Which of the following actions should be avoided to prevent hypercapnia?

To prevent hypercapnia, which is an excess of carbon dioxide in the bloodstream, it is crucial to avoid holding your breath. This action can lead to a buildup of carbon dioxide because, while you hold your breath, your body continues to produce CO2 as a byproduct of metabolism without the opportunity to exhale it. Holding your breath interrupts the normal respiratory process, causing an imbalance and potentially leading to elevated levels of CO2 in the body.

In contrast, actions like deep breathing, using oxygen-rich supplements, and conducting slow ascents promote efficient gas exchange and can help the body manage carbon dioxide levels. Deep breathing enhances ventilation and allows for the effective removal of CO2. Oxygen-rich supplements can assist in maintaining proper oxygen levels, especially in situations where breathing is compromised, and slow ascents are essential for allowing the body to equilibrate and avoid rapid changes in pressure that could exacerbate gas retention issues. Thus, avoiding breath-holding is a key component in preventing hypercapnia during advanced diving practices.