Acid - Base balance

Question 1

What is the DDx of acute respiratory acidosis ?

Answer 1

• CNS depression drugs.
• Neuromuscular disordes : Myopathies- neuropathies.
• Acute airway obstruction: upper airway, laryngospasm, bronchospasm.
• Severe pneumonia.
• Pulmonary edema.
• Impaired lung motion: pneumothorax, hemothorax.
• Thoracic cage injury - flail chest.
• Ventilator dysfunction.

Question 2

What is the DDx of acute respiratory alkalosis ?

Answer 2

• Anxiety.
• Hypoxia
• Lung disease with/out hypoxia
• CNS disease.
• Drug use: Salicylates, catecholamines, progesterone.
• Pregnancy
• Sepsis.
• Hepatic encephalopathy.
• Mechanical Ventilation.

Question 3

anion gap equation

Answer 3

AG= (Na + K) - (Cl + HCO3)

Question 4

What is the normal range of anion gap ?

Answer 4

12 +/- 2 mmol/L

Question 5

What is the normal range of the following:

• pH.
• PCO2
• HCO3

Answer 5

• pH = (acidosis) 7.35 - 7.45 (alkalosis).
• PCO2= (Alkalosis) 35 - 45 (mmHg) (Acidosis).
• HCO3 = (Acidosis) 22 - 26 (mmol/L) (Alkalosis).

Question 6

In acid base disorders , when do we say it is a primary metabolic acidosis regardless of pH or serum HCO3 concentration ?

Answer 6

when anion gap = 20 or more.

Question 7

Excess anion gap equation?

Answer 7

Total anion gap - normal anion gap (12) + HCO3

Question 8

What is the DDx of chronic respiratory acidosis with metabolic compensation?

Answer 8

• Chromic lung disease: obstructive or restrictive.
• Chronic neuromuscular disorders.
• Chronic respiratory center depression - central hypoventilation.

Question 9

What is the DDx of metabolic acidosis with high anion gap?

Answer 9

MUD PILES

• Methanol
• Uremia
• DKA
• Pyroglutamate and propylene glycol/ paraldehyde
• Isoniazid
• Lactic acidosis
• Ethylene glycol
• Salicylates

Question 10

In acid base disorders , when do we say it is a primary metabolic alkalosis regardless of pH or serum HCO3 concentration ?

Answer 10

when excess anion gap is greater than 30mmol/L.