Patrick Saintas 2007

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Introduction

• This Topic is part of the overall package on the safe administration of medicine and Fluid replacement therapy

Aims

• Facilitate your understanding of the metric system in measuring the quantity of drugs

• Build upon your familiarity with units of measurements

• Provide a number of examples and exercises to facilitate the development of skills in converting from one base unit to another

Learning Objectives

After working through this package, the user should be able to:-

• Explain the need for nurses to be conversant with the metric system

• Describe the need for a universal system of measurement such as the SI units in the prescription and administration of drugs

• Undertake the conversion of one base unit to another

The Metric System

• System used for measuring the quantity of drugs

• Use in the UK and many other countries of the world for measurements in clinical and pharmaceutical practice

• Already familiar with this measuring system- the chief unit of weight in this system is the Kilogram

The Problem/confusion

• Units of measurements which meant nothing to any one else

• Necessity of a uniform system• 1960 saw the adoption of the “Systeme

Internationale des Unites” SI units• SI units are simply metric units- The

internationally agreed versions of the metric system

• Use of SI ensured that all quantities expressed in metric units will be stated in the same manner in all disciplines

Metric System’s Familiarity

• Already familiar with many SI units• Pause the presentation to make a list of some of

the units you are familiar with.• You may wish to have a look at this link to view

a number of measurements used in real life http://www.thinkmetric.org.uk/index.html

• Check the items from this link against those which you may have listed in your maths’ diary and journal.

Units

Quantity Unit Symbol

Length Metre m

Mass/Weight Kilogram Kg

Time Second s

Temperature Degree Celsius oc

Volume Litre L

Multiple Units• Prefixes such as Kilo, milli and

micro are used to express large or very small quantities

• A Kilo is equal to 1000 and is represented by the symbol K

• A milli is 1divided by 1000 and is represented by the symbol m

• A micro is 1 divided by 1000 000 and is represented in clinical setting by the letter mc or is written in full, e.g microgram

10001

10000001

Multiple Units (Contd)

• A unit can be expressed either by writing its name in full (e.g gram), giving the appropriate prefix if necessary (e.g milligram)

Or• By putting the symbol for the prefix in front of the

symbol for the basic unit.

for example mg

milligram

• Care is needed to ensure that the symbols are accurate and that capital letters and small letters are properly differentiated

e.g M is the symbol for mega which means a million = 1000000

m is the symbol for milli =

Caution

10001

Application

• Drugs Millilitre (mL) and

Milligram (mg) have been used in metric quantities for some years

Errors are most likely to occur with milligrams and micrograms- it is recommended that no abbreviation should be used when prescribing or labelling medicine- it should be written as microgram.

Conclusion

• Hope that you have found this package helpful as background information. Please do not forget to complete your maths' diary and your journal

• Please have a go at the conversion exercises and quiz

• Have a look at the Resources in the topic area of the course site