The ‘Q’ In “V/Q Mismatch”

You can’t read about pulmonary physiology without encountering the topic of V/Q mismatch, otherwise known as ventilation-perfusion mismatch. In fact, of the five major etiologies of hypoxemia, V/Q mismatch is the most common!

‘Q’ from Skyfall – 007’s quartermaster

But that leaves one very important question – if the ‘V’ stands for “ventilation”, why does ‘Q’ stand for “perfusion?”

Without delving into too much history, ‘Q’ comes from “quantité“, the French word for quantity or amount. French scientists like Darcy and Poiseuille derived equations involving rate of flow represented by the variable ‘Q’, and till this day, we often use the same letter to represent flow rates in other branches of science. In this example, ‘Q’ refers to the effective arterial perfusion of alveolar segments. 🙂

Previous article
Next article

Related Articles


  1. to all who commented: even this semester, I made the comment to my students “the V makes sense ,,, but I have no idea where the Q came from. It’s probably just to confuse college students!”. NOW, I KNOW!!! Thanks heaps for the bit of trivia to share 🙂

  2. Loved! Great snipit of info that I didn’t know. Always assumed it would be Latin. Can’t wait to share. Thank you Rishi??


Please enter your comment!
Please enter your name here

Try EchoTools - my free, iOS ultrasonography reference application!

Latest Articles