You are preparing to administer a 3% hypertonic saline continuous infusion to a patient with severe TBI following a bolus of 250 mL. The IV tubing has a drip chamber of 10 gtt/mL. You plan to start the infusion at 100 mL/hr. What is the gtt/min rate?

You are preparing to administer a 3% hypertonic saline continuous infusion to a patient with severe TBI following a bolus of 250 mL. The IV tubing has a drip chamber of 10 gtt/mL. You plan to start the infusion at 100 mL/hr. What is the gtt/min rate?

• A. 12 gtt/min
• B. 22 gtt/min
• C. 25 gtt/min
• D. 17 gtt/min

Answer: (D)

Drip rate calculations use the tubing’s drip factor to convert mL per hour into drops per minute. With a drip factor of 10 drops per mL, delivering 100 mL per hour means 100 × 10 = 1000 drops per hour. Divide by 60 to get drops per minute: 1000 ÷ 60 ≈ 16.7 drops/min, which rounds to 17 gtt/min. The other rates would require different hourly volumes (for example, 12 gtt/min ≈ 72 mL/hr; 22 gtt/min ≈ 132 mL/hr; 25 gtt/min ≈ 150 mL/hr), so they don’t match the intended 100 mL/hr. Therefore, 17 gtt/min is the correct rate.

Drip rate calculations use the tubing’s drip factor to convert mL per hour into drops per minute. With a drip factor of 10 drops per mL, delivering 100 mL per hour means 100 × 10 = 1000 drops per hour. Divide by 60 to get drops per minute: 1000 ÷ 60 ≈ 16.7 drops/min, which rounds to 17 gtt/min. The other rates would require different hourly volumes (for example, 12 gtt/min ≈ 72 mL/hr; 22 gtt/min ≈ 132 mL/hr; 25 gtt/min ≈ 150 mL/hr), so they don’t match the intended 100 mL/hr. Therefore, 17 gtt/min is the correct rate.