What percentage of vital capacity should the patient inhale during the Single Breath-Hold Technique?

The correct answer indicates that a patient should inhale at least 85% of their vital capacity during the Single Breath-Hold Technique. This technique is commonly used in pulmonary function testing to assess gas exchange efficiency in the lungs. By inhaling a significant portion of their vital capacity, the patient ensures that a substantial volume of air is available for the measurement of gas diffusion and for assessing the function of alveoli.

Inhaling at least 85% of vital capacity is crucial because it maximizes the amount of gas available in the lungs for accurate testing. This high percentage helps in achieving a more complete sample of the gas in the lungs, leading to reliable and reproducible results. If the patient were to inhale less than this amount, it could compromise the test results, as there may not be enough gas to accurately measure the diffusion capacity and other parameters being evaluated.

This understanding of inhalation volume illustrates a key technical requirement for ensuring effective pulmonary function tests, particularly for assessing conditions like emphysema or pulmonary fibrosis, where diffusion capacity may be altered.