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 Advanced fluid management

Distribution of total body water Total body water 42 L BWx0.6 Intracellular fluid 28 L BWx0.4 Extracellular fluid 14 L BWx0.2 Intravascular fluid 3 L BWx0.05 Interstitial fluid 11 L BWx0.15

Distribution of total body water Total body water 42 L BWx0.6 Intracellular fluid 28 L BWx0.4 Extracellular fluid 14 L BWx0.2 Intravascular fluid 3 L BWx0.05 Interstitial fluid 11 L BWx0.15 Colloid/ Blood Crystalloid Dextrose

Composition of fluid compartments plasmainterstitialintracellular Cations Na K44150 Ca5310 Mg217 Anions Cl HCO SO411- HPO Protein16540

Contents of common iv fluids SolutionElectrolyte contentGlucose (mmol/L) Saline 0.9%Na + 154Cl Glucose 4%/Na + 31Cl g/l saline 0.18% Glucose 5%/ Na + 77 Cl g/l Saline 0.45% Glucose 5%Na + NilCl - Nil 50g/l Hartman’s Na + 131Cl solutionK + 5HCO Ca 2+ 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 ,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increasingly to be associated with renal failure and coagulopathy Evidence for increased mortality in sepsis Have been withdrawn in RBH (and Poole) You have to give more crystalloid to achieve same resus goals but ratio seems to be about 1.4:1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 mls/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 WeightNa mmol/kg/day K mmol/kg/day 0-10 kg kg >20 kg For adults Na 1-2mmol/kg/day (NICE say 1mmol/kg/day) K 1mmol/kg/day

Glucose NICE suggest give g/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

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 turgornormal↓↓ Cardiac output Normal May be low Ant fontanelle NormalSunken

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