Lung volumes and capacities

Several factors affect lung volumes; some can be controlled, and some cannot be controlled. Lung volumes vary with different people as follows:

A person who is born and lives at sea level will develop a slightly smaller lung capacity than a person who spends their life at a high altitude. This is because the partial pressure of oxygen is lower at higher altitude which, as a result means that oxygen less readily diffuses into the bloodstream. In response to higher altitude, the body's diffusing capacity increases in order to process more air. Also, due to the lower environmental air pressure at higher altitudes, the air pressure within the breathing system must be lower in order to inhale; in order to meet this requirement, the thoracic diaphragm has a tendency to lower to a greater extent during inhalation, which in turn causes an increase in lung volume.

When someone living at or near sea level travels to locations at high altitudes (e.g. the Andes; Denver, Colorado; Tibet; the Himalayas) that person can develop a condition called altitude sickness because their lungs remove adequate amounts of carbon dioxide but they do not take in enough oxygen. (In normal individuals, carbon dioxide is the primary determinant of respiratory drive.)

Lung function development is reduced in children who grow up near motorways{{Cite news |last=Reinberg |first=Steven |date=2007-01-26 |title=Living Near Freeways Hurts Kids' Lungs |newspaper=The Washington Post |language=en-US |url=http://www.washingtonpost.com/wp-dyn/content/article/2007/01/26/AR2007012600568.html |access-date=2023-04-26 |issn=0190-8286}}{{cite journal

| last = Gauderman

| first = W

| title = Effect of exposure to traffic on lung development from 10 to 18 years of age: a cohort study

| journal = The Lancet

| volume = 369

| issue = 9561

| pages = 571–577

| year = 2007

| doi = 10.1016/S0140-6736(07)60037-3

| pmid =17307103

| citeseerx = 10.1.1.541.1258

| s2cid = 852646

}} although this seems at least in part reversible.{{Cite web | url=https://healthstudy.usc.edu/study-findings/ |title = Study Findings – USC Children's Health Study}} Air pollution exposure affects FEV₁ in asthmatics, but also affects FVC and FEV₁ in healthy adults even at low concentrations.{{cite journal

| last = Int Panis

| first = L

| title = Short-term air pollution exposure decreases lung function: a repeated measures study in healthy adults

| journal = Environmental Health

| volume = 16

| issue = 1

| pages = 60

| year = 2017

| doi = 10.1186/s12940-017-0271-z

| pmid =28615020

| pmc = 5471732

| doi-access = free

}}

Specific changes in lung volumes also occur during pregnancy. Functional residual capacity drops 18–20%, typically falling from 1.7 to 1.35 litres,{{citation needed|date=January 2010}} due to the compression of the diaphragm by the uterus.{{citation needed|date=October 2013}} The compression also causes a decreased total lung capacity (TLC) by 5% and decreased expiratory reserve volume by 20%. Tidal volume increases by 30–40%, from 0.5 to 0.7 litres, and minute ventilation by 30–40%{{cite book |author= Guyton and hall |title=Textbook of Medical Physiology |edition= 11 |publisher=Saunders |location=Philadelphia |year=2005 |pages= 103g |isbn=978-81-8147-920-4 }} giving an increase in pulmonary ventilation. This is necessary to meet the increased oxygen requirement of the body, which reaches 50 ml/min, 20 ml of which goes to reproductive tissues. Overall, the net change in maximum breathing capacity is zero.{{cite book |last= Simpson |first= Kathleen Rice |author2=Patricia A Creehan |title= Perinatal Nursing |url= https://books.google.com/books?id=oz_4cTmVFD4C&pg=PA66 |edition= 3rd |year= 2007 |publisher= Lippincott Williams & Wilkins |isbn= 978-0-7817-6759-0 |pages= 65–66}}

The tidal volume, vital capacity, inspiratory capacity and expiratory reserve volume can be measured directly with a spirometer. These are the basic elements of a ventilatory pulmonary function test.

Determination of the residual volume is more difficult as it is impossible to "completely" breathe out. Therefore, measurement of the residual volume has to be done via indirect methods such as radiographic planimetry, body plethysmography, closed circuit dilution (including the helium dilution technique) and nitrogen washout.

In absence of such, estimates of residual volume have been prepared as a proportion of body mass for infants (18.1 ml/kg),{{cite journal | author = Morris, Mohy G.| title = Comprehensive integrated spirometry using raised volume passive and forced expirations and multiple-breath nitrogen washout in infants | journal = Respiratory Physiology & Neurobiology | volume = 170 | issue = 2 | pages = 123–140 | year = 2010 | issn = 1569-9048 | doi = 10.1016/j.resp.2009.10.010 | pmid = 19897058 | pmc = 2858579}} or as a proportion of vital capacity (0.24 for men and 0.28 for women){{cite journal | author = Wilmore, J. H. | title = The use of actual predicted and constant residual volumes in the assessment of body composition by underwater weighing | journal = Med Sci Sports | year = 1969 | volume = 1 | issue = 2 | pages = 87–90 | doi=10.1249/00005768-196906000-00006| doi-access = free }} or in relation to height and age ((0.0275* Age [Years]+0.0189*Height [cm]−2.6139) litres for normal-mass individuals and (0.0277*Age [Years]+0.0138*Height [cm]−2.3967) litres for overweight individuals).{{cite journal |author1=MILLER, WAYNE C. |author2=SWENSEN, THOMAS |author3=WALLACE, JANET P. | journal = Medicine & Science in Sports & Exercise | issue = 2 | volume = 30 |date=February 1998 | pages = 322–327 | title = Derivation of prediction equations for RV in overweight men and women | pmid=9502364 | doi=10.1097/00005768-199802000-00023| doi-access=free }} Standard errors in prediction equations for residual volume have been measured at 579 ml for men and 355 ml for women, while the use of 0.24*FVC gave a standard error of 318 ml.{{cite journal |author1=Morrow JR Jr |author2=Jackson AS |author3=Bradley PW |author4=Hartung GH. | title = Accuracy of measured and predicted residual lung volume on body density measurement | journal = Med Sci Sports Exerc |date=Dec 1986 | volume = 18 | issue = 6 | pages = 647–52 | pmid = 3784877 | doi=10.1249/00005768-198612000-00007| doi-access=free }}

[http://dynamicmt.com/dataform3.html Online calculators are available] that can compute predicted lung volumes, and other spirometric parameters based on a patient's age, height, weight, and ethnic origin for many reference sources.

British rower and three-time Olympic gold medalist Pete Reed is reported to hold the largest recorded lung capacity of 11.68 litres;English Institute of Sport, 17 November 2006, test ID 27781{{Cite web|url=http://www.worldrowing.com/news/making-sense-breathing-vo2max-and-lung-capacity|title=Making sense of breathing, VO2max and lung capacity|website=worldrowing.com|language=en-US|access-date=2019-11-28}}{{Cite news|url=https://www.bbc.co.uk/sport/rowing/50569807|title=Pete Reed: Three-time Olympic rowing champion on spinal stroke, paralysis and the future|date=2019-11-28|access-date=2019-11-28|language=en-GB}} US swimmer Michael Phelps is also said to have a lung capacity of around 12 litres.{{Cite news|url=https://www.telegraph.co.uk/sport/olympics/9449673/London-2012-Olympics-Faster.-Higher.-Longer.-Stronger.html|title=London 2012 Olympics: Faster. Higher. Longer. Stronger|journal=Daily Telegraph|last=Smith|first=Michael Hanlon and Jennifer|date=2012-08-03|access-date=2019-11-28|language=en-GB|issn=0307-1235}}

The mass of one breath is approximately a gram (0.5-5 g). A litre of air weighs about 1.2 g (1.2 kg/m³).Atmosphere of Earth#Density and mass A half litre ordinary tidal breath weighs 0.6 g; a maximal 4.8 litre breath (average vital capacity for males) weighs approximately 5.8 g.

File:Lung volumes in restricted, normal and obstructed lung.jpg

The results (in particular FEV₁/FVC and FRC) can be used to distinguish between restrictive and obstructive pulmonary diseases:

• Pulmonary function testing (PFT)
• Spirometry

{{reflist}}

• [http://www.anaesthetist.com/icu/organs/lung/lungfx.htm Lung function fundamentals (anaesthetist.com)]
• [http://hypertextbook.com/facts/2001/LaurenCalabrese.shtml Volume of human lungs]

{{Respiratory physiology}}

Category:Respiratory physiology

Category:Pulmonary function testing