Fluid and Electrolytes in the Critically Ill

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Fluid and Electrolytes in the Critically Ill

ACB South West and Wessex Region Scientific
Meeting 12th July 2005 Clinical Biochemistry in
Intensive Care

• Peter Gosling PhD FRCPath
• University Hospital Birmingham NHS Trust

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Claude Bernard (1813-1878) La fixité du milieu
intérieur est la condition de la vie libre
Cellular homeostasis Preservation of cellular
function Substrate delivery - metabolite removal
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Fluid balance - Normal
NaCl 100
Water 2500 ml
N2 500
Serum osmolarity 285 mosm/L
390 mosm/L
100
500
1800
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Fluid balance water restriction
NaCl 100
Water 2000
N2 500
Osmolarity 285 mosm/L
700 mosm/L
500
100
1000 mL
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Fluid balance water loading
NaCl 100
Water 5000 mL
N2 500
Osmolarity 285 mosm/L
100 mosm/L
100
500
4300 mL
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Endocrine response to injurySalt and water
retention
ADH thirst Water
retention
Catecholamines vasoconstriction Blood to
heart lungs brain
Renin angiotensin II aldosterone
Sodium

retention   Atrial
natruietic peptide
(Decrease)
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Metabolic response to inflammation
Proteolysis increased by Cortisol Tumour
necrosis factor IL-1 and IL-6 Glucagon Platelet
activating factor
Increased urinary nitrogen excretion Sufficient
water input required to provide enough urine to
excrete solute (Na and urea)
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Urine (Na K) x 2 plus urea urine osmolarity
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Normal 24 hr fluid and electrolyte balance
Input Output Water 2500 mL 1800 mL
urine 700 mL insensible Sodium 100 mmol 100
mmol Nitrogen 500 mmol 500 mmol Other 200
mmol 200 mmol Total 800 mosmols 800
mosmols Urine osmolality 800/1800 450
mosm/L Urine 40 maximally concentrated
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Fluid and electrolyte balance 24 hr post major
surgery
Input Output Fluid 8000 mL 1000 mL
Urine 1000 mL insensible Sodium 1200
mmol 50 mmol Nitrogen 600 (catabolism) 200
mmol mosmoles 4000 500 6000 mL positive
fluid balance 3500 mosmoles positive
balance Requires 7 litres of urine to clear
sodium urea (500 mosm/L maximum concentration)
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Oedema !
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Post Operative ICU patient
Water
8000 mL NaCl 1200 mmol
N2 700 mmol (catabolic)
Drugs
Colloids
NaCl
Normal NaCl
NaCl
500mosm/L
Sick ICU patients often cannot concentrate
urine gt500 mosm/L
Na 50
N2 400
1000 mL
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Sodium and chloride overload Sodium and chloride
retention Fluid retention Interstital
oedema Organ dysfunction lungs kidney gut
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Concerns about fluid and electrolyte prescribing
Hyponatraemia after orthopaedic surgery
BMJ 19993181363-64 Appropriateness
of fluid regimes
Variability in post-operative fluid and
electrolyte prescription

Stoneman et al Br J Clin Pract 19975182-84 Conc
ern about variability in perioperative fluid
administration
Extremes of age The 1999 report of the National
Confidential Enquiry into Perioperative Deaths
1999 Sherry et al. Fluid regimes highlighted
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Concerns about fluid and electrolyte prescribing
Changes in weight, fluid balance and serum
albumin in patients referred for nutritional
support Lobo et al Clinical Nutrition
199918197-201 12L mean fluid overload in
oedematous patients referred for nutritional
support
Hypernatraemia in the ICU an indicator of
quality of care ? Poldermann et al. Critical
Care Medicine 1999271105-8 Hospital acquired
hypernatraemia versus admission hypernatraemia
was associated with higher mortality rate
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Drowning in the brine of an inadequate knowledge
base(Lobo et al Clinical Nutrition
200120125-130)
Telephone survey

• PRHOs did 89 the fluid and electrolyte
  prescribing
• 27 did not know minimum urine 24h output
  (500-750 mL)
• 76 did not know Na and Cl- content of 0.9
  saline (154 mmol/L of each)
• 82 did not know Na daily requirements (60-100
  mmol)
• 98 did not know Na content of gelofusine
  (154mmol/L)

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Sodium and potassium measurement are our most
frequent requests, yet fluid and electrolyte
management is poorly understood by medical and
nursing staff This is a major challenge for
Clinical Biochemistry
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• What are we trying to achieve by giving
  intravenous fluid ?

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Fluid Compartments
Cells 28 Litres
Interstitial fluid 10.5 Litres
Blood volume 3.5 litres
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Fluid shifts in haemorrhage
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Fluid shifts in haemorrhage
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Fluid shifts in haemorrhage
Vasoconstriction redistribution
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Fluid shifts in haemorrhage
Interstitial fluid mobilisation
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Fluid shifts in haemorrhage
Reduced interstitial fluid
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Fluid shifts in haemorrhage
Intracellular fluid mobilisation
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Fluid shifts in haemorrhage
Reduced intracellular fluid
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• What are we trying to achieve by giving
  intravenous fluid ?
• Scenario Acute blood loss
• Replacement of RBCs, water and electrolytes -
  haemostasis

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Fluid shifts in trauma, infection,
ischaemia-reperfusion injury
Inflammation
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Fluid shifts in inflammation
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Fluid shifts in blunt trauma
Inflammatory cytokines
Neutrophils
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Fluid shifts in blunt trauma
Systemic capillary leak
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Leak of Water, Na Cl- Albumin to
Interstitium Vasodilatation loss of SVR
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Interstitial oedema
Hypovolaemia
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Interstitial oedema
Na Cl- water
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Na Cl- water
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Na and Cl- Loading Fluid retention Severe
interstitial oedema Organ dysfunction
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• What are we trying to achieve by giving
  intravenous fluid ?
• Scenario Acute inflammation
• Blood volume expansion, in the context of
  vascular dysfunction and leaky capillaries

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Two factors influencing choice of fluids
1. Microvascular inflammatory response
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Hamster cheek pouch studiesSystemic capillary
leak to FITC Dextran 150,000 mol wt (Range
10,000 500,000)Shearman CP, Gosling P, Simms
Br J Surg 1988 75 1273
Cheek pouch X 40
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Control hamster cheek pouch X40Following i.v.
FITC labelled Dextran 150 kD
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Cheek pouch 10 mins post laparotomy and chemical
peritonitis
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Cheek pouch 30 mins post laparotomy
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Scanning EM normal endothelial cell
junction Donald McDonald 1999
X 40,000
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Scanning EM 1 minute after substance P
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injury
18 x H2O
NaCl
Inflammatory mediator release
Albumin
Systemic capillary leak
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Transcapillary escape rate of radiolabelled
albumin and serum albumin before and after
cardiac bypass surgery
Fleck A et al Lancet 1985I781-784
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Capillary leak (microalbuminuria) and
inflammatory markers during burns/surgery/trauma
SIRS - Organ Failures
SIRS Organ Failures
Capillary Leak
Interleukin - 6
C-RP
Normal
Pre op Induct surgery 2h 6h 12h 24h
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Factors influencing choice of fluids
2. The effect of the salt and water loading in
acute illness
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Endocrine response to injurySalt and water
retention
ADH thirst Water
retention
Catecholamines vasoconstriction Blood to
heart lungs brain
Renin angiotensin II aldosterone
Sodium

retention   Atrial
natruietic peptide
(Decrease)
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Sodium content of common iv fluids
Fluid Sodium Chloride mmol/L Normal
plasma 140 95 Saline 0.9 154 154 Hartmanns
131 111 Gelofusine 154 130 Haemacel 145 145
4.5 Albumin solution 145 145 HAES-steril 154
154 5 dextrose 0 0
Abnormal !
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Effects of Saline Loading

• Hyperchloraemic metabolic acidosis
• Hyperosmolar states
• Stimulation of ADH - fluid retention
• Renal vasoconstriction fluid retention
• Nausea, vomiting, abdo pain, hyperventilation,
• headaches, thirst
• Hartmann AF, Senn MJE 1932 J Clin Invest
  11337-44
• Waters JH et al Anesthesiology 2000931184-7
• Williams EL et al Anesthesia Analgesia
  199988999-1003
• Skellett S et al. Arch Dis Child 200083514-6
• Healey MA et al J Trauma45894-9

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Normal sodium intake 100 mmol/24h
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Normal sodium intake 100 mmol/24h
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Volume therapy should be directed towards
maximum effect with minimum sodium, chloride and
water loading
Before a patient can recover they must excrete
the water, sodium and chloride given during
resuscitation
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Properties of resuscitation fluids
Volume expansion lasts 10 mins
0.9 Abnormal Saline 58 Da
Very large volumes required
Massive sodium, chloride and water load
Saline cannot be excreted easily Interstitial
oedema
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Properties of resuscitation fluids
4 Gelatine 30,000 Da
Volume expansion lasts 1-2 hours
Large volume required
Sodium, chloride and water load
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Properties of resuscitation fluids
Volume expansion lasts 2-4 hours
4.5 Albumin 68,000 Da
Large volume required
Sodium, chloride and water load
Normally 60 of albumin is in interstitial
space More albumin leaks out during inflammation
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Properties of resuscitation fluids
HES 200,000 Da 0.5 substitution
Volume expansion lasts 6-18 h
Compared with crystalloid- only, gelatine or
albumin less Na Cl- and H2O
Anti-inflammatory, less capillary leak
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Comparison of Gelatine with eloHES in Aortic
Surgery Rittoo et al Br J Surg 2001
40 patients elective AAA
Gelatine n 20
eloHES n 20
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Lung function during AAA Rittoo et al Brit J
Anaesth 20049261-6
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Capillary leak in AAA patients Medians (Mann
Whitney)
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Gastric tonometry during AAA Rittoo D et al
.Cardiovasc Surg. 200210128-33.
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Serum creatinine lower in eloHES and Voluven
groups
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Serum urea lower in eloHES and Voluven groups
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PRCTs of hydroxyethyl starch for acute volume
replacement
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Recent clinical study

• Model 66 elderly (gt65y) patients undergoing
  major abdominal surgery
• Fluids Hydroxyethyl starch (130 kD) v Ringers
  lactate v 0.9 saline
• Outcome In starch group 50 less fluid compared
  with both crystalloid groups.
• Lower CRP, IL-6 and IL-8 lower ELAM-1 and ICAM
• Boldt J et al Influence of different volume
  replacement strategies on inflammation and
  endothelial activation in the elderly undergoing
  major abdominal surgery. Intensive Care Med.
  2004 Mar30(3)416-22. Epub 2004 Jan 08.

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• Fluid therapy should be directed not only to
  effective volume expansion of a leaky circulation
  but also to microvascular protection

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Reasons for fluid therapy

• Preserve oxygen delivery to tissues
• Correct hypovolaemia
• Maintain cardiac output
• Optimise gas exchange
• Replace electrolytes water
• Maintain urine output

Colloids RBCs
Crystalloids
Identify what is the goal Choose fluid which
best achieves the goal
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Things to Remember
Sodium and chloride overload is a major problem
in critically ill patients
It is very easy to give salt water to
critically ill patients, and very difficult to
remove
Fluid therapy is often poorly taught, poorly
understood and poorly done
Urine electrolyte measurement is essential for
fluid management in the critically ill