Dosage Calculation

One formula covers most of the doses a nurse ever calculates: what you want, over what you've got, times the amount it comes in.

A decimal point written carelessly can turn a correct calculation into a tenfold medication error.

A correct calculation begins with a setup whose units prove the answer before the arithmetic starts.

The order is in grams, the bottle is in milligrams, and the decimal point is the only thing standing between the right dose and a thousand-fold error.

IV flow rate comes from volume and time — but the unit depends on the delivery method. A pump speaks mL/hr; a gravity drip speaks gtt/min and needs the tubing's drop factor.

You did the arithmetic perfectly. The question the reference book asks next is whether that dose should be given at all.

The chart says 44 pounds. The order says milligrams per kilogram. Divide before you dose, or the child gets more than twice what was intended.

Continuous IV drips run high-alert drugs — heparin, insulin, and vasopressors — at a calculated, titrated rate. Converting the order into a pump rate and re-titrating to the trend is the tested skill.

There is no standard adult dose to fall back on. Every number comes from the child's weight, and every check has to happen before the drug leaves your hand.

You add 1.8 mL of diluent and get 2 mL of solution. The powder took up the rest — and the label already told you so.