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Y4 Acute and Critical Care > Electrolyte Disturbance > Flashcards

Electrolyte Disturbance Flashcards

1
Q

What are normal total calcium levels?

A

A normal total calcium is about 2.2-2.6 mmol/L

However, a normal ionised calcium is about 1.1-1.3 mmol/L. You may also get a corrected total calcium that accounts for serum albumin levels.

Blood gas machines often measure ionised calcium values. The three should not be mixed up.

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2
Q

Hypercalcaemia causes

A

Primary or tertiary hyperparathyroidism

Malignancy

Sarcoidosis

Drugs

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3
Q

Hypercalcaemia presentation

A

Confusion

Weakness

Abdominal pain

Hypotension

Arrhythmias

Cardiac arrest

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4
Q

ECG changes associated with hypercalcaemia

A

Short QT interval

Prolonged QRS interval

Flat T-waves

AV block

Cardiac arrest

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5
Q

Hypercalcaemia treatment

A

Fluid replacement IV

Furosemide 1 mg/kg IV

Hydrocortisone 200-300 mg IV

Pamidronate 30-90 mg IV

Correct underlying cause

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6
Q

Causes of hypocalcaemia

A

Chronic renal failure

Acute pancreatitis

Calcium channel blocker OD

Toxic shock syndrome

Rhabdomyolysis

Tumor lysis syndrome

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7
Q

Presentation of hypocalcaemia

A

Paraesthesia

Tetany

Seizures

AV block

Cardiac arrest

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8
Q

ECG changes associated with hypocalcaemia

A

Prolonged QT interval

T wave inversion

Heart block

Cardiac arrest

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9
Q

Treatment of hypocalcaemia

A

Calcium chloride 10% 10-40 mL IV

Magnesium sulphate (2-4 mL:4-8 mmol) IV

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10
Q

Causes of hypermagnesaemia

A

Renal failure

Iatrogenic

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11
Q

Hypermagnesaemia presentation

A

Confusion

Weakness

Respiratory depression

AV block

Cardiac arrest

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12
Q

Hypermagnesaemia ECG changes

A

Prolonged PR and QT

T wave peaking

AV block

Cardiac arrest

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13
Q

Hypermagnesaemia treatment

A

Treat when Mg >1.75 mmol/L

Calcium chloride (10% 50-10 mL IV)

Saline diuresis: 0.9% saline with furosemide 1 mg/kg IV

Ventilatory support, if required

Haemodialysis

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14
Q

Hypomagnesaemia causes

A

GI loss

Polyuria

Starvation

Alcoholism

Malabsorption

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15
Q

Hypomagnesaemia presentation

A

Tremor

Ataxia

Nystagmus

Seizures

Arrhythmias (torsade de pointes)

Cardiac arrest

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16
Q

Hypomagnesaemia ECG changes

A

Prolonged PR and QT

ST depression

T wave inversion

Flattened P waves

Increased QRS duration

Torsade de pointes

17
Q

Hypomagnesaemia treatment

A

Severe or symptomatic:
- Magnesium sulphate (2g 50% IV over 15 min)

Torsade de pointes:
- Magnesium sulphate (2g 50% IV over 1-2 min)

Seizure:
- Magnesium sulphate (2g 50% IV over 10 min)

18
Q

True or false: The general treatment for hypomagnesaemia is magnesium sulphate (2g 50% [4 mL;8 mmol] IV) but the infusion time depends on the symptoms and signs.

A

True.

Treat hypomagnesaemia with magnesium sulphate 2g 50% (4 mL;8 mmol) IV.

Severe or symptomatic: over 15 mins

Torsade de pointes: over 1-2 mins

Seizure: over 10 mins

19
Q

Hyperkalaemia causes

A

Renal failure (AKI/CKD)

Drugs (e.g. ACEi, ARBs, K+ sparing diuretics, NSAIDs, B-blockers, trimethoprim)

Tissue breakdown (e.g. rhabdomyolysis, tumour lysis, haemolysis)

Metabolic acidosis (e.g. renal failure, DKA)

Endocrine disorders (e.g. Addison’s disease)

Diet

Spurious - psuedo-hyperkalaemia describes finding a raised serum (clotted blood) K+, when the actual value in plasma (non-clotted blood) is normal. This is because during clotting, K+ is released from cells and platelets. The most common cause is prolonged transit time to the lab or poor storage conditions.

20
Q

Hyperkalaemia presentation

A

Weakness, paralysis

Paraesthesia

Arrhythmia

Cardiac arrest

21
Q

Hyperkalaemia ECG changes

A

Most patients with K+ >6.7 mmol/L will have ECG changes.

  • First degree heart block (PR interval >0.2 s)
  • Flattened or absent P waves
  • Tall, tented P waves (larger than R wave in 2+ leads)
  • ST depression
  • S and T wave merging (sine wave pattern)
  • Widened QRS (>0.12 s)
  • Ventricular tachycardia
  • Bradycardia
  • Cardiac arrest (PEA, VF, pVT, asystole)
22
Q

Hyperkalaemia treatment

A

1) Cardiac protection: calcium.
- Give IV Calcium gluconate (30ml 10% over 10 mins)

2) Shift K+ into cells
- Insulin + glucose (10 units actrapid in 50ml of 50% dextrose solution over 10-15 minutes)
- Consider salbutamol nebuliser

3) Remove K+ from body
- Potassium binders (potassium exchange resins)
- Diuresis (fluids +/- furosemide)
- Dialysis

4) Monitor serum K+
- Check serum levels 30 minutes after each insulin infusion
- Regularly monitor levels for 24 hours to check for rebound hyperkalaemia (levels rise again after treatment wear off, roughly 4-6 hours)

23
Q

Hypokalaemia causes

A

GI loss (e.g. diarrhoea)

Drugs (diuretics, laxatives, steroids)

Renal losses (renal tubular disorders, diabetes insipidus, dialysis)

Endocrine disorders (e.g. Cushing’s, hyperaldosteronism)

Metabolic alkalosis

Magnesium depletion (important for K+ uptake and intracellular maintenance)

Poor dietary intake

Iatrogenic (e.g. treatment for hyperkalaemia)

24
Q

Hypokalaemia presentation

A

Fatigue, weakness

Muscle cramps

Constipation

Ascending paralysis

Respiratory difficulties

Arrhythmia

Cardiac arrest

25
Q

Hypokalaemia ECG features

A

U waves

T wave flattening

ST segment changes

Arrhythmias

Cardiac arrest (VF/pVT, PEA, asystole)

26
Q

Hypokalaemia treatment

A

Gradual replacement of potassium is preferable, but in an emergency IV K+ is required. The maximum IV dose is 20 mmol/hour, unless the patient is peri-arrest.

If cardiac arrest is imminent, give a rapid infusion (e.g. 2 mmol/minute for 10 minutes, followed by 10 mmol/minute over 5-10 minutes).

Giving magnesium alongside the K+ will facilitate a more rapid correction. This is because Mg+ is important for K+ uptake and for maintaining intracellular K+ values.

27
Q

What pattern of electrolyte disturbance is common in refeeding syndrome?

A
  • Hypophosphataemia
  • Hypokalaemia
  • Hypomagnesaemia (may predispose to torsades de pointes)
  • abnormal fluid balance (H2O and Na retention)
28
Q

What is refeeding syndrome?

A

Refeeding syndrome describes the metabolic abnormalities which occur on feeding a person following a period of starvation.

It occurs when an extended period of catabolism ends abruptly with switching to carbohydrate metabolism.

The metabolic consequences include:

  • hypophosphataemia
  • hypokalaemia
  • hypomagnesaemia: may predispose to torsades de pointes
  • abnormal fluid balance
29
Q

How can refeeding syndrome be prevented?

A

If a patient hasn’t eaten for >5 days aim to refeed at no more than 50% of requirements for the first 2 days.

Important to identify high-risk patients:

  • Low BMI
  • Unintentional weight loss
  • Little nutritional intake 5 days or more
  • History of alcohol abuse, insulin therapy, chemo, diuretics, antacids
30
Q

What pattern of electrolyte disturbance is seen in Addisonian crisis?

A

Hyponatraemia

Hyperkalaemia

Hypoglycaemia

Y4 Acute and Critical Care (27 decks)

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