Deltahedron: /* Properties */ better

2013-04-21T16:52:22Z

Properties: better

New page

{{Pulmonary function}}
{{Cleanup|date=November 2010|reason=article requires more precise statements and consensus on normal values}}
'''Respiratory minute volume''' (or '''minute ventilation''' or '''expired minute volume''') is the [[volume]] of gas [[inhalation|inhaled]] (inhaled minute volume) or [[exhalation|exhaled]] (exhaled minute volume) from a person's [[lung]]s per minute. It is an important parameter in respiratory medicine due to its relationship with blood carbon dioxide levels. It can be measured with devices such as a Wright respirometer, or can be calculated from other known respiratory parameters. Note that although its name implies that it is a volume, minute volume is actually a flow (it represents a volume change over time).

Several symbols can be used to represent minute volume. They include: <math> \dot{V}</math>, MV, and VE.

==Determination of minute volume==
Minute volume can either be measured directly or calculated from other known parameters.
===Measurement of minute volume===
Minute volume is the amount of gas inhaled or exhaled from a person's lungs in one minute. It can be measured by a Wright respirometer or other device capable of cumulatively measuring gas flow, such as [[Ventilator|mechanical ventilators]].
===Calculation of minute volume===
If both [[tidal volume]] (VT) and [[respiratory rate]] (ƒ or RR) are known, minute volume can be calculated by multiplying the two values. One must also take care to consider the effect of dead space on alveolar ventilation, as seen below in "Relationship to other physiological rates".

:<math> \dot{V} = V_T \times f </math>

==Physiological significance of minute volume==

Blood carbon dioxide (PaCO2) levels generally vary inversely with minute volume.{{Citation needed|date=November 2011}} For example, a person with increased minute volume (e.g. due to [[hyperventilation]]) should demonstrate a lower blood carbon dioxide level. The healthy human body will alter minute volume in an attempt to maintain physiologic homeostasis. A normal minute volume while resting is about 5–8 [[liter]]s per minute in humans.{{Citation needed|date=November 2011}} Minute volume generally decreases when at rest, and increases with exercise. For example, during light activities minute volume may be around 12 litres. Riding a bicycle increases minute ventilation by a factor of 2 to 4 depending on the level of exercise involved. Minute ventilation during moderate exercise may be between 40 and 60 litres per minute.<ref name="Zuurbier">{{cite journal
| last = Zuurbier, M., Hoek, G., van den Hazel, P., Brunekreef, B.
| first =
| title = Minute ventilation of cyclists, car and bus passengers: an experimental study.
| journal = Environmental Health
| volume = 8
| issue = 48
| pages =
| year = 2009
| url = http://www.ehjournal.net/content/8/1/48
| doi =
| pmid =
| month =}}</ref> <ref name="Int Panis">{{cite journal
| last = Int Panis
| first = L
| title = Exposure to particulate matter in traffic: A comparison of cyclists and car passengers
| journal = Atmospheric Environment
| volume = 44
| issue =
| pages = 2263–2270
| year = 2010
| url =
| doi = 10.1016/j.atmosenv.2010.04.028
| pmid =
| month =}}</ref>

[[Hyperventilation]] is the term for having a minute ventilation higher than physiologically appropriate. [[Hypoventilation]] describes a minute volume less than physiologically appropriate.

==Relationship to other physiological rates==

Minute volume comprises the sum of [[alveolar|alveolar ventilation]] and [[dead space ventilation]]. That is:

<math> \dot{V} = \dot{V}_A + \dot{V}_D </math>

where <math> \dot{V}_A</math> is alveolar ventilation, and <math> \dot{V}_D </math> represents dead space ventilation.

== References ==
{{reflist|2}}

==External links==
* [http://www.healthsystem.virginia.edu/Internet/Anesthesiology-Elective/airway/ventilation.cfm Overview at healthsystem.virginia.edu]
* [http://www.ccmtutorials.com/rs/mv/strategy/page16.htm Overview at ccmtutorials.com]
* {{GeorgiaPhysiology|4/4ch3/s4ch3_15}}
* [http://www.anesthesiageneral.com/general-anesthesia/what-is-minute-ventilation/ What is minute ventilation]

{{Respiratory physiology}}

[[Category:Respiratory physiology]]

Exponential polynomial - Revision history

Deltahedron: /* Properties */ better