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Getting the NAC; A retrospective review of a standardised intravenous Acetylcysteine ordering chart and comparison with manual calculation of prescriptions

A 2020/2021 Summer Studentship research project

Student: Kaleb Addy
Supervisors: Dr Sulaiman Almubarak, Dr Paul Gee
Sponsor: Maurice and Phyllis Paykel Trust


In 2019 CDHB introduced the “Acetylcysteine Infusion Chart for Paracetamol Overdose (adult)” for adult patients with Paracetamol overdose requiring an antidote.

The aim of the standardised chart was to reduce charting and administration error by:

  • Simplifying the calculation needed by using a “weight range” standardised table for dosing (rather than manual calculation of dosing.)
  • Change from a three to a two-bag regime
  • Change of practice from using the general hospital medication chart into a separate N-Acetylcysteine (NAC) Infusion Chart


We anticipate that the change to a standardised chart has reduced prescribing and administration errors, and therefore associated patient harms.


Retrospective review of medical records of patients presenting with Paracetamol overdose requiring NAC infusion pre and post change. We will consult with a statistician to perform a power calculation; this will determine how many patient charts we will need to review to detect a statistically significant reduction in harms. We anticipate that we will need to review between 50 and 100 patient charts.
We will review the charts of those patients who received NAC (half before the change, half afterwards.)

For each patient we will gather information on:

  • dose given
  • administration errors
  • prescribing errors

To determine the errors, we will use a combination of the CDHB error reporting system, as well as reading through the nursing notes and drug charts for the period that the drug was given. Not all errors are reliably reported on the error system, therefore this dual approach should minimize false negatives. Once we have the complete data set, then we will compare both the number and nature of errors pre- and post- implementation of the new chart.

Student researcher’s component of the study

Student Researcher Component We anticipate that the student will do the actual chart review to look for errors. They will have close oversight from both their supervisor and co-supervisor. There may be clinical components which they do not yet have experience of, and the supervisor will be on hand to help with this. The supervisor will review the first 5-10 patients with the student, until they have a firm grasp of how to navigate the relevant data independently.
While there may not be sufficient data to have a large publication from this project, we are able to provide the opportunity for the student to present their findings at:

  • Local ED departmental meeting/teaching
  • Local hospital Grand Round
  • NZ Clinical Toxicology Forum Webinar

Student prerequisites

The successful student should have an interest in clinical toxicology, as well as an enthusiasm for reducing human error in medicine.

How to apply