and real-time monitoring of VT and peak inspiratory pressure decreased the incidence of pneumothorax in our population of VLBW infants. These interventions can be considered in other NICUs with an above-average risk adjusted incidence of pneumothorax in VLBW infants. Our data illustrate the benefits of comparative benchmarking and organized quality improvement in advancing patient care outcomes.