Applied Sciences Lecture Course IV fluid therapy Dr Cathy

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IV fluid therapy
Applied Sciences Lecture Course

• Dr Cathy Armstrong
• SpR In Anaesthesia Clinical Fellow in
  Undergraduate Medical Education
• Manchester Royal Infirmary
• April 2011

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Objectives

• Review relevant physiology
• IV fluid preparations
• Clinical Assessment of fluid balance
• IV fluid strategies
• Special circumstances
• Practice scenarios

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Physiology
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Body Fluid Compartments

• Total Body water is
• 60 of total body weight in males
• 55 of total body weight in females

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Body Fluid Compartments

• 70Kg Man

Solids (40)
?
Interstitial fluid 11 Litres
Water (60) 42 Litres
ECF 14 Litres
Plasma 3 Litres
?
ICF 28 Litres
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Body fluid compartments
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Daily Input Vs Output
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Electrolyte Composition of fluid Compartments
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3rd space losses

• 1st Spacing Normal distribution within ECF and
  ICF
• 2nd spacing accumulation within the interstitial
  compartments oedema formation but available for
  physiological exchange between compartments
• 3rd spacing Accumulation in parts of the body
  where its not available for exchange between the
  different compartments Ascitis, tissue
  inflammation, oedema from burns/surgery

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IV Fluid Types
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IV fluid types

• Crystalloids
• Colloids
• Synthetic
• Human

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Crystalloid

• A substance in solution that can diffuse through
  a semipermeable membrane
• Electrolyte-containing solutions that are
  formulated to match to a greater or lesser extent
  the biochemical osmotic features of the plasma
• They do not contain high molecular weight
  compounds

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Crystalloids

• Examples
• 0.9 Saline (Normal saline)
• Hartmanns (compound sodium lactate)
• Glucose containing solutions
• 5 Glucose
• 10 Glucose
• Dex-saline
• 4 glucose 0.18 saline
• 5 glucose 0.45 saline

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Crystalloids composition
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Colloids

• Solutions that contain high molecular weight
  proteins as well as electrolytes
• Unable to diffuse through normal capillary
  membranes

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Colloids

• Examples
• Gelatin-based
• Gelofusine
• Haemaccel
• Hydroxyethyl starches (HES)
• Pentastarch
• 5 - Hemohes
• 10 - HAES-steril
• Tetrastarch - 6 (HES)
• Voluven
• Volulyte
• Dextran 70
• Rescuflow
• Human albumin solutions

Max 1.5l / 24hr
Max 2.5l / 24hr
50ml/kg/24hr (3.5l)
Use in trauma, (Max 1l) 250ml followed by
isotonic fluids Severe allergic reactions,
coagulation effects
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Colloid composition
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Distribution of IV fluids
Colloid
5 Dextrose
0.9 Saline
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Balanced vs unbalanced solutions

• Large volumes of 0.9 saline based products have
  been shown to cause hyperchloraemic acidosis
• Balanced solutions e.g Hartmanns, volulyte are
  now becoming more popular

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Basis of IV fluid therapy

• Does my patient need IV fluid therapy?
• Why does my patient need IV fluid therapy?
• Maintenance
• To supply daily needs
• Replacement
• To replace on-going losses
• Resuscitation
• To correct an intravascular or extracellular
  deficit

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Assessment of Fluid balance
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Definitions

• Dehydration
• the loss of water and salts essential for normal
  body function.
• Hypovolaemia
• Decreased circulating plasma volume
• Shock
• Systemic hypoperfusion tissue hypoxia

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Types of shock

• Hypovolaemic
• Cardiogenic
• Septic (distributive)
• Obstructive

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Causes of dehydration / hypovolaemia

• Increased loss
• Pyrexia
• Vomiting
• Diarrhoea
• 3rd space loses peritonitis / ascites / sepsis
• Diuretics
• Metabolic derangements e.g diabetes mellitus
• Diabetes insipidus
• Blood loss
• Reduced intake

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Presentation of dehydration
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Patient observations

• General ward
• HR
• BP
• Temp
• RR
• Urine output (oliguria lt0.5ml/kg/hr (30ml/hr)
• Critical care
• IABP
• CVP
• CO monitoring

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Electrolyte losses
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Input/output monitoring
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Fluid replacement strategies
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Basis of IV fluid therapy

• Does my patient need IV fluid therapy?
• Why does my patient need IV fluid therapy?
• Maintenance
• To supply daily needs
• Replacement
• To replace on-going losses
• Resuscitation
• To correct an intravascular or extracellular
  deficit

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Maintenance
Daily Requirement for 70kg man Fluid
2-3L Sodium 70 105 mmol Potassium 56 70
mmol
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Maintenance regimens

• Traditional approach
• 1 salt 2 sweet
• Potassium replacement guided by plasma levels but
  if normal - replace with daily requirements
  (60mmol)

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Exercise 1

• Tom Jones - 70Kg man, NBM, No extra losses
• Hospital number M10/5678
• DOB 12/12/1962
• Ward 12
• Serum potassium 3.8mmol/l
• Prescribe maintenance fluids for the next 24 hrs
• 1 x 1000mls 0.9 saline with 20mmol potassium
  chloride
• 2 x 1000mls 5 dextrose with 20mmol potassium
  chloride

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Exercise 1 - Answer
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Replacement fluids

• Maintenance plus replacement of on-going losses
• Consider the type of loss its likely
  electrolyte content

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Electrolyte losses
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Replacement example
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Resuscitation

• Treating deficit of intravascular or
  extracellular volume
• Caution
• Renal impairment
• pump failure reduced LV function

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Exercise 2

• Tom Jones
• Hospital number M10/5678
• DOB 12/12/1962
• Ward 12
• Day 3 Post-op laparotomy ileostomy minimal
  output from ileostomy
• HR 118
• BP 85/60
• RR 22
• T 38.50C
• Urine output 10mls/hr
• Currently has 1000mls 5Glucose with 20mmol KCL
  running over 8hrs Prescribe appropriate fluids
  for the immediate period
• Fluid bags available in store cupboard
• 1000mls 0.9 Saline
• 1000mls 5 Glucose
• 1000mls Hartmanns
• 1000mls 0.9 saline with 20mmol KCL

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Exercise 3 - example
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Crystalloids vs colloids

• Controversial
• Crystalloids require more volume
• 5L crystalloid replaces 1L intravascular loss
• Colloids
• Higher incidence of allergic reactions
• Compounds persist in the body
• Solutions containing 0.9 saline risk of
  hyperchloraemic acidosis in large volumes

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Resuscitation

• Do not use dextrose containing solutions
• Take care with potassium containing solutions

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Guidelines
www.bapen.org.uk/pdfs/bapen_pubs/giftasup.pdf
Forthcoming NICE guidelines IV fluids in
Hospitalised patients
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Special circumstances - Paediatrics

• Maintenance fluids (4,2,1 rule)
• 4ml/kg/hr for 1st 10kg
• 2ml/kg/hr for 2nd 10kg
• 1ml/kg/hr for remaining weight
• E.g 24kg child
• (4x10) (2x10) (1x4) 64ml/hr
• Dehydration (maintenance estimated deficit)
• dehydration x wt x 10
• E.g above child with 5 dehydration
• 5 x 24 x 10 1200ml to replace over 24hrs
  1200/24 50mls/hr
• Therefore Maintenance deficit 6450
  104mls/hr

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Special circumstances - Burns

• Parklands formula
• 4ml/kg x burned body surface area
• ½ volume given over 1st 8 hours
• ½ volume given over subsequent 16 hours
• E.g 70kg man with 25 burns
• (4x70) x 25 7000ml
• (7000/2) / 8 438mls/hr (for 1st 8 hrs)
• (7000/2) / 16 218 mls/hr (for subsequent 16 hrs)

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Exams

• Popular OSCE station in Year 5
• Involves choice of fluid prescribing
• Often twinned with practical skill
• Ie changing bag (remember to do appropriate
  checks incl exp date)
• Calculating setting drip rate most giving
  sets 20 drops 1ml

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Calculating drip rate

• Most giving sets 20 drops 1ml

STEP 1
STEP 2
As 2060 ? STEP 2 STEP3 can be
combined mls/hr x ? drops/min
Mls/min x 20 drops per min
STEP 3
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Exercise - Calculating drip rate

• 1000mls over 8 hours

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Summary

• Reviewed physiology
• Assessing fluid balance
• IV fluid types
• Fluid strategies
• Maintenance
• Replacement
• Resuscitation
• Future exam focus

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