respiratory rate
The respiratory rate is just how many breaths a person takes in a minute. Like checking a pulse, it is one of the quickest, cheapest readings of how the body is doing — you only need eyes and a clock.
A healthy adult at rest usually breathes about 12 to 20 times a minute; infants and young children breathe considerably faster. The count is most accurate when the person does not realise they are being watched, since knowing about it tends to change the pattern. It is best taken over a full minute, watching the chest or abdomen rise and fall.
Respiratory rate is one of the standard vital signs, alongside heart rate, blood pressure and temperature, and it is often the earliest warning that someone is becoming seriously ill. Breathing too fast (tachypnea) or too slow (bradypnea) can both signal trouble, which is why early-warning scores in hospitals lean heavily on this single, easily overlooked number.
Because people often breathe differently once they know they are being counted, clinicians frequently measure the respiratory rate discreetly, for example while appearing to take the pulse.