The most important functions of respiratory system are:
Failure of the system could result in hypoxemia, C02 retention and respiratory acidosis. Unfortunately, our physical assessment capabilities are of limited value and one should rely on blood gases for functional assessment. Physical exam can only detect extreme functional derangement. Many of the abnormalities noted could result from multi functional problems.
To Assess for Hypoxemia
Central cyanosis results from pulmonary dysfunction, the mucous membrane of conjunctiva and tongue are bluish. If there was chronic hypoxemia and secondary erythrocytosis, you can detect the conjunctival and scleral vessels to be full, tortuous and bluish.
There is no good way to clinically ascertain C02 retention and pH changes. Some of the findings reported in text books are late manifestations and unreliable. Papilloedema is seen in severe CO2 retention. Mental obtundation and coma are late signs of CO2 retention and respiratory acidosis. Rely on blood gases for assessment of functional accomplishments of lungs.
Blood gases were not obtained in this patient. This is not a routine test. His conjunctivae and tongue appeared normal.