It may seem ridiculously simple, but a preprinted decimal point on hospital drug prescription charts is saving patients from the kinds of common mistakes that can potentially kill.
Researchers have estimated that 150 public hospital patients die each year from medication errors, most of which are made in hospital although some occur beforehand.
But no one knows the real figure. District Health Boards' voluntary reports to the Health Quality and Safety Commission indicate there are only a few deaths a year.
A sample of medication errors from those reports include:
A Northland patient was given 10 times the correct dose of insulin, leaving them unresponsive and requiring emergency resuscitation.
A patient in Manawatu was given 50ml of methadone instead of 5ml, and had to be "intensively monitored".
A patient in Wellington who was having a suspected heart attack was mistakenly given a double dose of anticoagulant and died.
From the brief details given, it is not clear precisely what the errors were.
Asked about the number of reported decimal-point errors, the commission said one involving a 10-fold dosage error led to a patient's death in 2009/10 and the following year two errors, but no deaths, were reported.
Another common fault in handwritten prescriptions - expected to be replaced with electronic ones at all district health boards by the end of 2014 - is illegible or misleading abbreviations.
Nearly a third of health workers who were shown a badly written hospital prescription for a commission survey misread the dosage by a factor of 1000.
It was a copy of a real prescription in which the intended dose of 4mcg was written sloppily with an abbreviation that made it look like 4mg, or possibly 7mg or 1mg or microgram.
Fortunately for the patient, the error was spotted by someone who worked out that if it was 4mg, the patient would have to swallow 8000 capsules.
"We introduced the national medication chart last year," said Marilyn Crawley, chief pharmacist for the Waitemata District Health Board's hospitals and a champion of medication safety schemes.
"All our adult acute units have it," she said. It has improved clarity."
"We've got audits showing improved compliance with prescribing clearly so it can be easily read. It has a clear decimal point and there are a small number of approved abbreviations."
The nationally standardised chart is a forerunner to electronic prescriptions and is one of the key medication safety projects overseen by the commission.
It took six years to develop and still only 15 of the 20 district health boards have adopted it.
Waitemata is one of several boards on a pilot programme for electronic medicines reconciliation - a cross-check of a patient's medication history - and in November will join another pilot, for electronic prescribing.
It already has electronic dispensing machines in almost all its inpatient areas.
Ms Crawley, who oversaw the Southern Hemisphere's largest introduction of the Pyxis dispensing machines, said electronic prescribing could save lives.
"I think it will be really important," she said.
"It will allow us to improve the quality of our prescribing in the sense that it's very much more legible and enables decision-support systems on dose ranges and interactions."
The sample prescription
See goo.gl/ZLSAM for the report.
Five years of hospital death rates have been made public for the first time - in the Herald. We compare health boards, investigate where lives are being lost and the battle to save them.
Monday - District health boards compared, is death rate linked to healthcare quality, and how a simple checklist helps surgeons to avoid mistakes.
Yesterday - Waitemata DHB boosts heart-care capacity. A bereaved father questions medical justice.
Today - Waikato DHB strives to understand its high death rate, medication safety, and a doctor's apology.
Tomorrow - Palliative care helps Auckland DHB's good performance. A widow fights for changes.
Friday - Obesity skews the statistics in South Auckland. Lives saved by reduction of blood infections.
Tell us your experience of hospital care. Email Martin Johnston by clicking the link below.