fluids in healthcare.
In two separate Scottish nursing homes ‘International Unit’ had been shortened to ‘IU’. A prescription for 6 units of insulin became 61U, resulting in the patients receiving 61 units.
Communication errors
Communication is a vital part of healthcare and the quality and accuracy of writing is a source of calculation mistakes.
In 2005, a baby died in a Liverpool hospital after being given 15 000 units of the anticoagulant heparin instead of the prescribed 1500 units. The hand-written prescription read 1500U and the nurse mistook the ‘U’, wrongly used as an abbreviation for units, for a zero.
ERROR ALERT
Sometimes, what appears to be a drug calculation error isn’t.
At a West Midlands hospital in 2011, a nurse gave a patient ten times the amount of prescribed potassium chloride, an electrolyte that influences the heart rate and contraction. Predictably the patient suffered a fatal cardiac arrest.
The nurse had calculated the correct dose but did not get another nurse to witness the administration of the drug.
If another nurse had observed the administration (as demanded by the checking procedure), it would have become apparent that the infusion pump was set up wrongly, allowing it to give ten times the prescribed dose.
This catastrophic series of events, resulting in a patient death, was because of an administration error, not a calculation mistake.
Numeracy skills are essential in nursing, but following standardised procedures and being proficient in the use of medical devices that control drug administration are of equal importance.
1.3 Developing your calculation and numeracy skills
Having scared you by describing the worst possible outcomes of calculation errors, I will now ask you not to get overly anxious about making a mistake! Concerns about nurses’ calculation skills have featured in the literature since 1939, and span the globe, so this isn’t a recent problem or one that only occurs in the UK. But drug and calculation errors are currently widely reported, probably because mistakes in the prescribing and administration of drugs account for 25% of litigation claims in the UK, and government pledges to reduce this by 40% have failed. More importantly, these kinds of mistakes are of serious concern to healthcare consumers and in the aftermath of the Francis report (2013) into the failings at the Mid-Staffordshire NHS Foundation Trust, they could be seen as a quality indicator. Remember though that drug calculation errors are rare.
Fortunately, there are many methods and techniques to ensure that your calculation and numeracy skills are robust, safe and fit for modern clinical practice. Good starting points include:
reading this book
taking the self-tests
practising calculations.
The theory part of calculations is covered within undergraduate courses leading to registration and revised on nurse prescribing and similar courses. Like any skill, it is important to practise and taking self-tests is a large part of this. Numeracy skills are an essential clinical skill, so expect to practise these alongside your other clinical skills.
Before starting on a clinical placement:
Spend a few minutes thinking about the potential opportunities that lie ahead.
Remember that patient assessment and admission, taking and recording physiological observation like temperature, pulse and blood pressure and recording a fluid intake and output chart all demand calculation skills apart from administering medicines.
If you are unsure of the learning opportunities available on your next clinical placement and how these might allow you to practise calculations:
Talk to the Link tutor from your university.
Talk to other students who may have spent time on the placement.
Visit the placement and meet with your mentor before starting.
There may be a booklet for students outlining typical learning opportunities. Aim to make the most of every minute of your clinical experience. Working alongside an experienced nurse and getting involved in drug rounds will help you develop the required calculation skills, as well as help you to become familiar with common drug doses and to recognise when something isn’t right.
Self-assessment test 1.1
To help you identify a baseline where you are starting from, try the following self-assessment test, using pencil and paper where necessary but not a calculator. The NMC standards dictate that Registered Nurses must be able to perform calculations without the use of a calculator. If you are unable to answer some of the questions don’t worry, as the whole purpose of this book is to increase your understanding of drug and clinical calculations.
Once you have completed the test, check your answers with the answer section at the end of the book. The feedback and suggested actions below will give you advice about which chapters and sections you need to focus on to develop your numeracy and calculation skills.
1 25 + 34 =
2 Write 1005 in words.
3 Which of the following numbers is the larger, 2858 or 28 580?
4 56 – 24 =
5 What does the zero in 860 mean?
6 5 × 9 =
7 How many more is 104 than 97?
8 74 + 87 =
9 Write out 960 012 in words.
10 6 × 8 =
11 105 – 76 =
12 What does the 5 in 2 450 198 mean?
13 9 × 12 =
14 How many more is 1204 than 89?
15 If you scored 80 out of a possible 125 in a test, what percentage did you achieve?
16 14 × 18 =
17 What does the zero in 19 061 mean?
18 115 / 8 =
19 How many micrograms are there in 0.65 milligrams?
20 Write 80% as a fraction.
21 1.61 × 2.38 =
22 How many grams are there in 0.823 kilograms?
23 102 – 78 =
24 Write 0.75 as a percentage.
25 5.912 × 8.647 =
26 1.643 × 0.724 =
27 How many milligrams are there in 1.2 grams?
28
