In patients with low tidal volumes, what increases the risk of absorption atelectasis?

In patients with low tidal volumes, the use of high-flow oxygen can lead to an increased risk of absorption atelectasis. This condition occurs when oxygen is absorbed from the alveoli into the bloodstream more rapidly than nitrogen, which remains in the lungs, especially if there is little or no ambient air to replace it. In a situation where high flow oxygen is administered, particularly in the context of low tidal volumes, the dilution of nitrogen in the lungs becomes significant. As the nitrogen is gradually absorbed, the remaining volume in the alveoli decreases, potentially resulting in collapse or atelectasis.

In contrast, prolonged bed rest can also contribute to atelectasis due to decreased lung expansion and ventilation, but it does not directly tie into the mechanism of absorption atelectasis in the same way high-flow oxygen does. Low PEEP settings can further risk atelectasis by not maintaining end-expiratory lung volume, thereby encouraging collapse. Increased airway resistance can impact airflow and ventilation efficiency but is not specific to the absorption mechanism that high-flow oxygen introduces. Therefore, the use of high-flow oxygen stands out as a significant factor for increased risk of absorption atelectasis in patients experiencing low tidal volumes.