After drainage of a pelvic abscess, a 45 years old patient receiving 70% oxygen is found to have the following arterial blood gases:- pH 7.48; PO2 55 mmHg; Pco2 30 mmHg. These results are most consistent with the diagnosis of :
|A||Chronic obstructive pulmonary disease|
|B||Postoperative pain pulmonary disease|
|C||Adult respiratory distress syndrome|
a. The combination of hypoxemia that is resistant to high oxygen concentrations and hyperventilation is characteristic of ARDS.
b. Although there are four general causes of hypoxemia; hypoventilation, a low ventilation – perfusion ratio, diffuse abnormalities and pulmonary shunting.
c. Although the first three condition improve in response to an increased inspired oxygen concentration, most of the hypoxemia seen in ARDS is secondary to shunting so is not ameliorated by oxygen.