Macrodrip Tubing: Drop Factors and Drip Rate Example
Shows the work. Every example is computed with the formula and numbered steps. For study and exam practice, not for patient care.
Macrodrip: IV tubing that delivers large drops, usually 10, 15, or 20 drops per mL, as printed on its package.
Macrodrip tubing makes larger drops than microdrip tubing, so fewer drops make a milliliter. Its drop factor is usually 10, 15, or 20 gtt/mL; the exact number depends on the set, so read the package.
Because each drop carries more fluid, macrodrip tubing suits larger volumes and faster rates, where counting 60 small drops per mL would be impractical.
Order: 5% dextrose in water 500 mL IV over 2 hours. The IV tubing has a drop factor of 20 gtt/mL.
- Volume
- 500 mL
- Infusion time
- 120 minutes
- Drop factor
- 20 gtt/mL
Formula gtt/min = volume × drop factor ÷ minutes.
- gtt/min = volume × drop factor ÷ minutes.
- 500 mL × 20 gtt/mL ÷ 120 minutes = 83.33 gtt/min.
- A drop cannot be split, so round to a whole number: 83 gtt/min.
Answer 83 gtt/min
Sources
- Clinical Calculations: With Applications to General and Specialty Areas — Elsevier (Kee, Marshall, et al.)
- Calculate with Confidence — Elsevier (Morris)