A unit of 250 mL packed red blood cells to infuse over 4 hours with a drop factor of 10 gtt/mL. What is the IV flow rate in mL per hour?

A unit of 250 mL packed red blood cells to infuse over 4 hours with a drop factor of 10 gtt/mL. What is the IV flow rate in mL per hour?

• A. 50 mL/hr
• B. 63 mL/hr
• C. 75 mL/hr
• D. 100 mL/hr

Answer: (B)

When figuring IV flow rate in mL per hour, you divide the total volume to be infused by the infusion time. Here, 250 mL over 4 hours gives 250 ÷ 4 = 62.5 mL/hour. We typically round to a whole number, so 63 mL/hour. The drop factor (10 gtt/mL) would matter only if you needed drops per minute (gtt/min), not the mL per hour here.

When figuring IV flow rate in mL per hour, you divide the total volume to be infused by the infusion time. Here, 250 mL over 4 hours gives 250 ÷ 4 = 62.5 mL/hour. We typically round to a whole number, so 63 mL/hour. The drop factor (10 gtt/mL) would matter only if you needed drops per minute (gtt/min), not the mL per hour here.