scholarly journals Aortic input impedance in normal man: relationship to pressure wave forms.

Circulation ◽  
1980 ◽  
Vol 62 (1) ◽  
pp. 105-116 ◽  
Author(s):  
J P Murgo ◽  
N Westerhof ◽  
J P Giolma ◽  
S A Altobelli
Keyword(s):  
Input Impedance ◽  
Pressure Wave ◽  
Aortic Input Impedance ◽  
Wave Forms ◽  
Normal Man

scholarly journals Effects of exercise on aortic input impedance and pressure wave forms in normal humans.

1981 ◽  
Vol 48 (3) ◽  
pp. 334-343 ◽  
Author(s):  
J P Murgo ◽  
N Westerhof ◽  
J P Giolma ◽  
S A Altobelli
Keyword(s):  
Input Impedance ◽  
Pressure Wave ◽  
Aortic Input Impedance ◽  
Wave Forms ◽  
Normal Humans

Aortic input impedance in normal man and arterial hypertension: its modification during changes in aortic pressure

1982 ◽  
Vol 16 (11) ◽  
pp. 646-656 ◽  
Author(s):  
JEAN P MERILLON ◽  
GUY J FONTENIER ◽  
JEAN F LERALLUT ◽  
MICHEL Y JAFFRIN ◽  
GILBERT A MOTTE ◽  
...  
Keyword(s):  
Arterial Hypertension ◽  
Input Impedance ◽  
Aortic Pressure ◽  
Aortic Input Impedance ◽  
Normal Man

scholarly journals Aortic input impedance in heart failure.

Circulation ◽  
1978 ◽  
Vol 58 (3) ◽  
pp. 460-465 ◽  
Author(s):  
C J Pepine ◽  
W W Nichols ◽  
C R Conti
Keyword(s):  
Heart Failure ◽  
Input Impedance ◽  
Aortic Input Impedance

A model for the relation between respiratory neural and mechanical outputs. III. Validation

1981 ◽  
Vol 51 (4) ◽  
pp. 990-1001 ◽  
Author(s):  
M. Younes ◽  
W. Riddle ◽  
J. Polacheck
Keyword(s):  
Respiratory System ◽  
Pressure Wave ◽  
Time Course ◽  
Present Report ◽  
Occlusion Pressure ◽  
Single Breath ◽  
Wave Forms ◽  
Inspiratory Activity ◽  
Good Agreement

In the preceding two communications we described a model for the relation between respiratory neural and mechanical outputs. In the present report we test the accuracy of the model in predicting volume and flow from occlusion pressure wave forms, and vice versa. We performed single-breath airway occlusions in 21 unconscious subjects and determined the time course of occlusion pressure. We also measured the passive properties of the respiratory system. The time course of volume and flow was predicted from the occlusion pressure wave forms, and the results were compared with the spontaneous breaths immediately preceding occlusion. Inspiratory duration, shape and amplitude of occlusion-pressure wave forms, and the passive properties of the respiratory system varied widely among subjects. There was good agreement between predicted and observed values in all cases. Except for some prolongation of inspiration (Hering-Breuer reflex), diaphragmatic activity did not change during occlusion. Since occlusion pressure is proportional to inspiratory activity, we conclude that the model described provides a good approximation of the relation between inspiratory activity and spirometric output.

scholarly journals A new technique for assessing arterial pressure wave forms and central pressure with tissue Doppler

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Brian A Haluska ◽  
Leanne Jeffriess ◽  
Phillip M Mottram ◽  
Stephane G Carlier ◽  
Thomas H Marwick
Keyword(s):  
Arterial Pressure ◽  
Pressure Wave ◽  
Tissue Doppler ◽  
New Technique ◽  
Central Pressure ◽  
Wave Forms ◽  
A New Technique

Dual assessment of airway area profile and respiratory input impedance from a single transient wave

2001 ◽  
Vol 90 (2) ◽  
pp. 630-637 ◽  
Author(s):  
Bruno Louis ◽  
Redouane Fodil ◽  
Samir Jaber ◽  
Jérôme Pigeot ◽  
Pierre-Henri Jarreau ◽  
...  
Keyword(s):  
Input Impedance ◽  
Pressure Wave ◽  
Mechanical Characteristics ◽  
Upper Airway ◽  
Physical Models ◽  
Transient Wave ◽  
Airway Opening ◽  
Dual Analysis ◽  
Planar Wave ◽  
System Frequency

This report concerns the inference of geometric and mechanical airway characteristics based on information derived from a single transient planar wave recorded at the airway opening. We describe a new method to simultaneously measure upper airway area and respiratory input impedance by performing dual analysis of a single pressure wave. The algorithms required to reconstruct airway dimensions and mechanical characteristics were developed, implemented, and tested with reference to known physical models. Our method appears suitable to estimate, even under severe intensive care unit conditions, the respiratory system frequency response (above 10 Hz) in intubated patients and the patency of the endotracheal tube used to connect the patients to the ventilator.

scholarly journals Effects of Nicorandil on Aortic Input Impedance

1999 ◽  
Vol 63 (2) ◽  
pp. 111-116 ◽  
Author(s):  
Masami Fujita ◽  
Kenji Takazawa ◽  
Nobuhiro Tanaka ◽  
Chiharu Ibukiyama
Keyword(s):  
Input Impedance ◽  
Aortic Input Impedance

Differential Effects of Isoflurane and Halothane on Aortic Input Impedance Quantified Using a Three-element Windkessel Model

1995 ◽  
Vol 83 (2) ◽  
pp. 361-373. ◽  
Author(s):  
Douglas A. Hettrick ◽  
Paul S. Pagel ◽  
David C. Warltier
Keyword(s):  
Blood Flow ◽  
Input Impedance ◽  
Wave Reflection ◽  
Conscious State ◽  
Left Ventricular ◽  
Arterial System ◽  
Windkessel Model ◽  
Frequency Dependent ◽  
Aortic Input Impedance ◽  
Arterial Wave Reflection

Background Systemic vascular resistance (the ratio of mean aortic pressure [AP] and mean aortic blood flow [AQ]) does not completely describe left ventricular (LV) afterload because of the phasic nature of pressure and blood flow. Aortic input impedance (Zin) is an established experimental description of LV afterload that incorporates the frequency-dependent characteristics and viscoelastic properties of the arterial system. Zin is most often interpreted through an analytical model known as the three-element Windkessel. This investigation examined the effects of isoflurane, halothane, and sodium nitroprusside (SNP) on Zin. Changes in Zin were quantified using three variables derived from the Windkessel: characteristic aortic impedance (Zc), total arterial compliance (C), and total arterial resistance (R). Methods Sixteen experiments were conducted in eight dogs chronically instrumented for measurement of AP, LV pressure, maximum rate of change in left ventricular pressure, subendocardial segment length, and AQ. AP and AQ waveforms were recorded in the conscious state and after 30 min equilibration at 1.25, 1.5, and 1.75 minimum alveolar concentration (MAC) isoflurane and halothane. Zin spectra were obtained by power spectral analysis of AP and AQ waveforms and corrected for the phase responses of the transducers. Zc and R were calculated as the mean of Zin between 2 and 15 Hz and the difference between Zin at zero frequency and Zc, respectively. C was determined using the formula C = (Ad.MAP).[MAQ.(Pes-Ped)]-1, where Ad = diastolic AP area; MAP and MAQ = mean AP and mean AQ, respectively; and Pes and Ped = end-systolic and end-diastolic AP, respectively. Parameters describing the net site and magnitude of arterial wave reflection were also calculated from Zin. Eight additional dogs were studied in the conscious state before and after 15 min equilibration at three equihypotensive infusions of SNP. Results Isoflurane decreased R (3,205 +/- 315 during control to 2,340 +/- 2.19 dyn.s.cm-5 during 1.75 MAC) and increased C(0.55 +/- 0.02 during control to 0.73 +/- 0.06 ml.mmHg-1 during 1.75 MAC) in a dose-related manner. Isoflurane also increased Zc at the highest dose. Halothane increased C and Zc but did not change R. Equihypotensive doses of SNP decreased R and produced marked increases in C without changing Zc. No changes in the net site or the magnitude of arterial wave reflection were observed with isoflurane and halothane, in contrast to the findings with SNP. Conclusions The major difference between the effects of isoflurane and halothane on LV afterload derived from the Windkessel model of Zin was related to R, a property of arteriolar resistance vessels, and not to Zc or C, the mechanical characteristics of the aorta. No changes in arterial wave reflection patterns determined from Zin spectra occurred with isoflurane and halothane. These results indicate that isoflurane and halothane have no effect on frequency-dependent arterial properties.

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