Pressure Surge Research Articles

Turbulence in liquid phase and its influence on aeration and pressure surge in intermittent type two-phase flow

Nuclear industry considers intermittent type of two-phase flow as a complex flow pattern due to its intricate hydrodynamics. Turbulence causes aeration inside the liquid slug leading to sudden surge in pressure and large Reynolds stresses near the wall. This result in high mechanical impact associated with structural vibration and erosion-corrosion in the pipeline. Fast accelerated corrosion associated with high momentum of slug and aeration in the slug body leads to cracks in the pipeline. In order to avoid hazardous accidents in nuclear industry associated with leakages from these cracks, a detailed analysis of the phenomena of aeration in the liquid slug is vital. The present work reports how turbulence in the liquid phase leads to aeration and its augmentation in the slug. In the first part of the present article, flow visualization analysis is presented depicting that at low level of turbulence, aeration is absent in plug flow regime. Increase in level of turbulence in liquid phase causes aeration and its augmentation in slug. The second part deals with analysis of the measured instantaneous averaged velocity variations in the liquid phase using Laser Doppler Velocimetry (LDV). The turbulence characteristics in the liquid phase measured using LDV is used to depict the cause of aeration in slug and its consequences on the pressure fluctuations. Instantaneous pressure signals and the pressure drop per unit length are measured in plug, less aerated slug (LAS) and high aerated slug (HAS) regime and correlated to the turbulence characteristics. At the end, the consequence of turbulence and pressure surge on pipe failure are depicted.

Acute social jetlag augments morning blood pressure surge: a randomized crossover trial

Although social jetlag (SJL) is generally considered a chronic condition, even acute SJL may have unfavorable effects on the cardiovascular system. We focused on the acute effects of SJL on morning blood pressure (BP) surge. This randomized crossover trial recruited 20 healthy men. In the SJL trial, participants delayed their bedtime by three hours on Friday and Saturday nights. Participants in the control (CON) trial implemented the same sleep-wake timing as on weekdays. Pre- and post-intervention measurements were performed to evaluate resting cardiovascular variables on Friday and Monday mornings, respectively. The ambulatory BP was automatically measured during the sleep and awake periods for 2 h after the participant woke up at night before pre- and post-intervention measurements. SJL (average mid-sleep time on weekends – average mid-sleep time on weekdays) occurred only in the SJL trial (SJL: 181 ± 24 min vs. CON: 8 ± 47 min). Carotid-femoral pulse wave velocity (cfPWV) and morning BP surge on Monday in the SJL trial were significantly higher than those on Friday in the SJL trial (cfPWV: P = 0.001, morning BP surge: P < 0.001), and those on Monday in the CON trial (cfPWV: P = 0.007; morning BP surge: P < 0.001). Furthermore, a significant positive correlation was found between ΔcfPWV and Δmorning BP surge (R = 0.587, P = 0.004). These results suggest that even acute SJL augments morning BP surge. This phenomenon may correspond to increased central arterial stiffness.State the details of Clinical Trials: Name: Effect of acute social jetlag on risk factors of lifestyle-related diseases. URL: https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000053204. Unique identifier: UMIN000046639. Registration date: 17/01/2022

Study on water hammer effect and tubing string vibration in high-pressure high-production gas wells

The transient internal flow in high-pressure high-production gas wells generates severe water hammer and tubing string vibration, which accelerates fatigue damage, joint wear, thread loosening, and other wellbore integrity problems. Based on the analysis of transient flow in gas wells, a mathematical model for fluid pressure surge and the induced tubing string vibration is developed and validated by similarity experiments. This method considers fluid-structure interaction, initial loads of tubing string, and compressibility of natural gas, and can fill the gap in quantification of water hammer pressure and tubing sting dynamic load in high-pressure high-production gas wells. On this basis, the effects of valve closure time, production rate, liquid content, and tubing string structure on transient flow and tubing string characteristics are analyzed systematically. The calculations show that wellhead pressure increases rapidly, and pressure wave propagates along tubing string to induce vibrations in the string after an instantaneous shut-in at the wellhead. During this transient process, fluid pressure and axial stress at wellhead reach their maximum valves. Owing to the fixed constraint effect of wellhead and downhole packer, the lack of restrictions on tubing distant from wellhead and packer enhances the severity of axial vibration. As valve closure time increases, the maximum wellhead pressure, tubing vibration displacement, and velocity gradually decrease. Therefore, the most direct way to control water hammer effect and tubing string vibration is to extend the shut-in time or prevent a rapid shut-in of gas well. The methods used in this study and the results obtained therein can serve as both a theoretical framework and practical foundation for the prediction and control of water hammer effect and tubing string vibration in high-pressure high-production gas wells.

The Use of Cannabidiol in Metabolic Syndrome-An Opportunity to Improve the Patient's Health or Much Ado about Nothing?

Cannabis-derived therapies are gaining popularity in the medical world. More and more perfect forms of cannabinoids are sought, which could be used in the treatment of many common diseases, including metabolic syndrome, whose occurrence is also increasing. The purpose of this review was to investigate the usefulness of cannabinoids, mainly cannabidiol (CBD), in individuals with obesity, impaired glucose and lipid metabolism, high blood pressure, and non-alcoholic fatty liver disease (NAFLD). We summarised the most recent research on the broad topic of cannabis-derived influence on metabolic syndrome components. Since there is a lot of work on the effects of Δ9-THC (Δ9-tetrahydrocannabinol) on metabolism and far less on cannabidiol, we felt it needed to be sorted out and summarised in this review. The research results on the use of cannabidiol in obesity are contraindicatory. When it comes to glucose homeostasis, it appears that CBD maintains it, sensitises adipose tissue to insulin, and reduces fasting glucose levels, so it seems to be a potential target in this kind of metabolic disorder, but some research results are inconclusive. CBD shows some promising results in the treatment of various lipid disorders. Some studies have proven its positive effect by decreasing LDL and increasing HDL as well. Despite their probable efficacy, CBD and its derivatives will likely remain an adjunctive treatment rather than a mainstay of therapy. Studies have also shown that CBD in patients with hypertension has positive effects, even though the hypotensive properties of cannabidiol are small. However, CBD can be used to prevent blood pressure surges, stabilise them, and have a protective effect on blood vessels. Results from preclinical studies have shown that the effect of cannabidiol on NAFLD may be potentially beneficial in the treatment of the metabolic syndrome and its components. Nevertheless, there is limited data on CBD and NAFLD in human studies. Because of the numerous confounding factors, the conclusions are unclear, and more research in this field is required.

Анализ конструктивных и технологических особенностей шестеренчатых насосов

The article presents the main design and technological features of gear pumps with a description of the contacts of the gear wheels during their interaction and manufacturing accuracy. The increase in contacts in the interdental space reduces the pulsation by 75%, the noise level by 5 decibels. The use of helical gears increases the efficiency of gear pumps and reduces pulsation. External gear pump with axial compensation with high precision and high quality materials resistant to fatigue. Internal gear pumps have a compact body and are less noisy. In practice, external gear pumps are most commonly used due to their simple design and low cost. The gear pump housing is subject to wear due to high pressure. During operation of the pump, uneven stresses occur, which leads to fatigue loads on the shaft in one direction. Additional pulsation entails oscillations of the structure. The gear pump’s own vibrations contribute to its failure, especially if the rotation speed is 100,000 cycles. During the operation of a gear pump, noise occurs that can be dampened with silencers or dampers, which increases the price of the pump. The interdental spaces of a gear pump are prone to cavitation during sudden pressure surges, which increases wear. To eliminate wear, pulsation, vibration, noise, a new design of the gear pump is proposed using various types of oils and methods for correcting the shape of the teeth.

Research on the carbon emissions traceability inventory and multi-horizon prediction of ship carbon emissions: a case study of Tianjin Port

IntroductionIn recent years, the adverse effects of escalating maritime trade and international shipping– particularly in regard to increased greenhouse gas emissions and their impact on human health– have come to the fore. These issues have thus instigated a surge in pressure to enhance the regulation of shipborne carbon emissions.MethodsThe study utilized the automatic identification system (AIS) data, Lloyd’s register data, and pollutant emission parameters to calculate the carbon emissions from the main engine, auxiliary engine, and boiler of vessels under varying sailing conditions, utilizing the dynamic method of ships. In relation to geographic information and ship trajectory, a comprehensive inventory of ship carbon emissions was developed, revealing pronounced spatiotemporal characteristics. To assure the accuracy of the substantial AIS dataset, procedures including data cleaning, trajectory integration, data fusion, and completion were executed. Such processes are indispensable, given the potential for transmission and storage errors associated with AIS data. To forecast CO2 emissions over diverse time intervals, a temporal fusion transformer model equipped with attention mechanisms was employed.ResultThe paper furnishes a case study on Tianjin Port, wherein a high-resolution carbon emissions inventory was devised based on AIS data acquired from vessels. This inventory was subsequently employed to generate multi-feature predictions of future carbon emissions. Given the optimal parameter configuration, the proposed method attained P50 and P90 values of 0.244 and 0.118 respectively, thereby demonstrating its efficacy.DiscussionRecognizing the sources of ship carbon emissions in this region and forecasting such emissions in the future substantiates that this method accurately portrays the laws of ship carbon emissions. Our study provides a scientific basis for decision-making in port and pollution management, enabling the creation of targeted emission reduction policies for ships.

Morning Blood Pressure Surge and Glaucomatous Visual Field Progression in Normal-Tension Glaucoma Patients With Systemic Hypertension

To investigate the impact of a morning blood pressure surge (MBPS) at baseline on subsequent visual field (VF) progression in hypertensive, normal-tension glaucoma (NTG) patients receiving oral anti-hypertensive treatment. Retrospective cohort study. A total of 127 eyes from 127 newly diagnosed NTG patients treated for systemic hypertension and followed up for at least 2 years were analyzed. All patients underwent baseline 24-hour ambulatory blood pressure monitoring (ABPM) and at least 5 serial VF examinations during the follow-up period. VF progression was defined according to the Early Manifest Glaucoma Trial criteria. The associations of VF progression with 24-hour ABPM-based blood pressure (BP) parameters (including MBPS) and other clinical variables were analyzed using Cox regression analyses. Kaplan-Meier survival analysis was used to compare VF survival estimates in patients with and without MBPS. VF progression was detected in 38 eyes (29.9%) over a 5.2-year mean follow-up. In the multivariate Cox regression model, a greater MBPS (hazard ratio [HR]=1.033; P=.024) and lower nighttime mean arterial pressure (MAP) trough (HR=0.965; P=.031) at baseline were significant independent predictors of subsequent VF progression. The likelihood of VF progression was significantly greater in patients with higher MBPS (P=.021) at baseline according to Kaplan-Meier survival analysis. An increased MBPS at baseline is a significant independent predictor of subsequent VF progression in NTG patients with systemic hypertension. This may be another relevant BP parameter associated with VF progression in hypertensive NTG patients receiving oral anti-hypertensive treatment.

Respiratory Event-Induced Blood Pressure Oscillations Vary by Sleep Stage in Sleep Apnea Patients.

Obstructive sleep apnea (OSA) pathologically stresses the cardiovascular system. Apneic events cause significant oscillatory surges in nocturnal blood pressure (BP). Trajectories of these surges vary widely. This variability challenges the quantification, characterization, and mathematical modeling of BP surge dynamics. We present a method of aggregating trajectories of apnea-induced BP surges using a sample-by-sample averaging of continuously recorded BP. We applied the method to recordings of overnight BP (average total sleep time: 4.77 ± 1.64 h) for 10 OSA patients (mean AHI: 63.5 events/h; range: 18.3-105.4). We studied surges in blood pressure due to obstructive respiratory events separated from other such events by at least 30 s (274 total events). These events increased systolic (SBP) and diastolic (DBP) BP by 19 ± 7.1 mmHg (14.8%) and 11 ± 5.6 mmHg (15.5%), respectively, relative to mean values during wakefulness. Further, aggregated SBP and DBP peaks occurred on average 9 s and 9.5 s after apnea events, respectively. Interestingly, the amplitude of the SBP and DBP peaks varied across sleep stages, with mean peak ranging from 128.8 ± 12.4 to 166.1 ± 15.5 mmHg for SBP and from 63.1 ± 8.2 to 84.2 ± 9.4 mmHg for DBP. The aggregation method provides a high level of granularity in quantifying BP oscillations from OSA events and may be useful in modeling autonomic nervous system responses to OSA-induced stresses.

Comparative Experimental Study of Fracture Mechanisms and Characteristics of Coal-like Materials under Quasi-Static and High-Pressure Air Blasting Fracturing

High-pressure air blasting is a burgeoning technique for anhydrous fracturing. A crucial prerequisite for the application of air blasting is to comprehend the distinctions between air blasting and quasi-static fracturing, as well as the change in fracture control factors with variations in blasting pressure. This research undertook experiments on coal-like material specimens with quasi-static fracturing and blasting fracturing with blast pressures ranging from 5 to 10 MPa, by utilizing a self-designed air fracturing experimental system. The fracturing mechanism and characteristics of specimens subjected to different loading conditions were analyzed using a pressure sensor, high-speed camera, and fractal theory. The following primary findings were obtained: The average fracture pressure under quasi-static loading was 3.269 MPa, exhibiting similar absolute deviations. The pressure–time curve of blast fracturing was found to undergo four distinct stages: pressure surge, pressure fallback, pressure maintenance, and pressure plummet. The duration of the pressure maintenance stage exhibited a negative correlation with the blast pressure, ceasing to exist at pressures above 9 MPa. This suggests that the dynamic impact effect gradually supplants the dominant role of the air wedge effect. Quasi-static fracturing formed single fractures, whereas blast fracturing tended to generate complex fracture networks. The increase in blast pressure could significantly enhance the complexity of the fracture network in a logarithmic fashion. The fractal dimension of quasi-static fracturing was slightly higher than that of 6 MPa blast fracturing, indicating the prevalence of quasi-static action under low blast pressure. The smash district increased exponentially as the blast pressure increased, and the average particle size decreased gradually. These investigations provide valuable insights for designing high-pressure air blasting fracturing procedures.

Study of fusion boundary microstructure and local mismatch of SA508/alloy 52 dissimilar metal weld with buttering

A SA508/Alloy 52 dissimilar metal weld (DMW) mock-up with double-sided Alloy 52 butterings, which is fully representative of Ringhals pressurizer surge nozzle DMW repair solution, was studied. The microstructure, crystal structure, elemental diffusion, carbide formation and macro-, micro- and nano-hardness of the SA508/nickel-base Alloy 52 buttering fusion boundary (FB) were investigated. Three types of FBs were analyzed, i.e., narrow FB (∼80–85% of whole FB), tempered martensitic transition region (∼15%) and wide partially mixed zone (∼1–2%). The different FB types were induced by the local heat flow and respective elementary diffusion, which significantly influence the local hardness mismatch across the DMW interface and the local brittle fracture behavior.

COMPARISONS OF THE PREDICTIVE VALUE OF MORNING AND EVENING BLOOD PRESSURE FOR NOCTURNAL HYPERTENSION AND MORNING BLOOD PRESSURE SURGE

Objective: Evidences showed that morning blood pressure (BP) surge (MS) and nocturnal hypertension (NH) may increase the risk of cardiovascular events. The purpose of this study is to determine whether morning and evening hypertension can be used to predict NH and MS in hypertensive patients. Design and method: Participants with BP over 140/90 mmHg from 11 medical centers in Taiwan were included in the cohort. Every participant had ambulatory BP monitoring (ABPM) and home blood pressure values that were taken twice daily (morning and evening). According to the ABPM data, MS and NH were characterized as overnight BP 120 and/or 70 mmHg and sleep-trough morning (6AM-8AM) BP rise larger than 43.67 mmHg, respectively. The cut point of both morning home BP hypertension (MHBP) and evening home BP hypertension (EHBP) were 135/85 mmHg. We used MHBP and EHBP separately and together in logistic regression models to analyze the predictive value for NH and MS, adjusting for potential confounders, such as age, sex, alcohol usage, and smoking. Results: A total of 1621 individuals were included, with a median age of 58.9 years. MHBP and EHBP were present in 17.93% and 15.8% respectively. NH was present in 76.25% (n = 1361) and MS was present in 9.69% (n = 173) of the cohort. The accuracy of MHBP to predict NH, MS and NH or MS were 0.843, 0.889 and 0.865 respectively. The accuracy of EHBP to predict NH, MS and NH or MS were 0.837, 0.887 and 0.862 respectively. After adjusting for potential confounders, both MHBP and EHBP can significantly predict NH, MS and the combination of both. EHBP outperformed MHBP of predicting NH (OR 5.57 vs 1.65). The relationship between EHBP and NH or MS was also stronger for EHBP than for MHBP (OR 10.44 vs 2.37). Nevertheless, MHBP had a marginally higher predictive value for MS than EHBP (OR 2.40 vs 1.88). Conclusions: EHBP showed more predictive of NH and MHBP has a better predictive value of MS in hypertensive subjects. Both MHBP and EHBP are useful for detecting NH or MS and should not be overlooked for overall BP control.

ARTERIAL HYPERTENSION DOES NOT SLEEP

Objective: Sleep apnea is a secondary cause of hypertension and is suggested by non-dipper profile at ambulatory blood pressure monitoring (ABPM). The prevalence is estimated between 30-50% in hypertensive patients. Design and method: A 60 year-old man with cardiovascular risk factors (hypertension, diabetes, dislipidemia, obesity, transient ischemic attack) presented to the outpatient clinic with high values of self-monitoring blood pressure despide multiple lowering blood pressure therapy. On physical examination his body mass index was 39.6 kg/m2, neck circumference 50 cm. The ECG was in sinus rhythm with hypertrophic phenotype confirmed by echocardiogram, which also showed left ventricle preserved ejection fraction, grade III diastolic dysfunction, mildly enlarged left atrium. Laboratory tests exluded endocrinologic and renal causes. Despite lifestyle changes and a good adherence to multiple associated antihypertensive treatment, ABPM revealed a non-dipper profile (dipping index 4.86%) (figure 1). The patient underwent the polygraphy test which showed the apnea-hypopnea index (AHI) of 10.6, which led to a diagnosis of mild sleep apnea, the t90% of 57 pointed out severe hypoxia and high pulse variances 104 (figure 1). The further Holter monitoring revealed episodes of atrial flutter and atrial fibrillation. Results: After 3 months of continuous positive airways pressure (CPAP) therapy, on top of the same antihypertensive drugs and anticoagulation, led to optimal blood pressure values and normal ABPM profile (figure 2). The polygraphy parameters AHI, t90% and pulse variances normalised too. (figure 1) Conclusions: Obstructive sleep apnea is a prevalent secondary cause of hypertension and atrial arythmias, still greatly underdiagnosed. It is associated with abdominal obesity, large neck, snoring, daytime fatigue and a decrease in the quality of life. Polygraphy is a feasible method for diagnose sleep apnea and monitoring the treatment. CPAP treatment abolishes apnea, normalises blood oxigenation thereby prevents arterial pressure surges, restoring the nocturnal ‘dipping’ pattern and normal sinus rythm.

In Vivo Real-Time Study of Drug Effects on Carotid Blood Flow in the Ovine Fetus.

The ability of an organism to maintain a constant blood flow to the brain in response to sudden surges in systemic blood pressure (BP) is known as cerebral autoregulation (CAR), which occurs in the carotid artery. In contrast to full-term neonates, preterm neonates are unable to reduce the cerebral blood flow (CBF) in response to increased systemic BP. In preterm neonates, this exposes the fragile cerebral vessels to high perfusion pressures, leading to their rupture and brain damage. Ex vivo studies using wire myography have demonstrated that carotid arteries from near-term fetuses constrict in response to the activation of adrenergic alpha1 receptors. This response is blunted in the preterm fetus. Thus, to examine the role of alpha1-AR in vivo, presented here is an innovative approach to determine the effects of drugs on a carotid arterial segment in vivo in an ovine fetus during the developmental progression of gestation. The presented data demonstrate the simultaneous measurement of fetal blood flow and blood pressure. The perivascular delivery system can be used to conduct a long-term study over several days. Additional applications for this method could include viral delivery systems to alter the expression of genes in a segment of the carotid artery. These methods could be applied to other blood vessels in the growing organism in utero as well as in adult organisms.

Research on effects of rolling motion on a pressurizer surge line based on the fluid-solid-thermal coupling method

To investigate the effects of rolling motion on the thermal stress and deformation caused by thermal stratification of a pressurizer surge line in floating nuclear power plants (FNPP), the finite element simulation platform ANSYS Workbench 19.0 is utilized to conduct the fluid–solid-thermal coupling transient analysis of the surge line under different rolling motion conditions. The Large Eddy Simulation (LES) approach and the Frame Motion model are used in Computational Fluid Dynamics (CFD) analysis. By comparing different calculated results, it is found that rolling motion can significantly improve thermal stratification and reduce the peak thermal stress in some positions of the surge line, but may also result in periodic oscillations in temperature and thermal stress. The effects of the rolling period and the maximum rolling angle on the oscillation amplitude of temperature and thermal stress are investigated. This work provides a reference for evaluating pipeline fatigue damage and the structural integrity of the pressurizer surge line in FNPP under actual ocean conditions.

Using Transient Modeling to Define the Effects of Heave on Wellsite Operations

Summary The drilling industry is striving to be more efficient, reducing time, costs, and emissions to provide energy solutions for a more climate-conscious world. Reducing nonproductive time (NPT) and invisible lost time (ILT) by utilizing modeling software to optimize tripping operations is one method to combat this. Additional factors such as sea heave have a significant impact on tripping operations on semisubmersible drilling vessels, which do not show a linear response to increased heave. These vessels have compensation systems, but they are often not in use or not completely accurate. Typical heave experienced in the North Sea is between 0.5 and 3-m amplitude and 10–30-second heave period. In this study, transient modeling software is used to create a digital twin of the wellbore to safely predict the tripping speed and define the effect heave has on the tripping operations, from causing additional swab and surge pressures when in or out of slips to reducing tripping speed and improving efficiency by reducing mud gelling at connections. To further understand the effect heave has on tripping operations, experimental simulations of varying heave magnitude were completed in wellbore sections of 0°, 30°, 60°, and 90° inclination. Model validation was completed before running simulations. The results indicate that in horizontal holes, low heave magnitudes result in no bit or pressure response. The same cannot be said for vertical wells, which show smooth bit movement and pressure response throughout the heave magnitude spectrum. However, in a horizontal hole when the wave height is of a larger magnitude, sufficient to break wellbore friction, bit displacement is observed to display jerky axial stick and slip movement, and resultant increased swab and surge pressures are shown even when accounting for the reduced pressure fluctuations due to string eccentricity in an inclined wellbore. It is proposed that much of the related mechanical and pressure response is due to the properties of the drilling mud, string elasticity, and the forced frequency of the waves on the natural frequency of the drilling rig and drillstring. It is clear from definitive and experimental simulations that extra care must be taken when the heave is significant to maintain wellbore stability and reduce wellbore pressure cycling.

THE CIRCADIAN PATTERN OF 24-HOUR AMBULATORY BLOOD PRESSURE AND HEART RATE IN THE CEREBRAL INFRACTION PATIENTS WITH HYPERTENSION AND HYPERTENSIVES PATIENTS

Aims: Evaluation of the circadian rhythm of 24-hour ambulatory blood pressure and pulse rate in the cerebral infraction patients with hypertension and hypertensives patients with purpose prognostic, prevention and treatment in two group.&#x0D; Objects and methods: This study included 140 cerebral infarction patients with hypertension, hospitalized for the first 7 days (mean age 65.5±10.4 years) and 143 primary hypertensive patients (mean age of 64.4±7.5 years). All had 24-h ambulatory recording, with measurement 30 every minutes in the daytime (6.00 am - 10.00 pm) and every 60 minutes at night (10.00 pm - 6.00 am). Results: Blood pressure in patients with cerebral infarction oscillated significantly more than in hypertensive patients; mean standard deviation of systolic blood pressure (25.8 mmHg) and diastolic blood pressure (15.8 mmHg) in patients with cerebral infarction respectively was significantly higher than those with hypertension (20 mmHg and 12.1 mmHg) with p &lt;0.01. The rate of non-dipping blood pressure at night, the overload of systolic and diastolic blood pressure, morning surge blood pressure in patients with cerebral infarction was significantly higher than that of hypertensive patients (92.1; 75.5; 60.2; 57.8 versus 64.3; 60.1; 49.1; 36.3 respectively; p &lt;0.01). Conclusion: It is necessary to monitor 24-hours ambulatory blood pressure in hypertensive patients and patients with cerebral infarction in the first week of admission to identify some phenomena such as nocturnal non-dipping blood pressure, the overload of blood pressure, especially morning surge blood pressure early to plan for prevention of target organ damage, particularly cerebral stroke in hypertensive patients.

Flow Pressure Characteristics of the Ahmed Glaucoma Valve and Possible Effect of Entrapped Air in the Tube.

The purpose of this study was to assess the pressure characteristics of the Ahmed Glaucoma Valve (AGV) and possible effects of air trapped in the tube. Physiologic saline was pumped through 17 AGVs using a syringe infusion pump, and the flow pressure was measured by a set of pressure transducers. During the infusion at a rate of 2µL/minute, the pressure measurement was repeated twice in each AGV to determine the repriming pressures with/without air (1µL) in the tube. After a pressure surge occurred during the initial priming, the pressure decreased suddenly and then became constant. The repriming pressure, determined as the peak pressure before valve opening, was significantly (P < 0.0001, paired t-test) higher with air (26.5 ± 6.8 mm Hg) than without air (12.1 ± 3.8 mm Hg), whereas the constant pressures after repriming was equivalent between with (10.6 ± 3.7 mm Hg) and without (10.4 ± 2.9 mm Hg) air conditions (P = 0.68). Air in the AGV tube causes increased repriming pressure of about two-fold compared to repriming without air. This pressure increment caused by air in the capillary-sized tube might occur because of the effects of viscosity pressure and capillary pressure. To ensure stable surgical results, surgeons are advised to not allow air to remain in the tube. Pars plana tube insertion of the AGV combined with gas tamponade surgery may result in higher-than-expected intraocular pressure. Conversely, injection of air/gas can avoid postoperative hypotony when the AGV is implanted in eyes with a high risk of hypotony.

Blood pressure surge with alarm is reduced after exercise and diet intervention in firefighters.

Cardiac-related incidents are a public health concern for tactical occupations, and cardiovascular disease rates are higher in these populations compared with civilians. Research is needed to examine blood pressure (BP) responses in firefighters. The pager alert is one occupational hazard, and it is unknown if lifestyle change can reduce the systolic surge response. To measure BP surge with alarm in firefighters to determine whether the magnitude is lower after a 6-week tactical exercise and Mediterranean-diet intervention. SBP and DBP and BP surge levels, circulating markers, vascular health, and fitness were analyzed. BP surge with alarm was captured during a 12-hour workshift. Exercise and diet were self-reported. Diet was tracked with diet scores based on number of servings. Twenty five firefighters (43.4 ± 13.9 years) participated. We found changes in the magnitude of BP surge with alarm (SBP surge from16.7 ± 12.9 to 10.5 ± 11.7 mmHg, P < 0.05; DBP surge from 8.2 ± 10.8 to 4.9 ± 5.6 mmHg, P > 0.05) after intervention. We confirm that clinical (127.6 ± 9.1 to 120 ± 8.2 mmHg) and central (122.7 ± 11.3 to 118.2 ± 10.7 mmHg) SBP levels improve with exercise and diet. We report for the first time in firefighters that oxidative stress markers superoxide dismutase (9.1 ± 1.5 to 11.2 ± 2.2 U/ml) and nitric oxide (40.4 ± 7 to 48.9 ± 16.9 μmol/l) levels improve with an exercise and diet intervention. These findings have implications toward the benefit that short-term lifestyle changes make toward reducing the alarm stress response in first responders.

Joint statement for assessing and managing high blood pressure in children and adolescents: Chapter 1. How to correctly measure blood pressure in children and adolescents.

The joint statement is a synergistic action between HyperChildNET and the European Academy of Pediatrics about the diagnosis and management of hypertension in youth, based on the European Society of Hypertension Guidelines published in 2016 with the aim to improve its implementation. The first and most important requirement for the diagnosis and management of hypertension is an accurate measurement of office blood pressure that is currently recommended for screening, diagnosis, and management of high blood pressure in children and adolescents. Blood pressure levels should be screened in all children starting from the age of 3 years. In those children with risk factors for high blood pressure, it should be measured at each medical visit and may start before the age of 3 years. Twenty-four-hour ambulatory blood pressure monitoring is increasingly recognized as an important source of information as it can detect alterations in circadian and short-term blood pressure variations and identify specific phenotypes such as nocturnal hypertension or non-dipping pattern, morning blood pressure surge, white coat and masked hypertension with prognostic significance. At present, home BP measurements are generally regarded as useful and complementary to office and 24-h ambulatory blood pressure for the evaluation of the effectiveness and safety of antihypertensive treatment and furthermore remains more accessible in primary care than 24-h ambulatory blood pressure. A grading system of the clinical evidence is included.

Gallbladder perforation following peroral cholangioscopy‐guided lithotripsy: A case report

Peroral cholangioscopy-guided lithotripsy is highly effective in clearing difficult bile duct stones. It can cause adverse events, such as cholangitis and pancreatitis; however, gallbladder perforation is extremely rare. Herein, we describe the case of a 77-year-old woman who developed gallbladder perforation following peroral cholangioscopy -guided lithotripsy. She was referred to our hospital to treat multiple large bile duct stones. She underwent peroral cholangioscopy-guided lithotripsy because of conventional lithotripsy failure. After a cholangioscope was advanced into the bile duct, saline irrigation was used for visualization. Electronic hydraulic lithotripsy was performed, but it took time for fragmentation because the calculus was hard. The 2-h endoscopic procedure did not completely remove the stone, and treatment was discontinued after placing a biliary plastic stent and nasobiliary tube. After the endoscopic procedure, she started experiencing right hypochondrial pain, which worsened the next day. Computed tomography showed a gallbladder wall defect in the gallbladder fundus with pericholecystic fluid. She was diagnosed with gallbladder perforation and underwent emergency surgery. A perforation site was found at the gallbladder fundus. Open cholecystectomy, choledochotomy, and extraction of residual bile duct stones were performed. The patient was discharged 9 days post-surgery without any complications. The saline irrigation used for visualization may have caused a surge in intra-gallbladder pressure, resulting in gallbladder perforation. Therefore, endoscopists may need to conserve irrigation water during peroral cholangioscopy-guided lithotripsy.