Fluids’and’Electrolytes’ - St George's Hospital€¦ ·...
Transcript of Fluids’and’Electrolytes’ - St George's Hospital€¦ ·...
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Fluids and Electrolytes
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Your Curriculum • Describe how you assess the circulatory status of a pa:ent on the ward • Dis:nguish between the terms dehydra:on and salt and water deple:on and explain how this determines approach to treatments • Discuss the fluid requirements of a stable pa:ent and how they might change as a pa:ent becomes unwell • Discuss the electrolyte requirements of a sick pa:ent
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
• Fluid and electrolyte requirements in health • Fluid compartments and their composi:on • Prescrip:on of fluids
• Who • How • What
• Electrolytes – Approach to common electrolyte derangements.
What we will cover today:
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Oral intake 1.5-‐2L Saliva 1.5L
Bile 1L
Gastric Juice 1.5L
Pancrea:c Secre:ons 1.5-‐2L
3L Crosses jejunum and ileum
1.5L crosses ileo-‐caecal valve 150mls in
faeces
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Daily water balance in health
Intake (mls) Output (mls)
Oral Intake 1200mls Urine 1500mls
Food 1000mls Insensible losses 900mls
Water from oxida:on
300mls Faeces 100mls
Water 25-‐35mls/kg/day
Sodium 0.9-‐1.2mmol/kg/day
Potassium 1mmol/kg/day
Normal Maintenance requirements
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Prescrip:on of Fluids
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
What ques:ons should you be answering?
1. Does the pa:ent need any prescrip:on at all today? 2. If yes, would they be for
1. Resuscita:on 2. Replacement of losses 3. Maintenance
3. What is the pa:ent’s current fluid and electrolyte status?
4. Which is the simplest, safest and most effec:ve route of administra:on?
5. What is the most appropriate fluid to use and how is that fluid distributed in the body?
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Does the pa:ent need any fluid prescribing today?
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Does the pa:ent need any fluid prescribing today?
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Does the pa:ent need any fluid prescribing today?
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
1. Resuscita:on? 2. Replacement? 3. Maintenance?
This is probably the most important ques:on to be able to answer…….
For those that do need fluids do they need
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Who needs Resuscita:ng? Pa:ents ac:vely bleeding – Trauma – Surgery – GI bleeding -‐ variceal
• Severe sepsis/sep:c shock • GI losses – diarrhoea/vomi:ng • Pancrea::s • Burns These pa:ents need urgent restora:on and maintenance of circula:ng volume to maintain the func:on of vital organs
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Replacement Fluids Incorporate maintenance requirements AND Replacement of on-‐going abnormal losses: NG aspirate Fistula output Polyuria Swea:ng/high fever
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Maintenance Fluids
Restore insensible losses Provide sufficient water and electrolytes to maintain body fluid compartments
Provide sufficient water to enable kidney to excrete waste products
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
What ques:ons should you be answering?
1. Does the pa:ent need any prescrip:on at all today? 2. If yes, would they be for
1. Resuscita:on 2. Replacement of losses 3. Maintenance
3. What is the pa:ent’s current fluid and electrolyte status?
4. Which is the simplest, safest and most effec:ve route of administra:on?
5. What is the most appropriate fluid to use and how is that fluid distributed in the body?
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
What is your pa:ents current fluid and electrolyte status? History • Vomi:ng, diarrhoea, fever, drugs eg diure:cs, blood loss, poorly
controlled diabetes. Dura:on of symptoms. Passing urine? Examina:on • Capillary refill,skin turgor, BP, HR, pulse pressure, postural
hypotension, peripheral or sacral oedema, weight, JVP Bedside Tests: • Observa:on charts, urine output, fluid balance charts Inves:ga:ons: • Haematocrit, Urea, Electrolytes, Albumin, Osmolality, blood gas
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Which is the simplest, safest and most effec:ve route of administra:on? Oral route whenever possible – ORS
In acute situa:ons or with GI dysfunc:on or large fluid losses intravenous is going to be the preferred route – This should be reviewed and stopped at the earliest opportunity
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
What is the most appropriate fluid to use and how is that fluid distributed in the body? WHAT IS THE IDEAL
FLUID?
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
The Ideal Fluid • Produces a predictable and sustained increase in intravascular volume • Chemical composi:on as close as possible to
extracellular fluid • Is metabolised and excreted without accumula:on in :ssues • No adverse metabolic or systemic effects • Is cost-‐effec:ve
THERE IS CURRENTLY NO SUCH FLUID AVAILABLE
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Plasma 0.9% saline Hartmanns 5% Dextrose
Sodium (mmol/L) 135-‐145 154 131 0
Chloride (mmol/L) 95-‐105 154 111 0
Potassium (mmol/L) 3.5-‐5.3 0 5 0
Bicarbonate (mmol/L) 24-‐32 0 29 0
Calcium (mmol/L) 2.2-‐2.6 2 2 0
Magnesium (mmol/L) 0.8-‐1.2 0 0 0
Glucose (mmol/L) 3.5-‐5.5 0 0 227.8 (50g)
pH 7.35-‐7.45 4.5-‐7.0 5.0-‐7.0 3.5-‐5.5
Osmolality (mOsmol/L) 275-‐295 308 273 278
Commonly Used Crystalloids
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Fluid Infused Volume (mls)
Change in inters::al fluid volume (mls)
Change in intracellular fluid volume (mls)
5% Albumin 1400 -‐ 1500 400 -‐ 500
25% Albumin 250 -‐ 750
Hartmanns/0.9% saline
4000 -‐ 5000 3000 -‐ 4000
5% Dextrose 12000 -‐ 14000 3000 -‐ 4000 9000 -‐ 10000
Volume of Infusion Required to Expand Plasma Volume by 1L
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Colloids
Suspensions of molecules within a carrier solu:on – Rela:vely incapable of crossing the healthy semipermeable capillary membrane
– Exert an osmo:c effect in intravascular space causing fluid to remain within the vascular system
– Colloidal molecules take several hours to break down and so exert their effect for longer than crystalloids
Albumin is considered the reference colloidal solu:on – Natural colloids: Albumin – Synthe:c colloids: Gela:ns, Dextran, Starches
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
ELECTROLYTES
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Sodium • 135-‐145mmol/L • Hyponatraemia – severe when Na <120mmol/L
– Cerebral oedema, seizures – Too rapid correc:on can also be detrimental
• False hyponatraemia can occur • Need to assess overall fluid/water balance • Most commonly
– Excessive infusion of hypotonic solu:ons – Excessive losses – GIT or kidneys – Drugs – Syndrome of Inappropriate An:-‐Diure:c Hormone – Addisons – Cerebral Salt Was:ng
• Hypernatraemia – Na >145mmol/L – Net loss of hypotonic fluids from GIT or renal tract – Rarely primary hyperaldosteronism
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Potassium • Normal daily requirements 1mmol/kg body weight • Acutely rising serum potassium >6mmol/L is a medical emergency – Risk of cardiac arrest – Needs urgent treatment
• Most Common Causes – Acute kidney injury – Catabolic states – Tissue injury/damage – Drugs
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Potassium • Normal daily requirements 1mmol/kg body weight • Acutely rising serum potassium >6mmol/L is a medical emergency
– Risk of cardiac arrest – Needs urgent treatment
• Most common causes of hyperkalaemia – Acute kidney injury – Catabolic states – Tissue injury/damage – Drugs
• Most common causes of hypokalaemia – GI losses – Drugs (primarily diure:cs)
• Severe <2.5mmol/L – Muscle weakness, paralysis, cardiac arrythmias – Should be immediately replaced to >3mmol/L
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Chloride • Main anion in ECF (95-‐105mmol/L) • Hyperchloraemic acidosis common in Intensive Care Units
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Plasma 0.9% saline Hartmanns 5% Dextrose
Sodium (mmol/L) 135-‐145 154 131 0
Chloride (mmol/L) 95-‐105 154 111 0
Potassium (mmol/L) 3.5-‐5.3 0 5 0
Bicarbonate (mmol/L) 24-‐32 0 29 0
Calcium (mmol/L) 2.2-‐2.6 2 2 0
Magnesium (mmol/L) 0.8-‐1.2 0 0 0
Glucose (mmol/L) 3.5-‐5.5 0 0 227.8 (50g)
pH 7.35-‐7.45 4.5-‐7.0 5.0-‐7.0 3.5-‐5.5
Osmolality (mOsmol/L) 275-‐295 308 273 278
Commonly Used Crystalloids
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Chloride • Main anion in ECF (95-‐105mmol/L) • Hyperchloraemic acidosis common in Intensive Care Units
• Hypochloraemic acidosis is mainly caused by loss of gastric fluid (ie vomi:ng)
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St George’s NHS Trust and University of London, Cri:cal Care Directorate
Magnesium • Concentra:on 0.7-‐1.2mmol/L • Important component of many enzyme systems and helps
maintain enzyme stability • Symptoma:c hypomagnesaemia <0.4mmol/L
– Neuromuscular irritability – convulsions – Arrythmias
• Usually secondary to GI losses such as chronic diarrhoea or high output stomas
• Oral prepara:ons -‐ not well absorbed. Usually needs to be replaced IV
• Hypermagnesaemia – almost always iatrogenic due to therapeu:c use of Mg – Arrythmias – Acute Severe Asthma – Eclampsia and Pre-‐eclampsia