Alveolar gas equation
Alveolar gas equation is a mathematical formula used in pulmonology and anesthesiology to calculate the partial pressure of oxygen in the alveoli of the lungs. The equation is essential in understanding the gas exchange process in the lungs and is often used in the diagnosis and treatment of respiratory diseases.
Overview[edit | edit source]
The alveolar gas equation is derived from the ideal gas law and the principles of gas exchange in the lungs. It is used to estimate the alveolar concentration of oxygen (PaO2), which is the amount of oxygen available for diffusion into the blood.
The equation is as follows:
- PAO2 = FiO2 (Patm - PH2O) - PaCO2/R
Where:
- PAO2 is the partial pressure of oxygen in the alveoli
- FiO2 is the fraction of inspired oxygen
- Patm is the atmospheric pressure
- PH2O is the partial pressure of water vapor
- PaCO2 is the partial pressure of carbon dioxide in arterial blood
- R is the respiratory quotient
Application[edit | edit source]
The alveolar gas equation is used in clinical practice to assess the efficiency of gas exchange in the lungs. It is particularly useful in the diagnosis and management of conditions such as chronic obstructive pulmonary disease (COPD), pulmonary edema, and acute respiratory distress syndrome (ARDS).
By comparing the calculated PAO2 with the measured PaO2 (from arterial blood gas analysis), clinicians can determine whether a patient has a ventilation-perfusion mismatch or a diffusion limitation, both of which can lead to hypoxemia.
Limitations[edit | edit source]
While the alveolar gas equation is a useful tool, it has several limitations. It assumes a steady state of gas exchange, which may not be the case in rapidly changing conditions. It also does not account for variations in alveolar ventilation or regional differences in gas exchange within the lungs.
See also[edit | edit source]
 | This medical article is a stub. You can help WikiMD by expanding it. |
Search WikiMD
Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD
|
WikiMD's Wellness Encyclopedia |
| Let Food Be Thy Medicine Medicine Thy Food - Hippocrates |
Translate this page: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
தமிழ்,
తెలుగు,
Urdu,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
বাংলা
European
español,
Deutsch,
français,
Greek,
português do Brasil,
polski,
română,
русский,
Nederlands,
norsk,
svenska,
suomi,
Italian
Middle Eastern & African
عربى,
Turkish,
Persian,
Hebrew,
Afrikaans,
isiZulu,
Kiswahili,
Other
Bulgarian,
Hungarian,
Czech,
Swedish,
മലയാളം,
मराठी,
ਪੰਜਾਬੀ,
ગુજરાતી,
Portuguese,
Ukrainian
Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.
Contributors: Prab R. Tumpati, MD
