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Fluid Management
Nigel White Consultant ICU
Royal Bournemouth Hospital
Advanced fluid management
Fluid management
• Normal distribution of fluids and electrolytes
• Composition of replacement fluids
• Daily requirements (including paeds)
• Abnormal losses
• Dehydration
Advanced fluid management
NICE Guidance
• https://www.nice.org.uk/guidance/cg174
Advanced fluid management
Distribution of total body water
Total body water42 L BWx0.6
Intracellular fluid28 L BWx0.4
Extracellular fluid14 L BWx0.2
Intravascular fluid3 L BWx0.05
Interstitial fluid11 L BWx0.15
Distribution of total body water
Total body water42 L BWx0.6
Intracellular fluid28 L BWx0.4
Extracellular fluid14 L BWx0.2
Intravascular fluid3 L BWx0.05
Interstitial fluid11 L BWx0.15
Colloid/Blood
CrystalloidDextrose
Composition of fluid compartments
plasma interstitial intracellular
CationsNa 140 146 12K 4 4 150Ca 5 3 10Mg 2 1 7
AnionsCl 103 104 3HCO 24 27 10SO4 1 1 -HPO4 2 2 116Protein 16 5 40
Contents of common iv fluidsSolution Electrolyte content Glucose
(mmol/L)
Saline 0.9% Na+ 154 Cl- 154 0
Glucose 4%/ Na+ 31 Cl- 31 40g/lsaline 0.18%
Glucose 5%/ Na+ 77 Cl- 77 50g/lSaline 0.45%
Glucose 5% Na+ Nil Cl- Nil 50g/l
Hartman’s Na+ 131 Cl- 112 0solution K+ 5 HCO3
- 29 Ca2+ 4 (as lactate)
Fluid types
• Crystalloid: aqueous solutions of mineral salts or other water-soluble molecules.
• For the purpose of fluid management we think of crystalloid as aqueous solutions of mineral salts
Advanced fluid management
Fluid types
• Colloid• Contains large molecule MW>30KDa• Remains in IV space (?)• Albumin mw 30,000
– 4.5% expensive,
• Gelatin mw 30,000– Short circulatory half life
• Starch mw 100-200,000.– Long circulatory half life
Advanced fluid management
Colloid
• No evidence for any benefit for gelatins or albumin
• Starch appears increasingly to be associated with renal failure and coagulopathy
• Evidence for increased mortality in sepsis • Have been withdrawn in RBH (and Poole)• You have to give more crystalloid to achieve
same resus goals but ratio seems to be about 1.4:1
How to use fluids
• Calculate fluids
• Calculate electrolyte requirements
• NICE suggest add dextrose to avoid ketosis
Advanced fluid management
Daily fluid requirements
• 4/2/1 ratio (Holliday Segar)
• 0-10kg 4mls/kg/hr (100mls/kg/day)
• 10-20kg 2mls/kg/hr (50mls/kg/day)
• >20kg 1ml/kg/hr (25mls.kg/day)
• Works for children as well (except neonates)
Advanced fluid management
Daily fluid requirments
• For adults 1-1.25mls/kg/hr
• NICE suggest 25-30mls/kg
• Ideal body weight is best if overweight
• There are many formulae for ibw
• Should seldom have more than 3l/day
• Consider 20-25ml/kg/day if frail or heart failure
Daily electrolyte requirements
Advanced fluid management
Weight Na mmol/kg/day
K mmol/kg/day
0-10 kg 2-4 1.5-2.5
10-20 kg 1-2 0.5-1.5
>20 kg 0.5-1 0.2-0.7
•For adults
•Na 1-2mmol/kg/day (NICE say 1mmol/kg/day)
•K 1mmol/kg/day
Glucose
• NICE suggest give 50-100g/day of iv glucose to limit starvation ketosis
Why do children need more fluid and electrolytes?
• Larger BSA so higher insensible losses
• Relatively immature kidneys so less able to concentrate urine and retain Na and K
Advanced fluid management
How to give maintenance fluids??
• I would suggest
• Calculate hourly rate
• In adults give this as 4%Dex/0.18%Saline with 40mmol/L KCL.
• In children use either 5%Dex/0.45%Saline with 40mmol/L KCL or 5%Dex/0.9%Saline
Advanced fluid management
Why the difference?
Advanced fluid management
Advanced fluid management
RBH
• 0.18% Saline 4% dextrose is no longer available in places that treat children (A/E, eye unit.
• Replaced with 0.45%Saline/5% dextrose.• Guidelines on intranet (soon). Seek senior advice• Increasingly we think 0.45%Saline/5%dextrose
may be a better solution for adults as well.
Advanced fluid management
However
• These calculations are based on assumptions of normal fluid and electrolyte losses
• By definition hospital patients are not “normal” and may have abnormal losses whether apparent or not.
• Any patient receiving iv fluids should – have daily urea and electrolytes and their prescription altered
according to the results.
– have an accurate fluid balance chart
– Have twice weekly weightsThe
Advanced fluid management
Assessing volume status
• 2 concepts
• Shock – Refers to intravascular space
• Dehydration– Whole body fluid loss
Advanced fluid management
What is the difference
• Shock kills. – Loss of 20mls/kg from you intravascular space
is >25% loss of circulating fluid volume.
• Dehydration kills but slower– Loss of 20mls/kg from your total body water
represents about 3% of your total body water
Advanced fluid management
Shock
• Definition– Failure of delivery of oxygen (and nutrients) to
vital organs
• Effects– Rapid onset of tissue hypoxia and acidosis
• Outcome– Organ damage and death.
Advanced fluid management
What causes shock?
• Low cardiac output. Heart is either– Empty (hypovolaemic)– Failing (cardiogenic)
• Septic shock– Initially warm periphery (low SVR)– As shock develops periphery cool– Mostly hypovolaemic, rarely cardiogenic
Advanced fluid management
Diagnosis of hypovolaemic shock
• Clinical– Look pale/sweaty/cool peripheries/prolonged cap return
(vasoconstriction)– Organ perfusion– Pulse– Blood Pressure– Urine output
• Tests– Blood gas
• Lactate• Base excess
Advanced fluid management
Treatment of hypovolaemic shock
• Rapid expansion of intravascular volume
• Options– Crystalloid– Blood
• There is no place for dextrose containing solutions in shock resuscitation.
Advanced fluid management
Resuscitation of hypovolaemic shock
• Blood– Only if ongoing losses and Hb less than 100 or if
ongoing tissue ischamia, eg angina– Otherwise consider if Hb less than 80 1:1
• Colloid– NO!!– No convincing evidence better than crystalloid
• Crystalloid– Cheap, safe
Advanced fluid management
Resuscitation of shock
• CONTINUALLY REASSESS!!!!
• IF YOU HAVE GIVEN MORE THAN 40MLS/KG OF CRYSTALLOID OR COLLOID YOU MUST CALL HELP. THIS IS A SERIOUSY SHOCKED PATIENT WHO NEEDS ICU/HDU AND FURTHER Ix
Advanced fluid management
Diagnosis of cardiogenic shock
• Clinical– Look pale/sweaty/cool peripheries/prolonged cap return
(vasoconstriction)– Organ perfusion– Pulse– Blood Pressure– Urine output
• Tests– Blood gas
• Lactate• Base excess
• How to differentiate– Signs of failure (CVP, basal crackles)
Advanced fluid management
Management of cardiogenic shock
• Inotropes
• Mechanical aids
• Careful manipulation of volume status
• ICU/HDU or CCU
Advanced fluid management
Hypovolaemic shock is bad.So avoid it
• Assess losses and replace them
• Inpatients fluid balance charts– Often works of fiction– Use for rough guidance only– Losses from upper/lower GIT often missed– Assess patient.
Advanced fluid management
Avoiding hypovolaemia
• Replace losses with crystalloid
Advanced fluid management
Third space losses
• Third space is tissue oedema. It is unseen and occurs with any tissue damage be it trauma, elective surgery or serious illness
• It initially cannot be seen
Advanced fluid management
Third space losses
• Remember much third space loss is not lost but redistributed.
Advanced fluid management
How to avoid fluid overload
• Aggressive fluid loading in resuscitation with crystalloid
• After resuscitation give maintenance fluids
• Consider decreasing fluids to 80% if patient appears overloaded
• Diuretics may be necessary
Advanced fluid management
Dehydration
• Definition– Loss of total body water (and electrolytes)
• Effects– When severe patients become shocked
• Outcome– Rarely causes death in the absence of shock
Advanced fluid management
How to assess dehydration
• It is practically impossible
• The only reliable way is weight loss
Advanced fluid management
Dehydration
Advanced fluid management
Signs / Symptoms
Mild <5% Moderate 5-10%
Severe >10%
Urine output ↓ ↓↓ ↓↓↓
Dry mouth - + ++
Skin turgor normal ↓ ↓
Cardiac output
Normal Normal May be low
Ant fontanelle
Normal Sunken Sunken
Questions
?Advanced fluid management
Summary
• Fluids are drugs
• Know what and how you are prescribing
• There is no formula which accurately predicts requirements
• Do the nice on line learnign
• Regular review
• Daily u + e s
Advanced fluid management
Advanced fluid management