BACKGROUND Hypovolemic shock can lead to life-threatening organ dysfunction,and adequate fluid administration is a fundamental therapy.Traditionally,parameters such as vital signs,central venous pressure,and urine out...BACKGROUND Hypovolemic shock can lead to life-threatening organ dysfunction,and adequate fluid administration is a fundamental therapy.Traditionally,parameters such as vital signs,central venous pressure,and urine output have been used to estimate intravascular volume.Recently,pulse pressure variation(PPV)and non-invasive cardiac monitoring devices have been introduced.In this case report,we introduce a patient with massive active bleeding from giant renal angiomyolipoma(AML).During emergent nephrectomy,we used non-invasive cardiac monitoring with CSN-1901(Nihon Kohden,Tokyo,Japan)and PPV to evaluate the patient's intravascular volume status to achieve optimal fluid management.CASE SUMMARY A 30-year-old male patient with giant AML with active bleeding was referred to the emergency room complaining of severe abdominal pain and spontaneous abdominal distension.AML was diagnosed by computed tomography,and emergent nephrectomy was scheduled.Massive bleeding was expected so we decided to use non-invasive cardiac monitoring and PPV to assist fluid therapy because they are relatively easy and fast compared to invasive cardiac monitoring.During the surgery,6000 mL of estimated blood loss occurred.Along with the patient's vital signs and laboratory results,we monitored cardiac output,cardiac output,stroke volume,stroke volume index with a non-invasive cardiac monitoring device,and PPV using an intra-arterial catheter to evaluate intravascular volume status of the patient to compensate for massive bleeding.CONCLUSION In addition to traditional parameters,non-invasive cardiac monitoring and PPV are useful methods to evaluate patient's intravascular volume status and provideguidance for intraoperative management of hypovolemic shock patients.展开更多
Background and Aims: Pulse pressure variation (PPV) is a reliable and predictive dynamic parameter presently being utilized for fluid responsiveness. In the operating room, fluid administration based on PPV monitoring...Background and Aims: Pulse pressure variation (PPV) is a reliable and predictive dynamic parameter presently being utilized for fluid responsiveness. In the operating room, fluid administration based on PPV monitoring helps the physician in deciding whether to volume resuscitate or use interventions in patients undergoing surgery. Propofol is an intravenous induction agent which lowers blood pressure. There are multiple causes such as depression in cardiac output, and peripheral vasodilatation for hypotension. We undertook this study to observe the utility of PPV as a guide to fluid therapy after propofol induction. Primary outcome of our study was to monitor PPV as a marker of fluid responsiveness for the hypotension caused by propofol induction. Secondary outcome included the correlation of PPV with other hemodynamic parameters like heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP);after induction with propofol at regular interval of time. Methods: A total number of 90 patients were recruited. Either of the radial artery was then cannulated under local anaesthesia with 20G VygonLeadercath arterial cannula and invasive monitoring transduced. A baseline recording of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and PPV was then recorded. Patients were then induced with predetermined doses of propofol (2 mg/kg) and recordings of HR, SBP, DBP, and PPV were taken at 5, 10 and 15 minutes. Results: Intraoperatively, PPV was significantly higher at 5 minutes and significantly lower at 15 minutes after induction. It was observed that there were no statistically significant correlations between PPV and SBP or DBP. PPV was strongly and directly associated with HR. Conclusion: We were able to establish that PPV predicts fluid responsiveness in hypotension caused by propofol induction;and can be used to administer fluid therapy in managing such hypotension. However, PPV was not directly correlated with hypotension subsequent to propofol administration.展开更多
Background Whether mean arterial pressure(MAP)and pulse pressure(PP),two indicators of cerebral perfusion,could guide the selection of anti-hypertensive strategies after acute ischaemic stroke remains uncertain.Our st...Background Whether mean arterial pressure(MAP)and pulse pressure(PP),two indicators of cerebral perfusion,could guide the selection of anti-hypertensive strategies after acute ischaemic stroke remains uncertain.Our study was to explore the impact of early anti-hypertensive intervention on adverse clinical outcomes following ischaemic stroke stratified by the levels of MAP and PP based on the China Antihypertensive Trial in Acute Ischemic Stroke(CATIS).Methods The trial randomised 4071 acute ischaemic stroke patients with elevated systolic blood pressure(SBP)to receive anti-hypertensive treatment(targeting a 10%-25%reduction in SBP during the 24 hours postrandomisation,reaching a BP level<140/90 mm Hg in 7 days,further keeping these levels throughout hospitalisation)or discontinue anti-hypertensive treatment during hospitalisation.The primary outcome was death or major disability at 14 days or hospital discharge.Study outcomes were analysed by comparing the BP-lowering intervention group and control group,stratified by tertiles of MAP or PP levels.Results No significant difference was observed in the primary outcome between the intervention and control groups across all MAP(p=0.69 for homogeneity)and PP(p=0.78 for homogeneity)categories.The corresponding odds ratios(95%CIs)were 1.08(0.85-1.36),0.92(0.74-1.15)and 1.00(0.81-1.25)for participants with low,intermediate,and high MAP and were 0.99(0.79-1.25),1.06(0.84-1.34)and 0.95(0.77-1.18)for participants in PP subgroups,respectively.Furthermore,early anti-hypertensive intervention was not associated with secondary outcomes(including neurological deterioration,recurrent stroke,vascular events and all-cause mortality)by MAP and PP(all p>0.05).Conclusions Early anti-hypertensive therapy neither decreased nor increased the odds of major disability,mortality,recurrent stroke or vascular events in patients with acute ischaemic stroke regardless of different MAP and PP levels.展开更多
Introduction:Pulse pressure(PP),an indicator of aortic stiffening,may be associated with adverse cardiovascular outcomes.However,the relationship between PP levels and mortality risk in the Chinese population remains ...Introduction:Pulse pressure(PP),an indicator of aortic stiffening,may be associated with adverse cardiovascular outcomes.However,the relationship between PP levels and mortality risk in the Chinese population remains unclear.Methods:A total of 102,311 participants aged 40 and above were recruited in this prospective study in Beijing during 2010–2012,and followed up until 2021.Blood pressure measurements and related factors were collected at baseline.All-cause and cardiovascular or cerebrovascular disease(CCVD)related deaths were identified as endpoints.Results:Compared with the lowest quartile of PP(<40 mmHg),mortality risk increased by 9.8%–23.9%among individuals with PP in the second through fourth quartiles,with particularly elevated risk among females,adults aged 60–74 years,and overweight or obese individuals.The association between PP and CCVD-specific mortality risk was attenuated but remained statistically significant among people with PP≥60 mmHg.Conclusions:Death risk increased with rising PP levels in middle-aged and elderly populations in Beijing.These findings emphasize the need to develop comprehensive and effective PP management strategies to reduce mortality.展开更多
The first automatic algorithm was designed to estimate the pulse pressure variation (PPVPPV) from arterial blood pressure (ABP) signals under spontaneous breathing conditions. While currently there are a few publicly ...The first automatic algorithm was designed to estimate the pulse pressure variation (PPVPPV) from arterial blood pressure (ABP) signals under spontaneous breathing conditions. While currently there are a few publicly available algorithms to automatically estimate PPVPPV accurately and reliably in mechani-cally ventilated subjects, at the moment there is no automatic algorithm for estimating PPVPPV on sponta-neously breathing subjects. The algorithm utilizes our recently developed sequential Monte Carlo method (SMCM), which is called a maximum a-posteriori adaptive marginalized particle filter (MAM-PF). The performance assessment results of the proposed algorithm on real ABP signals from spontaneously breath-ing subjects were reported.展开更多
The wind pressure pulse events, among the most important characteristics of wind pressure fluctuations on large-span flat roofs, were investigated by wind tunnel tests in this paper. Incorporating the formation mechan...The wind pressure pulse events, among the most important characteristics of wind pressure fluctuations on large-span flat roofs, were investigated by wind tunnel tests in this paper. Incorporating the formation mechanism of wind pressure pulse events, the peak over threshold method was employed to study properties of this kind of events. The event duration time, the energy contribution, the number of the pulse events, and the distribution of average peak pressure were calculated. Probability density functions of some typical samples in separation region were also given. Results show that the non-Gaussian roof pressure is strong in the flow separation region owing to the wind pressure pulse events. Evaluations of the extreme peak pressures, which can be determined by the peak over threshold method effectively, are important to the design of building cladding.展开更多
Utilizing a bespoke CO_(2) phase transition pulse pressure experimental system,we conducted pulse pressure characterization tests across various activator masses,CO_(2) filling pressures,and energy discharge plate thi...Utilizing a bespoke CO_(2) phase transition pulse pressure experimental system,we conducted pulse pressure characterization tests across various activator masses,CO_(2) filling pressures,and energy discharge plate thick-nesses.This approach enabled us to ascertain the pulse pressure's response characteristics and variation patterns under diverse conditions.The formula for calculating the peak supercritical CO_(2) pulse pressure was deduced by modeling the ultimate load calculation of the clamped circular plate,and then the time-course expression of the supercritical CO_(2) phase transition pulse pressure and energy was carried out by introducing the time factor and taking into account the parameters of the activator mass and the thickness of the energy discharging plate.Our findings reveal a four-stage pressure evolution in the cracking tube during initiation:a gradual increase,a rapid spike,swift attenuation,and eventual negative pressure formation.The activator mass and discharge plate thickness critically influence the peak pressure's timing and magnitude.Specifically,increased activator mass hastens peak pressure onset,while a thicker discharge plate amplifies it.The errors between calculated and experimental values for peak supercritical CO_(2) phase transition pressure fall within5%–5%.Furthermore,the pressure peak and arrival time model demonstrates less than 10%error compared to experimental data,affirming its strong applicability.These insights offer theoretical guidance for controlling phase transition pressure and optimizing energy in supercritical CO_(2) systems.展开更多
Objective To compare the effect of chemomechanical caries removal （CMCR） to traditional drilling （TD） on blood pressure and pulse in children. Methods Of all 105 subjects, 53 were randomly assigned to CMCR group; ...Objective To compare the effect of chemomechanical caries removal （CMCR） to traditional drilling （TD） on blood pressure and pulse in children. Methods Of all 105 subjects, 53 were randomly assigned to CMCR group; 52, to TD group. For each subject, the systolic pressure （SP）, diastolic pressure （DP） and pulse （ P ） were measured at five time-point： pre-treatment, initiation of carious removal, the end of carious removal, the end of the cavity restoration, and the end of the dental care. They were recorded as To, T1 , T2, T3, and TE, respectively. The difference of SP, DP, and P within each group were analyzed. Results Of all 105 subjects, 14 were administered local anesthesia. Since local anesthesia may be a confounding factor for changes in blood pressure and pulse, only the data of the other 91 subjects that local anesthesia were not administered were analyzed. Regarding the SP, DP, and P for TD, the difference between TO and T1 was significant （ P = 0. 013, 0. 015, 0. 012 respectively）, while not significant between T1 and T2, T2 and T3, T3 and TE（ P 〉0. 05）. Regarding the SP, DP, and P for CMCR, the differences were not significant between every two consecutive time-points （ P 〉 0. 05）. The differences of the SP, DP, and P between CMCR and TD were not significant for time-points T0, T3 and Te （p 〉 0. 05 ）, while significant for T1 and T2 （ P 〈 0. 05 ）. Conclusion In general, CMCR induces less increase of blood pressure and pulse in children compared to traditional drilling （TD）. It may be inferred that CMCR is less distressing than TD.展开更多
Based on the documentation of the invited paper and the subsequent discussion at a virtual conference,discoveries are indicated,which are summarized in the following paper for further evaluation on the topic of non-th...Based on the documentation of the invited paper and the subsequent discussion at a virtual conference,discoveries are indicated,which are summarized in the following paper for further evaluation on the topic of non-thermal forces using terms of extremely powerful components of Maxwell’s stress tensor at the interaction of CPA(chirped pulse amplification)laser pulses in the fusion plasmas of hydrogen with the isotope 11 of boron.This is caused by a recoil mechanism given by the Fresnel formulas of the suppression of the reflectivity of inhomogeneous plasma given by optical constants of the plasma properties.展开更多
Natural characteristics of thin?wall pipe of the compressor under uniformly distributed pressure were presented in this paper based on a cylindrical shell model. In the traditional method, the beam model was usually u...Natural characteristics of thin?wall pipe of the compressor under uniformly distributed pressure were presented in this paper based on a cylindrical shell model. In the traditional method, the beam model was usually used to analyze the pipe system. In actual fact, the pipe segment of the compressor was always broken in the form of a long crack or a partial hole and the phenomenon was hardly explained by beam model. According to the structure characteristic of compressor pipe segment, whose radius is large and thickness is little, shell model shows the advantage in this kind of pipe problem. Based on Sanders’ shell theory, the vibration di erential equation of pipe was established by apply?ing the energy method. The influences of length to radius ratio(L/R), thickness to radius ratio(h/R), circumferential wave number(n) and pressure(q) on the natural frequencies of pipe were analyzed. The study shows: Pressure and structural parameters have a great e ect on the natural characteristics of the pipe. Natural frequency increases as the pressure increases, especially for the higher mode. The sensitivity of natural frequency on pressure becomes stronger with h/R ratio increases; when L/R ratio is greater than a certain critical value, the influence of the pressure on natural frequency will no longer be obvious. The value of n corresponding to the minimum natural frequency also depends on the value of pressure. In the end, analysis of the forced vibration of a specific pipeline model was given and the modal shapes were illustrated to understand the break of the pipe. The research here will provide the theory support for the dynamic design of related pressure pipe and further experiment study should be employed.展开更多
This article deals with the evaluation of the consumption of energy for a steady state solvent extraction in a novel L-shaped pulsed sieve-plate column, which is highly required for design and optimization of the peri...This article deals with the evaluation of the consumption of energy for a steady state solvent extraction in a novel L-shaped pulsed sieve-plate column, which is highly required for design and optimization of the periodic flow processes for industrial applications. In this regard, a comprehensive evaluation on the energy consumption in case of a pulsed flow for three different chemical systems is conducted and besides the influence of pulsation intensity, the effect of geometrical parameters including the plate spacing and the plate free area is investigated as well. Moreover, the concept of characteristic velocity models at flooding points is evaluated with respect to the variation of pressure drop along the column at different operational conditions.展开更多
Pressure and proximity measurements made in a tunnel indicate that a typical vehicle passage produced on the tunnel roof an initial pressure increase of small magnitude,followed by a sharp and more substantial drop in...Pressure and proximity measurements made in a tunnel indicate that a typical vehicle passage produced on the tunnel roof an initial pressure increase of small magnitude,followed by a sharp and more substantial drop in pressure below atmospheric.The magnitude of the pressure drop was found to increase with smaller clearances between the vehicle top and the tunnel roof,consistent with the Bernoulli relation and the vehicle speed.The dynamic pressures potentially may have significant effects on the vibration and noise environments on the lower floors of“air rights construction”buildings that span highways.展开更多
Cyclic pressure pulsing with nitrogen is studied for hydraulically fractured wells in depleted reservoirs.A compositional simulation model is constructed to represent the hydraulic fractures through local-grid refinem...Cyclic pressure pulsing with nitrogen is studied for hydraulically fractured wells in depleted reservoirs.A compositional simulation model is constructed to represent the hydraulic fractures through local-grid refinement.The process is analyzed from both operational and reservoir/hydraulic-fracture perspectives.Key sensitivity parameters for the operational component are chosen as the injection rate,lengths of injection and soaking periods and the economic rate limit to shut-in the well.For the reservoir/hydraulic fracturing components,reservoir permeability,hydraulic fracture permeability,effective thickness and half-length are used.These parameters are varied at five levels.A full-factorial experimental design is utilized to run 1250 cases.The study shows that within the ranges studied,the gas-injection process is applied successfully for a 20-year project period with net present values based on the incremental recoveries greater than zero.It is observed that the cycle rate limit,injection and soaking periods must be optimized to maximize the efficiency.The simulation results are used to develop a neural network based proxy model that can be used as a screening tool for the process.The proxy model is validated with blind-cases with a correlation coefficient of 0.96.展开更多
It is a complicated dynamic phenomenon when a transient pressure pulse is triggered by two high-speed trains passing each other in a tunnel. The air pressure pulse is a transient excitation to side wall of the car bod...It is a complicated dynamic phenomenon when a transient pressure pulse is triggered by two high-speed trains passing each other in a tunnel. The air pressure pulse is a transient excitation to side wall of the car body. It can stimulate almost all vibration modes of the car body and the correlated assemblies, cause serious aerodynamic noise, and have important impacts on car body distortion, train noise, and operation safety. This article analyzes the time- frequency characteristics and main parameters of field-measured the air pressure wave, and its relationship with the train velocity as well as the vibration of the car body. Cepstrum analysis concludes that in the process of the meeting, the air pressure wave in tunnel crossing is a multiplying pressure wave instead of a superposed wave. The pressure pulse during the meeting is non-symmetrical one featured with a sharp front, large amplitude, fluctuating central sec- tion, and less sharp tail. The pulse width is inversely proportional to the train speed. As the speed increases, the impulse amplitude is amplified, and the speed of pulse front is advanced.展开更多
Background and objective： Stroke volume variation（SVV） has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm（SR） and controlled mechanical ventilation（CV） are mandatory ...Background and objective： Stroke volume variation（SVV） has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm（SR） and controlled mechanical ventilation（CV） are mandatory for their application. Several studies suggest a limited applicability of SVV in intensive care unit（ICU） patients. We hypothesized that the applicability of SVV might be different over time and within certain subgroups of ICU patients. Therefore, we analysed the prevalence of SR and CV in ICU patients during the first 24 h of Pi CCO-monitoring（primary endpoint） and during the total ICU stay. We also investigated the applicability of SVV in the subgroups of patients with sepsis, cirrhosis, and acute pancreatitis. Methods： The prevalence of SR and CV was documented immediately before 1241 thermodilution measurements in 88 patients. Results： In all measurements, SVV was applicable in about 24%. However, the applicability of SVV was time-dependent： the prevalence of both SR and CV was higher during the first 24 h compared to measurements thereafter（36.1% vs. 21.9%; P0.001）. Within different subgroups, the applicability during the first 24 h of monitoring ranged between 0% in acute pancreatitis, 25.5% in liver failure, and 48.9% in patients without pancreatitis, liver failure, pneumonia or sepsis. Conclusions： The applicability of SVV in a predominantly medical ICU is only about 25%–35%. The prevalence of both mandatory criteria decreases over time during the ICU stay. Furthermore, the applicability is particularly low in patients with acute pancreatitis and liver failure.展开更多
Because decompensated heart failure(HF)patients present primarily with symptoms of congestion,the assessment of volume status is of paramount importance.Despite the addition of new technologies that can predict intrac...Because decompensated heart failure(HF)patients present primarily with symptoms of congestion,the assessment of volume status is of paramount importance.Despite the addition of new technologies that can predict intracardiac filling pressures,the physical exam(PE)remains the most accessible and cost-effective tool available to clinicians.An elevated jugular venous pressure(JVP) is considered the most sensitive sign of volume overload,although the commonly used‘method of Lewis’has several limitations.A useful cutoff is that if the JVP is greater than 3 cm in vertical distance above the sternal angle,the central venous pressure is elevated.In addition to assessment of volume status,the PE in HF can reveal adverse prognostic signs,namely:elevated JVP,presence of third heart sound,elevated heart rate,low systolic BP,and low proportional pulse pressure(＜25%).This article will review the evidence for the diagnostic and prognostic utility of common PE findings in HF.展开更多
<strong>Aim: </strong>To establish the prevalence of iron deficiency anemia and its clinical predictors in Emirati patients with type 2 diabetes. <strong>Patients & Methods:</strong> 237 pa...<strong>Aim: </strong>To establish the prevalence of iron deficiency anemia and its clinical predictors in Emirati patients with type 2 diabetes. <strong>Patients & Methods:</strong> 237 patients were included in the study. A full blood count was obtained in addition to routine blood and urine tests for all patients. Hemoglobin level and iron studies were done for diagnosis of anemia. Statistical analysis was done to find out the prevalence and independent predictors of anemia in the study population of Emirati type 2 diabetic patients.<strong> Results:</strong> Of the studied 237 patients;36.3% had iron deficiency anemia as per the WHO criteria. Independent predictors of iron deficiency anemia were age ≥ 60 years, female gender and wide pulse pressure ≥ 60 mmHg. Hemoglobin level was directly proportionate to e GFR (p < 0.001). Participants with age ≥ 60 years had 4.2 times higher odds to exhibit anemia. Female participants had 1.95 times higher odds to exhibit anemia. Participants with wide pulse pressure ≥ 60 mmHg have 2.4 higher odds to exhibit anemia. <strong>Conclusion: </strong>Iron deficiency anemia is common in type 2 diabetic patients. Testing the patient for iron deficiency anemia should be considered in type 2 diabetes patients especially with age ≥ 60 years, female patients and those with wide pulse pressure ≥ 60 mmHg.展开更多
With extensively using of centrifugal pumps,noise generation in these pumps is increasingly receiving research attention in recent years.The noise sources in centrifugal pumps are mainly composed of mechanical noise a...With extensively using of centrifugal pumps,noise generation in these pumps is increasingly receiving research attention in recent years.The noise sources in centrifugal pumps are mainly composed of mechanical noise and flow-induced noise.And the study of flow-induced noise has become a hotspot and important domain in the field.The flow-induced noise closely related to the inner pressure pulses and vibration of volute in pumps,therefore,it is necessary to research the interaction and mechanism among them.To investigate the relationships,a test system is designed which includes a test loop and a measurement system.The hydrophones and pressure sensors are installed on the outlet of the pump and vibration acceleration sensors are disposed on the pump body.Via these instruments,the signals of noise,pressure pulses and vibration are collected and analyzed.The results show that the level of flow-induced noise becomes smaller as the flow increment during low flow rate operations,and it is steadily close to the design point,then it increases with the growing of flow rate in high flow rate conditions.Furthermore,there are some similar peak points in the power spectrum charts of noise,pressure pulses and vibration.The broadband noise at low flow rate is mostly focused on the region of 0-40 times shaft frequency,which is mostly made by rotating stall and vortex;while the noise at high flow rate conditions is focused on the region of 60-100 times shaft frequency,which may be mostly made by cavitations.The proposed research is of practical and academic significance to the study of noise reduction for centrifugal pumps.展开更多
Experimental studies of a model pump-turbine S-curve characteristics and its improvement by misaligned guide vanes （MGV） were extended to prototype pump turbine through 3-D transient flow simulations. The unsteady R...Experimental studies of a model pump-turbine S-curve characteristics and its improvement by misaligned guide vanes （MGV） were extended to prototype pump turbine through 3-D transient flow simulations. The unsteady Reynolds-averaged Navier-Stokes equations with the SST turbulence model were used to model the transient flow within the entire flow passage of a reversible pump-turbine with and without misaligned guide vanes during turbine model start-up. The unstable S-curve and its improvement by using misaligned guide vane were verified by model test and simulation. The transient flow calculations were used to clarify the variations of pressure pulse and internal flow behavior in the entire flow passage. The use of misaligned guide vanes can eliminate the S-curve characteristics of a pump-turbine, and can significantly increase the pressure pulse amplitude in the entire flow passage and the runner radial forces during start-up. The MGV only decreased the pulse amplitude on the guide vane suction side when the rotating speed was less than 50% rated speed. The hydraulic reason is that the MGV dramatically changed the flow patterns inside the entire flow passage, and destroyed the symmetry of the flow distribution inside the guide vane and runner.展开更多
Transition on a flared cone with zero angle of at- tack was studied in our newly established Mach 6 quiet wind tunnel （M6QT） via wall pressure measurement and flow visualization. High-frequency pressure transducers ...Transition on a flared cone with zero angle of at- tack was studied in our newly established Mach 6 quiet wind tunnel （M6QT） via wall pressure measurement and flow visualization. High-frequency pressure transducers were used to measure the second-mode waves＇ amplitudes and frequencies. Using pulsed schlieren diagnostic and Rayleigh scattering technique, we got a clear evolution of the second-mode disturbances. The second-mode waves exist for a long distance, which means that the second-mode waves grow linearly in a large region. Strong Mach waves are radiated from the edge of the boundary layer. With further development, the second-mode waves reach their maximum magnitude and harmonics of the second-mode instability appear. Then the disturbances grow nonlinearly. The second modes become weak and merge with each other. Finally, the nonlinear interaction of disturbance leads to a relatively quiet zone, which further breaks down, resulting in the transition of the bound- ary layer. Our results show that transition is determined by the second mode. The quiet zone before the final breakdown is observed in flow visualization for the first time. Eventual transition requires the presence of a quiet zone generated by nonlinear interactions.展开更多
文摘BACKGROUND Hypovolemic shock can lead to life-threatening organ dysfunction,and adequate fluid administration is a fundamental therapy.Traditionally,parameters such as vital signs,central venous pressure,and urine output have been used to estimate intravascular volume.Recently,pulse pressure variation(PPV)and non-invasive cardiac monitoring devices have been introduced.In this case report,we introduce a patient with massive active bleeding from giant renal angiomyolipoma(AML).During emergent nephrectomy,we used non-invasive cardiac monitoring with CSN-1901(Nihon Kohden,Tokyo,Japan)and PPV to evaluate the patient's intravascular volume status to achieve optimal fluid management.CASE SUMMARY A 30-year-old male patient with giant AML with active bleeding was referred to the emergency room complaining of severe abdominal pain and spontaneous abdominal distension.AML was diagnosed by computed tomography,and emergent nephrectomy was scheduled.Massive bleeding was expected so we decided to use non-invasive cardiac monitoring and PPV to assist fluid therapy because they are relatively easy and fast compared to invasive cardiac monitoring.During the surgery,6000 mL of estimated blood loss occurred.Along with the patient's vital signs and laboratory results,we monitored cardiac output,cardiac output,stroke volume,stroke volume index with a non-invasive cardiac monitoring device,and PPV using an intra-arterial catheter to evaluate intravascular volume status of the patient to compensate for massive bleeding.CONCLUSION In addition to traditional parameters,non-invasive cardiac monitoring and PPV are useful methods to evaluate patient's intravascular volume status and provideguidance for intraoperative management of hypovolemic shock patients.
文摘Background and Aims: Pulse pressure variation (PPV) is a reliable and predictive dynamic parameter presently being utilized for fluid responsiveness. In the operating room, fluid administration based on PPV monitoring helps the physician in deciding whether to volume resuscitate or use interventions in patients undergoing surgery. Propofol is an intravenous induction agent which lowers blood pressure. There are multiple causes such as depression in cardiac output, and peripheral vasodilatation for hypotension. We undertook this study to observe the utility of PPV as a guide to fluid therapy after propofol induction. Primary outcome of our study was to monitor PPV as a marker of fluid responsiveness for the hypotension caused by propofol induction. Secondary outcome included the correlation of PPV with other hemodynamic parameters like heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP);after induction with propofol at regular interval of time. Methods: A total number of 90 patients were recruited. Either of the radial artery was then cannulated under local anaesthesia with 20G VygonLeadercath arterial cannula and invasive monitoring transduced. A baseline recording of heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP) and PPV was then recorded. Patients were then induced with predetermined doses of propofol (2 mg/kg) and recordings of HR, SBP, DBP, and PPV were taken at 5, 10 and 15 minutes. Results: Intraoperatively, PPV was significantly higher at 5 minutes and significantly lower at 15 minutes after induction. It was observed that there were no statistically significant correlations between PPV and SBP or DBP. PPV was strongly and directly associated with HR. Conclusion: We were able to establish that PPV predicts fluid responsiveness in hypotension caused by propofol induction;and can be used to administer fluid therapy in managing such hypotension. However, PPV was not directly correlated with hypotension subsequent to propofol administration.
基金funded by a Project of the Priority Academic Program Development of Jiangsu Higher Education Institutions(Grant no-NA)Project of MOE Key Laboratory of Geriatric Diseases and Immunology(JYN202406)+1 种基金Interdisciplinary Basic Frontier Innovation Program of Suzhou Medical College of Soochow University(YXY2302013)National Natural Science Foundation of China(82273706 and 82220108001).
文摘Background Whether mean arterial pressure(MAP)and pulse pressure(PP),two indicators of cerebral perfusion,could guide the selection of anti-hypertensive strategies after acute ischaemic stroke remains uncertain.Our study was to explore the impact of early anti-hypertensive intervention on adverse clinical outcomes following ischaemic stroke stratified by the levels of MAP and PP based on the China Antihypertensive Trial in Acute Ischemic Stroke(CATIS).Methods The trial randomised 4071 acute ischaemic stroke patients with elevated systolic blood pressure(SBP)to receive anti-hypertensive treatment(targeting a 10%-25%reduction in SBP during the 24 hours postrandomisation,reaching a BP level<140/90 mm Hg in 7 days,further keeping these levels throughout hospitalisation)or discontinue anti-hypertensive treatment during hospitalisation.The primary outcome was death or major disability at 14 days or hospital discharge.Study outcomes were analysed by comparing the BP-lowering intervention group and control group,stratified by tertiles of MAP or PP levels.Results No significant difference was observed in the primary outcome between the intervention and control groups across all MAP(p=0.69 for homogeneity)and PP(p=0.78 for homogeneity)categories.The corresponding odds ratios(95%CIs)were 1.08(0.85-1.36),0.92(0.74-1.15)and 1.00(0.81-1.25)for participants with low,intermediate,and high MAP and were 0.99(0.79-1.25),1.06(0.84-1.34)and 0.95(0.77-1.18)for participants in PP subgroups,respectively.Furthermore,early anti-hypertensive intervention was not associated with secondary outcomes(including neurological deterioration,recurrent stroke,vascular events and all-cause mortality)by MAP and PP(all p>0.05).Conclusions Early anti-hypertensive therapy neither decreased nor increased the odds of major disability,mortality,recurrent stroke or vascular events in patients with acute ischaemic stroke regardless of different MAP and PP levels.
基金Ethical approval was obtained from the Beijing Center for Disease Prevention and Control(BJCDC)Institutional Review Board(Approval No.2019-12).
文摘Introduction:Pulse pressure(PP),an indicator of aortic stiffening,may be associated with adverse cardiovascular outcomes.However,the relationship between PP levels and mortality risk in the Chinese population remains unclear.Methods:A total of 102,311 participants aged 40 and above were recruited in this prospective study in Beijing during 2010–2012,and followed up until 2021.Blood pressure measurements and related factors were collected at baseline.All-cause and cardiovascular or cerebrovascular disease(CCVD)related deaths were identified as endpoints.Results:Compared with the lowest quartile of PP(<40 mmHg),mortality risk increased by 9.8%–23.9%among individuals with PP in the second through fourth quartiles,with particularly elevated risk among females,adults aged 60–74 years,and overweight or obese individuals.The association between PP and CCVD-specific mortality risk was attenuated but remained statistically significant among people with PP≥60 mmHg.Conclusions:Death risk increased with rising PP levels in middle-aged and elderly populations in Beijing.These findings emphasize the need to develop comprehensive and effective PP management strategies to reduce mortality.
文摘The first automatic algorithm was designed to estimate the pulse pressure variation (PPVPPV) from arterial blood pressure (ABP) signals under spontaneous breathing conditions. While currently there are a few publicly available algorithms to automatically estimate PPVPPV accurately and reliably in mechani-cally ventilated subjects, at the moment there is no automatic algorithm for estimating PPVPPV on sponta-neously breathing subjects. The algorithm utilizes our recently developed sequential Monte Carlo method (SMCM), which is called a maximum a-posteriori adaptive marginalized particle filter (MAM-PF). The performance assessment results of the proposed algorithm on real ABP signals from spontaneously breath-ing subjects were reported.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50708030 and 90815021)
文摘The wind pressure pulse events, among the most important characteristics of wind pressure fluctuations on large-span flat roofs, were investigated by wind tunnel tests in this paper. Incorporating the formation mechanism of wind pressure pulse events, the peak over threshold method was employed to study properties of this kind of events. The event duration time, the energy contribution, the number of the pulse events, and the distribution of average peak pressure were calculated. Probability density functions of some typical samples in separation region were also given. Results show that the non-Gaussian roof pressure is strong in the flow separation region owing to the wind pressure pulse events. Evaluations of the extreme peak pressures, which can be determined by the peak over threshold method effectively, are important to the design of building cladding.
基金supported by the National Natural Science Foundation of China(Project Number 41907261)Natural Science Foundation of Chongqing Municipality(Project Number CSTB2023NSCQ-MSX0913)Chongqing Graduate Student Research Innovation Project(Project Number CYB23253).
文摘Utilizing a bespoke CO_(2) phase transition pulse pressure experimental system,we conducted pulse pressure characterization tests across various activator masses,CO_(2) filling pressures,and energy discharge plate thick-nesses.This approach enabled us to ascertain the pulse pressure's response characteristics and variation patterns under diverse conditions.The formula for calculating the peak supercritical CO_(2) pulse pressure was deduced by modeling the ultimate load calculation of the clamped circular plate,and then the time-course expression of the supercritical CO_(2) phase transition pulse pressure and energy was carried out by introducing the time factor and taking into account the parameters of the activator mass and the thickness of the energy discharging plate.Our findings reveal a four-stage pressure evolution in the cracking tube during initiation:a gradual increase,a rapid spike,swift attenuation,and eventual negative pressure formation.The activator mass and discharge plate thickness critically influence the peak pressure's timing and magnitude.Specifically,increased activator mass hastens peak pressure onset,while a thicker discharge plate amplifies it.The errors between calculated and experimental values for peak supercritical CO_(2) phase transition pressure fall within5%–5%.Furthermore,the pressure peak and arrival time model demonstrates less than 10%error compared to experimental data,affirming its strong applicability.These insights offer theoretical guidance for controlling phase transition pressure and optimizing energy in supercritical CO_(2) systems.
基金Supported by Science and Technology Commission of Shanghai(074119644,09DZ2272100)Shanghai Leading Academic Discipline Project(S30206)
文摘Objective To compare the effect of chemomechanical caries removal （CMCR） to traditional drilling （TD） on blood pressure and pulse in children. Methods Of all 105 subjects, 53 were randomly assigned to CMCR group; 52, to TD group. For each subject, the systolic pressure （SP）, diastolic pressure （DP） and pulse （ P ） were measured at five time-point： pre-treatment, initiation of carious removal, the end of carious removal, the end of the cavity restoration, and the end of the dental care. They were recorded as To, T1 , T2, T3, and TE, respectively. The difference of SP, DP, and P within each group were analyzed. Results Of all 105 subjects, 14 were administered local anesthesia. Since local anesthesia may be a confounding factor for changes in blood pressure and pulse, only the data of the other 91 subjects that local anesthesia were not administered were analyzed. Regarding the SP, DP, and P for TD, the difference between TO and T1 was significant （ P = 0. 013, 0. 015, 0. 012 respectively）, while not significant between T1 and T2, T2 and T3, T3 and TE（ P 〉0. 05）. Regarding the SP, DP, and P for CMCR, the differences were not significant between every two consecutive time-points （ P 〉 0. 05）. The differences of the SP, DP, and P between CMCR and TD were not significant for time-points T0, T3 and Te （p 〉 0. 05 ）, while significant for T1 and T2 （ P 〈 0. 05 ）. Conclusion In general, CMCR induces less increase of blood pressure and pulse in children compared to traditional drilling （TD）. It may be inferred that CMCR is less distressing than TD.
文摘Based on the documentation of the invited paper and the subsequent discussion at a virtual conference,discoveries are indicated,which are summarized in the following paper for further evaluation on the topic of non-thermal forces using terms of extremely powerful components of Maxwell’s stress tensor at the interaction of CPA(chirped pulse amplification)laser pulses in the fusion plasmas of hydrogen with the isotope 11 of boron.This is caused by a recoil mechanism given by the Fresnel formulas of the suppression of the reflectivity of inhomogeneous plasma given by optical constants of the plasma properties.
基金National Natural Science Foundation of China(Grant No.51575093)Fundamental Research Funds for the Central Universities of China(Grant Nos.N160313001,N170308028)
文摘Natural characteristics of thin?wall pipe of the compressor under uniformly distributed pressure were presented in this paper based on a cylindrical shell model. In the traditional method, the beam model was usually used to analyze the pipe system. In actual fact, the pipe segment of the compressor was always broken in the form of a long crack or a partial hole and the phenomenon was hardly explained by beam model. According to the structure characteristic of compressor pipe segment, whose radius is large and thickness is little, shell model shows the advantage in this kind of pipe problem. Based on Sanders’ shell theory, the vibration di erential equation of pipe was established by apply?ing the energy method. The influences of length to radius ratio(L/R), thickness to radius ratio(h/R), circumferential wave number(n) and pressure(q) on the natural frequencies of pipe were analyzed. The study shows: Pressure and structural parameters have a great e ect on the natural characteristics of the pipe. Natural frequency increases as the pressure increases, especially for the higher mode. The sensitivity of natural frequency on pressure becomes stronger with h/R ratio increases; when L/R ratio is greater than a certain critical value, the influence of the pressure on natural frequency will no longer be obvious. The value of n corresponding to the minimum natural frequency also depends on the value of pressure. In the end, analysis of the forced vibration of a specific pipeline model was given and the modal shapes were illustrated to understand the break of the pipe. The research here will provide the theory support for the dynamic design of related pressure pipe and further experiment study should be employed.
基金School of Chemical Engineering, College of Engineering, University of Tehran, for the financial support
文摘This article deals with the evaluation of the consumption of energy for a steady state solvent extraction in a novel L-shaped pulsed sieve-plate column, which is highly required for design and optimization of the periodic flow processes for industrial applications. In this regard, a comprehensive evaluation on the energy consumption in case of a pulsed flow for three different chemical systems is conducted and besides the influence of pulsation intensity, the effect of geometrical parameters including the plate spacing and the plate free area is investigated as well. Moreover, the concept of characteristic velocity models at flooding points is evaluated with respect to the variation of pressure drop along the column at different operational conditions.
文摘Pressure and proximity measurements made in a tunnel indicate that a typical vehicle passage produced on the tunnel roof an initial pressure increase of small magnitude,followed by a sharp and more substantial drop in pressure below atmospheric.The magnitude of the pressure drop was found to increase with smaller clearances between the vehicle top and the tunnel roof,consistent with the Bernoulli relation and the vehicle speed.The dynamic pressures potentially may have significant effects on the vibration and noise environments on the lower floors of“air rights construction”buildings that span highways.
文摘Cyclic pressure pulsing with nitrogen is studied for hydraulically fractured wells in depleted reservoirs.A compositional simulation model is constructed to represent the hydraulic fractures through local-grid refinement.The process is analyzed from both operational and reservoir/hydraulic-fracture perspectives.Key sensitivity parameters for the operational component are chosen as the injection rate,lengths of injection and soaking periods and the economic rate limit to shut-in the well.For the reservoir/hydraulic fracturing components,reservoir permeability,hydraulic fracture permeability,effective thickness and half-length are used.These parameters are varied at five levels.A full-factorial experimental design is utilized to run 1250 cases.The study shows that within the ranges studied,the gas-injection process is applied successfully for a 20-year project period with net present values based on the incremental recoveries greater than zero.It is observed that the cycle rate limit,injection and soaking periods must be optimized to maximize the efficiency.The simulation results are used to develop a neural network based proxy model that can be used as a screening tool for the process.The proxy model is validated with blind-cases with a correlation coefficient of 0.96.
基金supported by the National Science and Technology Pillar Programs of China (No.2009BAG12A01-E02,No. 2009BAG12A01-E03 and No. 2009BAG12A01-E04)
文摘It is a complicated dynamic phenomenon when a transient pressure pulse is triggered by two high-speed trains passing each other in a tunnel. The air pressure pulse is a transient excitation to side wall of the car body. It can stimulate almost all vibration modes of the car body and the correlated assemblies, cause serious aerodynamic noise, and have important impacts on car body distortion, train noise, and operation safety. This article analyzes the time- frequency characteristics and main parameters of field-measured the air pressure wave, and its relationship with the train velocity as well as the vibration of the car body. Cepstrum analysis concludes that in the process of the meeting, the air pressure wave in tunnel crossing is a multiplying pressure wave instead of a superposed wave. The pressure pulse during the meeting is non-symmetrical one featured with a sharp front, large amplitude, fluctuating central sec- tion, and less sharp tail. The pulse width is inversely proportional to the train speed. As the speed increases, the impulse amplitude is amplified, and the speed of pulse front is advanced.
文摘Background and objective： Stroke volume variation（SVV） has high sensitivity and specificity in predicting fluid responsiveness. However, sinus rhythm（SR） and controlled mechanical ventilation（CV） are mandatory for their application. Several studies suggest a limited applicability of SVV in intensive care unit（ICU） patients. We hypothesized that the applicability of SVV might be different over time and within certain subgroups of ICU patients. Therefore, we analysed the prevalence of SR and CV in ICU patients during the first 24 h of Pi CCO-monitoring（primary endpoint） and during the total ICU stay. We also investigated the applicability of SVV in the subgroups of patients with sepsis, cirrhosis, and acute pancreatitis. Methods： The prevalence of SR and CV was documented immediately before 1241 thermodilution measurements in 88 patients. Results： In all measurements, SVV was applicable in about 24%. However, the applicability of SVV was time-dependent： the prevalence of both SR and CV was higher during the first 24 h compared to measurements thereafter（36.1% vs. 21.9%; P0.001）. Within different subgroups, the applicability during the first 24 h of monitoring ranged between 0% in acute pancreatitis, 25.5% in liver failure, and 48.9% in patients without pancreatitis, liver failure, pneumonia or sepsis. Conclusions： The applicability of SVV in a predominantly medical ICU is only about 25%–35%. The prevalence of both mandatory criteria decreases over time during the ICU stay. Furthermore, the applicability is particularly low in patients with acute pancreatitis and liver failure.
文摘Because decompensated heart failure(HF)patients present primarily with symptoms of congestion,the assessment of volume status is of paramount importance.Despite the addition of new technologies that can predict intracardiac filling pressures,the physical exam(PE)remains the most accessible and cost-effective tool available to clinicians.An elevated jugular venous pressure(JVP) is considered the most sensitive sign of volume overload,although the commonly used‘method of Lewis’has several limitations.A useful cutoff is that if the JVP is greater than 3 cm in vertical distance above the sternal angle,the central venous pressure is elevated.In addition to assessment of volume status,the PE in HF can reveal adverse prognostic signs,namely:elevated JVP,presence of third heart sound,elevated heart rate,low systolic BP,and low proportional pulse pressure(＜25%).This article will review the evidence for the diagnostic and prognostic utility of common PE findings in HF.
文摘<strong>Aim: </strong>To establish the prevalence of iron deficiency anemia and its clinical predictors in Emirati patients with type 2 diabetes. <strong>Patients & Methods:</strong> 237 patients were included in the study. A full blood count was obtained in addition to routine blood and urine tests for all patients. Hemoglobin level and iron studies were done for diagnosis of anemia. Statistical analysis was done to find out the prevalence and independent predictors of anemia in the study population of Emirati type 2 diabetic patients.<strong> Results:</strong> Of the studied 237 patients;36.3% had iron deficiency anemia as per the WHO criteria. Independent predictors of iron deficiency anemia were age ≥ 60 years, female gender and wide pulse pressure ≥ 60 mmHg. Hemoglobin level was directly proportionate to e GFR (p < 0.001). Participants with age ≥ 60 years had 4.2 times higher odds to exhibit anemia. Female participants had 1.95 times higher odds to exhibit anemia. Participants with wide pulse pressure ≥ 60 mmHg have 2.4 higher odds to exhibit anemia. <strong>Conclusion: </strong>Iron deficiency anemia is common in type 2 diabetic patients. Testing the patient for iron deficiency anemia should be considered in type 2 diabetes patients especially with age ≥ 60 years, female patients and those with wide pulse pressure ≥ 60 mmHg.
基金supported by National Outstanding Young Scientists Founds of China (Grant No. 50825902)National Natural Science Foundation of China (Grant No. 50979034)+2 种基金Jiangsu Provincial Innovative Scholars "Climbing" Project of China (Grant No. BK2009006)Jiangsu Provincial Natural Science Foundation of China (Grant No. BK2009218)Priority Academic Program Development of Jiangsu Higher Education Institutions of China
文摘With extensively using of centrifugal pumps,noise generation in these pumps is increasingly receiving research attention in recent years.The noise sources in centrifugal pumps are mainly composed of mechanical noise and flow-induced noise.And the study of flow-induced noise has become a hotspot and important domain in the field.The flow-induced noise closely related to the inner pressure pulses and vibration of volute in pumps,therefore,it is necessary to research the interaction and mechanism among them.To investigate the relationships,a test system is designed which includes a test loop and a measurement system.The hydrophones and pressure sensors are installed on the outlet of the pump and vibration acceleration sensors are disposed on the pump body.Via these instruments,the signals of noise,pressure pulses and vibration are collected and analyzed.The results show that the level of flow-induced noise becomes smaller as the flow increment during low flow rate operations,and it is steadily close to the design point,then it increases with the growing of flow rate in high flow rate conditions.Furthermore,there are some similar peak points in the power spectrum charts of noise,pressure pulses and vibration.The broadband noise at low flow rate is mostly focused on the region of 0-40 times shaft frequency,which is mostly made by rotating stall and vortex;while the noise at high flow rate conditions is focused on the region of 60-100 times shaft frequency,which may be mostly made by cavitations.The proposed research is of practical and academic significance to the study of noise reduction for centrifugal pumps.
基金supported by the National Natural Science Foundation of China(51009077)State Key Laboratory of Hydroscience and Engineering(2014-KY-05)
文摘Experimental studies of a model pump-turbine S-curve characteristics and its improvement by misaligned guide vanes （MGV） were extended to prototype pump turbine through 3-D transient flow simulations. The unsteady Reynolds-averaged Navier-Stokes equations with the SST turbulence model were used to model the transient flow within the entire flow passage of a reversible pump-turbine with and without misaligned guide vanes during turbine model start-up. The unstable S-curve and its improvement by using misaligned guide vane were verified by model test and simulation. The transient flow calculations were used to clarify the variations of pressure pulse and internal flow behavior in the entire flow passage. The use of misaligned guide vanes can eliminate the S-curve characteristics of a pump-turbine, and can significantly increase the pressure pulse amplitude in the entire flow passage and the runner radial forces during start-up. The MGV only decreased the pulse amplitude on the guide vane suction side when the rotating speed was less than 50% rated speed. The hydraulic reason is that the MGV dramatically changed the flow patterns inside the entire flow passage, and destroyed the symmetry of the flow distribution inside the guide vane and runner.
文摘Transition on a flared cone with zero angle of at- tack was studied in our newly established Mach 6 quiet wind tunnel （M6QT） via wall pressure measurement and flow visualization. High-frequency pressure transducers were used to measure the second-mode waves＇ amplitudes and frequencies. Using pulsed schlieren diagnostic and Rayleigh scattering technique, we got a clear evolution of the second-mode disturbances. The second-mode waves exist for a long distance, which means that the second-mode waves grow linearly in a large region. Strong Mach waves are radiated from the edge of the boundary layer. With further development, the second-mode waves reach their maximum magnitude and harmonics of the second-mode instability appear. Then the disturbances grow nonlinearly. The second modes become weak and merge with each other. Finally, the nonlinear interaction of disturbance leads to a relatively quiet zone, which further breaks down, resulting in the transition of the bound- ary layer. Our results show that transition is determined by the second mode. The quiet zone before the final breakdown is observed in flow visualization for the first time. Eventual transition requires the presence of a quiet zone generated by nonlinear interactions.
