Module (1) – Intravenous Medications

IV access

IV Drug administration

Calculating Drug doses

IntroductionThis module, as with the other four, is designed so you may do the steps at any time over the next six months. You may re-visit the website whenever you wish, download the entire module, print it off or indeed repaper your bathroom with it.

However the skills and knowledge contained within it are essential to being a PRHO so you should be familiar and competent with them all before you qualify. They are often assessed and may be included in an assessment prior to finals. You should include all notes and answers in your PPD folder which will be appraised but not formally assessed

Aims and ObjectivesThis module is designed to facilitate your

learning around intravenous medications.

By the end of this module you should be• Aware of the steps necessary in obtaining

IV access.• Aware of the steps necessary to draw up

and administer an intravenous drug.• Able to calculate the dose of an IV

medication before administering it.

Challenging Practice

Before you start this part of the module

• Write out the generic steps you carry out every time you perform a procedure e.g. gain consent; wash hands

• Write out the specific steps for the following procedures

- Gaining IV access

- Drawing up an IV medication

- Administering an IV medication

Part (a) – Skills practiceIn order to perform the skills in this part of the

module – you will need to be in a skills centre with access to :-

• A mannekin arm• IV access set• IV medication (you can use saline or similar)• The drug chart provided

You will need to think what specific items you will need for each skill

Generic approach to all procedures• Introduce yourself with name and role• Check you have the correct patient by introduction and ID band (if in-patient)• Explain procedure and gain verbal consent – ‘Is that alright / OK?’• Check you have ALL the appropriate items to do the procedure and they are in

working order.• Wash hands prior and after procedure• Position the patient for ease of procedure and their comfort; Ensure they are able to

maintain this position for the duration of the procedure.• Proceed explaining and reassuring as you carry out the procedure.• Once completed thank the patient AND reposition them comfortably whilst

maintaining their dignity.• CLEAR UP THE MESS! Place sharps and other similar items e.g. bloodied items,

into the sharps bin.• Explain / Confirm to nursing staff what you have done and what if anything you

would like done as a result e.g. ‘I have re-sited a cannula in the left arm to be used for IV antibiotics’; Indwelling catheter – ‘Please measure and record hourly urine output’; Agree any observations that may need to be done and other issues – NBM; Analgesia; Possible complications.

• Record procedure in the notes – include any difficulties and possible complications. Accurately record any conversation with patient and relatives around these problems.

Siting a Peripheral Intravenous Cannula• Follow generic guidelines for all procedures• For this trick you will need

– Tourniquet– Gloves– Appropriate sized iv cannula– Steret – Cannula dressing e.g. vecafix– IV saline flush – saline; syringe and ‘drawing up’ needle– Sharps bin

• Having gained verbal consent, place patient’s arm comfortably on bedside or similar.• Ensures all correct equipment present; Draw up saline flush• Put on gloves• Place tourniquet on arm• Identify appropriate vein• Clean area with steret• Warn patient of sharp jab• Insert cannula into vein at approximately 45 degrees; Look for flash back.• Undo the tourniquet• Remove introducer whilst advancing the cannula; once sited cap it.• Fix cannula to skin with appropriate dressing• Flush the cannula using the saline flush.• Dispose of sharps and other items correctly.• Explain to staff what the cannula is to be used for and where it is sited.• Explain (when challenged) what they would do if the cannula is not sited successfully.

Drawing up an Intravenous Medication

This part of the procedure is often assessed in isolation but you should think about it as part of the administration of an IV medication; You will need to check you have the correct patient, explain to them what you are going to do, check they have no contra-indications or allergies to the medication. Then you can draw up the drug.

Drawing up an Intravenous MedicationCheck• You have the correct patient and drug chart.• The drug chart for drug, dose, route and time of administration.• You have all the necessary equipment

- ‘Green’ needle; appropriate syringe; the drug ampoule; steret; saline flush and for powdered preparations - mixing solution i.e. saline, water for injection or dextrose.

• Drug against drug chart and ensure it is in-date and correct dose• Mixing solution is correct and in-dateFor pre-mixed solutions simply draw up the medication into an appropriate syringe

For powdered preparations• Tear off protective cover from drug ampoule and clean with steret• Draw up appropriate volume of mixing solution• Insert needle into drug ampoule and inject small volume (1-2 ml) of solution; never force

the solution against pressure (unless you want to wear it!)• Gently mix the powder and solution; You may need to add a little more solution to

completely dissolve the powder. DON’T shake as this will lead to excessive bubbles and froth

• Once dissolved, draw the mixed solution back into the syringe; If you inject a little air from the syringe into the ampoule you will find the solution is drawn back into the syringe.

• Once all the solution is drawn up – make sure it is mixed and eject any air bubbles.• Keep the syringe hub covered until you are ready to inject the medication

Administering an intravenous medication

• Introduce yourself with name and role• Check you have the correct patient by introduction and ID band• Explain procedure and gain verbal consent – ‘Is that Ok?’• Check they have no

– Known drug or other allergy history – Contra-indications to the intervention

• Check the drug against the prescription• Check the drug is ‘in date’ ie not time expired• Administer drug slowly – usually over approximately 1 minute.• Sign for it on the drug chart.• Agree with nursing staff what you would like them to do next –

observations, monitor response, potential side effects or complications.

• Ask yourself ‘Are there any sequelae I need to consider as the PRHO?’ e.g. Monitor levels, Check bloods (FBC - post transfusion; U+Es – post IV diuretics, ACEI).

Calculating doses of IV medications

• When calculating the doses of any medication whether it be tablets, elixir, IV or IM injections or infusions it is essential to get the dose and the units correct. By following simple rules you should be confident in your ability to get the dose correct every time – getting it wrong can be fatal!

• For many of you with mathematic backgrounds, calculation using algebra is relatively easy. The following use of dimensional analysis may seem very basic but will keep you amused whilst the rest of us mere mortals struggle

Dimensional AnalysisDimensional analysis is commonly used by chemistry and physics students to ensure they don’t make basic calculation errors when using lots of values in an equation with different units; Each time one converts one unit to another we use a conversion factor, which we will call the dimensional analysis conversion factor (DACF) e.g 450g to kg – the DACF = 1000g / 1 kg

Thus 450g / Xkg = 1000g / 1 KgXKg = 450g x 1 Kg

1000g = 0.450 Kg

Dimensional analysis ensures that both sides of an equation are ‘singing from the same hymn sheet’. I.e. The units on both sides are the same. By cancelling the units above and below the line, the units you are left with on one side should equal those of the value you are seeking. If they don’t match, you have mucked up somewhere! However it will not ensure your maths is correct.

Dimensional analysisExample One

Farmer Giles is a sheep farmer. He is required by the Ministry of Agriculture to wash his sheep in a new wool protector. He is told by the ministry literature that if he washes 20 sheep per hour for 12 hours per day he can wash his entire Flock in 3 days.

Farmer Giles keeps his sheep in separate areas of the farm and uses his own nomenclature for his groupings. There are 5 sheep in a ‘BOX’, 5 Boxes in a ‘CORRAL’ and 5 Corrals in a ‘FLICK’. He estimates he has 10 FLICKS around the farm completing his FLOCK. Please calculate if the Ministry literature is correct.

Well did you get it correct? – Here’s the solution using dimensional analysis

20 sheep / hour = How many FlicksX Flicks = 20 sheep x IBox x 1 corral x 1 Flick1 hour 1 hour x 5 sheep x 5 Box x 5 corral

Note: the units all cancel each other out so you know you have flick/ hour as the units which means the equation is ok

= 0.16 FLICK / hourIf he works twelve hours per day for three days

= 0.16 x 12 hours / day x 3 days= 1.92 x 3= 5.76 Flicks in 3 days

If he has 10 flicks around the farm he will be there a few more days and thus he tells the Ministry to go take a running jump!

If that one confused you – try this one borrowed from www.wine1.sb.fsu.edu/chm1045/notes/Intro/Dimanal/Dimanal.htm - Dr

Michael Baker – a teacher with a similar outlook on education!

Dimensional analysis for party planning…

If you have ever had a party you have used dimensional analysis. The amount of beer (or soft drinks) and munchies you will need will depend on the number of people you expect. For 30 people you may estimate you need to go and buy 120 bottles of beer and 10 large pizzas (obviously not a medic party!) How did you guestimate these numbers? Here’s the dimensional analysis.

4 bottles / person and 1/3 of a pizza per person

30 persons x (4 beers) = 120 beers

person

30 persons x (0.333 pizza) = 10 pizzas

person

But should you buy beer in six packs or cases? – 1 case = 4 six packs = 24 Beers

120 beers x 1 six pack x 1case = 5 cases

6 Beers 4 six packs

1 case / 4 six packs = 5 cases / x six packs = 20 six packs it’s easier to carry cases so buy the cases!

Dose of medication = Rate of Infusion x Concentration

For each of the examples below you will need to use the following equations. Please refer back to them as you work through the problemsDose of medication = Rate of Infusion x Concentration

Where:Dose = volume or mass or units E.g. mcg / kg / min

unit time (usually minutes)Rate = volume in ml = ml per hour unless infusing

unit time (Hrs) an infusion in less than 1 hour

Concentration = dose available I.e. mg or mcg per ml

volume available

Infusion Rate From Dose = Rate x Concentration

Rate = Dose x 1 Concentration

If Concentration e.g. 250 mg / 1000mlThus Rate (ml) = Dose x 1000ml

Hr 250mgThis is a useful equation to remember for drip rates which are set in ml/Hr when run through a pump

Try this one for size ….

You are asked to set up an infusion with a pre-mixed bag of Phenytoin. The bag contains 1000mg / litre and you need to give an infusion of 500mg over 6 hours. What rate will you set the pump at (ml/hr) – Try to use multidimensional analysis to ensure your units are correct.

Ooh! – Suits you Sir!

Rate Xml = 500mg x 1000ml (Units are correct)

Hr 6Hr 1000mg

= 83.3 ie 83ml/Hr

Calculate the doses required for the following medications

(1) You are asked to give a patient 3mg/kg of gentamicin once per day. The patient weighs 83kg. How much will you give him?

(2) A patient is to be given 70mg of clexane. The only preparation contains 120mg in 5mls. What volume of clexane preparation will you draw up?

(3) A 50Kg patient is receiving 2g of killabug every eight hours. The recommended dose is 100 – 300mg/kg/day. Is the prescribed dose appropriate?

Hopefully you felt I was insulting you!

(1) 83Kg x 3mg = 249 mg Total

(2) If in 5mls there are 120mg – How many mls are needed for 70 mg?

5mls = Xmls Thus X = 70mg x 5mls = 2.92mls

120mg 70mg 120mg

Thus you would draw up 3 mls – as this is most appropriate volume

(3) 2g / 8 hourly = 6g / 24 hours

How many milligrams / Kg / 24 hours?

6g x 1000 mg x 1 = 120 mg / kg / 24 hours

24hrs 1g 50Kg

Thus the dose is appropriate

Try these for size …(1) You are asked to draw up and give 0.25 mg of Digoxin.

The vial contains 500mcg per ml. How many ml will you administer?

(2) A patient is prescribed Amoxycillin syrup 500mg tds. The syrup is 125mg/5ml. How many ml will you prescribe per dose?

(3) A patient is prescribed 250 mg of Augmentin IV. The nurse tells you that there are 600mg in the 5ml vial. How many ml will you draw up?

(4) A patient is prescribed Hy-life 400mcg subcut. You can only find a vial with 0.5mg / 5ml. How many ml will you administer?

Just taking the Michael aren’t I?

Answers – You will need to show your workings

(1) 0.5ml

(2) 20ml

(3) 2.1ml

(4) 4ml

And finally on this infusion front ..

You are asked to draw up and give an infusion of gentamicin over 45 minutes. The patient is to receive 3 mg / Kg and weighs 100Kg. The infusion is to be made up in a 50 ml bag of D5W.

What is the rate of the infusion set in ml/Hr?

Either …Or ….Rate ml = (3 x 100) mg x 50ml x 60 mins

Hr 45 mins (3 x 100mg)

= 50 x 60 = 66.7 = 67 ml / Hr

45

Or If 50 ml = Xml Thus X = 50 x 60 = 67 ml / Hr

45 mins 60mins 45 mins

Last Infusion calculation for 30 Km

An infusion of Kilabug is made up to be 2g in 500ml D5W. It should run at 3mg / minute. What rate will you set the infusion pump in ml/Hr?

Last Answer Saloon ….

An infusion of Kilabug is made up to be 2g in 500ml D5W. It should run at 3mg / minute. What rate will you set the infusion pump in ml/Hr?

(Did you use the sexy Multidimensional analysis or was it just too easy??)

Rate (ml) = 3mg x 500 ml x 60 mins x 1g = 90 = 45 mls

Hr 1 min 2g 1hr 1000mg 2 Hr

And now for something completely different ..

When you have been on anaesthetic or ITU attachments have you ever wondered what the 1: 10,000 or 2% by volume actually means?

Well let me put you out of your misery …

When a solution is written as 1:X,000 = Mass (g) : Volume (ml)Thus 1:1000 = 1g per 1000ml = 1g x 1000mg per 1000ml

1g = 1000mg per 1000ml

I.e 1mg per 1ml = 1mg / mlSo 1:10,000 is 1mg per 10 ml

A 2% solution means Mass (g) per 100ml volumeThus 2% = 2g per 100ml

2g x 1000mg per 100ml 1g

I.e. 2000mg per 100ml = 20mg per ml = 20mg /ml

Here’s some to tickle your ventricles(1) How many ml of 1:10,000 ADR will you draw up to

contain 0.25mg ADR?

(2) How many mg of ADR in 4ml of 1:1000 ADR?

(3) How many mg of Lignocaine are there in 25ml of 2% solution?

(4) You are asked to mix up a solution of Lignocaine with 250mg of Lignocaine 250ml. What is the mass by percentage (X%) solution you have mixed?

(1) How many ml of 1:10,000 ADR will you draw up to contain 0.25mg ADR?

Answer 1g per 10,000ml = 1mg/10ml 1mg = 0.25mg 10ml X ml

Thus you should draw up 2.5ml

(2) How many mg of ADR in 4ml of 1:1000 ADR?Answer 1g : 1000ml = 1mg / ml Thus 4mg of ADR in 4ml

(3) How many mg of Lignocaine are there in 25ml of 2% solution?2% = 2g / 100ml = 2000mg per 100ml = 20mg per ml

Thus in 25 ml - 25x 20 = 500mg Thus 500 mg Lignocaine

(4) You are asked to mix up a solution of Lignocaine with 250 mg of Lignocaine per 250ml. What is the mass by percentage solution you have mixed? 250mg per 250ml = 100mg in 100ml = 100mg x 1g = 0.1g: 100ml

1000mgThus 0.1g / 100 ml = 0.1% solution

Answers (1) 2.5ml (2) 4mg (3) 500mg (4) 0.1%

For further challenges …

Ability of hospital doctors to calculate drug doses – Rolfe S. and Harper NJN. – BMJ 1995, 310, 1173 -1174

Learning OutcomesBy the end of this module:(1) You should have practiced •Inserting an intravenous cannula•Drawing up and administering an intravenous medication(2) You should be able to calculate doses to be administered, infusion rates and mass by volume (1:X,000) and mass by percentage volume (X% solutions).

You will need to continue to practice these skills on all of your firms. They are necessary to be a competent PRHO and they may be assessed during this final year.

You will learn further skills around intravenous drips and infusions in module (4)

Recommended websiteswww.wine1.sb.fsu.edu/chm1045/notes/Intro/Dimanal/Dimanal.html

www.-isu.indstate.edu/nurs/mary/mathprac.html

www.classes.kumc.edu/son/nurs420/CalculatingDrugDosages.html

www.cs.jcu.edu.au/~michael/web/Sections6.html