Acid-Base Balance Disorders

Question 1

What are the clinical features of acidosis?

Answer 1

• Headache
• Confusion
• Tiredness
• Muscle weakness
• Flapping tremor
• Tachycardia
• Arrhythmia

Question 2

What are the clinical features of alkalosis?

Answer 2

• Headaches
• Muscle weakness
• Muscle cramps
• Tetany (involuntary contraction of muscle)
• Hypokalaemia

Question 3

What are the 2 common features between acidosis and alkalosis?

Answer 3

• Headaches

- Muscle weakness

Question 4

What is the differential diagnosis of acidosis?

Answer 4

• COPD
• Pneumonia
• Foreign body aspiration
• Renal loss of HCO3-
• Diabetic ketoacidosis
• Lactic acidosis

Question 5

What is the differential diagnosis of alkalosis?

Answer 5

• ARDS
• PE
• Pneumonia
• Sepsis
• Gastric acid loss via vomiting (can also cause hypokalaemia)
• Bicarbonate administration

Question 6

How does PE cause alkalosis?

Answer 6

• PE increases the total volume of dead space within the lung
• Makes it seem as if PaCO2 is lower (respiratory alkalosis)

Question 7

What are the causes of metabolic acidosis with increased anion gap?

Answer 7

=> Mnemonic - MUDPILES

M - Methanol
U - Uraemia 
D - Diabetic ketoacidosis 
P - Propylene glycol
I - Isoniazid 
L - Lactate 
E - Ethylene glycol
S - Salicylates

Question 8

What are the causes of metabolic acidosis in the normal anion gap?

Answer 8

=> Mnemonic - HARDUP

H - Hyperalimentation (excess IV saline)
A - Acetazolamide/Addisons disease
R - Renal tubular acidosis 
D - Diarrhoea 
U - Uretero sigmoidostomy 
P - Pancreatic fistula

Question 9

What are the causes of metabolic alkalosis?

Answer 9

• Vomiting
• K+ depletion
• Diuretics
• Liqourice, Carbenoxolone
• Primary hyperaldosteronism
• Cushing’s syndrome
• Barterr’s syndrome
• Congenital adrenal hyperplasia

Question 10

What are the causes of respiratory acidosis?

Answer 10

• Type 2 respiratory failure
• COPD
• Exhaustion from asthma, pneumonia, pulmonary oedema
• Anxiety
• Sedative drugs: benzo, opiate overdose

Question 11

What are the causes of respiratory alkalosis?

Answer 11

A result of hyperventilation from any cause:

• Stroke
• Subarachnoid haemorrhage
• Meningitis
• Mild to moderate asthma
• Anxiety
• Salicylate poisoning
• Altitude
• Pregnancy

Question 12

How do you calculate anion gap?

Answer 12

[Cations] - [Anions] = Anion Gap

Normal anion gap = 10-16 mmol/L