What condition describes headaches, lethargy, and nausea due to decreased O2 saturation after nitrous oxide use?

The condition characterized by headaches, lethargy, and nausea following the use of nitrous oxide is diffusion hypoxia. This phenomenon occurs when nitrous oxide rapidly diffuses out of the bloodstream and into the lungs after discontinuation of its administration. The rapid displacement of nitrous oxide can cause a decrease in the partial pressure of oxygen in the body, leading to symptoms such as headache, lethargy, and nausea.

Diffusion hypoxia typically arises because of reduced oxygen saturation in the blood as the nitrous oxide is being eliminated, which can temporarily impair oxygen delivery to tissues. This condition is often mild and reversible, making it important to provide supplemental oxygen after the use of nitrous oxide to mitigate its effects.

In contrast, aspiration pneumonia relates to the inhalation of foreign material into the lungs, which is not a direct consequence of nitrous oxide administration. Hypercapnia refers to elevated levels of carbon dioxide in the bloodstream, not specifically linked to the effects of nitrous oxide. Hypoxemia involves low levels of oxygen in the blood, which can result from different causes, but it does not specifically describe the rapid change associated with nitrous oxide elimination as diffusion hypoxia does.