Annals of Biomedical Engineering

, Volume 15, Issue 5, pp 427–441 | Cite as

Short-term regulation of arterial pressure and the calculation of open-loop gain in the intact anesthetized dog

  • R. Burattini
  • P. Borgdorff
  • N. Westerhof
Article

Abstract

Open-loop gain of the short-term systemic pressure regulation was determined under closed-loop conditions in the closed chest anesthetized dog (n=5). For this purpose, cardiac output and mean systemic pressure were varied by ventricular pacing after the production of complete heart block. From the pressure-flow data resistance gain (the ratio of peripheral resistance change to pressure change in the steady state) was obtained by means of a simple model. The value of this gain was automatically estimated by fitting the pressure-flow relation described by the model to the experimental data. The model allows the pressure-flow relation to be straight or curved with or without a zero-flow pressure intercept. The best fit was obtained when the pressure-flow curve was convex to the pressure axis and had no intercept.

When the model was linearized about the control values of pressure and flow (operating point), open-loop gain could be calculated from resistance gain. Its averaged value in the control condition, 1.63±0.45, is in agreement with values found by other investigators in open-loop conditions. During vasoconstriction open-loop gain, at the (new) operating point, increased to 2.51±0.51; during vasodilation it decreased to 1.17±0.27. Open-loop gain about an operating point thus can be determined in the intact animal from measurements of mean pressure and mean flow in the steady state.

Keywords

Parameter estimation Model linearization Closed-loop gain Cardiac pacing Baroreflex 

Nomenclature

P

mean systemic pressure

Pc

mean systemic pressure in control condition

ΔPs

change in systemic pressure from control to a new steady state

ΔPi

initial change of systemic pressure

P0

zero-flow pressure intercept

Q

cardiac output

Qc

cardiac output in control condition

ΔQ

change of flow from control to a new steady state

R

total peripheral resistance

Rc

total peripheral resistance in control condition

ΔR

change of peripheral resistance from control to a new steady state

GR

resistance gain

Go

open-loop gain

Gc

closed-loop gain

HR

heart rate

HRc

heart rate in control condition

SD

standard deviation

SE

standard error

RMSE

root mean square error

W

body weight

μg

microgram

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Copyright information

© Pergamon Journals Ltd 1987

Authors and Affiliations

  • R. Burattini
    • 1
  • P. Borgdorff
    • 2
  • N. Westerhof
    • 2
  1. 1.Department of Electronics and AutomaticaUniversity of AnconaAnconaItaly
  2. 2.Laboratory for PhysiologyFree University of AmsterdamAmsterdamThe Netherlands

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