Acid base balance Flashcards
What is the normal pH of blood?
7.37-7.43
What is the Henderson-Hasselbach equation?
pH = [HCO3] / PCO2
What is the bicarb buffer?
H+ + HCO3 – H2CO3 – H2O + CO2
What is the pH, pCO2 and HCO3 in metabolic acidosis?
pH down
pCO2 down
HCO3 really down
What is the cause of metabolic acidosis?
Decreased HCO3, either direct loss or buffering of increased H+
What are the causes of metabolic acidosis?
Increase an acid e.g. DKA, lactic acidosis
Decrease of base e.g. diarrhoea, AKI
What causes a normal anion gap and increased anion gap?
Increase in acid= invtased gap
Loss of base= normal anion gap
What is the normal anion gap?
10-18
What is the pH, pCO2 and HCO3 in metabolic alkalosis?
pH up
pCO2 up
HCO3 really up
What causes metabolic alkalosis?
Increased HCO3, either by direct gain or loss of H+
What are the causes of metabolic alkalosis?
Vomiting
Diuretics
Hypokalaemia
How does hypokalaemia cause metabolic alkalosis?
Intracellular shift of H+ to maintain neutrality
What is the pH, pCO2 and HCO3 in respiratory acidosis?
pH down
pCO2 really up
HCO3 up
What causes respiratory acidosis?
Hypoventilation –> increased CO2 –> increases H+
What are the causes of respiratory acidosis?
COPD
Decompensation in respiratory disease e.g. severe asthma
Sedative drugs e.g. opioids, BZDs
