Using the West nomogram scale, the nurse needs to calculate the safe dosage of a medication for a child. The child is 50 inches tall and weighs 76 lb. The normal dosage of the medication for an adult is 300 mg. Which of the following is the correct way to use the West nomogram scale?

Choice A reason: The “shortcut” scale is not a standard method for the West nomogram, which calculates body surface area (BSA) for precise dosing. Using BSA ensures accuracy for a 76-lb, 50-inch child, making this simplified approach incorrect for calculating a safe pediatric medication dosage in clinical practice. Choice B reason: Aligning height and weight to a percentage of adult dosage is not how the West nomogram works; it calculates BSA. The correct method uses BSA relative to adult BSA, making this incorrect, as it skips the critical step of surface area calculation for accurate pediatric dosing. Choice C reason: Multiplying height and weight and dividing the adult dosage is not a nomogram method. The West nomogram uses BSA to adjust doses, comparing child and adult surface areas, making this mathematically incorrect and inappropriate for calculating a safe pediatric medication dose for the child. Choice D reason: The West nomogram calculates a child’s BSA using height (50 inches) and weight (76 lb), then divides by the average adult BSA (1.7 m²) to find the proportion of the adult dose (300 mg). This method ensures accurate pediatric dosing, making it the correct choice for safe administration.