This viva will test your knowledge of hypoxemia, oxygen therapy and pulse 
oximetry. The following is a blood gas of a young person who has taken a sedative drug 
overdose. 

  • pH 7.2
  • PO2 40 mmHg
  • PCO2 80 mmHg
  • HCO3- 28 mmols/L

Describe this blood gas
Apart from being asked to describe the blood gas, candidates were also asked about 
the Henderson-Hasselbach equation, causes of hypoxaemia, pulmonary shunt, 
response to supplemental oxygen and pulse oximetry