bradypnea

Bradypnea means breathing more slowly than normal — too few breaths per minute. It is the mirror image of tachypnea: where rapid breathing usually signals the body trying harder, an unusually slow rate often signals that the breathing control system itself has been turned down.

In a resting adult, a rate persistently below about twelve breaths a minute is generally considered bradypnea, though what counts as too slow depends on age and context, and a fit person can breathe slowly and deeply while perfectly well. Because rate alone says nothing about depth, slow breathing must be read together with how deep each breath is and how much air is actually moved per minute.

The concerning causes act on the brain's respiratory center: opioid and sedative drugs are the classic example, depressing the drive to breathe and dangerously slowing the rate; others include raised pressure inside the skull, severe low body temperature, and end-stage exhaustion of a tiring patient. In the overdose setting, a falling respiratory rate is an early and ominous warning that breathing may stop, and it is one of the signs that prompts urgent reversal and support.