In vitro and in vivo rates of fluid flow through catheters in peripheral veins of dogs

Abstract

Summary In vitro and in vivo fluid flow rates of 14-, 16-, 18-, and 20-gauge catheters at fluid heights of 0.91 and 1.75 m above the catheters were determined. Flow rates were significantly faster in vitro than in vivo, at a greater height, and with larger catheter radius. In vivo flow rates averaged 7% less than in vitro flow rates. Fluid flow increased approximately 50% for each gauge catheter when the height was raised from 0.91 to 1.75 m. Flow rates increased linearly with increasing catheter radius. The flow rate of each gauge of catheter was significantly different from flow rates of all other gauges that were used. In vivo flow rates for 14-, 16-, 18-, and 20-gauge catheters at fluid heights of 0.91 and 1.75 m were 137, 88, 75, and 45 ml/min and 206, 152, 114, and 75 ml/min, respectively. Knowledge of flow rates allows selection of a catheter gauge that will provide adequate volume loading for the size of patient being treated in the time needed.