Transit time flow measurement: experimental validation and comparison of three different systems.
BACKGROUND
Bloodflow measurements are of major clinical importance for quality control in vascular surgery. They allow detection of low-flow situations which may influence outcome adversely. The purpose of the present study was to validate three different flow systems for measuring absolute blood flow.


METHODS
Measurements were performed in an experimental flow model using arteries and veins and blood or saline at two different temperatures. As a reference method true flow was measured by volume sampling.


RESULTS
Correlation coefficients between transit time flow and true flow measurements ranged between 0.71 and 0.92. Systematic overestimation and underestimation of transit time flow were observed, but after second-order correction all correlations were excellent, ranging from 0.93 to 0.95 irrespective of flow medium and temperature.


CONCLUSIONS
Transit time flow measurements are exact and reproducible. Second-order correction yields good accuracy and high precision, with minimal differences among the three systems evaluated.
Department of Cardiovascular Surgery, University Hospital Insel, Bern, Switzerland.
G
G
Beldi
A
A
Bosshard
O M
OM
Hess
U
U
Althaus
B H
BH
Walpoth
D001783:Blood Flow Velocity; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D016014:Linear Models; D012212:Rheology / Q000295:instrumentation*; D013997:Time Factors