A nurse needs to administer 500 mL of 0.9% normal saline over 8 hours using a manual IV set with a drip factor of 20 gtt/mL. How many gtt/min should be set for this infusion?

A. 30 gtt/min: This rate would deliver approximately 180 mL per hour, meaning the 500 mL would be finished in less than 3 hours. This is much faster than the 8-hour duration prescribed by the physician. Rapid infusion of saline can lead to fluid overload, especially in patients with cardiac or renal issues. B. 15 gtt/min: At this drip rate, the patient would receive only about 45 mL per hour, totaling 360 mL over 8 hours. This results in an under-infusion that fails to meet the patient's prescribed fluid requirements. It would take over 11 hours to finish the 500 mL bag at this speed. C. 35 gtt/min: This setting would deliver 105 mL per hour, resulting in the total volume being infused in under 5 hours. This significantly deviates from the 8-hour order and increases the risk of complications associated with rapid fluid administration. It represents a calculation error in the drip rate formula. D. 21 gtt/min: Using the formula (500 mL multiplied by 20 gtt/mL) divided by 480 minutes, the result is 20.83. Rounding to the nearest whole number gives 21 drops per minute. This precisely ensures that the 500 mL of normal saline is delivered over the intended 8-hour period.