Ventilation-perfusion mismatch pathophysiology: Difference between revisions
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==Pathogenesis== | ==Pathogenesis== | ||
In the upright position of the normal [[lung]], the amount of [[ventilation]] and [[perfusion]] is higher in the [[Base of lung|base of the lung]] compare to [[Apex of lung|apex of the lung]]. Although ventilation and perfusion are low in the apex of the lung, the perfusion is lower than ventilation in the apex. So, the V/Q is higher in the apex of the lung compare to the base <ref name="pmid25063240">{{cite journal |vauthors=Petersson J, Glenny RW |title=Gas exchange and ventilation-perfusion relationships in the lung |journal=Eur. Respir. J. |volume=44 |issue=4 |pages=1023–41 |date=October 2014 |pmid=25063240 |doi=10.1183/09031936.00037014 |url=}}</ref>. In a normal lung V/Q is 0.8 which means 4 liters of oxygen and 5 liters of blood transfer in the lung per minute. V/Q mismatch is one of the common reason of hypoxemia in patients with [[lung]] disease like [[Obstructive lung disease|obstructive lung]] diseases, pulmonary vascular diseases, and [[Interstitial lung disease|interstitial diseases]] . Usually hypoxemia due to V/Q mismatch will resolve by [[Oxygen therapy|oxygen therapy.]]<ref name="pmid26545142">{{cite journal |vauthors=Baumgardner JE, Hedenstierna G |title=Ventilation/perfusion distributions revisited |journal=Curr Opin Anaesthesiol |volume=29 |issue=1 |pages=2–7 |date=February 2016 |pmid=26545142 |doi=10.1097/ACO.0000000000000269 |url=}}</ref> | In the upright position of the normal [[lung]], the amount of [[ventilation]] and [[perfusion]] is higher in the [[Base of lung|base of the lung]] compare to [[Apex of lung|apex of the lung]]<ref name="pmid7818053">{{cite journal |vauthors=Schaffartzik W |title=[Ventilation-perfusion ratios] |language=German |journal=Anaesthesist |volume=43 |issue=10 |pages=683–97 |date=October 1994 |pmid=7818053 |doi= |url=}}</ref>. Although ventilation and perfusion are low in the apex of the lung, the perfusion is lower than ventilation in the apex. So, the V/Q is higher in the apex of the lung compare to the base <ref name="pmid25063240">{{cite journal |vauthors=Petersson J, Glenny RW |title=Gas exchange and ventilation-perfusion relationships in the lung |journal=Eur. Respir. J. |volume=44 |issue=4 |pages=1023–41 |date=October 2014 |pmid=25063240 |doi=10.1183/09031936.00037014 |url=}}</ref>. In a normal lung V/Q is 0.8 which means 4 liters of oxygen and 5 liters of blood transfer in the lung per minute. V/Q mismatch is one of the common reason of hypoxemia in patients with [[lung]] disease like [[Obstructive lung disease|obstructive lung]] diseases, pulmonary vascular diseases, and [[Interstitial lung disease|interstitial diseases]] . Usually hypoxemia due to V/Q mismatch will resolve by [[Oxygen therapy|oxygen therapy.]]<ref name="pmid26545142">{{cite journal |vauthors=Baumgardner JE, Hedenstierna G |title=Ventilation/perfusion distributions revisited |journal=Curr Opin Anaesthesiol |volume=29 |issue=1 |pages=2–7 |date=February 2016 |pmid=26545142 |doi=10.1097/ACO.0000000000000269 |url=}}</ref> | ||
In normal condition when there is a low ventilation, the body tries to keep this ratio in a normal range by restricting the perfusion in that specific area of the lung. This unique mechanism is called hypoxic pulmonary vasoconstriction. If this process continues for a long time it can cause pulmonary hypertension . | In normal condition when there is a low ventilation, the body tries to keep this ratio in a normal range by restricting the perfusion in that specific area of the lung. This unique mechanism is called hypoxic pulmonary vasoconstriction. If this process continues for a long time it can cause pulmonary hypertension . | ||
Revision as of 17:46, 3 August 2018
Template:Ventilation-perfusion mismatch
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aida Javanbakht, M.D.
Overview
Any disruption between blood flow and ventilation is called V/Q mismatch.
Pathogenesis
In the upright position of the normal lung, the amount of ventilation and perfusion is higher in the base of the lung compare to apex of the lung[1]. Although ventilation and perfusion are low in the apex of the lung, the perfusion is lower than ventilation in the apex. So, the V/Q is higher in the apex of the lung compare to the base [2]. In a normal lung V/Q is 0.8 which means 4 liters of oxygen and 5 liters of blood transfer in the lung per minute. V/Q mismatch is one of the common reason of hypoxemia in patients with lung disease like obstructive lung diseases, pulmonary vascular diseases, and interstitial diseases . Usually hypoxemia due to V/Q mismatch will resolve by oxygen therapy.[3]
In normal condition when there is a low ventilation, the body tries to keep this ratio in a normal range by restricting the perfusion in that specific area of the lung. This unique mechanism is called hypoxic pulmonary vasoconstriction. If this process continues for a long time it can cause pulmonary hypertension .
Associated Conditions
Some conditions that cause decrease in V/Q are:
Some conditions that cause increase in V/Q are:
Genetics
The association between V/Q mismatch and genetic depends on the etiology of the mismatch. For example ORMDL3 and GSDML genes play a role in causing asthma .
Gross Pathology
The gross pathology depends on the exact reason for the V/Q mismatch.
Microscopic Pathology
The microscopic pathology depends on the exact reason for the V/Q mismatch. For example in asthma there are extracellular Charcot-Leyden crystals and increased mucosal goblet cells.
- ↑ Schaffartzik W (October 1994). "[Ventilation-perfusion ratios]". Anaesthesist (in German). 43 (10): 683–97. PMID 7818053.
- ↑ Petersson J, Glenny RW (October 2014). "Gas exchange and ventilation-perfusion relationships in the lung". Eur. Respir. J. 44 (4): 1023–41. doi:10.1183/09031936.00037014. PMID 25063240.
- ↑ Baumgardner JE, Hedenstierna G (February 2016). "Ventilation/perfusion distributions revisited". Curr Opin Anaesthesiol. 29 (1): 2–7. doi:10.1097/ACO.0000000000000269. PMID 26545142.