For each clinical setting described below, select the set of ABG determinations with which it is most likely to be associated.
A 29-year-old diabetic with blood glucose of 280 mg/dL
pH PaO2 PaCO2
- 7.23 64 80
- 7.39 88 40
- 7.22 74 33
- 7.54 75 24
- 7.37 67 52
Answer(s): C
Explanation:
ABG determinations are essential in the diagnosis of respiratory and acid-based disturbances. Extremely obese patients suffer from increased work of breathing, as well as elevation of the diaphragm with decrease in lung volume. The resultant hypoventilation is characterized by carbon dioxide retention leading to chronic respiratory acidosis with metabolic compensation (ABG set E in the question). When associated with somnolence, excessive appetite, and polycythemia, this is known as the pickwickian syndrome.
Modest weight loss can lead to dramatic improvement in respiratory functioning. The earliest derangement in salicylate poisoning is hyperventilation, resulting in decreased PaCO2 and increased arterial pH (ABG set D). Eventually, there is CNS depression with somnolence and hypoventilation resulting in respiratory acidosis. Diabetic ketoacidosis may cause acute metabolic acidosis. In a healthy young adult with no lung disease, appropriate respiratory compensation occurs (ABG set C). Without insulin to reverse this process, the patient may go on to develop worsening acidosis and an inability to compensate adequately. ABG set A reflects acute respiratory acidosis (hypoventilation) without metabolic compensation. ABG set B is normal.