Quantitative assessment of low blood flow using an electromagnetic flowmeter

This study evaluated the behavior and reliability of an electromagnetic flowmeter for the quantitative assessment of low mean blood flow. Cuff-type probes with lumen diameters of 0.75, 1.0, 1.5, and 2.0 mm were used on excised canine vessels of external diameter less than 4.0 mm for in vitro calibrations. Flows ranged from 0 to 30 ml/min. Standard calibration plots were linear through zero with a mean error of ± 4.2%. Linear plots were significantly shifted by vascular constrictions of 50% and greater. Mechanical occlusion of the vessel for zero baseline determination was found to be important. To date, this report is the most extensive and accurate quantitative study of low blood flow with small transducers. We feel that the equipment can function as a valuable surgical tool.