VALIDATION OF A FLOW-DIFFERENTIAL TECHNIQUE FOR THE RECORDING OF SPLENIC BLOOD-VOLUME CHANGES TO VASOACTIVE AGENTS

Splenic blood-volume changes to norepinephrine were determined in the anesthetized cat by recording the integral of the difference between s plenic arterial flow and splenic venous flow (flow-differential techni que) with ultrasonic transit-time flowmeters, and the changes recorded with this technique were compared with those recorded with an indepen dent technique, the gravimetric method. Norepinephrine (0.003-0.3 mu g /min/kg of body weight) induced dose-related decreases in splenic volu me, and the values recorded by the flow-differential technique were no t significantly different from those recorded with the gravimetric tec hnique. The values recorded by the two methods were highly correlated (r = 0.86). The slope of the line plotting the relation between the tw o methods was close to unity (0.97 +/- 0.12), and the intercept of the line was close to zero (-0.46 +/- 1.6 ml). The results suggest that t he recording of the flow differential between splenic arterial flow an d splenic venous flow with ultrasonic transit time flowmeters is a val id method for the recording of splenic blood-volume changes to vasoact ive agents.