Normal respiration rate in adults is 12 breaths/min. Normal breathing, as we discussed, is strictly nasal (in and out), mainly diaphragmatic (i.e., abdominal), slow (in frequency) and imperceptible (or small/shallow in its volume).
The physiological and medical norm for respiratory minute ventilation at rest is 6 liters per minute for a 70 kg man (see references for textbooks below: Guyton, 1984; Ganong, 1995; Straub, 1998; Castro, 2000; etc.). These textbooks also provide the following numbers for normal breathing:- normal TV (tidal volume or air volume breathed in during a single breath): 500 ml;- normal Rf (respiratory frequency or respiratory rate): 12 breaths per minute;- inspiration: about 1.5-2 seconds;- normal exhalation is 1.5-2 seconds, followed by an automatic pause (no breathing for 1-2 seconds).
Respiratory Rate Chart (Graph)
This graph represents the normal-breathing pattern at rest or the dynamic of the lungs' volume as a function of time. You can see that it corresponds to the normal breathing rate of 12 breaths/minute."If a person breath-holds after a normal exhale, it takes about 40 s before breathing commences” (McArdle et al, 2000). Hence, the normal breath-holding number (immediately after usual exhalation and after an exhale) is around 40 s. This indicates normal oxygenation of cells and tissues.
The current medical norm for CO2 pressure in the alveoli of the lungs or arterial blood is 40 mm Hg. This number was established about one century ago by famous British physiologists Charles G. Douglas and John S. Haldane (Oxford University). Their results were published in 1909 in their article "The regulation of normal breathing", Journal of Physiology (Douglas & Haldane, 1909).
What is known about other parameters of normal breathing? It is invisible (no chest or belly movements), regular, and inaudible (no panting, no wheezing, no sighing, no yawning, no sneezing, no coughing, no deep inhalations or exhalations).
Pediatric Respiratory Rate Chart
(Newborn, Toddlers, Infants, and Children)
(the source for this chart: Normal respiration rate for children; source: health.msn.com)
| Groups and ages | Normal rates |
| Newborns to 6 months old | 30-60 breaths/min |
| 6 to 12 months old | 24–30 breaths/min |
| 1 to 5 years old | 20–30 breaths/min |
| 6 to 12 years old | 12–20 breaths/min |
Important note. Clinical evidence suggests that respiratory rates
in healthy children are near the lower limits or even below it.
Article contributed by Nirvana science consultant dr.Artour Rakhimov