Oliver constructs "Oxygen" as a free verse poem written in 24 lines. "Oxygen" lacks unified rhymes, meter, and repetitions as a free verse poem. Meter is a repeating sequence of syllables across lines or stanzas. As such, the poem resembles natural speech and takes on an informal and conversational tone. This connects well with the setting, which is at the home of the speaker and their partner, as well as the natural feeling of a familiar, long-term relationship.

Oliver breaks her poem into three-line stanzas. The contrast between the uniform three-line stanzas and the lack of uniform line length, rhymes, meter, and repetition mirrors the act of breathing. The stanzas represent a person's need to breathe. However, breathing varies in depth, length, and speed, just as Oliver uses enjambment to connect between stanzas. The unrestricted free verse allows Oliver to capture the variety of ways a person experiences breathing.

An axiom consists of a statement or proposition generally accepted as true, accurate, or established. Writers and debaters then use this accepted truth as the starting point for an argument.