Ventilation/perfusion ratio

From Wikipedia, the free encyclopedia

Jump to: navigation, search

In respiratory physiology, the ventilation/perfusion ratio (or V/Q ratio) is a measurement used to the efficiency and adequacy of the matching of two variables:[1]

A normal value is approximately 0.8.[2]

Because the lung is centered vertically around the heart, part of the lung is superior to the heart, and part is inferior. This has a major impact on the V/Q ratio:[3]

The V/Q ratio can be measured with a ventilation/perfusion scan.

An area with no ventilation (and thus a V/Q of zero) is termed a shunt.[4] An area with no perfusion (and thus a V/Q of infinitiy) is termed "dead space"

  1. ^ MedEd at Loyola Medicine/pulmonar/physio/pf9.htm#q1
  2. ^ http://www.rnceus.com/abgs/abgvq.html
  3. ^ http://www.capnography.com/Physiology/Componentsoftime.htm
  4. ^ http://www.nda.ox.ac.uk/wfsa/html/u12/u1211_02.htm

v • d • e
Respiratory system, physiology: respiratory physiology
Volumes lung volumes - vital capacity - functional residual capacity - respiratory minute volume - closing capacity - dead space - spirometry - body plethysmography - peak flow meter - thoracic independent volume - bronchial challenge test
Airways ventilation (V) (positive pressure) - breath (inhalation, exhalation) -respiratory rate - respirometer - pulmonary surfactant - compliance - hysteresivity - airway resistance
Blood pulmonary circulation - perfusion (Q) - hypoxic pulmonary vasoconstriction - pulmonary shunt
Interactions ventilation/perfusion ratio (V/Q) and scan - zones of the lung - gas exchange - pulmonary gas pressures - alveolar gas equation - hemoglobin - oxygen-haemoglobin dissociation curve (2,3-DPG, Bohr effect, Haldane effect) - carbonic anhydrase (chloride shift) - oxyhemoglobin - respiratory quotient - arterial blood gas - diffusion capacity - Dlco
Control of respiration pons (pneumotaxic center, apneustic center) - medulla (dorsal respiratory group, ventral respiratory group) - chemoreceptors (central, peripheral) - pulmonary stretch receptors (Hering-Breuer reflex)
Insufficiency high altitude - oxygen toxicity - hypoxia
Retrieved from "http://en.wikipedia.org/wiki/Ventilation/perfusion_ratio"
close
Advanced Search
close
Included Web Search Engines

Choose the search engines to include in your metasearch




Safe Search

Smart Search
close

Top Matching Results

Occasionally Search.com will highlight specialized results that are based on the context of your query. Examples of specialized results include specific links to news, images, or video.

Top Matching Results may highlight information from other Search.com pages, content from the CNET Network of sites, or third party content. The listings are based purely on relevance. Search.com does not receive payment for listings in this section but our partners that provide this data may get paid for listing these products.

Sponsored Links

This section contains paid listings which have been purchased by companies that want to have their sites appear for specific search terms and related content. These listings are administered, sorted and maintained by a third party and are not endorsed by Search.com.

Search Results

Search.com sends your search query to several search engines at one time and integrates the results into one list which has been sorted by relevance using Search.com's proprietary algorithm. You can customize the list of search engines included in your metasearch from the preferences.

The search engines that are used in your metasearch may allow companies to pay to have their Web sites included within the results. To view the Paid Inclusion policy for a specific search engine, please visit their Web site. Search.com does not accept payment or share revenue with any search engine partner for listings in this section.