Why is nitric oxide testing used in pulmonary function assessments?

Nitric oxide testing is primarily utilized to evaluate airway inflammation, particularly in patients with asthma. This test measures the concentration of exhaled nitric oxide (FeNO), which is an indicator of eosinophilic airway inflammation. Elevated levels of nitric oxide in the breath suggest that there is inflammation present in the airways, which is often a characteristic feature of asthma.

In asthma, the airway inflammation can lead to increased production of nitric oxide due to the activation of inflammatory cells and the subsequent release of mediators that stimulate nitric oxide synthase. Therefore, measuring the levels of exhaled nitric oxide can help in both the diagnosis and management of asthma, including guiding treatment decisions such as the use of inhaled corticosteroids.

The other options do not directly relate to the primary function of nitric oxide testing. For instance, measuring lung elasticity is more associated with other pulmonary function tests such as spirometry or lung volume measurements. Similarly, diagnosing restrictive lung diseases typically involves different parameters, such as total lung capacity and forced vital capacity measurements, rather than nitric oxide levels. Lastly, assessing overall lung function encompasses a broader range of evaluations beyond just inflammation, including airway resistance and lung volumes.