Variability in infusion pressure and continuous flow rate delivered from pressurized bag pump flush systems

Using 10 different infusion bag pressure pumps, indicated manometer pressures were compared with measured infusion pressures proximal to the flow-regulating device in an in vitro experiment. Flow rates delivered through the flow-regulating device were gravimetrically measured at different monitored pressure levels. Significant differences were found between manometer and measured infusion pressures among the tested pressure bagpumps (e.g. 500 ml bag volumepressurized to 300 mmHg manometerpressure: 219.6 +/- 7.8 to 407.2 +/- 2.7 mmHg). The infusion pressures were additionally affected by the vertical level of the infusion bag pump and by the volume of the infusion bag. Flow rates delivered through the flow-regulating device were directly correlated to the measured infusion pressure (r2= 0.9926). Differences inflow rates can have a considerable impact on maintaining catheter patency and avoidance of fluid overload and retrograde flushing into the central arterial circulation in neonates and small children. A simple manoeuvre using the invasive pressure transducer allows monitoring and adjustment of the infusion pressure in the clinical setting.