Infusionsrate

Infusionsrate, or infusion rate, is the speed at which a fluid is delivered intravenously to a patient. It is typically expressed in milliliters per hour (mL/h) and, in gravity-based systems, may also be shown as drops per minute (gtt/min) or milliliters per minute (mL/min). The chosen rate determines how quickly the prescribed fluid, medication, nutrition, or blood product reaches the circulation.

Infusion administration relies on devices such as infusion pumps and gravity-fed systems. Infusion pumps provide precise control by delivering a defined volume per unit time, while gravity-fed systems rely on the height of the fluid bag and the drop factor of the IV set. The drop factor, measured in drops per milliliter (gtt/mL), converts flow into drops per minute for gravity setups.

Calculating the rate can be straightforward: rate (mL/h) = total volume (mL) / time (h). For example, 1000 mL over 8 hours equals 125 mL/h. For gravity systems, drops per minute are calculated as rate (gtt/min) = (volume mL × drop factor gtt/mL) / time (min). Example: 1000 mL × 20 gtt/mL over 480 minutes yields about 41.7 gtt/min.

Applications include administration of intravenous fluids, medications, total parenteral nutrition, and blood products. Factors affecting the actual rate include device accuracy, catheter occlusion, line kinking, air bubbles, and changes in patient vascular access. Clinically, careful monitoring is necessary to prevent fluid overload or under-infusion and to manage drug compatibility, electrolyte balance, and potential adverse reactions.