Fluid And Electrolyte Flashcards
Why prescribe IV
Maintainance - vomiting and diarrhoea
Replacement- people that are already dehydrated
Resuscitation- rapidly restore after haemorrhage or shock
Total body water is what % of weight
60 man
50-55 woman
icf
Ecf % of total water
ICF 60
EFC30
How does fluid enter body
Food drink
Metabolism
How fluid lost
Faeces
Sweat/skin
Lungs
What% of NA in body not exchangeable
Exchangeable
25 non
75 exchangeable
Normal range of NA in plasma
135-145 mmol/l
Sodium excretion regulated by
Renin-Angiotensin-Aldosterone • Natriuretic Peptides • Intrinsic Renal mechanisms
Osmoreceptor detect
Increased osmotic pressure
Baroreceptors
Detect decrease blood pressure
Aim of fluid replacement
Maintain normovolaemia
Main Tain electrolyte concs
Compensate extra fluid loss
Features of colloids
E.g
Stay in compartment administered to
Mainly in plasma
E.g blood
Normal prescription for someone who is otherwise well and has no extra losses
So… 1L Normal Saline 0.9% & 2L 5% dextrose with added K+
Or… 3l dextrose saline with k+
How to maintain patient with physiological losses
AsAssess patient regularly. Keep a careful fluid balance chart • Stop iv fluids as soon as not required • > 3 days use oral/enteral feed or consider total parenteral
nutrition if necessary • Include fluid given in IV drugs, and pumps
Entrap feed is
Straight through GI
Parenteral feed is
Not through GI
Fluid balance assessment
Limbs – temperature, pulse (volume and rate), BP sitting and standing
(postural), skin turgor, peripheral oedema • Head and neck - ? Sunken eyes, mucous membranes, JVP, carotid pulse • Chest – Capillary refill, lung auscultation for pulmonary oedema • Abdomen - ? ascites • Fluid balance chart • Weight chart
Resuscitation therapy used when
Re suscitation therapy is used when a patient is hypotensive
First thing todo in resuscitation therapy
Test the response to fluid with a
fast IV bolus of a crystalloid • Reassess the patient using ABCDE
approach and repeat the above if
necessary • Use blood as soon as available if
the patient is bleeding • Seek expert help early
Hyponatremia is
NA less than 135 mmol/l
Hyponatraemia results from
The intake and subsequent retention of water. Excess of water in relation to Na
Depletion of total body Na in excess of concurrent body water losses
Hyponatraemia Good history and examination of the patient can lead to
Causes and rapidity of condition
Hyponatraemia key feature
Volume status of patient
Symptoms of mild hyponatraemia
• MILD hyponatraemia (130-135 mmol/L) – Asymptomatic
Symptoms of moderate hyponatraemia
MODERATE hyponatraemia (121-129 mmol/L) – Cramps, Weakness, Nausea
Symptoms of severe hyponatraemia
SEVERE hyponatraemia (<120 mmol/L) – Lethargy, Headache, Confusion
Severe and rapidly evolving hyponatraemia symptoms
Severe and rapidly evolving hyponatraemia – Seizures, Coma, respiratory arrest
Treatment of hyponatraemia
Hypovolaemia – Correct volume depletion e.g. IV 0.9% saline
• Euvolaemia – Underlying cause, fluid restriction
• Hypervolaemia – Underlying cause, fluid restriction, (vasopressin receptor
antagonists)
Aggressive therapy for hyponatraemia when
Severe symptoms Acute onset (less than 24 hours)
Hypernatraemia is i
NA over 145 mmol/l
Hypernatraemia results from
Net water loss
Hypertonic NA gain
Symptoms of hypernatraemia
Similar to hyponatraemia
Hypernatraemia treatment
Chronic hypernatraemia
• Treat underlying cause • Use of hypotonic fluid e.g. 5% Dextrose givne slowly •
Lower Na by maximum of 10 mmol/L per day • Always re-assess
Hypokalaemia is
Less tthan 3.5 mol/l
Hypokalaemia results from
Decreased K intake (rare) • Increased entry into cells • Increased losses - GI / urine
Symptoms of hypokalaemia
Muscle weakness
ECG change and arythmias
Hypokalaemia ECG
Flat T wave • U waves • ST depression • PR interval prolonged • Prolonged QT interva
Hyperkalaemia is
K over 5.5 mol/l
Symptoms of hyperkalaemia
Paraesthesiae
• Muscle weakness – paralysis
• Arrhythmias
Hyperkalaemia ECG changes
Tall peaked T waves • Shortened QT interval • PR interval lengthening • QRS widening • P waves disappear – Sine wave
Hyperkalaemia treatment
IV calcium gluconate – antagonise membrane action of high K
• IV insulin with glucose – drive K into cells
• Remove K from the body
• Consider loop diuretics • Consider haemodialysis or haemofiltration
• Other therapies to drive K into cells
• Sodium bicarbonate • Beta agonists
• Monitor
• Treat underlying cause
• Longer term – drug changes, diet changes
