The respiratory rate, also known as the respiration rate, ventilation rate, ventilatory rate,
ventilation frequency, respiration frequency, pulmonary ventilation rate, or breathing frequency,
is the rate of ventilation, that is, the number of breaths taken within a set amount of time.
A normal respiratory rate is termed eupnea, an increased respiratory rate is termed tachypnea
and a lower than normal respiratory rate is termed bradypnea.
Breathing is a part of respiration.
Thus, in precise usage, the words breathing and ventilation are hyponyms, not synonyms,
of respiration; but this prescription is not consistently followed, even by most health
care providers, because the term respiratory rate is a well-established term in health
care, even though it would need to be consistently replaced with ventilation rate if the precise
usage were to be followed.
Measurement Human respiration rate is measured when a
person is at rest and involves counting the number of breaths for one minute by counting
how many times the chest rises.
An optical breath rate sensor can be used for monitoring patients during a magnetic
resonance imaging scan.
Respiration rates may increase with fever, illness, or other medical conditions.
When checking respiration, it is important to also note whether a person has any difficulty
breathing.
Inaccuracies in respiratory measurement have been reported in the literature.
One study compared respiratory rate counted using a 90 second count period, to a full
minute, and found significant differences in the rates.
Another study found that rapid respiratory rates in babies, counted using a stethoscope,
were 60–80% higher than those counted from beside the cot without the aid of the stethoscope.
Similar results are seen with animals when they are being handled and not being handled—the
invasiveness of touch apparently is enough to make significant changes in breathing.
Various other methods to measure respiratory rate are commonly used, including impedance
pneumography, and capnography which are commonly implemented in patient monitoring.
Normal range The typical respiratory rate for a healthy
adult at rest is 12–20 breaths per minute.
Average resting respiratory rates by age are: birth to 6 weeks: 30–60 breaths per minute
6 months: 25–40 breaths per minute 3 years: 20–30 breaths per minute
6 years: 18–25 breaths per minute 10 years: 12–15 breaths per minute
Adults: 12–20 breaths per minute Minute volume
Respiratory minute volume is the volume of air which is inhaled or exhaled from the lungs
in one minute.
Diagnostic value The value of respiratory rate as an indicator
of potential respiratory dysfunction has been investigated but findings suggest it is of
limited value.
One study found that only 33% of people presenting to an emergency department with an oxygen
saturation below 90% had an increased respiratory rate.
An evaluation of respiratory rate for the differentiation of the severity of illness
in babies under 6 months found it not to be very useful.
Approximately half of the babies had a respiratory rate above 50 breaths per minute, thereby
questioning the value of having a "cut-off" at 50 breaths per minute as the indicator
of serious respiratory illness.
It has also been reported that factors such as crying, sleeping, agitation and age have
a significant influence on the respiratory rate.
As a result of these and similar studies the value of respiratory rate as an indicator
of serious illness is limited.
Abnormal respiratory rates Apnea
Dyspnea Hyperpnea
Tachypnea Hypopnea
Bradypnea Orthopnea
Platypnea Biot's respiration
Cheyne-Stokes respiration Kussmaul breathing
References