Continuous stroke volume monitoring by modelling flow from non-invasive measurement of arterial pressure in humans under orthostatic stress

1999 ◽  
Vol 97 (3) ◽  
pp. 291-301 ◽  
Author(s):  
Mark P. M. HARMS ◽  
Karel H. WESSELING ◽  
Frank POTT ◽  
Morten JENSTRUP ◽  
Jeroen VAN GOUDOEVER ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Stroke Volume ◽  
Element Model ◽  
Aortic Flow ◽  
Orthostatic Stress ◽  
Non Invasive ◽  
Head Up Tilt ◽  
The Relationship ◽  
Finger Pressure

The relationship between aortic flow and pressure is described by a three-element model of the arterial input impedance, including continuous correction for variations in the diameter and the compliance of the aorta (Modelflow). We computed the aortic flow from arterial pressure by this model, and evaluated whether, under orthostatic stress, flow may be derived from both an invasive and a non-invasive determination of arterial pressure. In 10 young adults, Modelflow stroke volume (MFSV) was computed from both intra-brachial arterial pressure (IAP) and non-invasive finger pressure (FINAP) measurements. For comparison, a computer-controlled series of four thermodilution estimates (thermodilution-determined stroke volume; TDSV) were averaged for the following positions: supine, standing, head-down tilt at 20 ° (HDT20) and head-up tilt at 30 ° and 70 ° (HUT30 and HUT70 respectively). Data from one subject were discarded due to malfunctioning thermodilution injections. A total of 155 recordings from 160 series were available for comparison. The supine TDSV of 113±13 ml (mean±S.D.) dropped by 40% to 68±14 ml during standing, by 24% to 86±12 ml during HUT30, and by 51% to 55±15 ml during HUT70. During HDT20, TDSV was 114±13 ml. MFSV for IAP underestimated TDSV during HDT20 (-6±6 ml; P < 0.05), but that for FINAP did not (-4±7 ml; not significant). For HUT70 and standing, MFSV for IAP overestimated TDSV by 11±10 ml (HUT70; P < 0.01) and 12±9 ml (standing; P < 0.01). However, the offset of MFSV for FINAP was not significant for either HUT70 (3±8 ml) or standing (3±9 ml). In conclusion, due to orthostasis, changes in the aortic transmural pressure may lead to an offset in MFSV from IAP. However, Modelflow correctly calculated aortic flow from non-invasively determined finger pressure during orthostasis.

Non-invasive continuous arterial pressure, heart rate and stroke volume measurements during graded head-up tilt in normal man

1997 ◽  
Vol 7 (2) ◽  
pp. 97-101 ◽  
Author(s):  
L. A. H. Critchley ◽  
F. Conway ◽  
P. J. Anderson ◽  
B. Tomlinson ◽  
J. A. J. H. Critchley
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Non Invasive ◽  
Volume Measurements ◽  
Head Up Tilt ◽  
Normal Man

Continuous stroke volume monitoring by modelling flow from non-invasive measurement of arterial pressure in humans under orthostatic stress

1999 ◽  
Vol 97 (3) ◽  
pp. 291 ◽  
Author(s):  
Mark P.M. HARMS ◽  
Karel H. WESSELING ◽  
Frank POTT ◽  
Morten JENSTRUP ◽  
Jeroen VAN GOUDOEVER ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Stroke Volume ◽  
Orthostatic Stress ◽  
Non Invasive ◽  
Invasive Measurement

Dynamics of Circulatory Adjustments to Head-Up Tilt and Tilt-Back in Healthy and Sympathetically Denervated Subjects

1998 ◽  
Vol 94 (4) ◽  
pp. 347-352 ◽  
Author(s):  
W. Wieling ◽  
J. J. Van Lieshout ◽  
A. D. J. Ten Harkel
Keyword(s):  
Blood Pressure ◽  
Cardiac Output ◽  
Arterial Pressure ◽  
Stroke Volume ◽  
Systemic Vascular Resistance ◽  
Vascular Resistance ◽  
Healthy Subjects ◽  
Mean Blood Pressure ◽  
Head Up Tilt ◽  
Change In Mean

1. The initial circulatory adjustments induced by head-up tilt and tilt-back were investigated in six healthy subjects (aged 30–58 years) and six patients with orthostatic hypotension due to pure autonomic failure (aged 33–65 years). 2. Continuous responses of finger arterial pressure and heart rate were recorded by Finapres. A pulse contour algorithm applied to the arterial pressure waveform was used to compute stroke volume responses. 3. In the healthy subjects, head-up tilt induced gradual circulatory adjustments. After 1 min upright stroke volume and cardiac output had decreased by 39 ± 9% and 26 ± 10% respectively. Little change in mean blood pressure at heart level (+1 ± 7 mmHg) indicated that systemic vascular resistance had increased by 39 ± 24%. The gradual responses to head-up tilt contrasted with the pronounced and rapid circulatory responses upon tilt-back. After 2–3 s a rapid increase in stroke volume (from 62 ± 8% to 106 ± 10%) and cardiac output (from 81 ± 11% to 118 ± 20%) was observed with an overshoot of mean arterial pressure above supine control values of 16 ± 3 mmHg at 7 s. In the patients a progressive fall in blood pressure on head-up tilt was observed. After 1 min upright mean blood pressure had decreased by 59 ± 8 mmHg. No change in systemic vascular resistance and a larger decrease in stroke volume (60 ± 7%) and cardiac output (53 ± 8%) were found. On tilt-back a gradual recovery of blood pressure was observed. 4. In healthy humans upon head-up tilt neural compensatory mechanisms are very effective in maintaining arterial pressure at heart level. The gradual circulatory adjustments to head-up tilt in healthy subjects contrast with the pronounced and abrupt circulatory changes on tilt-back. In patients with a lack of neural circulatory reflex adjustments, gradual blood pressure decreases to head-up tilt and gradual increases to tilt-back are observed.

scholarly journals A NEW METHOD OF DIAGNOSIS OF THE HIATAL HERNIA ASSOCIATED WITH GASTROESOPHAGEAL REFLUX DISEASE

2019 ◽  
Vol 72 (2) ◽  
pp. 186-188
Author(s):  
Andriy R. Stasyshyn ◽  
Mykola A. Bychkov ◽  
Solomiia V. Bychkova
Keyword(s):  
Gastroesophageal Reflux Disease ◽  
Gastroesophageal Reflux ◽  
Hiatal Hernia ◽  
Reflux Disease ◽  
Diagnostic Method ◽  
Calcium Content ◽  
Control Group ◽  
Non Invasive ◽  
The Relationship

Introduction: Gastroesophageal reflux disease (GERD) is one of the most common gastroduodenal diseases. The relationship between the hiatal hernia and the GERD is established. It is advisable to develop an accessible non-invasive diagnostic method for this combined pathology. The aim of the research was to estimate measuring of calcium in patients’ saliva samples as simple non-invasive diagnostic method of GERD associated with the hiatal hernia. Materials and methods: The samples of saliva were obtained from 37 patients with hiatal hernia associated with GERD and 22 healthy volunteers. The content of calcium in saliva was measured using calcium-sensitive dye Arsenazo III by photometrical method at a wavelength of 590-650 nm. Results: It has been established that in the saliva of patients with hiatal hernia, the calcium content was increased by 100.9% compared to the control group. Such a significant increase in the level of calcium in the saliva of patients with hiatal hernia may be due to the fact that the development of this pathology is a disorder of calcium homeostasis. Conclusions: It has been found that the calcium content in the saliva of patients with hiatal hernia exceeded the norm almost twice. Thus, the determination of calcium content in saliva can be used as a simple non-invasive diagnostic marker of hiatal hernia associated with GERD.

Abstract 513: Impaired Hemodynamic Response to Head up Tilt in Adolescents Presenting with Chronic Nausea and Orthostatic Intolerance

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Hossam A Shaltout ◽  
Ashley L Wagoner ◽  
John E Fortunato ◽  
Debra I Diz
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Orthostatic Intolerance ◽  
Frequency Method ◽  
Non Invasive ◽  
Head Up Tilt ◽  
Blood Pressures ◽  
Chronic Nausea

We previously reported that ~70% of adolescents presenting to a Pediatric GI clinic for chronic nausea exhibit orthostatic intolerance (OI) in response to head upright tilt testing (HUT). The objective of this study was to determine whether supine mean arterial pressure or hemodynamic responses to HUT differ in these patients. Forty-eight patients (mean age of 15 [10-18] years, 36 females) completed a 45 minutes 0 to 70° HUT. Continuous blood pressure and heart rate recordings were acquired using non-invasive finger cuff. Thirteen subjects had normal tilt (Normal) while thirty five demonstrated OI. There were no differences between the two groups in supine blood pressures (BP), baroreflex sensitivity measured by frequency method in HF range (BRS), heart rate variability (HRV) measured as the root of mean square of successive differences (rMSSD), blood pressure variability (BPV) measured as standard deviation of mean arterial pressure (SDMAP) or the sympathovagal balance measure LF RRI /HF RRI . HUT caused a greater increase in heart rate in OI group (from 71 ± 6 beats/min to 104 ± 4 in OI vs from 75 ± 3 to 95 ±3 in normal, p=0.01) which was accompanied with lesser increase in BP (mainly due to lack of increase in diastolic) in the OI group. There was a trend for greater reduction in BRS in OI subjects (from 28.5 ± 13 ms/mm Hg to 6.3 ± 0.8 in OI vs from 21.1 ± 3.6 to 12.0 ± 2.9 in normal, p=0.09). HUT impaired HRV in both groups compared to supine values but the reduction was greater in OI group (-66.7 ± 4 % vs -52.0 ±5.6 in normal, p=<0.001). SDMAP increased by HUT compared to supine but to a greater extent in OI (40.6 ± 4 % vs 13.4 ± 8 in normal, p=0.02). LF RRI /HF RRI increased to a greater magnitude in OI group with HUT (from 1.8 ± 0.8 to 6.8 ± 0.8 in OI vs from 1.14 ± 0.18 to 4.1 ±0.7 in normal, p=0.02). These data reveal that the adolescents with orthostatic intolerance have attenuated parasympathetic responses and exaggerated activation of the sympathetic system to the heart and blood vessels. Despite these responses, subjects fail to maintain BP. Similar to previous studies in other subjects with OI, the excessive tachycardia often followed by syncope in most of these adolescents may reflect a loss of vascular responses to the activation of sympathetic and neurohumoral stimuli. Support: AHA12CRP9420029

Computation of aortic flow from pressure in humans using a nonlinear, three-element model

1993 ◽  
Vol 74 (5) ◽  
pp. 2566-2573 ◽  
Author(s):  
K. H. Wesseling ◽  
J. R. Jansen ◽  
J. J. Settels ◽  
J. J. Schreuder
Keyword(s):  
Cardiac Output ◽  
Arterial Pressure ◽  
Arterial Compliance ◽  
Element Model ◽  
Aortic Pressure ◽  
Aortic Flow ◽  
Mean Deviation ◽  
Mean Flow ◽  
Thermodilution Cardiac Output ◽  
Flow Pulsations

We computed aortic flow pulsations from arterial pressure by simulating a nonlinear, time-varying three-element model of aortic input impedance. The model elements represent aortic characteristic impedance, arterial compliance, and systemic vascular resistance. Parameter values for the first two elements were computed from a published, age-dependent, aortic pressure-area relationship (G. J. Langewouters et al. J. Biomech. 17:425–435, 1984). Peripheral resistance was predicted from mean pressure and model mean flow. Model flow pulsations from aortic pressure showed the visual aspects of an aortic flow curve. For evaluation we compared model mean flow from radial arterial pressure with thermodilution cardiac output estimations, 76 times, in eight open heart surgical patients. The pooled mean difference was +7%, the SD 22%. After using one comparison per patient to calibrate the model, however, we followed quantitative changes in cardiac output that occurred either during changes in the state of the patient or subsequent to vasoactive drugs. The mean deviation from thermodilution cardiac output was +2%, the SD 8%. Given these small errors the method could monitor cardiac output continuously.

scholarly journals The Relationship between the Strength Characteristics of Cerebral Aneurysm Walls with Their Status and Laser-Induced Fluorescence Data

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 537
Author(s):  
Elena Tsibulskaya ◽  
Anna Lipovka ◽  
Alexandr Chupakhin ◽  
Andrey Dubovoy ◽  
Daniil Parshin ◽  
...  
Keyword(s):  
Cerebral Aneurysms ◽  
Strength Characteristics ◽  
Cerebral Tissue ◽  
Non Invasive ◽  
Excitation Emission Matrix ◽  
Significant Difference ◽  
The Status ◽  
The Subject ◽  
The Relationship

Background: Cerebral aneurysms (CA) are a widespread vascular disease affecting 50 per 1000 population. The study of the influence of histological, morphological and hemodynamic factors on the status of the aneurysm has been the subject of many works. However, an accurate and generally accepted relationship has not yet been identified. Methods: In our work, the results of mechanical and spectroscopic measurements are considered. Total investigated 14 patients and 36 their samples of CA tissue. Results: The excitation–emission matrix of each specimen was evaluated, after which the strength characteristics of the samples were investigated. Conclusions: It has been shown that there is a statistically significant difference in the size of the peaks of two components, which characterizes the status of the aneurysms. In addition, a linear regression model has been built that describes the correlation of the magnitude of the ultimate strain and stress with the magnitude of the peaks of one of the components. The results of this study will serve as a basis for the non-invasive determination of the strength characteristics of the cerebral tissue aneurysms and determination of their status.

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