Acid-Base Balance and Disorders (1)

Question 1

What’s the normal PH range?

How does PH affect potassium levels?

Answer 1

➊ 7.35 - 7.45

➋ • Acidosis comes with Hyperkalaemia
• Alkalosis comes with Hypokalaemia

Question 2

Respiratory Acidosis:
What occurs here?

What are its causes?

How is it compensated?

Answer 2

➊ CO2 retention, leading to a low blood pH, and is usually due to hypoventilation

➋ • COPD
• Severe asthma attack
• Respiratory centre depression - GA, Sedatives, Cerebral trauma
• Pulmonary disease - Pulmonary fibrosis, Pneumonia, RDS
• Neuromuscular disease - MND, GBS

➌ Metabolic - Kidneys excrete more H+ and reabsorb more HCO3-
• Take a few days and can never be fully compensated

Question 3

Respiratory Alkalosis:
What occurs here?

What are its causes?

How is it compensated?

Answer 3

➊ Low CO2, leading to a high blood pH, and is usually due to hyperventilation

➋ • Kussmaul breathing
• High altitude
• Anxiety
• Hyperthyroidism
• Salicylate poisoning

➌ Metabolic - Kidneys reasborb H+ and excrete more HCO3- via

Question 4

Metabolic Acidosis:
What are the 2 types of it?

What are the causes of both types?

How is it compensated?

Answer 4

➊ • Raised anion gap
• Normal anion gap

➋ • Raised anion gap type is usually due to increased production or ingestion of acid - MUDPILES:
‣ Methanol, Uraemia, DKA, Propylene, Iron/Isoniazid, Lactic acidosis, Ethylene, Salicylates
• Normal anion gap is usually due to excessive loss of HCO3-
‣ Renal tubular acidosis, Diarrhoea, Adrenal insufficiency, Spironolactone, Pyloric stenosis

➌ Respiratory - Kussmaul breathing (deep, laboured) to excrete more CO2 and raise PH

N.B. Anion gap = (Na + K) - (Cl + HCO3) - NR is 16-20

Question 5

Metabolic Alkalosis:
What are its causes?

How is it compensated?

Answer 5

➊ • Vomiting (loss of acid)
• Diuretics
• Cushing syndrome
• Conn’s syndrome

➋ Respiratory - hypoventilation but one can only hold breath up to a limit