gttmin

gttmin is a commonly used unit in intravenous (IV) therapy that expresses the rate of fluid administration as drops per minute. The term is most often encountered as gtt/min, with gtt short for goutte (French for drop) and min representing minutes. In some notes or older records, the combined form gttmin may appear, but the standard notation remains gtt/min.

The rate of infusion depends on the drop factor of the IV administration set, which is measured in drops per milliliter (gtt/mL). The flow rate in gtt/min is calculated by multiplying the volume to be delivered (in mL) by the drop factor (gtt/mL) and then dividing by the time (in minutes): rate = (volume in mL) × (drop factor) / (time in minutes). For example, delivering 1000 mL over 600 minutes with a drop factor of 20 gtt/mL yields approximately 33 gtt/min.

Common IV sets have drop factors such as 10, 15, 20, or 60 gtt/mL, and the chosen factor determines the actual gtt/min rate for a given prescription. In modern clinical practice, many facilities use electronic infusion pumps that display the rate in mL/hr, with manual conversions used to obtain gtt/min when required. Manual rates using gtt/min were more common before widespread adoption of pumps and remain in use in some settings or for backup purposes.

Accuracy of gtt/min depends on correct drop factor, proper tube priming, and careful adjustment of the roller clamp or pump. Incorrect rates can lead to under- or over-infusion, with potential patient risk.