A patient breathing 100% O2 for 24 hours or longer would most likely exhibit what?

Breathing 100% oxygen for an extended period, such as 24 hours or longer, can lead to pulmonary oxygen toxicity, which may cause various physiological changes in the lungs. One significant outcome of prolonged exposure to high concentrations of oxygen is a decrease in lung compliance due to the effects on the alveolar and epithelial cells, leading to inflammation and potential damage to the lung tissue. This inflammation can result in atelectasis (collapse of alveoli), which contributes to decreased lung function and subsequently can reduce vital capacity.

Vital capacity is the maximum amount of air a person can exhale after a maximum inhalation, and a decreased vital capacity may be observed due to the onset of such complications. Therefore, patients exposed to 100% oxygen for extended periods are likely to experience decreased vital capacity, making this option the most accurate in reflecting the physiological responses expected under those conditions.