Resuscitation in Special circumstances Flashcards
What is the normal range for extracellular potassium?
3.5-5
When serum pH decreases what happens to serum potassium and why?
It increases because potassium shifts from cellular to vascular space
What usually causes hyperkalaemia?
Increased potassium release from cells or impaired excretion by the kidneys
What is the definition of hyperkalaemia?
> 5.5
What is the definition of severe hyperkalaemia?
> 6.5
What are the causes of hyperkalaemia?
- renal filure
- drugs
- tissue breakdown
- metabolic acidosis
- endocrine disorders
- diet
- spurious
Which drugs cause hyperkalaemia?
ACE-I
ARB
potassium sparing diuretics
NSAIDS
b-blockers
trimethoprim
What are the causes of tissue breakdown contributing to hyperkalaemia?
Tumour lysis
Rhabdomyolysis
Haemolysis
Which endocrine disorders might cause hyperkalaemia?
Addison’s disease
What may be the presentation of hyperkalaemia?
Weakness progressing to flaccid paralysis
Paraesthesia
Depressed deep tendon reflexes
At what level does hyperkalaemia tend to cause ECG changes?
6.7
What are the ECG changes that might be seen in hyperkalaemia?
- first degree heart block
- flattened/absent P waves
- tall, peaked (tented) T waves
- ST depression
- S and T wave merging- sine wave
- widened QRS
- Ventricular tachycardia
- bradycardia
What are the 5 key steps in treating hyperkalaemia?
- Cardiac protection
- Shifting potassium into cells
- removing potassium from the body
- monitoring serum potassium and glucose concentration
- prevention of recurrence
What are the main risks associated with treating hyperkalaemia?
- hypoglycaemia
- tissue necrosis
- rebound hyperkalaemia
Why can tissue necrosis occur after treatment of hyperkalaemia?
2ry to extravasation of IV calcium salts
What is the treatment of mildly elevated K?
5.5-5.9
- address cause
- if treatment is indicated then use potassium binders (Calcium resonium) 15-30g
What is the treatment of a moderately elevated K- without ECG changes?
6.0-6.4
- shift K intracellularly with glucose/insulin
- 10 units short-acting insulin and 25g of glucose IV over 15-30 minutes
- follow up with 10% glucose infusion at 50ml h for 5 h in patients with a pre treatment BM of <7
- remove potassium with calcium resonium
What is the treatment of severe hyperkalaemia >6.5 without ECG changes?
- seek expert help
- give glucose/insulin
- give salbutamol 10-20mg nebulised
- remove k from the body, consider dialysis, sodium zirconium cyclosilicate and/or patiromer
- consider cardiac monitoring
What is the treatment of severe hyperkalaemia with ECG changes?
Protect the heart with calcium salts: 6.8mmol Ca via 10mL calcium chloride IV over 2-5 minutes or 30mL 10% calcium gluconate over 15min
Use shifting agents- glucose+insulin/salbutamol
Remove K
Start cardiac monitoring
Calcium salts protect the heart by reducing the risk VF/pVT
What is the treatment of severe hyperkalaemia during CPR?
10mL calcium chloride 10% by rapid IV bolus
give insulin/glucose 10 units short acting insulin and 25g glucose IV by rapid injection
Give sodium bicarbonate 50mmol (50ml of 8.4% solution) IV by rapid injection if severe acidosis or renal failure
Consider dialysis
What is the definition of hypokalaemia?
<3.5
severe <2.5
What are the causes of hypokalaemia?
- GI losses
- drugs
- renal losses
- endocrine disorders
- metabolic acidosis
- magnesium depletion
- poor diet
Which drugs cause hypokalaemia?
diuretics, laxatives, steroids
Which conditions/procedures cause renal losses of k?
renal tubular disorders
diabetes insipidus
dialysis
Which endocrine conditions may cause K loss?
Cushings, hyperaldosteronism
What are the symptoms of hypokalaemia?
- fatigue
- weakness
- leg cramps
- constipation
- rhabdomyolysis
- ascending paralysis
- respiratory difficulties
What are the ECG features of hypokalaemia?
U waves
T wave flattening
ST segment changes
arrythmias
What is the maximum recommended dose of iv K?
20mmol h
When is a higher dose of K indicated?
When cardiac arrest is imminent
- 2mmol /min for 10 minutes followed by 10mmol over 5-10 min
Which other mineral is essential for K uptake?
Mg
What is the definition of hypercalcaemia?
> 2.6mmol
ionised calcium is usually measured on blood gas machines
Normal ionised Ca is 1.1-1.3
What are the causes of hypercalcaemia?
- primary or tertiary hyperparathyroidism
- malignancy
- sarcoidosis
- drugs
What are the symptoms of hypercalcaemia?
- abdominal pain
- confusion
- weakness
- hypotension
- arrhythmias
- cardiac arrest
What are the ECG signs of hypercalcaemia?
- short QT interval
- prolonged QRS
- flat T waves
- AV block
- cardiac arrest
What are the treatments for hypercalcaemia?
- fluid replacement IV
- furosemide 1mg kg
- hydrocortisone 200-300mg iV
- pamindronate 30-90mg iV
What is hypocalcaemia?
<2.1 total calcium
What are the causes of hypocalcaemia?
- chronic renal failure
- acute pancreatitis
- calcium channel blocker overdose
- toxic shock
- rhabdomyolysis
- tumour lysis syndrome
What are the symptoms of hypocalcaemia?
Paraesthesia
Tetany
Seizures
AV block
Cardiac arrest