A continuous regular insulin infusion is prescribed at 4.5 units/hour. The bag contains 250 mL of saline with 100 units of insulin. How many mL per hour should the client receive? Round to the nearest tenth.

A continuous regular insulin infusion is prescribed at 4.5 units/hour. The bag contains 250 mL of saline with 100 units of insulin. How many mL per hour should the client receive? Round to the nearest tenth.

• A. 9.5 mL/hr
• B. 11.3 mL/hr
• C. 12.0 mL/hr
• D. 13.5 mL/hr

Answer: (B)

Calculating infusion rate from concentration. The insulin bag has 100 units in 250 mL, so the concentration is 100/250 = 0.4 units per mL. To deliver 4.5 units each hour, convert units to volume: 4.5 units/hour ÷ 0.4 units/mL = 11.25 mL/hour. Rounding to the nearest tenth gives 11.3 mL/hour. A quick check with a proportion confirms the same result: 100 units/250 mL = 4.5 units/x mL, so x = (4.5 × 250) / 100 = 11.25 mL/hour.

Calculating infusion rate from concentration. The insulin bag has 100 units in 250 mL, so the concentration is 100/250 = 0.4 units per mL. To deliver 4.5 units each hour, convert units to volume: 4.5 units/hour ÷ 0.4 units/mL = 11.25 mL/hour. Rounding to the nearest tenth gives 11.3 mL/hour. A quick check with a proportion confirms the same result: 100 units/250 mL = 4.5 units/x mL, so x = (4.5 × 250) / 100 = 11.25 mL/hour.