You are asked to review a 44-year-old male known epileptic following a prolonged generalised tonic-clonic convulsion. He is intubated and ventilated.
The arterial blood gas analysis is as follows:
|Parameter||Patient value||Normal adult range|
|pCO2||35 mmHg (4.6 kPa)||35-45 (4.6-6)|
|pO2||105 mmHg (14 kPa)||75-98 (10-13)|
List the abnormalities on the blood gas and give the most likely cause of each abnormality.
Metabolic acidosis – lactic acidosis secondary to prolonged seizures
Respiratory acidosis (or inadequate compensation) – central hypoventilation or Inadequate mechanical ventilation
Increased A-a gradient - aspiration pneumonia
Let us dissect these results systematically.
Thus, there is:
The college expected their candidates to make an intuitive leap, and to assume that the history of prolonged seizure is enough to explain the acidosis (because lactate) and the hypoxia (because aspiration).