The five errors that kill: traps in the numeral itself
A horizontal logarithmic axis ticked at one, ten, one hundred and one thousand times the intended dose, with five carets dropping onto it on labeled leaders, everything right of the one mark washed in warning tone, and a row of boxes beneath showing only the safe typeset form of each numeral.
These failures do not come from not knowing the formula. They come from how the number was written, read, or carried.
Trap 1 — The decimal shift
A digoxin order for 0.125 mg is read or keyed as 1.25 mg. Magnitude: tenfold. The pump accepts it, because 1.25 is a plausible number for something. Correction: read the decimal aloud as a fraction of the whole unit, and confirm against the label before drawing up.
Trap 2 — The trailing zero
A whole-number dose written with a decimal point and a zero after it. If the point is faint, faxed, photocopied or handwritten, the reader sees a number ten times larger. Correction: whole numbers carry no decimal point and no following zero. This book never typesets the unsafe form.
Trap 3 — The missing leading zero
A dose smaller than one unit written with a bare decimal point and no zero in front of it. The point disappears against a ruled line and the reader sees a number ten times larger. Correction: always 0.5 mg, always 0.125 mg, never the bare form.
Memory hookLEAD IT, NEVER TRAIL IT.
Trap 4 — Unit mismatch
A levothyroxine order written in milligrams checked against a label printed in micrograms. 0.088 mg and 88 mcg are the same dose. 88 mg is a thousandfold overdose. Correction: convert both sides to one unit before comparing, and let the cancellation refuse an illegal pairing.
Trap 5 — Pounds entered as kilograms
A child charted at 44 lb is 20 kg. A gentamicin order at 2.5 mg/kg is 20 kg × 2.5 mg/kg = 50 mg. Enter 44 as kilograms and you get 44 kg × 2.5 mg/kg = 110 mg, a 2.2-fold overdose that no pump alert catches, because the arithmetic is internally consistent. Correction: the weight is confirmed on a scale, in kilograms, as the first line of every weight-based check.
Trap 6 — The abbreviation
The single-letter abbreviation for units, the abbreviation for international units, the once-daily and every-other-day abbreviations, and the shortened forms of morphine and magnesium sulfate are on the ISMP Do-Not-Use list because each one has been misread into a death. Correction: spell the word. This book prints no example.
Watch outTENFOLD. Four of these are a factor of ten and one is a factor of 2.2. None of them is a hard problem, and that is exactly why they get through.
Margin noteno pump alert catches a pounds-for-kilograms entry. → BOOK 01 · P23
Takeawayevery one of these is caught by reading the number back against the label before the drug leaves the counter.