PMID- 9139989
OWN - NLM
STAT- MEDLINE
DCOM- 19970528
LR  - 20171213
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 272
IP  - 4 Pt 2
DP  - 1997 Apr
TI  - Indicator-dilution dispersion models and cardiac output computing methods.
PG  - H2004-12
AB  - The general theory of indicator-dilution methods provides a basis for computing 
      improved cardiac output estimates. Interpretation is via indicator-dispersion 
      modeling with Brownian motion of drifting particles. Detected curves indicate the 
      distribution of passage times from the injection site: the local density random 
      walk (LDRW) function of a Wiener process. Fitting the LDRW to 70 dye curves by 
      nonlinear regression for examples, I show how all possible undistorted curves 
      can, in principle, be simulated. I show via semilogarithmic plots that 
      conventional exponential decay constructs systematically underestimate cardiac 
      output by up to 8%. To help reconcile the predictions of LDRW-fitted dilution 
      curves and contemporary practice, I show how curve-shape asymmetry (skewness) 
      dramatically affects the enclosed areas. Mean transit times may overestimate 
      blood volumes by 15-100% in very skewed thermodilution curves if the dispersion 
      effects are overlooked. Triangle constructions, which accounted for hundreds of 
      experimental findings, also have theoretical explanations. Curve-fitting methods 
      reduce the extrapolation biases inherent in many computers and in any 
      respiration-induced artifacts. Compatibility of cardiac output predictions from 
      various dilution methods and modules becomes feasible.
FAU - Millard, R K
AU  - Millard RK
AD  - Department of Anaesthetics, University of Bristol, United Kingdom.
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
SB  - IM
MH  - Artifacts
MH  - Body Temperature
MH  - *Cardiac Output
MH  - *Computer Simulation
MH  - Humans
MH  - *Models, Cardiovascular
MH  - Models, Statistical
MH  - Models, Theoretical
MH  - Random Allocation
MH  - Regression Analysis
MH  - Respiration
MH  - Time Factors
EDAT- 1997/04/01 00:00
MHDA- 1997/04/01 00:01
CRDT- 1997/04/01 00:00
PHST- 1997/04/01 00:00 [pubmed]
PHST- 1997/04/01 00:01 [medline]
PHST- 1997/04/01 00:00 [entrez]
AID - 10.1152/ajpheart.1997.272.4.H2004 [doi]
PST - ppublish
SO  - Am J Physiol. 1997 Apr;272(4 Pt 2):H2004-12. doi: 
      10.1152/ajpheart.1997.272.4.H2004.