Dynamic Pressure Changes Research Articles

Application of Intelligent Monitoring of Percutaneous Partial Oxygen Pressure in Evaluating the Evolution of Scar Hyperplasia.

The study aimed to investigate the dynamic changes of percutaneous partial oxygen pressure during the development and evolution of a hypertrophic scar. Twenty cases of hypertrophic scar patients at different stages were selected. A percutaneous oxygen monitor was used to measure oxygen partial pressure in the scar and normal skin tissue at 14, 30, 60, and 90 days after surgery. The changes of oxygen partial pressure, tissue structure, HIF-1α, and VEGF expression in the scar tissue were observed, and the correlation was analyzed. In the scar maturation process, with the prolongation of time, the partial oxygen pressure in the tissue increased gradually. The expression intensity of HIF-1α and VEGF decreased gradually, HIF-1α was positively correlated with VEGF (r = 0.98, P < 0.01), there was a negative correlation between oxygen partial pressure and HIF-1 α expression (r = −0.92, P < 0.01), and it was negatively correlated with VEGF (r = −0.88, P < 0.01). TcPO2 measurement can be used to assess scar maturity; HIF-1 α and VEGF may play an essential role in regulating partial oxygen pressure in the scar tissue.

A Chip-Scale GaN-Based Optical Pressure Sensor With Microdome-Patterned Polydimethylsiloxane (PDMS)

In this letter, a novel integration of GaN chip with microdome-patterned polydimethylsiloxane (PDMS) film for pressure sensing is demonstrated. The compact <inline-formula> <tex-math notation="LaTeX">$1\times {1}\times {0.2}$ </tex-math></inline-formula> mm³ GaN-on-sapphire chip consisting of light emitter and photodetector is formed through wafer-scale, high-throughput microfabrication processes. The integration of deformable dome-shaped PDMS enables the GaN chip to respond to the pressure variation effectively. The sensor exhibits a sensitivity of <inline-formula> <tex-math notation="LaTeX">$0.989~\mu \text{A}$ </tex-math></inline-formula>/kPa for a wide pressure range of 0&#x2013;50 kPa. In addition to the optical and electrical characteristics of the sensor, its prominent sensing performances of high repeatability and stability to dynamic pressure changes are studied through a range of experiments. The compact assembly scheme has advantages in manufacturing cost, compactness, and robustness, which is of great value for real-time pressure monitoring in a wide range of practical applications.

Real-time dynamic changes in intraocular pressure after occlusion break: comparing 2 phacoemulsification systems.

To compare real-time intraocular pressure (IOP) response to occlusion break event in 2 phacoemulsification systems. Iladevi Cataract and IOL Research Center, India. Randomized, experimental study. Rabbits were randomized to:Group I (n = 10 eyes), Centurion Vision system with active fluidics, or, Group II (n = 10 eyes), Centurion with Active Sentry. Within each group, parameter set 1 (IOP 30 mm Hg, aspiration flow rate [AFR] 20 mL/min, and vacuum 600 mm Hg) and parameter set 2 (IOP 50 mm Hg, AFR 25 mL/min, and vacuum 600 mm Hg) were tested. Real-time rate of drop and rise of IOP after occlusion break event (mm Hg per second) and percentage reduction of IOP from maximum during nuclear fragment removal were compared. 10 rabbits (20 eyes) were included. Rate of drop of IOP after occlusion break was not significantly different between groups. Rate of rise of IOP was statistically significantly higher in Group II with both parameter sets (199.09 ± 69.28 vs 94.33 ± 45.66 in parameter set 1, P = .006; and 256 ± 45.05 vs 165.25 ± 51.80 in parameter set 2, P = .005), suggesting faster recovery to baseline IOP after occlusion break. The mean percentage reduction of IOP from maximum was significantly higher in Group I (P = .003). Rise of IOP to baseline after occlusion break event was faster and mean percentage reduction of IOP from maximum during nuclear fragment removal was lower when using the Centurion Vision system with the Active Sentry upgrade compared with the traditional handpiece. The ability to sense IOP at the level of the handpiece with the Active Sentry upgrade allows faster mitigation of surge response.

Recognizing blood pressure patterns in sedated critically ill patients on mechanical ventilation by spectral clustering.

BackgroundBlood pressure is a critical therapeutic goal in intensive care unit (ICU). One important factor influencing blood pressure are analgesia and sedation. Analgesic and sedative drugs are commonly used in critically ill patients. These drugs affect blood pressure by reducing the tension of the venous system, the cardiac preload, and cardiac output and inhibiting cardiac functions. Consequently, vasoactive agents are commonly used to increase blood pressure. The indications for the usage of vasoactive agents are unequivocal. However, opinions on when to stop raising blood pressure vary. This study explored the relationship between blood pressure and sedation.MethodsPatients in the Multiparameter Intelligent Monitoring in Intensive Care-III (MIMIC) database who had received mechanical ventilation, had been administered sedative analgesics during their ICU stay, and met the inclusion criteria were included in this study. The mean arterial pressure (MAP) tendency patterns were identified using spectral clustering and visualized using the t-distributed Stochastic Neighbor Embedding (t-SNE) algorithm. The 28-day mortality rates of patients with different MAP patterns during their first 24 hours in the ICU and their sedation levels were calculated in the crosstab.ResultsFourteen thousand seven hundred and eighty-five patients from the MIMIC-III database were included in this study. Three MAP patterns were identified by spectral clustering. The median MAP of the low, moderate, and high MAP groups was 71.2, 80.4, and 97.6 mmHg, respectively. The 28-day mortality rate of patients in the moderate MAP group (13.0%) was lower than that of patients in the low (16.6%) and high (15.6%) MAP groups. No difference was found in the 28-day mortality rate between the low and high MAP groups. Dynamic changes in blood pressure at different sedation depths were also examined. Notably, compared with light and moderate sedation level, patients in the deep sedation group, especially those in the high MAP group (48.5%), had a higher 28-day mortality rate (36.5%).ConclusionsLow MAP in the first 24 hours in ICU indicates a high possibility of poor prognosis for critically ill patients on mechanical ventilation. For patients under deep sedation, maintaining a high mean arterial pressure also indicates poor prognosis. A personalized MAP target should be determined according to the severity of illness and level of sedation for each patient.

Association Between Longitudinal Blood Pressure Trajectory and the Progression of Chronic Kidney Disease: Results From the KNOW-CKD.

[Figure: see text].

Automated Technique for the Detection of Step‐Like Solar Wind Dynamic Pressure Changes: Application to the Response of the Transpolar Potential to Solar Wind Dynamic Pressure Fronts

AbstractThe input from the solar wind (SW) and the accompanying Interplanetary Magnetic Field (IMF) is the defining feature of the solar wind‐magnetosphere interactions. One of the most important SW drivers is the solar wind dynamic pressure, and most significantly its sharp changes known as pressure fronts. Sudden enhancements in solar wind dynamic pressure, , have been shown to lead to intensification of the auroral electrojets (and Region 1 field‐aligned currents), increase in auroral emissions, and significant enhancement in ionospheric convection and the transpolar potential. Case studies of the interaction between pressure fronts and the terrestrial space environment shed great light on their importance to the structure and dynamics of the system. However, thorough understanding of the interaction requires fully statistical investigations. These statistical studies require a large number of suitable pressure front events. In the past these have been obtained through laborious manual inspection of solar wind data. We present an automated procedure that identifies sudden step enhancements in that satisfy a desired set of limiting step‐like characteristics, such as magnitude of the change, sign of the change (positive/negative), and rate of change. The procedure yields a list of suitable events, along with their step features within minutes. The technique is tested for missed events and false positives by direct comparison to manual inspection of the data. Its utility is illustrated by application to the statistical effect of pressure fronts to the transpolar potential as measured by the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) technique.

Could clinical nursing procedures lead to tracheal cuff pressure drop? A prospective observational study.

To evaluate the dynamic changes in tracheal cuff pressure before and after four clinical nursing procedures including sputum suction, oral care, atomisation inhalation, and turning over, and thus provide references for the adjustment time of cuff pressure in clinical practice. Cuff pressure must be kept within the range of 25-30cmH2 O to ensure effective ventilation and prevent aspiration, while maintaining tracheal bloodflowperfusion. A prospective observational study. The cuff pressure of 56 intubated patients was adjusted to 28-30cmH2 O. A cuff pressure monitor was used to continuously monitor cuff pressure changes before and after four clinical nursing procedures (sputum suction, oral care, atomisation inhalation, and turning over) and the cuff pressures at various time points were compared. The semi-quantitative cough strength score (SCSS) was used to evaluate cough strength during sputum suction and the effect of cough strength on cuff pressure during sputum suction. This study followed the STROBE checklist for cross-sectional studies. The cuff pressures during the four clinical nursing procedures of sputum suction, atomisation inhalation, turning over, and oral care, all temporarily increased (p<0.001) and decreased to varying degrees 20min later (p<0.001). Among them, the cuff pressure rose the highest under a state of moderate or strong coughing during sputum suction (78.38±12.13cmH2 O) and dropped the most at 20min after the procedure (21.71±4.80cmH2 O). The four clinical nursing procedures of sputum suction, atomisation inhalation, turning over, and oral care can all cause different degrees of cuff pressure drop. Thedecision on whether the cuff pressure needs to be corrected depends on the specific situation. During clinical practice, the cuff pressure can be individually corrected according to different clinical nursing procedures, which can increase the qualified rate of cuff pressure and reduce the workload of nurses.

Significance of monitoring pulmonary arterial pressure and cardiac function in neonates with pulmonary or extra-pulmonary acute respiratory distress syndrome

To evaluate the dynamic changes of pulmonary arterial pressure (PAP) and cardiac function in neonates with pulmonary or extra-pulmonary acute respiratory distress syndrome (ARDSp/ARDSexp). An observational study was conducted. A total of 128 neonates with ARDS admitted to neonatology department of the Affiliated Yancheng Hospital of Southeast University Medical College from January 2016 to December 2020 were enrolled, with 67 neonates in ARDSp group and 61 neonates in ARDSexp group. After starting mechanical ventilation, oxygenation index [OI, OI = mean airway pressure (Pmean)×fraction of inspired oxygen (FiO2)/arterial partial pressure of oxygen (PaO2)×100], PAP, cardiac function parameters [cardiac index (CI), left ventricular ejection fraction (LVEF), right ventricular Tei (RV-Tei)], and plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) were compared between the two groups; the incidence of pulmonary arterial hypertension [PAH, pulmonary artery systolic pressure (PASP) was more than 35 mmHg (1 mmHg = 0.133 kPa) or more than 2/3 of the systolic blood pressure of the body circulation] of neonates was recorded. The correlation between PAP and NT-proBNP was analyzed by Pearson correlation method. The dynamically changes in PAP and RV-Tei before and after using Milrinone in neonates with ARDSp and ARDSexp combined with moderate-severe PAH (PASP 50-69 mmHg was moderate, and PASP ≥ 70 mmHg was severe) were observed. The duration of mechanical ventilation, total length of hospital stay and prognosis were recorded; Kaplan-Meier survival curve was drawn to analyze the 28-day survival of the two groups. The occurrence rate of PAH in ARDSp group was significantly higher than that in ARDSexp group (97.01% vs. 70.49%, P < 0.01). OI, PAP, NT-proBNP and RV-Tei were also higher [OI: 17.61±6.12 vs. 11.04±5.35, PAP (mmHg): 64.27±9.54 vs. 53.61±6.47, NT-proBNP (ng/L): 23 126.32±1 485.14 vs. 18 624.24±1 647.15, RV-Tei: 0.61±0.22 vs. 0.52±0.19, all P < 0.05], but there was no significant difference in CI or LVEF between the two groups. Pearson correlation analysis showed that PAP was significantly positively correlated with NT-proBNP (r = 0.918, P < 0.01). There were 97 ARDS neonates with moderate-severe PAH with 63 in ARDSp group and 34 in ARDSexp group. Both PAP and RV-Tei in the two group showed a decreasing trend with the prolongation of Milrinone treatment, the decrease was more significant in the ARDSexp group compared with ARDSp group, the difference was statistically significant at 72 hours of treatment [PAP (mmHg): 38.42±8.95 vs. 45.67±13.32, RV-Tei: 0.58±0.19 vs. 0.61±0.13, both P < 0.05]; there was no significant difference in PAP or RV-Tei before extubation between the two groups. The duration of mechanical ventilation and the total length of hospital stay in ARDSp group were significantly longer than those in ARDSexp group [duration of mechanical ventilation (days): 10.12±1.36 vs. 6.31±1.31, total length of hospital stay (days): 16.52±3.25 vs. 13.12±3.57, both P < 0.01]. Kaplan-Meier survival curve showed that neonate in ARDSp group had a significantly lower 28-day cumulative survival rate as compared with ARDSexp group (82.09% vs. 95.01%; Log-Rank test: χ2 = 5.062, P = 0.025). Both PAP and RV-Tei were significantly increased in neonates with ARDS, PAP in neonates with ARDSp were significantly higher than that in neonates with ARDSexp. Dynamic monitoring of PAP and RV-Tei can reflect the severity of ARDS in neonates, and targeted intervention of pulmonary surfactant combined with Milinone for improving oxygenation and reducing PAP is one of the effective methods for the treatment of PAH.

A Modular Model of Jupiter's Magnetospheric Magnetic Field Based on Juno Data

AbstractAccurate modeling of Jupiter's magnetospheric magnetic field is important for not only scientific research but also mission planning. We develop a new empirical global model of Jupiter's magnetic field in the Juno era, including components from the planetary dynamo, Chapman‐Ferraro currents, and equatorial current sheet. The internal field is based on the JRM09 model. The shielding field is obtained by minimizing the component normal to Jupiter's magnetopause and varies due to the change of solar wind dynamic pressure. Combined with the curved magnetodisk, the high‐resolution TS07 method is used for modeling Jupiter's magnetodisc and tail currents. The best‐fitting results show an asymmetric magnetodisc current system in azimuthal direction with a tilted angle to Jupiter's magnetic equator. The sweep‐back effects of Jupiter's magnetic fields are also reproduced by the radial current system. This new model is validated by comparing with Juno's magnetometer data in the range from 5 Rj to 60 Rj, where Rj = 71,492 km is the radius of Jupiter.

Mechanical properties of external confinement modulate the rounding dynamics of cells

Many studies have demonstrated that mitotic cells can round up against external impediments. However, how the stiffness of external confinement affects the dynamics of rounding force/pressure and cell volume remains largely unknown. Here, we develop a theoretical framework to study the rounding of adherent cells confined between a substrate and a cantilever. We show that the rounding force and pressure increase exclusively with the effective confinement on the cell, which is related to the cantilever stiffness and the separation between cantilever and substrate. Remarkably, an increase of cantilever stiffness from 0.001 to 1 N/m can lead to a 100-fold change in rounding force. This model also predicts an active role of confinement stiffness in regulating the dynamics of cell volume and hydrostatic pressure. We find that the dynamic changes of cellular volume and hydrostatic pressure after osmotic shocks are opposite if the cantilever is soft, whereas the dynamic changes of cellular volume and pressure are the same if the cantilever is stiff. Taken together, this work demonstrates that confinement stiffness appears as a critical regulator in regulating the dynamics of rounding force and pressure. Our findings also indicate that the difference in cantilever stiffness need to be considered when comparing the measured rounding force and pressure from various experiments.

Fluid Responsiveness Predictability in Immediate Postoperative Pediatric Cardiac Surgery. Is the Old Slandered Central Venous Pressure Back Again?

Acute low cardiac output (CO) is a frequent scenario in pediatric cardiac intensive care units (PCICU). While fluid responsiveness has been studied extensively, literature is scarce for the immediate postoperative congenital heart surgery population admitted to PCICUs. This study analyzed the utility of hemodynamic, bedside ultrasound, and Doppler parameters for prediction of fluid responsiveness in infants and neonates in the immediate postoperative cardiac surgery period. A prospective observational study. University affiliated, tertiary care hospital, PCICU. Immediate postoperative pediatric patients displaying a presumed hypovolemic low CO state were included. A clinical, arterial derived, hemodynamic, sonographic, Doppler-based, and echocardiographic parameter assessment was performed, followed by a fluid bolus therapy. Fifteen to 20 cc/kg crystalloid fluid bolus. Fluid responsiveness was defined as an increase in cardiac index >10% by echocardiography. Of 52 patients, 34 (65%) were fluid responsive. Arterial systolic pressure variation, continuous-Doppler preload parameters, and inferior vena-cava distensibility index (IVCDI) by bedside ultrasound all failed to predict fluid responsiveness. Dynamic central venous pressure (CVP) change yielded a significant but modest fluid responsiveness predictability of area under the curve 0.654 (P = 0.0375). In a distinct population of mechanically ventilated, young, pediatric cardiac patients in the immediate postoperative period, SPV, USCOM preload parameters, as well as IVC-based parameters by bedside ultrasound failed to predict fluid responsiveness. Dynamic CVP change over several hours was the only parameter that yielded significant but modest fluid responsiveness predictability.

Hemodynamic impact of molecular adsorbent recirculating system in refractory vasoplegic shock due to calcium channel blocker poisoning.

To report the hemodynamic effect of to the molecular adsorbent recirculating system (MARS™) therapy for patients in refractory vasoplegic shock due to calcium channel blocker (CCB) poisoning. We report a retrospective cohort of patients who were hospitalized for CCB poisoning with refractory vasoplegic shock and treated by MARS therapy, at Amiens Hospital University, from January 2010 to December 2019. Improvement in hemodynamic was assessed by dynamic changes in mean arterial pressure (MAP) and norepinephrine levels over a 24-h period after MARS therapy. Cardiac function was assessed by transthoracic echocardiography. MARS therapy was performed on seven patients for CCB poisoning. CCB poisoning included nicardipine (n = 3, 43%) amlodipine (n = 3, 43%), and verapamil (n = 1, 14%). The median time to start MARS therapy was 24 [14-27] h after drug ingestion and 6 [2-9] h after ICU admission. Cardiac output was preserved for all patients. MAP values improved from 56 [43-58] to 65 [61-78] 16 mmHg (p = 0.005). Norepinephrine dose significantly decreased from 3.2 [0.8-10] µg/kg/min to 1.2 [0.1-1.9] µg/kg/min (p = 0.008) and lactate level decreased from 3.2 [2.4-3.4] mmol/l-1 to 1.6 [0.9-2.2] mmol/l-1 (p = 0.008). The median length of ICU stay was 4 (2-7) days and hospital stay was 4 (4-16) days. No complication related to the MARS therapy were reported. No patient died and all were discharged from the hospital. We reported the largest case-series of MARS therapy for refractory vasoplegic shock due to CCB poisoning. We observed that MARS therapy was associated with an improvement of hemodynamic parameters.

Research on injection speed control algorithm of oral anesthesia booster based on dynamic pressure detection

Oral anesthesia booster is an automatic injection system that replaces manual precise injection and solves the problem of abnormal pain caused by traditional oral anesthesia injection. Through the analysis of the system composition and model, it is determined that the pressure at the output end of the motor collected by the system in real time mainly reflects the load torque of the motor, so as to obtain the dynamic pressure detection method. According to the results of comparison with the high and low pressure thresholds, the oral anesthesia booster is controlled to select an appropriate injection speed mode. In addition, the pressure detection process is described, and the dynamic characteristics of the system are simulated and analyzed, which proves that the speed response of the system is timely after the dynamic pressure changes. The system can automatically alarm for obstruction or leakage according to the monitoring results, remind the doctor to correct the pressure and needle insertion position applied to the handle, so as to maintain the most rational needle insertion position and pressure, reduce the patient’s pain, and improve the comfort of treatment.

Function of arteries and veins in conditions of simulated cardiac arrest.

Introduction: The study examined the behavior of vasculature in conditions of eliminated cardiac function using mathematical modeling. In addition, we addressed the question of whether the stretch-recoil capability of veins, at least in part accounts for the slower response to simulated cardiac arrest. Methods: In the first set of computational experiments, blood flow and pressure patterns in veins and arteries during the first few seconds after cardiac arrest were assessed via a validated multi-scale mathematical model of the whole cardiovascular system, comprising cardiac dynamics, arterial and venous blood flow dynamics, and microcirculation. In the second set of experiments, the effects of stretch-recoil zones of venous vessels with different diameters and velocities on blood velocity and dynamic pressure analyzed using computational fluid dynamics (CFD) modeling. Results: In the first set of experiments, measurement of changes in velocity, dynamic pressure, and fluid flow revealed that the venous system responded to cardiac arrest more slowly compared to the arteries. This disparity might be due to the intrinsic characteristics of the venous system, including stretch-recoil and elastic fiber composition. In the second set of experiments, we attempted to determine the role of the stretch-recoil capability of veins in the slower response to cardiac arrest. During the second set of experiments, we found that this recoil behavior increased dynamic pressure, velocity, and blood flow. The enhancement in dynamic pressure through combining the results from both experiments yielded a 15-40% increase in maximum dynamic pressure due to stretch-recoil, depending on vein diameter under normal conditions. Conclusion: In the situation of cardiac arrest, the vein geometry changes continue, promoting smooth responses of the venous system. Moreover, the importance of such vein behavior in blood displacement may grow as the pressure on the venous side gradually decreases with time. Our experiments suggest that the driving force for venous return is the pressure difference that remains within the venous system after the energy coming from every ventricular systole spent to overcome the resistance created by arterial and capillary systems.

A sealed ceramic GEM-based neutron detector

The GEM-based neutron detector has flourished in the past decade. However, most of the GEM-based neutron detectors operate in the flow-gas mode, and the long-term performances of the detectors may be unstable due to the dynamic changes of atmospheric pressure and ambient temperature. In this work, a sealed ceramic GEM-based neutron detector with 100 mm × 100 mm sensitive area was developed at China Spallation Neutron Source (CSNS). Various characteristics of the detector were determined. These included the plateau curve, neutron beam profile, neutron wavelength spectrum, spatial resolution (FWHM: 2.77 ± 0.01(stat) mm), two-dimensional (2D) imaging ability, neutron detection efficiency and long-term counting rate instability (Relative Standard Deviation (RSD): 0.80%). The results revealed the good performance of the detector in sealed mode. Furthermore, the detector can be used for measurements of the direct neutron beam at CSNS.

Indirect Damage Identification in Bridges Based on Dynamic Tyre Pressure Monitoring

This paper deals with an indirect health monitoring strategy for bridges using an instrumented vehicle. Thermodynamic principles are used to relate the change in Vehicle–Bridge-Interaction (VBI) forces to the change in dynamic tyre pressure. The damage identification process involves two stages. In the first stage, the unknown tyre model parameters are estimated using Bayesian inference based on the calibration data. The approach uses a Stein variational gradient descent implementation of the Bayes rule to quantify the uncertainty in the estimated tyre parameters. In the second stage, the calibrated tyre model is used to reconstruct the change in VBI force from measured tyre pressure data considering a damaged bridge. It is observed that damage present in the bridge produces notable changes in VBI force. Contour plots based on VBI force and natural frequency are developed for damage detection. The reconstructed VBI force change is used to quantify damage using the contour plots. Further, the least square estimation approach is adopted for damage identification by defining appropriate objective functions and imposing constraints on the damage indicators. The damage is estimated by minimizing the objective function using Cuckoo search algorithm. Numerical experiments reveal that the developed method could be used for accurate damage identification in the presence of measurement noise, uncertainty in estimated tyre parameters, and the uncertainty in bridge model parameters.

Dynamic exercise changes in venous pressure and liver stiffness in Fontan patients: effects of Treprostinil.

Systemic venous hypertension and low cardiac output are believed to be important mediators of liver injury after the Fontan procedure. Pulmonary vasodilators have the potential to improve such haemodynamics. The aim of this study was to assess the acute effects of exercise on liver stiffness and venous pressures and to assess the impact of inhaled Treprostinil on this response. In this prospective, double-blind, placebo-controlled, crossover trial, 14 patients with a Fontan circulation were randomised to inhalation of placebo and Treprostinil. Incremental and constant work rate exercise tests were performed to assess the effect of Treprostinil on exercise tolerance. Venous pressures were measured throughout and liver stiffness at rest and immediately after peak exercise. Mean age was 27.8 ± 7.9 years and 66% were females. Exercise acutely increased liver stiffness by 30% (mean shear wave speed: 2.38 ± 0.71 versus 2.89 ± 0.51 ms, p = 0.02). Peripheral venous pressures increased acutely during both incremental (12.1 ± 2.4 versus 22.6 ± 8.0 mmHg, p < 0.001) and constant work rate exercise (12.5 ± 2.5 versus 23.4 ± 5.2 mmHg, p < 0.001). Overall, Treprostinil failed to attenuate exercise-induced increases in liver stiffness. Compared with placebo, Treprostinil did not significantly impact venous pressure responses, VO2peak, nor exercise endurance times. Peripheral venous pressure increased acutely during exercise by an average of 88% above baseline and was not altered by administration of inhaled Treprostinil. Liver stiffness measured immediately post-exercise increased acutely by an average of 30%, with no attenuation following Treprostinil inhalation.

Biomimetic Tympanic Membrane Replacement Made by Melt Electrowriting.

The tympanic membrane (TM) transfers sound waves from the air into mechanical motion for the ossicular chain. This requires a high sensitivity to small dynamic pressure changes and resistance to large quasi-static pressure differences. The TM achieves this by providing a layered structure of about 100µm in thickness, a low flexural stiffness, and a high tensile strength. Chronically infected middle ears require reconstruction of a large area of the TM. However, current clinical treatment can cause a reduction in hearing. With the novel additive manufacturing technique of melt electrowriting (MEW), it is for the first time possible to fabricate highly organized and biodegradable membranes within the dimensions of the TM. Scaffold designs of various fiber composition are analyzed mechanically and acoustically. It can be demonstrated that by customizing fiber orientation, fiber diameter, and number of layers the desired properties of the TM can be met. An applied thin collagen layer seals the micropores of the MEW-printed membrane while keeping the favorable mechanical and acoustical characteristics. The determined properties are beneficial for implantation, closely match those of the human TM, and support the growth of a neo-epithelial layer. This proves the possibilities to create a biomimimetic TM replacement using MEW.

Preliminary experimental study on the influence of different tidal volume and frequency of normal minute ventilation on the dynamic changes of carotid blood oxygen in living goats

Objective: On the basis of preliminarily verifying the use of ultra-fast reaction polymer matrix optical fiber oxygen sensor and its measuring system to record the continuous and dynamic changes of carotid artery oxygen partial pressure (PaO2), in order to analyze and discuss the influence of lung ventilation on the continuous and dynamic changes of PaO2, we designed a whole animal experimental study in vivo. Methods: Four hybrid goats were selected, and the skin was cut and exposed directly under general anesthesia and tracheal intubation. The oxygen sensor, connected with the measuring system, was inserted directly into the left carotid artery to continuously record the dynamic changes of PaO2. With normal minute ventilation,mechanical ventilation is implemented through three tidal volumes: normal tidal volume (VT=15 ml/kg, Rf=20 bpm), half tidal volume (halved VT, doubled Rf) and double tidal volume (doubled VT, halved Rf). Each tidal volume was stable for 10~15 min respectively. We analyzed and calculated the average values of PaO2, the fluctuation magnitudes of PaO2 changes between breaths of last 180 s and the delay times of lung-carotid artery were. We analyzed the effects of different tidal volumes. Results: The heart rate and blood pressure of living goats were maintained stable during the mechanical ventilation experiment with normal ventilation volume Lung-carotid artery delay time is 1.4~1.8 s (about 3 heartbeats at this time). Under normal tidal volume of mechanical ventilation, the average value of PaO2 was (102.94±2.40, 99.38~106.16) mmHg, and the fluctuation range was (21.43±1.65, 19.21~23.59) mmHg, accounting for (20.80± 1.34, 18.65~22.22)% of the average value. Under the condition of halving tidal volume, the average value of PaO2 was maintained at (101.01±4.25, 94.09~105.66) mmHg, which was slightly decreased but not significant (P>0.05 compared with normal mechanical ventilation), but the fluctuation range of PaO2 was significantly reduced to (18.14±1.43, 16.46~20.05) mmHg, accounting for 17.5% of the average value. Under double tidal volume mechanical ventilation, although the average value of PaO2 increased slightly remained at (106.42±4.74, 101.19~114.08) mmHg (P>0.05 compared with normal mechanical ventilation and P<0.05 compared with half tidal volume mechanical ventilation), the fluctuation magnitude of PaO2 increased significantly to (26.58±1.88, 23.46~28.46)mmHg. Conclusion: Inspiration and expiration of normal lung ventilation are the initial factors for the increase and decrease of PaO2 in carotid artery. Under normal ventilation, halving tidal volume and doubling tidal volume significantly changed the fluctuation magnitude of PaO2, but the average value of PaO2 changed only slightly, while the lung-carotid delay time was similar.

A wearable contact lens sensor for noninvasive in-situ monitoring of intraocular pressure

Glaucoma is the second leading cause of blindness in the world. Intraocular pressure (IOP) is a primary indicator of glaucoma which can be measured for the treatment of the disease. This paper presents a piezo-resistive principle pressure sensor to monitor IOP continuously and non-invasively. The sensor is designed based on the Wheatstone bridge circuit and fabricated by the spray-coating method. The hybrid nanomaterials of graphene and carbon nanotubes are introduced as sensing layers which are embedded inside the soft contact lens substrate composed of flexible polydimethyl siloxane (PDMS) and parylene. The sensing performance is discussed followed by a brief description of our sensor design and fabrication. Tests on a PDMS eyeball model indicate that it has a high sensitivity of 36.01 μV mmHg−1. Also, the frequency response and the ability to track dynamic pressure change cycles are demonstrated in normal IOP variation range from 9 to 34 mmHg. It shows good repeatability and linearity, and can accurately track fluctuating IOP. Thus, this sensor, with its ease of fabrication and simple design, as well as allowance for continuous pressure measurement, offers a promising approach for IOP monitoring in clinical diagnosis of glaucoma.