The patient in respiratory distress from smoke inhalation is likely to be experiencing a respiratory acidosis that may or may not be compensated. Therefore, a pH of 7.27, which is less than 7.35, reflects the expected respiratory acidosis. A PaO2 of 152 is higher than normal, which would not be expected in a patient in respiratory distress. A PaCO2 of 40 is within normal limits; a patient in respiratory acidosis would have an elevated carbon dioxide level. In respiratory acidosis, the level of bicarbonate (HCO3), indicates the degree to which the body is compensating for the acidosis; 18 mEq/L is below normal limits. Such a low bicarb would be reflective of a metabolic acidosis, which is not indicated in the question.