Day4 Intravenous Fluids

8/6/2019 Day4 Intravenous Fluids

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Prescribing Intravenous Fluids and

Infusions

Intravenous Fluids

Fluid charts

Intravenous infusions


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Introduction

You will need to be competent in all areas

pertaining to the prescription of intravenous

fluids and infusions prior to becoming a

PRHO; This module will direct yourlearning but it is up to you to put the

knowledge and skills into practice. The

skills included in this module should be

attempted in a skills centre before being

practiced in the clinical setting.


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Aims and ObjectivesThis module is designed to direct your learning

around the knowledge and skills associated withintravenous fluids and infusions

By the end of this module students should be awareof

The different intravenous fluids available

The main differences between their composition,side effects and clinical application

How to prescribe fluids on a fluid chart

The steps required in setting up an intravenousinfusion

How to calculate the rate of a drip

How to calculate the rates and dosage of infusions


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Aims and Objectives

Many of the aims and objectives for thismodule follow on from modules (1) and (2)- You may feel this a little repetitive but itmeans you will be highly competent (never

a bad thing) in performing the skills andapplying the knowledge. Please miss therepeated sections if you feel confident;However you must include the examples

and calculations in your PPD folders. Youcan re-visit the website whenever you feelthe urge and print/copy any sections!


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Challenge to Knowledge and Practice

Before starting this module

(a) What do you understand by the terms

crystalloid and colloid

(b) List some examples of each

(c) Give some examples of circumstances

where you would prescribe a crystalloid.

(d) Which patients should not receive normalsaline unless closely monitored?


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Colloids and Crystalloids - What Surgeons and

Anaesthetists talk about over coffee

Intravenous fluids may be divided into

Crystalloid solutions - clear fluids made up of waterand electrolyte solutions; Will cross a semi-permeablemembrane e.g Normal, hypo and hypertonic saline

solutions; Dextrose solutions; Ringers lactate andHartmanns solution.

Colloid solutions Gelatinous solutions containingparticles suspended in solution. These particles will not

form a sediment under the influence of gravity and arelargely unable to cross a semi-permeable membrane. e.g.Albumin, Dextrans, Hydroxyethyl starch [HES];Haemaccel and Gelofusine


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Saline Solutions(1) 0.9% Normal Saline Think of it as Salt and water Principal fluid used for intravascular resuscitation and replacement of salt loss e.g

diarrhoea and vomiting

Contains: Na+ 154 mmol/l, K+ - Nil, Cl- - 154 mmol/l; But K+ is often added IsoOsmolar compared to normal plasma

Distribution: Stays almost entirely in the Extracellular space

Of 1 litre 750ml Extra cellular fluid; 250ml intravacular fluid

So for 100ml blood loss need to give 400ml N.saline [only 25% remains intravascular]

(2) 0.45% Normal saline = Half Normal Saline = HYPOtonic saline Reserved for severe hyperosmolar states E.g. H.O.N.K and severe dehydration Leads to HYPOnatraemia if plasma sodium is normal

May cause rapid reduction in serum sodium if used in excess or infused too rapidly. Thismay lead to cerebral oedema and rarely, central pontine demyelinosis ; Use withcaution!

(3) 1.8, 3.0, 7.0, 7.5 and 10% Saline = HYPERtonic saline Reserved for plasma expansion with colloids In practice rarely used in general wards; Reserved for high dependency, specialist areas

Distributed almost entirely in the ECF and intravascular space. This leads to an osmoticgradient between the ECF and ICF, causing passage of fluid into the EC space. Thisfluid distributes itself evenly across the ECF and intravascualr space, in turn leading tointravascular repletion.

Large volumes will cause HYPERnatraemia and IC dehydration.


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Dextrose solutions(1) 5% Dextrose (often written D5W) Think of it as Sugar and Water Primarily used to maintain water balance in patients who are not able to take

anything by mouth; Commonly used post-operatively in conjuction with saltretaining fluids ie saline; Often prescribed as 2L D5W: 1L N.Saline [Physiologicalreplacement of water and Na+ losses]

Provides some calories [ approximately 10% of daily requirements]

Regarded as electrolyte free contains NO Sodium, Potassium, Chloride orCalcium

Distribution: 66% intracellular

When infused is rapidly redistributed into the intracellular space; Less than 10%stays in the intravascular space therefore it is of limited use in fluid resuscitation.

For every 100ml blood loss need 1000ml dextrose replacement [10% retained inintravascular space

Common cause of iatrogenic hyponatraemia in surgical patient

(2) Dextrose saline Think of it as a bit of salt and sugar Similar indications to 5% dextrose; Provides Na+ 30mmol/l and Cl- 30mmol/l Ie a

sprinkling of salt and sugar! Primarily used to replace water losses post-operatively

Limited indications outside of post-operative replacement Neither really saline ordextrose; Advantage doesnt commonly cause water or salt overload.


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Colloid solutions The colloid solutions contain particles which do not readily

cross semi-permeable membranes such as the capillarymembrane

Thus the volume infused stays (initially) almost entirelywithin the intravascular space

Stay intravascular for a prolonged period compared to

crystalloids However they leak out of the intravascular space when thecapillary permeability significantly changes e.g. Severetrauma or sepsis

Until recently they were regarded as the gold standard forintravascular resuscitation (see next slide)

Because of their gelatinous properties they cause plateletdysfunction and interfere with fibrinolysis and coagulationfactors (factor VIII) thus they can cause significantcoagulopathy in large volumes.


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The Colloid / Crystalloid debate An interesting

night out with Surgeons and Anaesthetists

Until recently the use of colloid or crystalloid in acute resuscitation was a point ofheated debate between surgeons and anaesthetists

Through their redistribution after infusion it takes approximately 2- 3 x volume ofcrystalloid to cause the same intravascular expansion as a single volume of colloid

Thus in unstable patients, with hypotension and tachycardia, colloid, often in largevolumes (3 4 units) were immediately infused in preference to crystalloid

However in the last 5 - 10 years there have been several meta-analyses of the literaturearound this subject

Results suggest

(a) No short or long term benefits of the use of colloid in the resuscitation of patientswith severe sepsis, trauma, haemorrhage, burns or coronary artery by-pass. In severelyill patients with sepsis and trauma there was in fact a significant rise in mortalitycompared to the use of crystalloid

(b) However, in patients undergoing elective surgery there was a rise in mortalityusing crystalloid compared to colloid when used for restoring the intravascular volume.


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Colloid orCrystalloid Resuscitation -

what should you do?Recommendations: Colloid should NOT be used as the sole fluid replacement

in resuscitation; Volumes infused should be limitedbecause of side effects and lack of evidence for theircontinued use in the acutely ill.

In severely ill patients principally use crystalloid andblood products; Colloid may be used in limited volume toreduce volume of fluids required or until blood productsare available

In elective surgical patients replace fluid loss with

physiological Hartmanns and Ringers solutions; Bloodproducts and colloid may be needed to replaceintravascular volume acutely

Dont get in between an anaesthetist and a surgeon whenthe words colloid and crystalloid are mentioned!


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The Fluid chart


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The Fluid Chart You need to fill in all the areas of the chart, just like a drug

chart.

Useful to record the patients weight if known; Guestimateand record it if not.

You will note there is a drop rate advised at the bottom of

the chart shown in the previous slide

Using one of the blank charts supplied - Pleasewrite up 3 x 1litre of normal saline with 20

mmol/l of KCl in each litre to run at 1litre/ 8hourly; Patient is Mr Ali Khan Number326587, DOB 13/09/81, weight 81Kg.Consultant Ms Cuttem; Ward B3


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Your fluid chart should look something like this. (I

have written it out twice as I was unconvinced of my

first attempt)


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So now youre experts and all aglow,

Have a go, at the examples below

(Dr Zeus and the IV calculations)

Using the fluid charts provided please prescribe intravenous fluids for thefollowing patients for the next 24 hours. You may wish to ask a friendlyPRHO or SHO for advice with regard the correct fluid regimes.

(a) A 29 yo man who is nil by mouth awaiting an OGD for a small upper GIbleed. He is haemodynamically stable and well.

(b) A 74 yo woman who is 24 hours post laparotomy. The drains contain180mls of blood stained fluid. She is NBM; BP 105 /70, Pulse 96 bpm.

(c) A 17 yo man admitted with suspected salmonella gastroenteritis. He ispassing frequent fluid like stools and vomiting hourly. Urea 9.6mmol/l; BP110/70, Pulse 100 bpm

(d) A 34 yo Type 1 Diabetic man who is admitted with DKA secondary tourinary sepsis; BP = 90/60, Pulse 120 bpm; Urea 38.9mmol/l Creatinine231 mol/l.

(e) A 91 yo man who is admitted with severe dehydration, left sidedhemiparesis and carpet burns. He is confused but it is estimated he has beenon the floor of his bedroom for 72 hours. BP = 100/70, Pulse 120 bpm,Urea 42.6mmol/l , Creatinine 311 mol/l, CK 12,098 iu/l


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Calculating the correct infusion rate

If you feel confident calculating infusionrates and drop rates please skip to the

calculation exercises. If not here are the

basic calculations we used in the blood

transfusion module.

Please include these calculationexercises in your folder


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Example one Calculate the Transfusion rate

E.g. A unit of blood is prescribed to run over 4 hours; The giving set has adrop factor of 20 gtt /ml. What is the drip rate (drops /min) ?

Drip rate = 400 ml x 20 gtt ; Drip Rate is drops / minute

4 hour 1ml

Thus Drip Rate = 400ml x 20 gtt x 1 hour

4 hour 1 ml 60 minutes

By multidimensional analysis units are correct (drops / minute)

Drip Rate = 100 / 3 = 33 drops / minute

Drop rate is rounded up or down to the nearest drop

In the clinical setting to be able to count drops / minute it is sensible to

have a number divisable by 4 - Thus you would set this drip at 32

drops per minute


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Converting drip rate (gtt /min) to ml /hour

In high dependency areas caring for critically illpatients it may be necessary to know the infusion

rate in ml/hour this is important in setting

infusion pumps (usually set in ml/hour) and when

calculating fluid balance.

E.g. What is the transfusion rate in ml /hour of a

blood transfusion being run at 40 drops /minute through a giving set with drop factor of

20 gtt / ml?


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E.g. What is the transfusion rate in ml /hour of a blood

transfusion being run at 40 drops / minute through a

giving set with drop factor of 20 gtt / ml?

If there are 40 drops in one minute then in 1 hour

40 drops = X drops thus X = 40 x 60 = 2400 drops / hour

1 minute 60 minutes

If the giving set has drop factor of 20 drops/ 1 ml

20 drops = 2400 drops thus Xml = 2400 = 120 ml / hour

1 ml X ml 20

Therefore one could set an infusion pump to deliver this

volume or it can be factored into the fluid input /hour.


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Please work your way through the following

problems.

(1) You are asked to run an intravenous infusion of 1litre of D5W over 6 hours.What drop rate will you set the infusion at if the giving set has a drop factorof 10 gtt/ml?

(2) You are asked to set up a 1litre normal saline infusion to run over 10 hours.The giving set has a drop factor of 20 gtt / ml. what rate will you set thedrip at in drops/minute?

(1) A 91 yo woman is receiving intravenous fluids for dehydration. The SHOasks you to make sure her drip is running at the correct rate as he isconcerned she may rapidly go into heart failure if it is infused too quickly.

There are 350ml remaining of a 1000ml bag which has been running for 6hours. It is prescribed to run through in 12 hours. The drop rate is 10 drops/minute and the giving set has a drop factor of 20gtt/ml. How long will thepresent drip take to run through? What adjustments (if any) will you needto make to ensure the drip runs through in 12 hours as prescribed?


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You are asked to run an intravenous infusion of 1litre of

D5W over 6 hours. What drop rate will you set the infusion

at if the giving set has a drop factor of 10 gtt/ml?

Drops = 1000ml x 1 hour x 10 gtt

Minute 6 hours 60 mins 1ml

= 1000 = 27.8 drops / min36

Since we always round up or down to the nearest drop

the actual rate will be 28 drops / minute


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You are asked to set up a 1litre normal saline infusion to run

over 10 hours. The giving set has a drop factor of 20 gtt / ml.

what rate will you set the drip at in drops/minute?

Drops = 1000ml x 1 hour x 20 gtt

minute 10 hr 60 min 1 ml

= 100 = 33 drops / minute

3


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A 91 yo woman is receiving intravenous fluids for dehydration. The SHO asks you to make sure her drip

is running at the correct rate as he is concerned she may rapidly go into heart failure if it is infused too

quickly. There are 350ml remaining of a 1000ml bag which has been running for 6 hours. It is prescribed

to run through in 12 hours. The drop rate is 25 drops /minute and the giving set has a drop factor of

20gtt/ml. How long will the present drip take to run through? What adjustments (if any) will you need to

make to ensure the drip runs through in 12 hours as prescribed?

Present Rate

650 ml = 1000ml Thus X = 6000 = 9.2 hours

6 hours X hours 650

To Run in 12 hours

X drops = 350ml x 1 hr x 20 drops pm

minute 6 hr 60 min 1ml

= 350 =19 drops / minute

18

Thus you will have to change the rate of the drip to run at 19 drops /

minute ie reduce the rate by 6 drops/ minute


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A 750ml infusion of 5% dextrose is infusing at 65gtt/min. The drop factor

of the giving set is 60 gtt/ml. How long will the infusion take?

65 gtt = 750ml x 60 gtt x 1 hr

min X hr ml 60min

X = 750 x 60 x 165 x 60

X = 11.5 hours


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A litre of normal saline is meant to be running over 8 hours. The drip is

set at 83gtt/min,the giving set has a drop factor of 20gtt/ml.

83 drops = 1000ml x 20 gtt x 1 hr

min X hr ml 60min

X hr = 20,000 = 20,000 = 4 hours

83 x 60 4980

Thus you need to halve the drops /min to 42 drops / minute


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A litre of 5% dextrose is running at 80 gtt/min. The drop factor is

60 gtt/ml. What will the pump be set at in ml/Hr.

If 80 drops = X dropsminute 60minutes

X = 60 x 80 = 4800 drops / Hr

If 60 drops = 4800 drops

1ml Xml

Xml = 4800 = 80mls / Hr

60


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Try these for size ..(1) A heparin infusion is prescribed to run at 5000 units / Hr. The infusion is made up of

25,000 units in 500ml 5% dextrose. What rate in ml/hr will you set the pump?

(2) An aminophylline infusion is running at 30ml/hr. There is 0.5g / 500ml. It should berunning @ 12mg / hour. What is the infusion rate and what will you do to ensure itruns at the correct rate?

(3) 2g of Kilabug is mixed up in 500ml of 5% dextrose. It is set to run at 5mg / min.What rate in ml/hr will you set the infusion pump?

(4) A patient is on a GTN infusion for pulmonary oedema. The infusion is made up of50mg in 250ml 5% dextrose. It is presently running at 20ml/hr. How many mcg /minute is the patient receiving?

(5) A patient is started on an inotrope infusion for cardiogenic shock. The infusion is750mg in 250ml N. saline. It is running at 5 ml/hr. The patient becomes increasinglyhypotensive and his urine output is dropping off. The infusion rate is changed to

12ml/hr. The patient is 70Kg. What dose in mcg / Kg/ min is the patient receiving?

(6) A second patient who weighs 100Kg is on an inotrope infusion running at10mcg/kg/min. You receive a pharmacy prepared bag with 1g in 500ml. A what rate(ml/hr) will you set the pump


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A heparin infusion is prescribed to run at 5000 units / Hr. The

infusion is made up of 25,000 units in 500ml 5% dextrose. What

rate in ml/hr will you set the pump?

Rate (ml) = 5000 units x 500ml

Hr 1 hour 25,000 units

= 100 ml / Hr


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An aminophylline infusion is running at 30ml/hr. There is 0.5g /

500ml. It should be running @ 12mg / hour. What is the infusion

rate and what will you do to ensure it runs at the correct rate?

30 ml = Xmg x 500ml x 1g

1 hour Hour 0.5g 1000mg

X = 30 mg / hrThe drip should be running at 12 mg/hr

Thus need to reduce the rate to 12 ml/hr

(30mg: 12mg = 30ml:12ml)


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2g of Kilabug is mixed up in 500ml of 5% dextrose. It is set to run

at 5mg / min. What rate in ml/hr will you set the infusion pump?

Rate Xml = 5mg x 60 min x 500ml x 1g

Hr min 1 hr 2g 1000mg

Rate = 75ml /Hr


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A patient is started on an inotrope infusion for cardiogenic shock. The

infusion is 750mg in 250ml N. saline. It is running at 5 ml/hr. The patient

becomes increasingly hypotensive and his urine output is dropping off. The

infusion rate is increased to 12ml/hr. The patient is 70Kg. What dose in mcg /

Kg/ min is the patient now receiving?

12ml = X mcg x 250ml x 70Kg x 60 min x 1mg

Hr min.Kg 750mg 1hr 1000 mcg

X = 8.6 mcg / Kg / min


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A second patient who weighs 100Kg is on an inotrope infusion

running at 10mcg/kg/min. You receive a pharmacy prepared bag

with 1g in 500ml. At what rate (ml/hr) will you set the pump?

Rate ml = 10 mcg x 500 ml x 100Kg x 60 min x 1g x 1mg

Hr Kg.min 1g 1 hr 1000mg 1000mcg

= 30 ml / hr


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Mr Jones in extremis

Mr Jones is a 60 year old man with known IHD. He is brought to A&E in

extemis (makes a change from an ambulance) after suddenly becoming short ofbreath whilst watching television. He is clinically and radiologically in severe

pulmonary oedema.

He is electively ventilated and sent to ITU. He is started on

Frusemide 50mg/ml running at 5mg/hr

Dobutamine 500mg in 250ml running at 8mcg / Kg.min

GTN 100mg in 500ml running at 20 mcg / Kg.min

He weighs 80 Kg. After one hour he is haemodynamically stable and his urine

output is satisfactory.

(1)What rate is the GTN infusion running at in ml /hr?

(2)What rate is the dobutamine infusion running at in ml /hr?

Overnight he goes into fast AF and is started on an Amiodarone infusion.After the

loading dose, he is started on 5mcg/kg/min. The infusion is 500mg in 50ml.

(3) What rate in ml/hr is the pump set out?


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Mr Jones still unwell

Overnight he goes into fast AF and is started on an Amiodarone infusion.After the

loading dose, he is started on 5mcg/kg/min. The infusion is 500mg in 50ml.(3) What rate in ml/hr is the infusion pump set out?

Despite the infusion he remains in fast AF and the SpR asks you to increase theinfusion to 5ml/hr. However the ITU nurse tells you that the maximum dose ofamiodarone is 12 mcg/kg.min.

(4) What is the maximum rate of the infusion?

Two days later he develops severe gram negative sepsis. He is started on agentamicin infusion. The dose recommended by the microbiologist is 3mg/Kg.The dose is made up in 50 ml D5W and is meant to run over 45 minutes.

(5) What rate (ml/hr) will you set the infusion rate?

You will need to show the workings for each calculation.The answers are shown overleaf.


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Mr Jones case - Answers

(1) 6 ml/hr(2) 19.2ml/hr

(3) 2.4 ml / hr

(4) 5.8 ml/hr

(5) 66.7 ml/hr


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Learning outcomes

At the end of this module you should now:-

Be aware of

The difference between crystalloids and colloids

The clinical indications for the different fluids

The steps required in setting up an intravenousinfusion

Be able to

Prescribe fluids on a fluid chart Calculate the rate of a drip

Calculate the rates and dosage of infusions


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Recommended websites

www.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

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Day4 Intravenous Fluids