Estimation of blood pressure-related parameters by electrical impedance measurement

1992 ◽  
Vol 73 (5) ◽  
pp. 1946-1957 ◽  
Author(s):  
J. H. Muntinga ◽  
K. R. Visser
Keyword(s):  
Blood Pressure ◽  
Blood Volume ◽  
Electrical Impedance ◽  
Cuff Pressure ◽  
Arterial Compliance ◽  
Blood Pressure Measurement ◽  
Venous Blood ◽  
Impedance Measurement ◽  
Total Blood ◽  
Arterial Blood

In 13 healthy volunteers a computerized experimental set-up was used to measure the electrical impedance of the upper arm at changing cuff pressure, together with the finger arterial blood pressure in the contralateral arm. On the basis of a model for the admittance response, the arterial blood volume per centimeter length (1.4 +/- 0.3 ml/cm), the venous blood volume as a percentage of the total blood compartment (49.2 +/- 12.6%), and the total arterial compliance as a function of mean arterial transmural pressure were estimated. The effective physiological arterial compliance amounted to 2.0 +/- 1.3 microliters.mmHg-1.cm-1 and the maximum compliance to 33.4 +/- 12.0 microliters.mmHg-1.cm-1. Additionally, the extravascular fluid volume expelled by the occluding cuff (0.3 +/- 0.3 ml/cm) was estimated. These quantities are closely related to patient-dependent sources of an unreliable blood pressure measurement and vary with changes in cardiovascular function, such as those found in hypertension. Traditionally, a combination of several methods is needed to estimate them. Such methods, however, usually neglect the contribution of extravascular factors.

scholarly journals The major cerebral arteries proximal to the Circle of Willis contribute to cerebrovascular resistance in humans

2015 ◽  
Vol 36 (8) ◽  
pp. 1384-1395 ◽  
Author(s):  
Esther AH Warnert ◽  
Emma C Hart ◽  
Judith E Hall ◽  
Kevin Murphy ◽  
Richard G Wise
Keyword(s):  
Blood Pressure ◽  
Blood Volume ◽  
Arterial Compliance ◽  
Cerebral Arteries ◽  
Circle Of Willis ◽  
Post Exercise ◽  
Cerebrovascular Resistance ◽  
Arterial Blood ◽  
Cerebral Arterial Compliance ◽  
Arterial Blood Volume

Cerebral autoregulation ensures constant cerebral blood flow during periods of increased blood pressure by increasing cerebrovascular resistance. However, whether this increase in resistance occurs at the level of major cerebral arteries as well as at the level of smaller pial arterioles is still unknown in humans. Here, we measure cerebral arterial compliance, a measure that is inversely related to cerebrovascular resistance, with our novel non-invasive magnetic resonance imaging-based measurement, which employs short inversion time pulsed arterial spin labelling to map arterial blood volume at different phases of the cardiac cycle. We investigate the differential response of the cerebrovasculature during post exercise ischemia (a stimulus which leads to increased cerebrovascular resistance because of increases in blood pressure and sympathetic outflow). During post exercise ischemia in eight normotensive men (30.4 ± 6.4 years), cerebral arterial compliance decreased in the major cerebral arteries at the level of and below the Circle of Willis, while no changes were measured in arteries above the Circle of Willis. The reduction in arterial compliance manifested as a reduction in the arterial blood volume during systole. This study provides the first evidence that in humans the major cerebral arteries may play an important role in increasing cerebrovascular resistance.

scholarly journals BLOOD VOLUME IN WOUNDED SOLDIERS

1919 ◽  
Vol 29 (2) ◽  
pp. 155-171 ◽  
Author(s):  
Oswald H. Robertson ◽  
Arlie V. Bock
Keyword(s):  
Blood Pressure ◽  
Blood Volume ◽  
Alimentary Tract ◽  
Venous Blood ◽  
Hemoglobin Concentration ◽  
Individual Case ◽  
The Body ◽  
Total Blood ◽  
Secondary Hemorrhage ◽  
Total Hemoglobin

Blood volume tests made on a number of soldiers recovering from hemorrhage have shown that in many instances dilution of the blood occurs very slowly. The principal reasons for this seem to be (a) an initial lack of reserve fluid of the tissues, and (b) the absence of any subsequent attempt by the body to make up this fluid deficiency. By putting such patients on a large fluid intake by mouth and rectum it has been found that their blood volume can be promptly and greatly increased. Hemorrhage cases transfused, yet still showing a low blood volume, were first treated in this way. Then the effect of forced fluids without transfusion was tried. Immediately after a hemorrhage, or as soon as the patient came under observation, he was given large quantities of water by mouth, and salt solution by rectum. Under such treatment the blood pressure soon began to show a progressive rise, the volume increased, and the red cells became more evenly redistributed, as shown by the relative hemoglobin percentages of the capillary and venous blood. These changes were often well marked after only 2 or 3 hours of the treatment. More than this, forcing fluids in cases where the amount of bleeding is difficult to estimate on account of the presence of a high hemoglobin percentage is of distinct value, since the dilution of the blood which results serves to show the extent of the hemorrhage through the drop in hemoglobin that it entails. In attempting to determine the condition of the patient after hemorrhage with a view to deciding the most suitable form of treatment, it is of much importance to learn the total blood loss—which is often not even indicated by the hemoglobin concentration of the remaining blood. With a total hemoglobin reduced to 25 per cent or under transfusion is needful. New blood is necessary, not only to supply more oxygen-carrying cells, but also because it actually enables the circulation to increase its volume. For, as has been pointed out in Paper I, the hemoglobin percentage must be above a certain point if a rapid restoration of the blood volume by means of the organism's own activities is to come about. With the total hemoglobin above 25 per cent the chief need is for increased blood volume, and if the patient's condition demands an immediate and large addition of circulating fluid, gum acacia solution should be given. If the condition is not so urgent, forced fluids by the alimentary tract are indicated. The blood volume can be considerably reduced and yet a normal blood pressure maintained. It is pointed out that the vasomotor mechanism which, has adapted itself to the diminished blood bulk may in any individual case be very near the margin of its compensatory power. Increased strain in such instances may cause a failure of this mechanism with a resulting fall in blood pressure. The beneficial results of forced fluids after secondary hemorrhage suggest the value of the early use of fluids by the alimentary tract in cases of primary hemorrhage.

scholarly journals BLOOD VOLUME IN WOUNDED SOLDIERS

1919 ◽  
Vol 29 (2) ◽  
pp. 139-153 ◽  
Author(s):  
Oswald H. Robertson ◽  
Arlie V. Bock
Keyword(s):  
Blood Pressure ◽  
Blood Volume ◽  
Relative Concentration ◽  
Venous Blood ◽  
Bone Marrow Stimulation ◽  
Total Blood ◽  
Gum Acacia ◽  
Cell Counts ◽  
Complete Restoration ◽  
Rapid Restoration

Blood volume tests made by the vital red method (Keith, Rowntree, and Geraghty) on patients after hemorrhage showed a marked reduction in the total blood bulk. Not uncommonly the blood volume was less than 60 per cent of the normal. The reduction after a certain point had been reached seemed to parallel the decrease in blood pressure. This relation of diminished blood volume to low pressure suggested a rough method of estimating blood volume from the change in blood pressure. By means of the blood volume and the hemoglobin per cent the actual amount of blood loss was determined. Cases of severe anemia showed a loss of as much as five-sixths of their total hemoglobin. Progressive changes in blood volume following hemorrhage were estimated in three ways: (1) repeated vital red tests; (2) calculation from changes in hemoglobin per cent produced by the injection of gum acacia; (3) calculation from changes in hemoglobin per cent following the dilution of the blood by the patient's own body fluids. The effects of the different methods of transfusion and of injection of gum acacia on blood volume were observed. No differences were apparent. It was found that transfusion and gum injections only partially restored the blood volume. Forced fluids by mouth were found to bring about its complete restoration in a comparatively short time. It was observed that the organism did not restore its blood volume beyond a certain point when a further increase in it would, by dilution, have brought the hemoglobin per cent to a very low figure. In such cases a further increase of the blood volume occurred only when the hemoglobin rose. In cases with a low hemoglobin per cent as the result of a restoration of the blood bulk an abnormally high blood pressure appeared, which continued until the hemoglobin per cent again increased. Accompanying the low blood pressure seen shortly after hemorrhage was a well marked difference in hemoglobin per cent between capillary and venous blood, with a relative concentration on the capillary side. As compensation occurred and blood pressure rose this difference lessened until the two readings were identical, indicating an even redistribution of the red blood cells. Reticulated red cell counts made in these cases showed that a marked bone marrow stimulation occurs after hemorrhage. However, except in the very anemic cases the degree of increased blood production seemed to depend largely on the restoration of the blood volume. The patients who were put on forced fluids, with consequent rapid restoration of blood volume, showed a much higher per cent of reticulated cells than those in whom no attempt was made to increase the amount of fluid in circulation.

Oscillometric Determination of Diastolic, Mean and Systolic Blood Pressure—A Numerical Model

1986 ◽  
Vol 108 (4) ◽  
pp. 359-364 ◽  
Author(s):  
F. K. Forster ◽  
D. Turney
Keyword(s):  
Blood Pressure ◽  
Diastolic Pressure ◽  
Cuff Pressure ◽  
Arterial Compliance ◽  
Blood Pressure Measurement ◽  
Pressure Curve ◽  
Pressure Waveform ◽  
Blood Pressure Waveform ◽  
Collapse Behavior ◽  
Oscillometric Blood Pressure Measurement

A theoretical model of oscillometric blood pressure measurement is presented. Particular emphasis is paid to the collapse behavior of the artery, and an exponential volume-pressure curve is used. The results of this study suggest that mean blood pressure can be accurately predicted from the peak of the oscillometric curve if corrections related to the cuff pressure waveform are applied. It is also shown, however, that systolic and diastolic pressure may not in general be accurately determined from fixed amplitude ratios based on the oscillometric peak due to the sensitivity of the method to variations in blood pressure waveform, pulse pressure, and arterial compliance. No simple procedures are found to correct for these effects.

Indirect measurement of instantaneous arterial blood pressure in the rat

1979 ◽  
Vol 237 (5) ◽  
pp. H632-H637
Author(s):  
K. I. Yamakoshi ◽  
H. Shimazu ◽  
T. Togawa
Keyword(s):  
Blood Pressure ◽  
Cuff Pressure ◽  
Blood Pressure Measurement ◽  
Vascular Wall ◽  
Indirect Measurement ◽  
Servo Control ◽  
Hydraulic Pressure ◽  
Spontaneously Hypertensive ◽  
Arterial Blood ◽  
Hydraulic Servo

We devised a hydraulic servo-control system for indirect blood pressure measurement in the rat's tail, by which beat-to-beat systolic and diastolic blood pressure can be obtained. In this method the principle of "unloading vascular wall" proposed by Shirer (1962) is employed. The proposed system is composed of a transmittance photoelectric plethysmograph with an occluding cuff, a small diaphragm actuator for compressing and decompressing the segment by the hydraulic pressure, and an electromagnetic shaker driven by a volume servo circuit in accordance with the signal from the photoelectric plethysmograph. The plethysmographic signal is clamped at a proper value corresponding to the unload vascular volume by the instantaneous hydraulic servo control. The cuff pressure thus automatically controlled follows the intra-arterial pressure in the tail segment. The accuracy of this method was evaluated in comparison with direct measurement of blood pressure recorded simultaneously from 16 unanesthetized spontaneously hypertensive and normotensive rats. Close agreement between the simultaneous data from these two methods were observed.

scholarly journals A Comparison of Deep Learning Techniques for Arterial Blood Pressure Prediction

2021 ◽  
Author(s):  
Annunziata Paviglianiti ◽  
Vincenzo Randazzo ◽  
Stefano Villata ◽  
Giansalvo Cirrincione ◽  
Eros Pasero
Keyword(s):  
Blood Pressure ◽  
Neural Networks ◽  
Deep Learning ◽  
Arterial Blood Pressure ◽  
Blood Pressure Measurement ◽  
National Standards ◽  
Detection Methods ◽  
Physiological Parameter ◽  
Arterial Blood ◽  
Learning Techniques

AbstractContinuous vital signal monitoring is becoming more relevant in preventing diseases that afflict a large part of the world’s population; for this reason, healthcare equipment should be easy to wear and simple to use. Non-intrusive and non-invasive detection methods are a basic requirement for wearable medical devices, especially when these are used in sports applications or by the elderly for self-monitoring. Arterial blood pressure (ABP) is an essential physiological parameter for health monitoring. Most blood pressure measurement devices determine the systolic and diastolic arterial blood pressure through the inflation and the deflation of a cuff. This technique is uncomfortable for the user and may result in anxiety, and consequently affect the blood pressure and its measurement. The purpose of this paper is the continuous measurement of the ABP through a cuffless, non-intrusive approach. The approach of this paper is based on deep learning techniques where several neural networks are used to infer ABP, starting from photoplethysmogram (PPG) and electrocardiogram (ECG) signals. The ABP was predicted first by utilizing only PPG and then by using both PPG and ECG. Convolutional neural networks (ResNet and WaveNet) and recurrent neural networks (LSTM) were compared and analyzed for the regression task. Results show that the use of the ECG has resulted in improved performance for every proposed configuration. The best performing configuration was obtained with a ResNet followed by three LSTM layers: this led to a mean absolute error (MAE) of 4.118 mmHg on and 2.228 mmHg on systolic and diastolic blood pressures, respectively. The results comply with the American National Standards of the Association for the Advancement of Medical Instrumentation. ECG, PPG, and ABP measurements were extracted from the MIMIC database, which contains clinical signal data reflecting real measurements. The results were validated on a custom dataset created at Neuronica Lab, Politecnico di Torino.

Resonance in a mathematical model of baroreflex control: arterial blood pressure waves accompanying postural stress

2005 ◽  
Vol 288 (6) ◽  
pp. R1637-R1648 ◽  
Author(s):  
Peter E. Hammer ◽  
J. Philip Saul
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Blood Volume ◽  
Low Frequency ◽  
Pressure Waves ◽  
Central Blood Volume ◽  
Arterial Baroreflex ◽  
Arterial Blood ◽  
Gain Margin ◽  
The Stability

A mathematical model of the arterial baroreflex was developed and used to assess the stability of the reflex and its potential role in producing the low-frequency arterial blood pressure oscillations called Mayer waves that are commonly seen in humans and animals in response to decreased central blood volume. The model consists of an arrangement of discrete-time filters derived from published physiological studies, which is reduced to a numerical expression for the baroreflex open-loop frequency response. Model stability was assessed for two states: normal and decreased central blood volume. The state of decreased central blood volume was simulated by decreasing baroreflex parasympathetic heart rate gain and by increasing baroreflex sympathetic vaso/venomotor gains as occurs with the unloading of cardiopulmonary baroreceptors. For the normal state, the feedback system was stable by the Nyquist criterion (gain margin = 0.6), but in the hypovolemic state, the gain margin was small (0.07), and the closed-loop frequency response exhibited a sharp peak (gain of 11) at 0.07 Hz, the same frequency as that observed for arterial pressure fluctuations in a group of healthy standing subjects. These findings support the theory that stresses affecting central blood volume, including upright posture, can reduce the stability of the normally stable arterial baroreflex feedback, leading to resonance and low-frequency blood pressure waves.

Effect of unilateral resistance training on arterial compliance in elderly men

2007 ◽  
Vol 32 (4) ◽  
pp. 670-676 ◽  
Author(s):  
Fleur Poelkens ◽  
Mark Rakobowchuk ◽  
Kirsten A. Burgomaster ◽  
Maria T.E. Hopman ◽  
Stuart M. Phillips ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Resistance Training ◽  
Arterial Compliance ◽  
Stiffness Index ◽  
Elderly Men ◽  
Arterial Diameter ◽  
Healthy Elderly ◽  
Arterial Blood ◽  
The Impact ◽  
Peak Blood

An increase in age coincides with a decrease in arterial compliance, which is related to a higher risk for cardiovascular accidents. Evidence regarding the effects of resistance training on arterial compliance is conflicting. Currently, little information is available about the effect of resistance training on arterial compliance in elderly men. We assessed the impact of 10 weeks of unilateral arm and leg resistance training on carotid, brachial, and femoral arterial compliance in 12 healthy elderly men (mean age ± SD, 71 ± 7 y). Arterial compliance was evaluated before, after 4 weeks, and after 10 weeks of unilateral resistance training by simultaneously measuring arterial diameter and blood pressure in each artery. There were no significant differences in arterial compliance or stiffness index in any of the arteries examined after 10 weeks of training. However, after 10 weeks of resistance training, resting heart rate decreased from 76 ± 4 beats/min to 61 ± 3 beats/min (p < 0.05), plasma glucose decreased from 6.0 ± 0.9 to 5.1 ± 0.9 mmol/L (mean ± SE) (p < 0.05), and carotid artery peak blood flow increased from 1831 mL/min to 2245 mL/min (p < 0.05). There were no significant changes in resting arterial blood pressure. Unilateral resistance training for 10 weeks does not alter peripheral and central arterial compliance elderly men.

Abstract 119: Influence of Anesthetics on the Hemodynamic Response in a Rat Model of Hemorrhagic Shock

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Claudius Balzer ◽  
Franz J Baudenbacher ◽  
Susan S Eagle ◽  
Michele M Salzman ◽  
William J Cleveland ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Hemorrhagic Shock ◽  
Rat Model ◽  
Cardiovascular Response ◽  
Femoral Vein ◽  
Blood Pressure Measurement ◽  
Experimental Models ◽  
Sprague Dawley ◽  
Compensatory Mechanisms ◽  
Arterial Blood

Introduction: Experimental models of hemorrhagic shock (HS) in rats are important to test new treatments that may improve outcomes in humans, and general anesthesia is required during these experiments. The volatile anesthetic Isoflurane is known for its beneficial effects in rat HS models. Focusing on cardiovascular compensatory mechanisms, we wanted to evaluate Isoflurane versus the injectable anesthetic Pentobarbital in our rat model of mild HS (class 2). We hypothesize that Isoflurane during development of HS improves hemodynamics compared to Pentobarbital. Methods: Twelve Sprague-Dawley rats were initially anesthetized with an intraperitoneal (IP) injection of Pentobarbital (45 mg/kg) and intubated (1 L/min, FiO 2 0.25); heart rate (HR) was monitored by subcutaneous ECG needles. Femoral artery and vein were cannulated for continuous blood pressure measurement and delivery of fluids, respectively. In one group (n=7), anesthesia was continued with repeated IP injections of Pentobarbital (dose mg/kg), the other group (n=5) received continuous Isoflurane (1%). After 30 min of stabilization and administration of Heparin (100 IU/kg), HS was induced by removal of 1 ml of blood over 1 min via the femoral vein, repeated every 3 min until a volume of 5 ml of blood was removed. Mean arterial blood pressure (MAP) and HR were recorded and analyzed in LabChart. Results: During baseline, rats showed no significant differences in HR and MAP between both groups. After 5 ml of hemorrhage, both groups showed significant changes compared to baseline, with significantly higher MAP and HR in rats given only Pentobarbital. Conclusions: In our rat model of HS, Isoflurane dampens the physiologic response to compensate for mild hemorrhage. The cardiovascular response of rats in the Isoflurane group was a decrease of HR and MAP to every ml of hemorrhage, while rats given only Pentobarbital were able to maintain their MAP by raising their HR until decompensation.

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