Nontuberculous mycobacterial lung infection is often misdiagnosed. Unfortunately, this sometimes delays proper diagnosis until after the patient has had recurrent infections. This may make treatment more difficult because prior use of single drug therapy may have created some drug resistance. Recurrent infections and associated inflammation may have also resulted in additional damage to the respiratory system.
The tests for NTM diagnosis are not complex, but the doctor needs to suspect NTM and order the correct tests.
The diagnosis of NTM involves the following:
Some of the most common Pulmonary Function Tests are:
Spirometry: the patient breathes in deeply and exhales as fully and forcibly as possible, to assess airflow in and out of the lungs.
Plethysmography: measures the gas volume of the lung, using changes of pressure that occur during breathing.
Diffusion capacity: the patient breathes in small amounts of carbon monoxide and the test measures how much of this gas gets into the blood. This indicates the ability of the lung to allow oxygen into the blood.
Arterial blood gas measurements: a small amount of blood is extracted from one of the small arteries in the body (usually in the wrist) in order to analyze the amount of oxygen and carbon dioxide in the blood.
Oxymetry: also provides a measurement of the oxygen level in the blood using a pulse oximeter placed on the patient’s finger for a minute or two.