Recognize blood gas abnormalities in patients with hypoventilation and pneumonia.

Explanation:

Pneumonia causes hypoxia and thus hyperventilation. In the ordinary case of pneumonia the pCO2 should therefore be low   unless there is associated hypoventilation -either because of severe disease or because of COPD.

If it is secondary to COPD alone - the pH will be almost normal and the HCO3 would be high because of metabolic compensation but if it is due to severe illness, the patient will have poor vital signs, exhausted look and an acidotic pH. The latter patient needs emergency intubation while the other would be managed as per his clinical appearance.