Ventilation Perfusion (VQ) Mismatch Explained Clearly
HTML-код
- Опубликовано: 26 сен 2024
- Understand V/Q mismatch (ventilation/perfusion mismatch) with this clear review from Dr. Roger Seheult of www.medcram.co...
This is video 5 of the five main causes of hypoxemia: VQ Mismatch.
The remaining causes of hypoxemia are explained in other lectures in this series: high altitude, pulmonary diffusion, hypoventilation, and shunting.
Speaker: Roger Seheult, MD
Clinical and Exam Preparation Instructor
Board Certified in Internal Medicine, Pulmonary Disease, Critical Care, and Sleep Medicine.
MedCram: Medical topics explained clearly including: Asthma, COPD, Acute Renal Failure, Mechanical Ventilation, Oxygen Hemoglobin Dissociation Curve, Hypertension, Shock, Diabetic Ketoacidosis (DKA), Medical Acid Base, VQ Mismatch, Hyponatremia, Liver Function Tests, Pulmonary Function Tests (PFTs), Adrenal Gland, ARDS, Respiratory Failure, Shunt, Ventilation Perfusion Ratio, Pulmonary Embolism, Pneumonia Treatment, and many others. New topics are often added weekly- please subscribe to help support MedCram and become notified when new videos have been uploaded.
Subscribe: www.youtube.co...
Recommended Audience: Health care professionals and medical students: including physicians, nurse practitioners, physician assistants, nurses, respiratory therapists, EMT and paramedics, and many others. Review for USMLE, MCAT, PANCE, NCLEX, NAPLEX, NDBE, RN, RT, MD, DO, PA, NP school and board examinations.
More from MedCram:
Complete Video library: / medcram
Facebook: / medcram
Google+: plus.google.co...
Twitter: / medcramvideos
Produced by Kyle Allred PA-C
Please note: MedCram medical videos, medical lectures, medical illustrations, and medical animations are for medical education and exam preparation purposes, and not intended to replace recommendations by your health care provider.
![DDG & G Herbo - Nosey [Official Video]](http://i.ytimg.com/vi/I9Ra0Zc2NlQ/mqdefault.jpg)
best 14 minutes ever spent! your video summarized in 14 minutes what 2 hrs of ventilation lectures didn't at my school... THANK YOU!!!
+Jennifer Torres Glad the video was helpful- thanks for the feedback!
I have stage IV COPD with VQ mismatch and PH and nobody ever explained what this meant to me. Thank you!! Now I realize why I must keep 02 on always and monitor with pulse oximeter.
wow, compared to the PhD teaching at my medschool............
this is pure gold.
I'm studying to take my Step one next month and never understood this, after a youtube search on V-Q mismatch I stumbled upon this, thank you so much! It's so clear now, better late than never! :)
Jenny Gonzalez Glad we were able to clear up VQ mismatch for you- thanks for the feedback
You got a very rare talent that many people dont have..thanks a lot...
shakhir rt
ICU nurse here: hard to keep up with, but still very helpful. Thank you guys.
Thank you so much for all your videos.
I'm in my third month as a first year pulmonary/CC fellow and have been using your videos to reinforce concepts that during residency I found very confusing. You have such a talent.
Thank you
Came here to grasp it for nursing school... And DANG. This was fantastic! Exactly what I needed. Thank you!
ur lectures go hand in hand with your picture - you explain so clearly that it is like you are spoonfeeding us the exam answers :) so glad to be subscribed.
You are a god! Pulmonary Physiology exam coming up & this explained it so much better than my professors rambling!
I am a pulmonary hypertension patient and have to have a double lung transplant. This lecture really helped me understand what the docs are talking about when they say my pressures are at certain levels. Thank you
You are helping me get through nursing school. Thank you so much for these videos.
Incredible illustration, Doctor. Bravo! The best I have ever seen. Crisp, eloquent and to the T.
Blew my mind how simply it was explained! Loved the illistrations
Hallelujah !!!!!!!!!!!!!!!! May God bless you million times million. I completely understood the concept, I was so lost before i watched this video. :') Thank you
After reading over the same 3 paragraphs about 4 times in my text book, i bounced up this you tube explanation and i can finally read on. Thank you very much.
Ruanne Lynch Good to hear the video made the textbook more readable- thanks for the comment
DR you are a genius.i know understand hypoxema better than after reading all those stuffy texts.thank you
Legend. If only you were my lecturer! So clear & easy to understand! THANKS A MILLION!!!
Very helpful! But one suggestion: Khan's professors are great at using different colors to help organize paths ways or thought. I would have appreciated that especially in the beginning of the video.
Straight forward, concise and in layman's terms. Very well done, thank you for your time and effort.
Doc am grateful for all your materials.have learnt a lot
Anaesthestist resident in Nigeria
Love the analogy of ' air goes in and out and blood goes round and round' - this is what I jokingly tell people my bachelor of paramedical science taught me. However, essentially keeping a VR and HR going is one very good end goal for treating acute patients, generally speaking. I'm sure you know where I am coming from. Peace
Finally a well explain concise video with ways to apply this concept
Dude! You are a rockstar at explanations!!
thank you for such a clear explanation of V/Q mismatch
Thank you so much. My professor didnt even let me know that Q was perfusion
I was just diagnosed with this today and my head was spinning. Thanks for an easy to understand tutorial.
You can not be diagnosed with v/q mismatch... You can be diagnosed with pneumonia or asthma or anything else but not v/q mismatch...
Payden Aronson Interesting...I have documentation stating VQ mismatch from a Cardiologist and a pulmonary team. Had 2 right heart cats done and one was a stress cath ... I am not contradicting you, I don't know enough about it to say who is correct.
This is a really thorough and clear concise explanation of V/Q mismatch thank you so much!
Very good explanation of quite difficult topics for the USMLE step 1. Thank you Sir.
Thank you for helping me on my National Respiratory Therapist exam.
Absolutely awesome! Why can't clinicians just explain it like this? Thank you ever so much for making study easier
Excellent for the biggner and really very talented explanation which makes easier
you are unique at making difficult concept easier..god bless you
Love this series! I may pass this exam after all!
thank you! very informative!Please make a video also for respiratory failure.
My understanding of V/Q in the different Lung Zones. where the alveoli get smaller as its gets to the lower zones of the lungs are high V/ Q since the alveoli are smaller and easier to ventilate and perfuse but in the higher zones have larger alveoli has less V/Q since the alveoli are larger in the higher zones of the lungs. Your video showed me a total opposite of what I understand or think I remember with respect the V/Q in the Alveoli in the different Lung Zones.
Words cannot describe how grateful I am for this video! Dr. Seheult did an EXCELLENT job in breaking down the concepts. I am clearly able to grasp the concepts!!
Lifesaver please continue doing this!!!!
+JelliBaby780 Thanks! More videos coming soon
Very Helpful!! I would love to you go through a few more examples of pathology that lead to V/Q mismatch for example when V/Q is low like in bronchospasm or something like COPD/Asthma that affects both lungs in their entirety.
+Jenna Israel Thanks for the comment and suggestion!
Fabulous! great visuals and clear instruction!
Great video! Now (just to tie it all in) I gotta go find the one where you describe and explain "Shunt". I am a Trauma/Burn ICU RN who loves to understand the rationale behind what we do. Thank you!
from the bottom of my heart..... thank you
Very helpful!! Thanks so much!
great video and easy to understand!
please keep posting
GREAT demo! Clear and informative!
One thing, V/Q mismatch doesn't necessary mean that part of lung has lower rate and other part higher than usual, it means that V/Q is different than normal for lungs. In pneumonia for example there aren't pulmonary segments with higher ratio. Only lower, and result is hypoxic blood.
Very good tutorial, very well explained. One thing you do that is soo--o-o often done badly in medical tutorials/discussions is that you have made sure the basic terminology and concepts are explained along the way.
Btw this video also taught me PE fundamentals better than anything I've read on PE!
+Simon Barry Good to hear- glad this helped in your understanding, and thank you for your topic suggestion. We look at all topic suggestions like yours in planning for new videos
These have been great, thanks for posting. Everything is clearer now!
You have a great way of teaching. Simple and precise! Thank you!
Great material, simple to understand.. thank you
Chris Jauregui Thank you- glad it was helpful
very good explanation.. V/Q mismatch isn't difficult again with this lecture..
Wauw, this is soooo incredibly helpful! My test is tomorrow and I have higher hopes now haha! Thanks a lot!! X
Doc you are the best
Fantastic explanation. You are doing great job!
Very clear explanation, thanks !
Made it very easy to follow and understand. Thanks
D Long thanks for the feedback- glad the video helped
Awesome video!
you did a better job than my patho teacher
Beautifully explained.. Thank you
Thank you for your video. I just have one question regarding pneumonia and pulmonary edema, i.e. In those states, is it that you have increased fluid in the alveoli resulting in impaired ventilation but normal perfusion, creating an intrapulmonary shunt? So why would supplemental oxygen improve oxygen status in this case? Thank you in advance.
Thank you so much for your clear explanation. I finally understand V/Q balance and imbalance, yay!
Roddy Gee Good to hear- Thanks for the comment!
Thank you! This is super helpful.
Great lecture. Would like a topic "cardiopulmonary exercise testing Explained Clearly. Tq
great explanation! this made V/Q very easy to understand. thank you!
@Tye, Aa refers to alveolar-arterial gradient and the concentration of oxygen of both areas.
Great video has made it all a bit clearer!
Thanks hugely
Excellent video, very helpful
Manoj Regmi Thank you for the comment
Thanks, you made it very simple, my lecture was shocking in comparison
superb and simplified
Extremely helpful and concise. Thank you very much!
Wonderful explanation ++ Thank you very much!! (from France)
+Yellobra Merci beaucoup!
Roger. Thank you for all the videos. Please keep them coming!! Very helpful for a respiratory therapist student that's just entering his/her clinical practice :D
Great explanation!
Very helpful, the explanation is very clear. Thanks!
Such a great video!
so easy to understand!
awesome!!
K Levanter thank you for the feedback
great video
Thank you.
Great explanation!
Just need some clarification. I was taught that:
- in lobar pneumonia, a portion of the lung has gunk in it and therefore is effectively a partial shunt (for that part of the lung) - V/Q ratio is very low
- in pulmonary embolism, a portion of the lung cannot not be perfused and therefore is effectively in dead space ventilation (for that part of the lung) - V/Q ratio is very high
SO when you say breathing 100% oxygen will correct a decreased arterial PO2 caused by V/Q mismatch but NOT shunt, are you referring to the shunt as being a very large shunt that blocks off an entire lung like widespread "white out" pneumonia?
Is there a gradient for when V/Q mismatch becomes a complete shunt or complete dead space when the V/Q ratio reaches extremes?
I believe the principle he is speaking to is blood flow through a shunt, either from a pneumonia (blocked alveoli with mucus) or physiologic (like deoxygenated blood from the lung parenchyma) will not be exposed to oxygen at all (very low V/no change in Q). Increasing the PiO2 will have no effect on shunted blood because it is never within diffusion distance of blood. Hope this helps.
i wish the test questions were that easy... its usually critical thinking with different variable to take into account...
This was Very helpful. Thanks.
If you know the barometric pressure then you can use the Alveolar air equation.
thank u so much for this great explanation
Great made the mismatch make sense
That was great. Thank you for your time in explaining.
thanks for making every thing easy
thanks a lot verry good explanation
Thank you sooooo much.
Bless you.
I appreciated your simple & clear explanation.
+Vanessa James Thank you for the feedback
Very good video, but would APO be another cause of V/Q mismatch
Excellent video, thanks.
Perhaps a "clarification" is needed to explain the mechanism for why mismatch causes hypoxemia. When two blood samples are mixed, each with a known condition of SaO2, Hb, and PaO2, the oxygenation of the mixed blood is defined by the oxygen content (CaO2 in mLO2 per dL). CaO2 is the concentration of total O2 in the sample. When mixing two samples, the calculation is (CaO21 x Vol1 + CaO22 x Vol2)/ (Vol 1 + Vol 2). From the oxygen content equation, most of the CaO2 is due to the SaO2 and the [Hb], not the PaO2. In the case here, the Hb is constant. So the major determinant of the differences in CaO2 between the two blood samples is the SaO2. Therefore, the CaO2 of the mixed blood can be estimated by (SaO21 x vol1 +SaO22 x vol2)/(vol1 + vol2). Another way of saying this is that the O2 composition of two samples of blood after mixing is the flow-weighted average of the two SaO2s.
Consider the case where the two volumes (perfusion or flow) of the two respiratory units happen to be the same, but the ventilation to each is different, there will be a V/Q mismatch. Each unit will have blood leaving it with a different SaO2. The resulting mixture of the two will be defined exactly by the average of the two SaO2s (because the two volumes (perfusion rates) are the same). So to make the general comment that the mixture will NOT be the average of the two SaO2s, as did Dr. Seheult, does not lead to any understanding of the mechanism involved and is not always correct!
Another point I can make is that this video does not explain why there would be a P(A-a) difference in a V/Q mismatch situation. That requires an understanding of the relationship between SaO2 and PaO2, and the shape of the Hb-O2 dissociation curve. The curve is very flat at high PaO2 region, so the PaO2 can drop precipitously with very little change in SaO2. So when you get that flow-weighted average of the two SaO2s, even if if is only depressed a little bit by the poorly oxygenated unit, the end result is a large decrement in the PO2, much more than if you were to take the average PaO2. If the PaO2 is much lower, this will lead to the A-a difference being much larger.
The major point here is students should understand that the CaO2 is what defines whether or not your patient has enough O2. Some people define hypoxemia as low PaO2 for a persons age, but a better definition is a lower than normal CaO2 of the blood.
brilliant
Could you please explain why hypoventilation is not considered a type of a V/Q mismatch (low V/Q) if there is lowered alveolar ventilation (V) with normal perfusion (Q) in this condition ? (e.g. the alveolar ventilation 2,5 l/min and the perfusion 5 l/min -> V/Q = 0,5) This is the thing I cannot understand so i'd be grateful for some clarification on this matter. (sorry for posting this question under your hypoventilation lecture too :) )
this was incredibly helpful!! one topic of interest (may already be covered, havent looked to see yet) differentiating PA02 from Pa02 from percent saturation from Fi02, and the different pathologies impacting all of these values (CO poisoning, altitude sickness, methemglobinemia, etc)
You are amazing! Love your videos!
Very good, thanks, gary, paramedic
that is cool
VERY helpful and informative. Thank you!
Thank you very much for these lectures - really helps!!
Dank uit Amsterdam !
what i know is that both shunting and dead space are disorders of V\Q mismatch and both resulting in hypoxemia but dead space effect ( ^ V\Q mismatch) is responding to 100% O2 therapy while shunting effect (low V\Q mismatch) is not.
also, hypercapnia is more evident in high V\Q mismatch (dead space ) than low V\Q mismatch (shunting)
greetings,