Electrolytes Flashcards
Discuss Hyponatramia aetiology
Can be split into hypo-osmolar or non hypo-osmolar hyponatreamia
Discuss non hypo-osmolar hyponatraemia
May be due to pseudo hypontaraemia (secodnary to hyperproteinaemia or hypercholesterolaemia)
- excess effective osmols in the ECG (glucose)
- excess ineffective osmols (urea)
Excess effective osmoles in the ECF usually glucose, mannitol or glycine result in a shift of water from intracellular to extracellular fluid
Patient with pseudohyponatramia and those in whom hyponatraemia is soley due to effective osmoles are not at risk of cerebral odema
Those with non hypo-osmolar hyponatraemia with ineffective osmoles (urea) or who have hypotonic hyponatraemia are at risk of cerebral odema
Describe formula for correcting NA
Na corrected = Na measured +2.4(( glucose measured -5.5) divided by 5.5)
Discuss aetiology of hypo-
Fluid deplete (urinary sodium >20)
- -Renal loss
- -polyuric phase of acute renal failure
- -post obstructive
- chronic renal failure
- -cerebral salt wasting
- -diuretic excess
- -mineralocorticoid defiency (primary/secondary)
Fluid deplete (urinary sodium <20)
- -extra renal losses
- GI
- -Skin
- -Abdominal sequestration
Euvolumic (urinary sodium >20)
- Acute/chronic renal failure
- -SIAD
- -Glucocoritcoid
- -Hypothyroidism
Euvolumic (urinary sodium <20)
- Severe polydipsia
- -inappropriate IV fluid
Fluid overload (>20) -Acute/chronic renal failure
Fluid overload (<20)
- nephrotic syndrome
- cirrhosis
- cardiac failure
Discuss clinical features of hyponatraemia
Severe
- vomiting
- coma
- seizure
Moderate
- nausea
- confusion
- headache
Discuss treatment of hyponatraemia
Severe symptoms
- ABC
- Control aiway/ventilation/seizures
- 2ml/kg 3% saline over 20 minutes then send a sample for serum sodium concentration. Give further 2ml/kg 3% sialine while waiting
- repeat 2ml/kg infusions over 20 min until serum sodium increases by 5mmol or until symptoms improve
- limit rise in sodiumto 10mmol in the first 24 hours and then 8mmol every day after that until you reach 130mmol/l
Moderate symptoms
- 2ml/kg 3% saline over 20 minutes
- aim for a rise of 5mmol on first 24 hours and then 8mmol in subsequent
Discuss consequences of raising serum sodium to quickly
Risk of osmotic demyelination resulting in severe permanent brain damage
If sodium rises more rapidly then guidlines
- stop ongoing infusion
- give non sodium fluid bolus 10ml/kg (5%dextrose) over 1 hour
- consider desmopressin
Discuss treatment of hyponatraemia in odematous states
Despite odema usually intravascularly dry
- resp[onds to effective therapy of underlying cause – should fluid restrict to 1-1.5L a day
- hypertonic saline should not be given (total Na level is high) unless signs of severe hyponatramia are present
- give frusemide concurrently to avoid expansion of extracellular fluid
Discuss hypokalaemia aetiology
Inadequate intake Excessive GI loss -vomiting, diarrhoea, fistulae, recent ileostomy excessive renal loss -hyperaldosteronism -cushing -renal tubular acidosis -polyuric phase of acute renal failure Redistribution -drugs -alkalosis -pyloric stenosis -hypokalaemic periodic paralysis
Discuss feature of hypokalaemia
- weakness
- depression
- ileus constipation
- ventricular arrythmias
- rhabdomyolysis in severe and prolonged cases
- nephrogenic diabetes insuipidus
- ECG prolonged PR, inverted T wave and u waves
Discuss aetiology of hyperkalaemia
Spurious – haemolysis, failure to seperate red cells from plasma
Iatrogenic Renal -hypoaldosteronism -k sparing diuretics -renal failure
Redistribution
-suxamethonium (particularly in presence of burns or spinal cord damage)
> 1 mechanism
- acidosis
- global hypoxia
- digoxin overdose
Discuss DKA
Initially high metabolic gab acidosis progressing to normal anion gab
Discuss complications of treatment of DKA
Cerebral odema
-95% occur in patients <20 years of age with 1/3 of those in the <5year age group
–mannitol over 5-10 minutes
ICP monitoring
