In-line blood warming and microfiltration devices. I. Testing of flow and warming properties by pressure transfusion...

Homogeneous microaggregate-free whole blood at +5 degrees C was transfused at constant pressures of 20 and 40 kPa through two micro-filtration and blood warming devices, and the temperature of the blood was recorded before it reached the venous cannula. The flow rates with the Fenwal system were 58 and 139 g/min, whereas the micro-filter MF10B combined with the Portex Coil allowed flow rates of 143 and 224 g/min. The warming capacities of the two warmers were almost equal and this did not prove to be their weak point. The infusion temperature varied considerably during the transfusion. Increasing the priming volume of the coil would raise the mean infusion temperature. A pressure infusor (Fenwal) was tested, and the internal pressures of the blood bag and the infusor were determined separately. The bag pressure differed significantly from the infusor pressure as the blood bag emptied, making the usefulness of the infusor manometer questionable.