Hepatic venous pressure gradient: Inaccurately estimates portal venous pressure gradient in alcoholic cirrhosis and portal hypertension

BACKGROUND Portal hypertension(PHT)in patients with alcoholic cirrhosis causes a range of clinical symptoms,including gastroesophageal varices and ascites.The hepatic venous pressure gradient(HVPG),which is easier to measure,has replaced the portal venous pressure gradient(PPG)as the gold standard for diagnosing PHT in clinical practice.Therefore,attention should be paid to the correlation between HVPG and PPG.METHODS Between January 2017 and June 2020,134 patients with alcoholic cirrhosis and PHT who met the inclusion criteria underwent various pressure measurements during transjugular intrahepatic portosystemic shunt procedures.Correlations were assessed using Pearson’s correlation coefficient to estimate the correlation coefficient(r)and determination coefficient(R^(2)).Bland-Altman plots were constructed to further analyze the agreement between the measurements.Disagreements were analyzed using paired t tests,and P values<0.05 were considered statistically significant.RESULTS In this study,the correlation coefficient(r)and determination coefficient(R2)between HVPG and PPG were 0.201 and 0.040,respectively(P=0.020).In the 108 patients with no collateral branch,the average wedged hepatic venous pressure was lower than the average portal venous pressure(30.65±8.17 vs.33.25±6.60 mmHg,P=0.002).Hepatic collaterals were identified in 26 cases with balloon occlusion hepatic venography(19.4%),while the average PPG was significantly higher than the average HVPG(25.94±7.42 mmHg vs 9.86±7.44 mmHg;P<0.001).The differences between HVPG and PPG<5 mmHg in the collateral vs no collateral branch groups were three cases(11.54%)and 44 cases(40.74%),respectively.CONCLUSION In most patients,HVPG cannot accurately represent PPG.The formation of hepatic collaterals is a vital reason for the strong underestimation of HVPG.

Prediction of pressure gradient and hold-up in horizontal liquid-liquid pipe flow

This paper aims to propose correlations to predict pressure gradient,friction factor and fluid phase hold-up in liquid-liquid horizontal pipe flow.To develop the correlations,experiments are conducted using high viscous oils(202 and 630 mPa⋅s)in a steel pipe of length 11.25 m and length-to-diameter ratio of 708.In addition,the experimental data from the literature comprising wide range of flow and fluid properties is analyzed.For the analysis,the liquid-liquid pipe flow data is categorized into two as:stratified and dispersed.The existing friction factor correlations are modified to incorporate the effects of viscosity of the oil phase,interfacial curvature(contact/wetting angle-in lieu of material of the pipe)and fluid phase fraction.In the two-fluid model of stratified flow,the wall stress and interfacial stress correlations are substituted with superficial velocities of fluids and superficial Reynolds numbers of fluid phases replacing fluid phase velocities and fluid Reynolds numbers.Similarly,for dispersed flow,an effective Reynolds number is described as the sum of superficial Reynolds number of oil and water phases.Substituting the generally employed mean or mixture Reynolds number with the effective Reynolds number into the existing single-phase turbulent flow friction factor correlation,an effective friction factor for oil-water flow is proposed.Employing the proposed correlations,the pressure gradient across the oil-water flow and hold-up volume fraction are predicted with significant reduction in error compared with that of conventionally employed correlations.The average error and standard deviation values of−7.06%,20.72%and 0.31%,18.79%are found for stratified flow and dispersed flow respectively.

Pre-transjugular-intrahepatic-portosystemic-shunt measurement of hepatic venous pressure gradient and its clinical application: A comparison study

BACKGROUND It is controversial whether transjugular intrahepatic portosystemic shunt(TIPS)placement can improve long-term survival.AIM To assess whether TIPS placement improves survival in patients with hepaticvenous-pressure-gradient(HVPG)≥16 mmHg,based on HVPG-related risk stratification.METHODS Consecutive variceal bleeding patients treated with endoscopic therapy+nonselectiveβ-blockers(NSBBs)or covered TIPS placement were retrospectively enrolled between January 2013 and December 2019.HVPG measurements were performed before therapy.The primary outcome was transplant-free survival;secondary endpoints were rebleeding and overt hepatic ence-phalopathy(OHE).RESULTS A total of 184 patients were analyzed(mean age,55.27 years±13.86,107 males;102 in the EVL+NSBB group,82 in the covered TIPS group).Based on the HVPG guided risk stratification,70 patients had HVPG<16 mmHg,and 114 patients had HVPG≥16 mmHg.The median follow-up time of the cohort was 49.5 mo.There was no significant difference in transplant-free survival between the two treatment groups overall(hazard ratio[HR],0.61;95%confidence interval[CI]:0.35-1.05;P=0.07).In the high-HVPG tier,transplant-free survival was higher in the TIPS group(HR,0.44;95%CI:0.23-0.85;P=0.004).In the low-HVPG tier,transplantfree survival after the two treatments was similar(HR,0.86;95%CI:0.33-0.23;P=0.74).Covered TIPS placement decreased the rate of rebleeding independent of the HVPG tier(P<0.001).The difference in OHE between the two groups was not statistically significant(P=0.09;P=0.48).CONCLUSION TIPS placement can effectively improve transplant-free survival when the HVPG is greater than 16 mmHg.

Numerical Simulation of a Two-Phase Flow with Low Permeability anda Start-Up Pressure Gradient

A new numerical model for low-permeability reservoirs is developed.The model incorporates the nonlinear characteristics of oil-water two-phase flows while taking into account the initiation pressure gradient.Related numerical solutions are obtained using a finite difference method.The correctness of the method is demonstrated using a two-dimensional inhomogeneous low permeability example.Then,the differences in the cumulative oil and water production are investigated for different starting water saturations.It is shown that when the initial water saturation grows,the water content of the block continues to rise and the cumulative oil production gradually decreases.

Computed tomography perfusion in differentiating portal hypertension: A correlation study with hepatic venous pressure gradient

BACKGROUND Hepatic venous pressure gradient(HVPG)is the gold standard for diagnosis of portal hypertension(PH),invasiveness and potential risks in the process of measurement limited its widespread use.AIM To investigate the correlation of computed tomography(CT)perfusion parameters with HVPG in PH,and quantitatively assess the blood supply changes in liver and spleen parenchyma before and after transjugular intrahepatic portosystemic shunt(TIPS).METHODS Twenty-four PH related gastrointestinal bleeding patients were recruited in this study,and all patients were performed perfusion CT before and after TIPS surgery within 2 wk.Quantitative parameters of CT perfusion,including liver blood volume(LBV),liver blood flow(LBF),hepatic arterial fraction(HAF),spleen blood volume(SBV)and spleen blood flow(SBF),were measured and compared before and after TIPS,and the quantitative parameters between clinically significant PH(CSPH)and non-CSPH(NCSPH)group were also compared.Then the correlation of CT perfusion parameters with HVPG were analyzed,with statistical significance as P<0.05.RESULTS For all 24 PH patients after TIPS,CT perfusion parameters demonstrated decreased LBV, increased HAF, SBV and SBF, with no statistical difference in LBF. Compared withNCSPH, CSPH showed higher HAF, with no difference in other CT perfusion parameters. HAFbefore TIPS showed positive correlation with HVPG (r = 0.530, P = 0.008), while no correlation wasfound in other CT perfusion parameters with HVPG and Child-Pugh scores.CONCLUSIONHAF, an index of CT perfusion, was positive correlation with HVPG, and higher in CSPH thanNCSPH before TIPS. While increased HAF, SBF and SBV, and decreased LBV, were found afterTIPS, which accommodates a potential non-invasive imaging tool for evaluation of PH.

Effect of quadratic pressure gradient term on a one-dimensional moving boundary problem based on modified Darcy's law

A relatively high formation pressure gradient can exist in seepage flow in low-permeable porous media with a threshold pressure gradient, and a significant error may then be caused in the model computation by neglecting the quadratic pressure gradient term in the governing equations.Based on these concerns, in consideration of the quadratic pressure gradient term, a basic moving boundary model is constructed for a one-dimensional seepage flow problem with a threshold pressure gradient. Owing to a strong nonlinearity and the existing moving boundary in the mathematical model,a corresponding numerical solution method is presented.First, a spatial coordinate transformation method is adopted in order to transform the system of partial differential equations with moving boundary conditions into a closed system with fixed boundary conditions; then the solution can be stably numerically obtained by a fully implicit finite-difference method. The validity of the numerical method is verified by a published exact analytical solution. Furthermore, to compare with Darcy's flow problem, the exact analytical solution for the case of Darcy's flow considering the quadratic pressure gradient term is also derived by an inverse Laplace transform.A comparison of these model solutions leads to the conclusion that such moving boundary problems must incorporatethe quadratic pressure gradient term in their governing equations; the sensitive effects of the quadratic pressure gradient term tend to diminish, with the dimensionless threshold pressure gradient increasing for the one-dimensional problem.

Correlation of pressure gradient in three hepatic veins with portal pressure gradient

BACKGROUND The liver is one of the most important organs in the human body,with functions such as detoxification,digestion,and blood coagulation.In terms of vascular anatomy,the liver is divided into the left and the right liver by the main portal vein,and there are three hepatic efferent veins(right,middle,and left)and two portal branches.Patients with impaired liver function have increased intrahepatic vascular resistance and splanchnic vasodilation,which may lead to an increase in the portal pressure gradient(PPG)and cause portal hypertension(PHT).In order to measure the increased pressure gradient of portal vein,the hepatic venous pressure gradient(HVPG)can be measured to reflect it in clinical practice.The accuracy of PPG measurements is directly related to patient prognosis.AIM To analyze the correlation between HVPG of three hepatic veins and PPG in patients with PHT.METHODS From January 2017 to December 2019,102 patients with PHT who met the inclusion criteria were evaluated during the transjugular intrahepatic portosystemic shunt procedure and analyzed.RESULTS The mean HVPG of the middle hepatic vein was 17.47±10.25 mmHg,and the mean HVPG of the right and left hepatic veins was 16.34±7.60 and 16.52±8.15 mmHg,respectively.The average PPG was 26.03±9.24 mmHg.The correlation coefficient and coefficient of determination of the right hepatic vein,middle hepatic vein,and left hepatic vein were 0.15 and 0.02(P=0.164);0.25 and 0.05(P=0.013);and 0.14 and 0.02(P=0.013),respectively.The mean wedged hepatic vein/venous pressure(WHVP)of the middle and left hepatic veins was similar at 29.71±12.48 and 29.1±10.91 mmHg,respectively,and the mean WHVP of the right hepatic vein was slightly lower at 28.01±8.95 mmHg.The mean portal vein pressure was 34.11±8.56 mmHg.The correlation coefficient and coefficient of determination of the right hepatic vein,middle hepatic vein,and left hepatic vein were 0.26 and 0.07(P=0.009);0.38 and 0.15(P<0.001);and 0.26 and 0.07(P=0.008),respectively.The average free hepatic venous pressure(FHVP)of the right hepatic vein was lowest at 11.67±5.34 mmHg,and the average FHVP of the middle and left hepatic veins was slightly higher at 12.19±4.88 and 11.67±5.34 mmHg,respectively.The average inferior vena cava pressure was 8.27±4.04 mmHg.The correlation coefficient and coefficient of determination of the right hepatic vein,middle hepatic vein,and left hepatic vein were 0.30 and 0.09(P=0.002);0.18 and 0.03(P=0.078);and 0.16 and 0.03(P=0.111),respectively.CONCLUSION Measurement of the middle hepatic vein HVPG could better represent PPG.Considering the high success rate of clinical measurement of the right hepatic vein,it can be the second choice.

Computed tomography perfusion in liver and spleen for hepatitis B virus-related portal hypertension:A correlation study with hepatic venous pressure gradient

BACKGROUND Hepatic venous pressure gradient(HVPG)is the gold standard for diagnosis of portal hypertension(PH).However,its use can be limited because it is an invasive procedure.Therefore,it is necessary to explore a non-invasive method to assess PH.AIM To investigate the correlation of computed tomography(CT)perfusion of the liver with HVPG and Child-Pugh score in hepatitis B virus(HBV)-related PH.METHODS Twenty-eight patients(4 female,24 male)with gastroesophageal variceal bleeding induced by HBV-related PH were recruited in our study.All patients received CT perfusion of the liver before transjugular intrahepatic portosystemic stent-shunt(TIPS)therapy.Quantitative parameters of CT perfusion of the liver,including liver blood flow(LBF),liver blood volume(LBV),hepatic artery fraction,splenic blood flow and splenic blood volume were measured.HVPG was recorded during TIPS therapy.Correlation of liver perfusion with Child-Pugh score and HVPG were analyzed,and the receiver operating characteristic curve was analyzed.Based on HVPG(>12 mmHg vs≤12 mmHg),patients were divided into moderate and severe groups,and all parameters were compared.RESULTS Based on HVPG,18 patients were classified into the moderate group and 10 patients were classified into the severe group.The Child-Pugh score,HVPG,LBF and LBV were significantly higher in the moderate group compared to the severe group(all P<0.05).LBF and LBV were negatively associated with HVPG(r=-0.473,P<0.05 and r=-0.503,P<0.01,respectively),whereas splenic blood flow was positively associated with hepatic artery fraction(r=0.434,P<0.05).LBV was negatively correlated with Child-Pugh score.Child-Pugh score was not related to HVPG.Using a cutoff value of 17.85 mL/min/100 g for LBV,the sensitivity and specificity of HVPG≥12 mmHg for diagnosis were 80%and 89%,respectively.CONCLUSION LBV and LBF were negatively correlated with HVPG and Child-Pugh scores.CT perfusion imaging is a potential non-invasive quantitative predictor for PH in HBV-related liver cirrhosis.

Local topography-induced pressure gradient effects on the wake and power output of a model wind turbine

Wind-tunnel experiments were performed to study the effect of favorable and adverse constant pressure gradients(PG)from local changes in the topography right downwind of a model wind turbine.Particle image velocimetry was used to characterize the near and intermediate wake regions.We explored five scenarios,two favorable,two adverse PG,and a case with negligible PG.Results show that the PGs induce a wake deflection and modulate the wake.They imposed a relatively small impact on the turbulence kinetic energy and kinematic shear stress but a comparatively dominant effect on the bulk flow on the flow recovery.Based on this,a simple formulation is used to describe the impact of PG on the wake.We modeled the base flow through a linearized perturbation method;the wake is obtained by solving a simplified,integrated streamwise momentum equation.This approach reasonably estimated the flow profile and PG-induced power output variations.

A fluid flow model in the lacunar-canalicular system under the pressure gradient and electrical field driven loads

The lacunar-canalicular system(LCS)is acknowledged to directly participate in bone tissue remodeling.The fluid flow in the LCS is synergic driven by the pressure gradient and electric field loads due to the electro-mechanical properties of bone.In this paper,an idealized annulus Maxwell fluid flow model in bone canaliculus is established,and the analytical solutions of the fluid velocity,the fluid shear stress,and the fluid flow rate are obtained.The results of the fluid flow under pressure gradient driven(PGD),electric field driven(EFD),and pressure-electricity synergic driven(P-ESD)patterns are compared and discussed.The effects of the diameter of canaliculi and osteocyte processes are evaluated.The results show that the P-ESD pattern can combine the regulatory advantages of single PGD and EFD patterns,and the osteocyte process surface can feel a relatively uniform shear stress distribution.As the bone canalicular inner radius increases,the produced shear stress under the PGD or P-ESD pattern increases slightly but changes little under the EFD pattern.The increase in the viscosity makes the flow slow down but does not affect the fluid shear stress(FSS)on the canalicular inner wall and osteocyte process surface.The increase in the high-valent ions does not affect the flow velocity and the flow rate,but the FSS on the canalicular inner wall and osteocyte process surface increases linearly.In this study,the results show that the shear stress sensed by the osteocyte process under the P-ESD pattern can be regulated by changing the pressure gradient and the intensity of electric field,as well as the parameters of the annulus fluid and the canaliculus size,which is helpful for the osteocyte mechanical responses.The established model provides a basis for the study of the mechanisms of electro-mechanical signals stimulating bone tissue(cells)growth.

Pressure Gradient Control Strategies Based on Disturbance Rejection for Typical Pharmaceutical Cleanrooms

Keeping pressure gradient is an excellent approach to prevent the reveal of airflow direction and cross infection in manufacturing circumstances of pharmaceutical cleanrooms, thus how to keep cleanroom’s pressure is critical. In the paper, we study a positive pressure pharmaceutical cleanroom system which is composed by a cleanroom and an airlock. We divide the system’s disturbances into step disturbance, ramp disturbance and sine wave disturbance. We design its pressure gradient control strategies, including CAV control, PID control and active-disturbance-rejection-control. We build the system’s model and make simulations based on Matlab/Simulink software platform. Results show that active-disturbance-rejection-control algorithm has good capabilities for shorter responding time and lower overshot of the pressure gradient. The results reveal that active-disturbance-rejection-control method has good control performances in responding time, accuracy and disturbance rejection.

Impacts of proppant distribution on development of tight oil reservoirs with threshold pressure gradient

Field evidence indicates that proppant distribution and threshold pressure gradient have great impacts on well productivity.Aiming at the development of unconventional oil reservoirs in Triassic Chang-7 Unit,Ordos Basin of China,we presented an integrated workflow to investigate how(1)proppant placement in induced fracture and(2)non-linear flow in reservoir matrix would affect well productivity and fluid flow in the reservoir.Compared with our research before(Yue et al.,2020),here we extended this study into the development of multi-stage fractured horizontal wells(MFHWs)with large-scale complicated fracture geometry.The integrated workflow is based on the finite element method and consists of simulation models for proppant-laden fluid flow,fracture flow,and non-linear seepage flow,respectively.Simulation results indicate that the distribution of proppant inside the induced cracks significantly affects the productivity of the MFHW.When we assign an idealized proppant distribution instead of the real distribution,there will be an overestimation of 44.98%in daily oil rate and 30.63%in cumulative oil production after continuous development of 1000 days.Besides,threshold pressure gradient(TPG)also significantly affects the well performance in tight oil reservoirs.If we simply apply linear Darcy’s law to the reservoir matrix,the overall cumulative oil production can be overrated by 77%after 1000 days of development.In general,this research provides new insights into the development of tight oil reservoirs with TPG and meanwhile reveals the significance of proppant distribution and non-linear fluid flow in the production scenario design.

A novel numerical simulation of CO_(2) immiscible flooding coupled with viscosity and starting pressure gradient modeling in ultra-low permeability reservoir

CO_(2) immiscible flooding is an environmentally-friendly and effective method to enhance oil recovery in ultra-low permeability reservoirs.A mathematical model of CO_(2) immiscible flooding was developed,considering the variation in crude oil viscosity and starting pressure gradient in ultra-low permeability reservoirs based on the non-Darcy percolation theory.The mathematical model and numerical simulator were developed in the C++language to simulate the effects of fluid viscosity,starting pressure gradient,and other physical parameters on the distribution of the oil pressure field,oil saturation field,gas saturation field,oil viscosity field,and oil production.The results showed that the formation pressure and pressure propagation velocity in CO_(2) immiscible flooding were lower than the findings without considering the starting pressure gradient.The formation oil content saturation and the crude oil formation viscosity were higher after the consideration of the starting pressure gradient.The viscosity of crude oil considering the initiation pressure gradient during the formation was higher than that without this gradient,but the yield was lower than that condition.Our novel mathematical models helped the characterization of seepage resistance,revealed the influence of fluid property changes on seepage,improved the mathematical model of oil seepage in immiscible flooding processes,and guided the improvement of crude oil recovery in immiscible flooding processes.

Subharmonic aided pressure estimation in portal hypertension:A noninvasive ultrasound-based technique to assess portal pressure gradient

Portal hypertension(PH)is a clinical syndrome,characterized by elevated pressure gradient between portal vein and inferior vena cava.These elevated pressures gradient due to increased vascular resistance and/or increased volume of blood flowing through the portal vein circulation,results in blood outflow difficulty from portal vein to hepatic veins and inferior vena cava.

Hepatic venous pressure gradient measurement guiding nonselective beta-blocker therapy in a patient with clinically significant portal hypertension

Clinically significant portal hypertension(CSPH),defined as a hepatic venous pressure gradient(HVPG)≥10 mmHg,is an independent risk factor for decompensated events in patients with compensated cirrhosis.Currently,the Baveno VII consensus recommends using nonselective beta-blockers to treat compensated cirrhosis in patients with CSPH.Here,we report a unusual case of compensated cirrhosis with CSPH caused by hepatitis B,and we successfully adjust NSBBs drug treatment strategies monitoring by HVPG results and achieve response standards.Timely adjustment of NSBBs drug treatment strategies based on HVPG test results for patients with CSPH can improve the final response rate.

Effects of adverse pressure gradient on Reynolds stresses inturbulent boundary layers

The effects of adverse pressure gradient(APG)on Reynolds stresses in turbulent boundary layers(TBLs)with APG were analyzed.The difficulty of this work was attributable to the Reynolds stresses in TBLs with APG under two combined effects,i.e.:effect of upstream flow and effect of APG.The effect of upstream flow is an inherent effect no matter pressure gradient exists or not.The individual effect was analyzed from absolute developments of Reynolds stresses in TBLs with zero pressure gradient(ZPG)firstly.Effect of APG was then analyzed from absolute developments of Reynolds stresses in TBLs with APG.Result showed that,for absolute development of mean streamwise Reynolds stresses,APG accelerated its development in TBL with ZPG;for absolute development of mean normal or shear Reynolds stresses,APG increased their magnitude in the outer part,and decreased their extent of large value region.

On linearization method to MHD boundary layer convective heat transfer with low pressure gradient

The paper highlights the application of a recent semi-numerical successive linearization method(SLM)in solving highly coupled,nonlinear boundary value problem.The method is presented in detail by solving the problem of boundary layer convective heat transfer with low pressure gradient in the presence of viscous dissipation and radiation effects.The effects of the parameters on the flow are investigated.The velocity,temperature,skinfriction,and heat transfer coefficients have been obtained and discussed for various physical parametric values.

Design method for hypersonic bump inlet based on transverse pressure gradient

Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump inlet.This paper proposes a novel TPG-based hypersonic bump inlet design method.This method consists of two steps.First,a parametric optimization approach is employed to design a series of 2D inlets with various compression efficiencies.Then,according to the prescribed TPG,the optimized inlets are placed in different osculating planes to generate a 3D bump inlet.This method provides a means to directly control the aerodynamic parameters of the bump rather than the geometric parameters.By performing this method to a hypersonic chin inlet,a long and wide bump surface is formed in the compression wall,which leads to good integration of the bump/inlet.Results show that a part of the near-wall boundary layer flow is diverted by the bump,resulting in a slight decrease in the mass flow but a significant improvement in the total pressure recovery.In addition,the starting ability is significantly improved by adding the bump surface.Analysis reveals that the bump has a 3D rebuilding effect on the large-scale separation bubble of the unstarted inlet.Finally,a mass flow correction is performed on the designed bump inlet to increase the mass flow to full airflow capture.The results show that the mass flow rate of the corrected bump inlet reaches up to 0.9993,demonstrating that the correction method is effective.

Discussion of liquid threshold pressure gradient

Some authors believe that a minimum pressure gradient(called threshold pressure gradient(TPG))is required before a liquid starts to flow in a porous medium.In a tight or shale oil formation,this TPG phenomenon becomes more important,as it is more difficult for a fluid to flow.In this paper,experimental data on TPG published in the literature are carefully reviewed.What we found is that a very low flow velocity corresponding to a very low pressure gradient cannot be measured in the experiments.Experiments can only be done above some measurable flow velocities.If these flow velocities and their corresponding pressure gradients are plotted in an XY plot and extrapolated to zero velocity,a non-zero pressure gradient corresponds to this zero velocity.This non-zero pressure gradient is called threshold pressure gradient in the literature.However,in the regime of very low velocity and very low pressure gradient,the data gradually approach to the origin of the plot,demonstrating a non-linear relationship between the pressure gradient and the velocity.But the data do not approach to a point of zero velocity and a threshold pressure gradient.Therefore,the concept of threshold pressure gradient is a result of data misinterpretation of available experimental data.The correct interpretation is that there are two flow regimes:nonlinear flow regime(non-Darcy flow regime)when the pressure gradients are low,and linear flow regime(Darcy flow regime)when the pressure gradient is intermediate or high.The nonlinear flow regime starts from the origin point.As the pressure gradient is increased,the curve becomes a straight line demonstrating the linear flow regime.We have verified our views by first analyzing the causes of non-Darcy flow,and then systematically analyzed typical experimental data and correlations in the literature.We conclude that TPG does not exist.We also use several counter examples to support our conclusion.

Extreme cold wave in early November 2021 in China and the influences from the meridional pressure gradient over East Asia

In early November 2021,China experienced its second strongest cold wave event during 1981-2021.Although the Siberian high is considered the main factor influencing cold wave events in East Asia,it was not extremely strong from 4 to November 9,2021.The spatial distribution of the correlation coefficients between the sea level pressure and the daily temperature anomalies shows a monopole pattern,with a notable negative centre in the southern part of the Siberian high monitoring domain.However,the correlation between the sea level pressure and temperature drop presents a typical dipole pattern,with a distinct negative centre in the northern monitoring domain and a positive centre in southern East Asia.During the November 2021 super cold wave process,the sea level pressure anomalies display a dipole pattern with a higher centre in the north and a lower centre in the south owing to the northward shift of the Intertropical Convergence Zone.The meridional pressure gradient index clearly reveals the non-negligible effect of subtropical low-pressure on this super cold wave process,indicating its possibly essential supplementary role in enhancing this process.The above findings provide a new understanding of its mechanism and long-range forecasts.