Possible Sources of Discrepancy Between Sphygmomanometer Cuff Pressure and Blood Pressure Quantified in a Collapsible-Tube Analogue

1992 ◽  
Vol 114 (1) ◽  
pp. 68-77 ◽  
Author(s):  
C. D. Bertram ◽  
K. S. A. Butcher
Keyword(s):  
Blood Pressure ◽  
Pressure Drop ◽  
Flow Rate ◽  
Pressure Difference ◽  
Cuff Pressure ◽  
Collapsible Tube ◽  
Rate Dependency ◽  
External Compression ◽  
Viscous Term ◽  
Viscous Pressure

This paper examines the assumption that the audible events detected as Korotkov sounds in sphygmomanometry occur when blood pressure equals arm-cuff pressure. Several effects that contribute to discrepancy between these pressures are quantified using an idealised arm-and-cuff system consisting of a thick-walled collapsible tube subject to external compression along a central part of its length. The effects studied are (1) transverse pressure difference, resulting from tissues sustaining a part of the external compression through (a) circumferential bending stiffness and (b) longitudinal curvature of the tensed localised neck at the site of initial collapse, (2) longitudinal pressure difference between upstream pressure and pressure at the collapse point due to both (a) viscous and (b) inertial pressure drop. These effects are found to compensate partially for each other; the pressure within the vessel at the collapse point is less than the cuff pressure, but is also less than the blood pressure at the upstream end of the cuff. All four of the contributing terms increase proportionally to the flow-rate raised to a power greater than one, except the viscous pressure drop. Owing to a progressive shortening of the collapsed neck as flow-rate increases, the viscous term is almost independent of the flow-rate. The overall discrepancy displays less flow-rate dependency and is smaller than some of the terms which contribute to it. This means that considerable accuracy is needed if measurements of the effects are to be used to correct the raw data on cuff pressure at the time of Korotkov sound emission so as to obtain an improved estimate of the blood pressure.

A Numerical Analysis on the System Impedance in a Fan Cooling System

2003 ◽  
Author(s):  
Dong-Il Kim ◽  
Ki-So Bok ◽  
Han-Bae Lee
Keyword(s):  
Numerical Analysis ◽  
Pressure Drop ◽  
Flow Rate ◽  
Pressure Difference ◽  
Cooling System ◽  
Computational Time ◽  
Computational Domain ◽  
Impedance Curve ◽  
Fan Cooling ◽  
Large Investment

To seek the fan operating point on a cooling system with fans, it is very important to determine the system impedance curve and it has been usually examined with the fan tester based on ASHRAE standard and AMCA standard. This leads to a large investment in time and cost, because it could not be executed until the system is made actually. Therefore it is necessary to predict the system impedance curve through numerical analysis so that we could reduce the measurement time and effort. This paper presents how the system impedance curve (pressure drop curve) is computed by CFD in substitute for experiment. In reverse order to the experimental principle of the fan tester, pressure difference was adopted first as inlet and outlet boundary conditions of the system and then flow rate was calculated. After determining the system impedance curve, it was compared with experimental results. Also the computational domain of the system was investigated to minimize computational time.

Effect of flow rate and temperature on transmembrane blood pressure drop in an extracorporeal artificial lung

Perfusion ◽  
2014 ◽  
Vol 29 (6) ◽  
pp. 517-525 ◽  
Author(s):  
M Park ◽  
ELV Costa ◽  
AT Maciel ◽  
EVS Barbosa ◽  
AS Hirota ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Pressure Drop ◽  
Flow Rate ◽  
Artificial Lung

Viscous flow in collapsible tubes of slowly varying elliptical cross-section

1977 ◽  
Vol 81 (2) ◽  
pp. 273-294 ◽  
Author(s):  
Rosemary Wild ◽  
T. J. Pedley ◽  
D. S. Riley
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Transverse Velocity ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Collapsible Tube ◽  
Experimental Conditions ◽  
Cross Sectional ◽  
Elliptical Cross ◽  
Collapsible Tubes

This paper is concerned with steady flow in collapsible tubes, such as veins, at fairly low Reynolds number. Lubrication theory is used to calculate the velocity and pressure distribution in an elliptical tube whose cross-sectional area and eccentricity vary slowly and in a given way with longitudinal distance x. The transverse velocity field and the effect of inertia on the primary velocity and pressure distributions are calculated to first order in the relevant small parameter. The results of these calculations are combined with a relationship between transmural pressure and the cross-sectional area at any x which is close to that measured in (large) veins, and are used to predict the pressure and flow in a collapsible tube when a given distribution of external pressure is applied. Different relationships between the tube perimeter and cross-sectional area are examined. The theory is applied to an experiment in which a segment of collapsible tube is supported between two rigid segments, and squeezed; predictions of the relationship between the pressure drop and flow rate are made for various experimental conditions. In particular, when the resistance of the downstream rigid segment is held constant, a range of flow rates is found in which the pressure drop falls as the flow rate is raised; this agrees with experiment.

scholarly journals The existence of steady flow in a collapsed tube

1989 ◽  
Vol 206 ◽  
pp. 339-374 ◽  
Author(s):  
O. E. Jensen ◽  
T. J. Pedley
Keyword(s):  
Pressure Drop ◽  
Energy Loss ◽  
Steady Flow ◽  
Flow Rate ◽  
Transmural Pressure ◽  
Tube Model ◽  
Collapsible Tube ◽  
One Dimensional ◽  
Flow Through ◽  
Range Of Values

Self-excited oscillations arise during flow through a pressurized segment of collapsible tube, for a range of values of the time-independent controlling pressures. They come about either because there is an (unstable) steady flow corresponding to these pressures, or because no steady flow exists. We investigate the existence of steady flow in a one-dimensional collapsible-tube model, which takes account of both longitudinal tension and jet energy loss E downstream of the narrowest point. For a given tube, the governing parameters are flow-rate Q, and transmural pressure P at the downstream end of the collapsible segment. If E = 0, there exists a range of (Q, P)-values for which no solutions exist; when E ≠ 0 a solution is always found. For the case E ≠ 0, predictions are made of pressure drop along the collapsible tube; these solutions are compared with experiment.

Numerical Simulation of Noninvasive Blood Pressure Measurement

2006 ◽  
Vol 128 (5) ◽  
pp. 680-687 ◽  
Author(s):  
Satoru Hayashi ◽  
Toshiyuki Hayase ◽  
Atsushi Shirai ◽  
Masaru Maruyama
Keyword(s):  
Blood Pressure ◽  
Pressure Measurement ◽  
Cuff Pressure ◽  
Blood Pressure Measurement ◽  
Force Balance ◽  
Dimensional System ◽  
Collapsible Tube ◽  
Noninvasive Blood Pressure ◽  
Windkessel Model ◽  
Noninvasive Blood Pressure Measurement

In this paper, a simulation model based on the partially pressurized collapsible tube model for reproducing noninvasive blood pressure measurement is presented. The model consists of a collapsible tube, which models the pressurized part of the artery, rigid pipes connected to the collapsible tube, which model proximal and distal region far from the pressurized part, and the Windkessel model, which represents the capacitance and the resistance of the distal part of the circulation. The blood flow is simplified to a one-dimensional system. Collapse and expansion of the tube is represented by the change in the cross-sectional area of the tube considering the force balance acting on the tube membrane in the direction normal to the tube axis. They are solved using the Runge-Kutta method. This simple model can easily reproduce the oscillation of inner fluid and corresponding tube collapse typical for the Korotkoff sounds generated by the cuff pressure. The numerical result is compared with the experiment and shows good agreement.

INTERARM SYSTOLIC BLOOD PRESSURE DIFFERENCE IS ASSOCIATED WITH A HIGH PREVALENCE OF CARDIO VASCULAR DISEASES- A CROSS-SECTIONAL STUDY IN POLICE WORKER

2020 ◽  
Vol 4 (11) ◽  
Author(s):  
Somesh Raju ◽  
Rina Kumari ◽  
Sunita Tiwari ◽  
NS Verma
Keyword(s):  
Blood Pressure ◽  
Systolic Blood Pressure ◽  
Blood Sugar ◽  
Pressure Difference ◽  
Systolic Pressure ◽  
Working Environment ◽  
Vascular Events ◽  
Cross Sectional ◽  
Blood Pressure Difference ◽  
High Prevalence

Background: Interarm systolic blood pressure difference more than 10 mm of Hg is predictor of cardiovascular and metabolic risk. Despite of sufficient physical activity there is high prevalence of obesity in police personal because of stressful working environment. No studies have addressed the significance of interarm pressure difference among them. Therefore, the present study conducted to access the relation of interarm blood pressure difference with obesity in police personnel. Aims and Objective: To estimate the interarm pressure difference in police personal to see its association with their obesity. Material and Method: This cross-sectional observational study done on 245 police workers in PAC, Sitapur, India. Subjects having more than ten years of working experience were included in study. Anthropometric measurements of subject recorded by following standard protocol. Measurement of systolic pressure in both arm recorded simultaneously by mercury sphygmomanometer. Available data analyze and expressed in percentage, mean with SD and chi square test to see the significance of association. Results: According to anthropometric results of subjects 77.14 prcent subjects were having generalised obesity and 82.04 percent of subjects having abdominal obesity. 34.29 percent of subjects showed abnormally high (?10 mmHg) inter-arm systolic blood pressure difference. Both type of obesity showed positive association with blood sugar level but no association with interarm pressure difference. Conclusion: Interarm blood pressure difference is greater in individual having obesity or prolong duration of service. Such subjects are more susceptible to develop coronary artery disease or peripheral arterial disease in future. Early screening can help to detect the vascular events likely to occur in the future Keywords: Body mass index, Waist circumference, Interarm pressure difference, Random blood sugar

Study of fluid flow through a channel deformed by piezoelement

2018 ◽  
Vol 13 (3) ◽  
pp. 1-10 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh Nasibullaeva ◽  
O.V. Darintsev
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Contact Surface ◽  
Piezoelectric Element ◽  
Neumann Boundary ◽  
Differential Pressure ◽  
Physical Parameters ◽  
Flow Through

The flow of a liquid through a tube deformed by a piezoelectric cell under a harmonic law is studied in this paper. Linear deformations are compared for the Dirichlet and Neumann boundary conditions on the contact surface of the tube and piezoelectric element. The flow of fluid through a deformed channel for two flow regimes is investigated: in a tube with one closed end due to deformation of the tube; for a tube with two open ends due to deformation of the tube and the differential pressure applied to the channel. The flow rate of the liquid is calculated as a function of the frequency of the deformations, the pressure drop and the physical parameters of the liquid.

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