Ventilation-perfusion mismatch pathophysiology: Difference between revisions
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==Associated Conditions== | ==Associated Conditions== | ||
Some conditions that cause decrease in V/Q are: | Some conditions that cause decrease in V/Q are:<ref name="pmid28144061">{{cite journal |vauthors=Sarkar M, Niranjan N, Banyal PK |title=Mechanisms of hypoxemia |journal=Lung India |volume=34 |issue=1 |pages=47–60 |date=2017 |pmid=28144061 |pmc=5234199 |doi=10.4103/0970-2113.197116 |url=}}</ref> | ||
* [[Bronchitis]] | * [[Bronchitis]] | ||
* [[Asthma]] | * [[Asthma]] | ||
Revision as of 17:48, 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:[4]
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.
- ↑ Sarkar M, Niranjan N, Banyal PK (2017). "Mechanisms of hypoxemia". Lung India. 34 (1): 47–60. doi:10.4103/0970-2113.197116. PMC 5234199. PMID 28144061.