Describe the acid-base changes that occur in acute hypoxaemia

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College Answer

The main points expected for a pass were

  • Definition of hypoxaemia
  • Physiological causes of hypoxaemia
  • Formation of a lactic acidosis
  • Development ofhypocarbia secondary to stimulation ofrespiration from hypoxia and acidosis
  • Explanation of the decreased bicarbonate concentration and negative base excess
  • Extra points were given for more detailed explanation of the lactic acidosis, commenting on the anion gap and some consequences of hypoxaemia.

A common problem was to incorrectly state the relationship between pH and hydrogen ion
concentration.