What is the function of an infrared analyzer in pulmonary function tests?

An infrared analyzer plays a significant role in pulmonary function tests, particularly in measuring the concentrations of specific gases. The primary function of an infrared analyzer is to detect changes in the levels of gases such as carbon dioxide (CO2) and other hydrocarbons like methane (CH4), or it can be calibrated to measure noble gases such as helium (He). This capability is crucial in various pulmonary tests that analyze gas exchange and respiratory function.

In the context of pulmonary function testing, infrared analyzers are often used during procedures such as the assessment of diffusing capacity, where the uptake of carbon monoxide is measured to evaluate the efficiency of gas transfer in the lungs. The presence of infrared light allows the analyzer to determine the concentration of gases based on their specific absorption characteristics.

This functionality is distinct from the other options listed. Measuring lung volumes typically involves techniques such as spirometry or body plethysmography. Testing airway resistance deals with dynamic testing protocols that measure how easily air can flow through the airways, while assessing blood oxygen levels is generally done via pulse oximetry or arterial blood gas analysis, neither of which involves infrared analysis. Thus, the function of an infrared analyzer is uniquely suited to the detection of specific gases in the context of pulmonary function tests.