Fluids and Electrolytes Flashcards
When is oral potassium an adequate compensation for potassium loss?
Those taking digoxin or anti-arrhythmic drugs, where potassium depletion may induce arrhythmias
Those whom secondary hyperaldosteronism occurs, e.g. renal artery stenosis, cirrhosis of the liver, nephrotic syndrome, and severe heart failure.
Excessive losses of potassium in the faeces e.g. chronic diarrhoea associated with intestinal malabsorption or laxative abuse.
When should potassium levels be measured and corrected in the elderly?
Inadequate dietary intake
Long-term administration of corticosteroids
When potassium salts are given, what side effects lead to poor compliance?
Potassium salts cause nausea and vomiting
Acute severe hyperkalaemia (>6.5 mol/litre or with ECG changes) urgent management?
Treatment with calcium gluconate 10% by slow IV injection titrated and adjusted to ECG improvement, to temporarily protect against myocardial excitability.
What does an IV injection of insulin (5-10 units) with 50 mL glucose 50% do to a person with acute severe hyperkalaemia?
Reduces serum-potassium concentration; this is repeated if necessary or a continuous infusion instituted.
Which bronchodilator may reduce plasma-potassium concentration?
Salbutamol
In mild hyperkalaemia or moderate hyperkalaemia, what may be used to remove excess potassium?
Ion-exchange resins
Replacement of fluid and electrolytes lost through diarrhoea can be achieved by giving solutions containing? (4)
Sodium
Potassium
Glucose
Another carbohydrate such as rice starch
In chronic conditions associated with mild or moderate sodium depletion, e.g salt-losing bowel or renal disease, which oral supplements may be sufficient?
Sodium chloride
Sodium bicarbonate
Either of the above according to the acid-base status of the patient.
In chronic acidotic states, like uraemia acidosis or renal tubular acidosis, what can be given?
Sodium bicarbonate orally
What can be given for severe metabolic acidosis?
Sodium bicarbonate IV
What are the potential side effects of sodium supplements?
Increase blood pressure
Cause fluid retention
Pulmonary oedema
Hypokalaemia may be exacerbated
Gastro-enteritis, diabetic ketoacidosis, blues, and ascites are examples of conditions that can cause what electrolyte depletion?
Sodium depletion
Why should be given to people who are suffering with sodium depletion?
Sodium chloride in isotonic solution.
Why should sodium chloride be given slowly for acute or chronic hyponatraemia?
To avoid the risk of osmotic demyelination syndrome.
The rise in plasma concentration should not exceed 10 mol/litre in 24 hours.
Why could compound sodium lactate (Hartmann’s solution) be used instead of isotonic sodium chloride?
It may reduce the risk of hyperchloraemic acidosis
What solution and ration are indicated when there is a combined water and sodium depletion?
Sodium chloride with glucose
1:1 mix of isotonic sodium chloride and 5% glucose
What fluids should be given for combined sodium, potassium , chloride and water depletion (e.g. severe diarrhoea)?
Sodium chloride IV infusion 0.9% and glucose IV infusion 5% with potassium as appropriate
Glucose solutions (5%) are used mainly to _______ _____ _______
Replace water deficit
Glucose is given in regimens with calcium and insulin for the emergency management of ______________
- Hyperkalaemia
and - After correction of hyperglycaemia
- During treatment of DKA
What is the initial treatment for the correction of severe hypokalaemia?
Potassium chloride with sodium chloride IV infusion, only when sufficient potassium cannot be taken by mouth.
Why should initial potassium replacement therapy not involve glucose infusions?
Because glucose may cause a further decrease in the plasma-potassium concentration.
What is sodium bicarbonate’s mechanism of action?
Sodium bicarb buffers metabolic acidosis and lactic buildup in the body caused by anaerobic metabolism secondary to severe hypoxia by reaction with hydrogen ions to form watch and carbon dioxide.
What are the indications for sodium bicarbonate?
- Alkalinisation of urine
- Relief of discomfort in mild UTIs
- Maintenance of alkaline urine
- Chronic acidotic states such as uraemia acidosis or renal tubular acidosis
- Severe metabolic acidosis
- Removal of earwax
What are the side-effects can occur with sodium bicarb use?
For removal of ear wax: Dry Ear
With IV use:
- Skin exfoliation
- Soft tissue necrosis
- Ulcer
With oral use:
- Abdominal cramps
- Burping
- Flatulence
- Hypokalaemia
- Metabolic alkalosis
In more severe metabolic acidosis (or unresponsive acidosis to correction of anoxia or hypovolaemia), what treatment should be given?
Sodium bicarbonate (1.26%) can be infused over 3-4 hours with plasma-pH and electrolyte monitoring.
In severe shock, metabolic acidosis can develop without sodium or volume depletion, in these circumstances, how should sodium bicarbonate be given?
A small volume of hypertonic solution, such as 50mL of 8.4% solution IV
Why is sodium lactate IV infusion no longer used in metabolic acidosis?
Because of the risk of producing lactic acidosis, particularly in seriously ill patient with poor tissue perfusion or impaired hepatic function.
What are colloids?
Plasma and plasma substitutes that contain large molecules that do not readily leave the intravascular space where they exert osmotic pressure to maintain circulatory volume.
What are crystalloids?
Fluids containing electrolytes such as sodium chloride and glucose, a small volume of colloid is required to produced the same expansion of blood volume, thereby shifting salt and water from the extravascular space.
Which plasma substitute can be given without regard to the recipient’s blood group?
Albumin solution
What is and isn’t in albumin solution?
Contains:
- soluble proteins
- electrolytes
Does not contain:
- clotting factors
- blood group antibodies
- plasma cholinesterase’s
What are the indications of albumin solution?
- Acute or subacute loss of plasma volume
e. g. burns, pancreatitis trauma, and complications of surgery, plasma exchange, – - Generalised oedema where salt and water restriction with plasma volume expansion are required
- Paracentesis of large volume ascites associated with portal hypertension
What should Hydroxyethyl starches be used for?
The treatment of hypovolaemia due to acute blood loss when crystalloids alone are not sufficient.
Name 3 macromolecular substances which are plasma substitutes and are metabolised slowly?
Dextran, gelatin, and the hydroxyethyl start, tetrastarch.
When should dextran and gelatinous be used?
To expand and maintain blood volume in shock arising from conditions such as burns or septicaemia
Also as immediate short term measure for haemorrhage until blood is available
