The respiratory rate in humans is measured by counting the number of breaths for one minute through counting how many times the chest rises. A fibre-optic 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.
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. In addition novel techniques for automatically monitoring respiratory rate using wearable sensors are in development, such as estimation of respiratory rate from the electrocardiogram, photoplethysmogram and accelerometry signals.
For humans, the typical respiratory rate for a healthy adult at rest is 12–18 breaths per minute. The respiratory center sets the quiet respiratory rhythm at around two seconds for an inhalation and three seconds exhalation. This gives the lower of the average rate at 12 breaths per minute.
- birth to 6 weeks: 30–40 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: 17–23 breaths per minute
- Adults: 12-18 breaths per minute
- Elderly ≥ 65 years old: 12-28 breaths per minute.
- Elderly ≥ 80 years old: 10-30 breaths per minute.
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.
Nonetheless respiratory rate is widely used to monitor the physiology of acutely-ill hospital patients. It is measured regularly to facilitate identification of changes in physiology along with other vital signs. This practice has been widely adopted as part of early warning systems.
Abnormal respiratory rates
- "OSA -". Retrieved 30 September 2016.
- "Vital Signs 101". www.hopkinsmedicine.org.
- Simoes EA, Roark R, Berman S, Esler LL, Murphy J (October 1991). "Respiratory rate: measurement of variability over time and accuracy at different counting periods". Archives of Disease in Childhood. 66 (10): 1199–203. doi:10.1136/adc.66.10.1199. PMC 1793530. PMID 1953002.
- Grenvik A, Ballou S, McGinley E, Millen JE, Cooley WL, Safar P (October 1972). "Impedance pneumography. Comparison between chest impedance changes and respiratory volumines in 11 healthy volunteers". Chest. 62 (4): 439–43. doi:10.1378/chest.62.4.439. PMID 5077999.
- Charlton P, Birrenkott DA, Bonnici T, Pimentel MA, Johnson AE, Alastruey J, Tarassenko L, Watkinson PJ, Beale R, Clifton DA (2018). "Breathing Rate Estimation from the Electrocardiogram and Photoplethysmogram: A Review". IEEE Reviews in Biomedical Engineering. 11: 2–20. doi:10.1109/rbme.2017.2763681. PMID 29990026.
- Bailón R, Sõrnmo L, Laguna P. "Advanced Methods and Tools for ECG Data Analysis - ECG Derived Respiratory Frequency Estimation - Chapter 8". www.robots.ox.ac.uk. Retrieved 2016-02-23.
- Karlen W, Raman S, Ansermino JM, Dumont GA (July 2013). "Multiparameter respiratory rate estimation from the photoplethysmogram". IEEE Transactions on Biomedical Engineering. 60 (7): 1946–53. doi:10.1109/TBME.2013.2246160. PMID 23399950.
- Lapi S, Lavorini F, Borgioli G, Calzolai M, Masotti L, Pistolesi M, Fontana GA (January 2014). "Respiratory rate assessments using a dual-accelerometer device". Respiratory Physiology & Neurobiology. 191: 60–6. doi:10.1016/j.resp.2013.11.003. PMID 24263211.
- Barrett, Kim E.; Barman, Susan M.; Boitano, Scott; Brooks, Heddwen (2012-04-05). Ganong's Review of Medical Physiology (24 ed.). p. 619. ISBN 0071780033.
- Scott L. DeBoer (4 November 2004). Emergency Newborn Care. Trafford Publishing. p. 30. ISBN 978-1-4120-3089-2.
- Lindh WQ, Pooler M, Tamparo C, Dahl BM (9 March 2009). Delmar's Comprehensive Medical Assisting: Administrative and Clinical Competencies. Cengage Learning. p. 573. ISBN 978-1-4354-1914-8.
- Rodríguez-Molinero A, Narvaiza L, Ruiz J, Gálvez-Barrón C (December 2013). "Normal respiratory rate and peripheral blood oxygen saturation in the elderly population". Journal of the American Geriatrics Society. 61 (12): 2238–40. doi:10.1111/jgs.12580. PMID 24329828.
- Mower WR, Sachs C, Nicklin EL, Safa P, Baraff LJ (November 1996). "A comparison of pulse oximetry and respiratory rate in patient screening". Respiratory Medicine. 90 (10): 593–9. doi:10.1016/S0954-6111(96)90017-7. PMID 8959116.
- Smith GB, Prytherch DR, Meredith P, Schmidt PE, Featherstone PI (April 2013). "The ability of the National Early Warning Score (NEWS) to discriminate patients at risk of early cardiac arrest, unanticipated intensive care unit admission, and death" (PDF). Resuscitation. 84 (4): 465–70. doi:10.1016/j.resuscitation.2012.12.016. PMID 23295778.