Shunting Explained Clearly (Pulmonary Shunt)

Understand shunting with this clear review from Dr. Seheult of www.medcram.co...
This is video 4 of the 5 main causes of hypoxemia: the shunt.
Other causes of hypoxemia are covered in this series: high altitude, pulmonary diffusion, hypoventilation, and ventilation perfusion mismatch (VQ mismatch).
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), Shnunting (Pulmonary Shunt), Adrenal Gland, 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.
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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.
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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.

[@Medcram]

Hi, thanks for the question. ARDS is generally a shunt mechanism. Pulmonary edema if very severe can also be shunt, but mild pulmonary edema is usually V/Q mismatch.

[@nnekaa.4591]

Best med educator in KZbin 👏🏾👏🏾

[@kennedymungai7350]

I never feel bothered to comment but man you make it easy to study. Thanks a bunch.

[@Medcram]

Thank you for commenting!

[@markcarrensalazar]

MedCram - Medical Lectures Explained CLEARLY

[@GabrielleMUrban]

Nursing student here in a critical care class. Thank you so much!!!

[@Medcram]

You are very welcome!

[@88Grey]

Great video. I'm an RT student doing a project on ARDS and I didn't understand the different ways the term shunting is used...until I watched your video. Thank you!

[@theshadowfixer]

Thank you @MEDCRAMvideos for the wonderful explanations and making concepts clear.

[@kayaksta]

excellent teacher. thank you

[@stephanieosmond7677]

That was the best explanation I've ever had! Thank you so much!!!

[@melmather]

Shunting is by definition no ventillation. PE affects perfusion, causing VQ mismatch

[@jmargarita50]

Excellent video, very clear, simple without oversimplify, and it goes straight to the point in very difficult topic, in addition, beautiful diction; my second language is English and I really appreciate a clean diction, thank you very much

[@outdoorvanlife]

Or you can get a mixed venous blood gas from pulmonary artery catheter to measure O2 Sat and PvO2. Then you get a regular ABG. And now you can get your shunt fraction and C(a-v)O2 difference.

[@rdseheult]

It's tricky. yes, you are right. but on;y if there is absolutely no ventilation. ARDS causes this most often. PNA can too. but it can also cause V/Q mismatch. If you ever have to guess - always guess V/Q mismatch unless it's obvious that the O2 is not correcting with supplemental o2.

[@carolinaguinand4254]

Excellent and easy to follow. I love the old fashion drawing e- learning methods

[@Ingrid2955]

Very helpful for an aspiring Respiratory therapist like me. Thank you so much 🙏

[@Medcram]

Ingrid2955 Good to hear- best wishes with your RT career

[@bonnyfok4476]

Thank you so much. that is very helpful. Very easy to understand and follow.

[@Medcram]

+Bonny Fok Good to hear- thank you

[@Hellastorytella]

6:08 - If you can see math like this, you can become an absolutely amazing pulmonologst or anasthesiologist

[@timyone]

You are a legend! great vid!

[@radmilakaran2032]

Great Job! This is great, short, concise, all that you need to fully understand the problem! I was wondering if you could make a lecture about inotropes in different cardiac pathology...

[@lioness3412]

This lecture helps me a lot. Thank you from Med students in South Korea

[@Medcram]

Lee Jinsoo Greetings to South Korea- glad the lecture helped

[@dereksmith119]

My go to videos during PA school. Keep up the good work!

[@Medcram]

+Derek Smith Good to hear and best of luck in PA school

[@karansingh4227]

Very good explanation

[@ja2223489]

great explanation

[@emilyritchie3343]

Finally it makes sense! Thank you!

[@mahmoudhadhoud9133]

Right to left shunting, how would that affect this mechanism? Also isnt PDA Left to right shunting not what you mentioned?

[@deaniehead]

Extremely helpful video. Thank you.

[@AnnHustle]

I clicked that advertisment because you rock ;)

[@frederickfrenchjr08]

excellent vid, pls do hemodynamics, no one had done it on you tube.

[@mom2angelson]

CRT studying for RRT. This is excellent review.

[@aladinn2002]

Simply Brilliant. Thanks and God Bless

[@sarahmina1442]

Thank you so much, you saved my physiopath :D Merci

[@Medcram]

+Nour Baya love it!

[@cj7ification]

Can i please ask something? At first you were talking about shunting in the pulmonary artery but later when you described the RT to Lt shunt of ARDS, the shunting was happening in the heart. My question is does the pulmonary artery shunting happen in the lungs or somewhere else? also, where does the Rt to Lt shunting of blood due to ARDS happen, in the heart or lungs?

[@yasmine4754]

He only briefly mentioned the heart to explain, that shunting can happen in other places too, for example in the heart. Another word for shunting could be "bypassing", but the video itself is only about pulmonary shunting, blood continuing to flow without being oxygenated, ARDS is an example of shunting, so is pulmonary edema and pneumonia, think of a bus driving down a road, people standing at the bus stop to be picked up, but the bus never stops to pick them up, just continues to drive. : )

[@marszalikm89]

I think it's more like, the buses are coming, but no one is even there to be picked up.

[@drrajurajan]

More like no bus stop!!!

[@MegaJunebug420]

Anatomical shunt vs Physiological shunt

[@brittaneykhong5376]

Another great video! Thanks!

[@ofebell]

thanks, good lesson for understanding shunting

[@Medcram]

ofebell thanks for the comment

[@anon2114]

Thank you for the video. I do not understand why the Aa gradient is increased. There is nothing in the interstitial space like in diffusion.

[@fatboy117]

Hi Dr. This was a great video. But I'm still a little confused. I had a USMLE question that said, Pulmonary Embolism isn't considered shunting, but it's more of a Deadspace problem. Why isn't ARDS considered a Deadspace problem, but more of a Shunting problem. Isn't it like of similar? Both situations Ventilation is normal, ..... is it because shunting has normal profusion, while Deadspace have no profusion?

[@Medcram]

+H ta da izo Pulmonary Embolism is actually V/Q mismatch. There is dead space in the fact that lung is being ventilated and not perfused or perfused rather poorly. ARDS clearly is a situation where the opposite is happening (Perfusion but no ventilation) The protein rish exudative lung secretions are preventing any oxygen exchange with the pulmonary capillaries --> effectively shunt.

[@fatboy117]

Hi dr. Medcram... thanks for the update. I got it!! pls more videos! =) and Happy new year best of luck.

[@nicholasdesnoyer8505]

So in this case, would pneumonia be a shunting of diffusion problem?

[@soaringup1035]

Hi! Would appreciate if you could give a reply because I cannot seem to find an answer anywhere else. In shunts like ARDS, does PAO2 not decrease since there is no ventilation? Therefore, doesn't PAO2 and PaO2 both decrease and this lead to no change in the A-a gradient? thank you very much!

[@Coco-wm8yj]

Thank you so much, this is very helpful!

[@michelesantilhano4649]

thanks hugely

[@sarahtayyab9957]

THANK YOU 👌👍 was very helpful

[@drrajatmohanty6527]

thanks you very much.. very nice presentation and clearly explained the topic..

[@Medcram]

DR RAJAT MOHANTY Thank you for the feedback

[@Rayyan36]

ASD,VSD,PDA = Left to right shunt........ Tricuspid atresia, Tetralogy of fallot, Transposition = Right to left shunt..

[@jess30115]

Where exactly does the shunted blood go then since it doesn't go to the lungs?

[@TweetyBird4551]

***** Start watching this at 10:00 and pay attention! Dr. Seheult covers this.

[@ameliak9424]

I think it is very important to point out that this is only accurate if you are talking about a R to L shunt. Also you mentioned that a VSD and ASD would be R to L shunts but that is not necessarily correct most of the time (assuming your pulmonary resistance has dropped as it is supposed to) an ASD and VSD and PDA become L to R shunts. Am I correct?

[@vedio0vedio]

Thanks Proff marvelous explanations.......

[@doctorshelp9944]

Butifully explained.

[@gesztenye001]

Great, thank you !

[@nezarrifaat6458]

Very illustrative but need to add shunt equation and methods of mesuring shunt.

[@vandypk318]

Thank you for the video! Very helpful!

[@82Rooster]

Can you explain why medications such as, Nitro, nipride, and cleveprex, would cause shunting?

[@gonzojed1]

So by definition a hemothorax is one giant shunt, bipap with high epap would oxygenate better than 100% alone ?

[@patriciahaldas5361]

Your videos are great. They helped me get a A in all my nursing classes. I also have a respiratory degree and I am reviewing. I just have one question about his video. I may be wrong but don't you get a L-R shunt because the pressures on the L side of the heart are greater than the R side of the heart. (through the ASD and VSD) it still results with oxygenated blood on the left side mixing with unoxygenated blood on the right side? Just wondering. Thanks.

[@YouAreLoved21]

I have the same question about the mentioned R-L shunt, is it supposed to be L-R shunt for ASD,VSD and PDA?

[@hjdksplt]

beautiful and clear. thanks a lot.

[@ducopieterse7103]

Dank u wel ! Groet uit Amsterdam

[@tinaarena4297]

Very interesting and very helpful indeed. Thank you so much.

[@Medcram]

Tina Arena thanks for the feedback- glad it was helpful

[@reeshashahid8825]

Hi, can anyone please explain what does R to L shunting in pulmonary embolism mean? Is it R to L cardiac shunting or pulmonary shunting?

[@user-sv4qf1ym7p]

What causes shunting during general anaesthesia?

[@taniamukherjee8590]

This was excellent! Thank you

[@rdseheult]

yesm but they act differently. Look up "inert gas technique" to see ore technical and sometimes confusing information.

[@ajzzz9246]

isnt pulmonary arteries the ones with oxygen and veins the ones without?

[@Medcram]

+Aj no. Pulmonary artery has low oxygen. Then lungs give it oxygen then it goes back to heart via pulmonary veins.

[@dlwc6223]

thx for the clear explanation!!! my doubt was cleared^^

[@ranmasaotome6931]

Can ARDS and Pulmo Edema present as either VQ shunt or Diffusion limited, depending on the severity of the case? I see what your saying, but I see different diseases, like ARDS, fibrosis, presenting as different types of Hypoxia. Thanks for putting this topic is clear and simple terms. I was confused when during my profs lecture

[@medachraf1552]

You are amazing

[@ToewaiAung-ue8po]

Thanks a lot 👍

[@JC-cq2nw]

This is so helpful! Could you please post videos on HCM?

[@SuperWaveygravey]

Really clear explanation! However just wanted to check, if pulmonary oedema causes pathological shunting, do the following also apply? pulmonary embolus, pneumonia, atelectasis, pneumo/haemothorax?

[@UrsusCor]

??? ... Isn't ARDS and pulmonary edema examples of wasted ventilation and having nothing to do with shunt ??? I have more questions then answers now ...

[@lostmonkey18]

Would it be accurate to say that a diffusion problem taken to its absolute limit would be a shunt?

[@ducanhduong6526]

why high PaO2 blood in the normal segment dont increase SaO2 in shunted segment after joining each other?

[@Medcram]

+duc anh duong it does. But only a very small amount: o2 content = 1.34 x hgb x sat + pao2 x .003.

[@rajhetti6]

thanks

[@karolgilbertosolanosuarez9094]

Thank you so much!!!!! 🎉🎉🎉🎉🎉

[@mistymoor7114]

What about the Bohr effect ?

[@safety32729]

awesome video! i dont understand one thing however, if ARDS is considered a shunt then why isnt fibrosis considered a shunt? Or can ARDS be a diffusion problem too?

[@turma101medicinaunb5]

Awesome! Just awesome.

[@snoopytroops]

Great video - thanks! One question: why is ARDS/pulmonary oedema considered a shunting problem, and not a diffusion problem? Or is it both?

[@snoopytroops]

Think I partly understand: the extra fluid causes alveolar collapse, rendering areas of lung non-viable. Therefore blood passing through these areas can't exchange gas, and is shunted back into the systemic circulation deoxygenated. Still think this sounds pretty similar to what happens in diffusion failure...?

[@sabaali457]

THANK YOU!!

[@kunleirojah6680]

Atelectasis?

[@FREDfan105]

Excellent ....aziz

[@nbkbelen]

this is great. thanks a lot

[@hagaicohen1922]

I understood most of this. Thank you very much! But I do have one question though... If hypoxemia due to shunts does not improve well with 100% oxygen therapy, could that be used as a diagnostic tool? To identify the cause of the hypoxemia? Thanks in advance!

[@Medcram]

+Hagai Cohen Yes - absolutely. It also pops u[p on tests as well. I often see it in the ICU when a patient has ARDS. Turning up the FIO2 just doesn't seem to correct the hypoxemia. PEEP does. Look at the ventilator lecture for more info.

[@jamiesculley1026]

great video! thanks so much!

[@SirFowler1]

Where's Thomas?

[@umasrivastava4142]

Awesome thanks 👍😀

[@jt3388]

PLEASE HELP. In pneumonia you have alveolar infiltrates correct? In ARDS you have your alveola are filled. Doesn't that mean both situations have deceased ventilation and thus both are shunting.

[@poonehbarati2494]

Both of them can cause intrapulmonary shunts ;thus, you are right!

[@analizasamboa4260]

How can I download your very informative videos?

[@sandy123288]

thank you for your videos. i have a question; can you please clarify the difference between anatomic dead space and shunting. Please. thank you.

[@Medcram]

+sandy123288 Thank you for the question. Dead space: all ventilation and no perfusion (Example: trachea) Shunting: no ventilation and all perfusion (example: alveolus filled with fluid)

[@hausachemist5082]

@@Medcram All in all, awesome explanation thank you so much.

[@rnhanna2214]

Can COPD be a shunt problem?

[@l7nee939]

Thank you for your video and explanation But, I wanna ask about something Is it a normal thing in the healthy body?

[@Medcram]

+L7nee 9 yes but only if it is less than 1%. There are a few veins in the heart that can do this. Thesibian veins.

[@nusaibashamsi4969]

Awesome explanation :)

[@drrajurajan]

Asd vsd PDA are L>R I think u meant TOF sir?R>L

[@Medcram]

+guruinvestor add is at first a L to R. But as pressure goes up it can become R to L.

[@fsujci]

great!

[@ummehaniridi5226]

You are amazing 💖

[@kerap834]

Also, her lips turned blue, that seems to be very important to add.

[@kerap834]

Hello, thank you for this video! My daughter has had 3 instances of crying/vomiting, then falling unconscious with her eyes open and not breathing. We were told she had a VSD at birth and it hasn't gone away (she's 15 months old). My mom's aunt had a RTL shunt - is it common to pass out/stop breathing with a RTL shunt? What's the reason for this? Thank you for any help! (P.S. - we are going to the cardiologist and have an echo scheduled.)

[@FOFOanb]

That was really good, thank you alot professor.

[@tuttifruti27]

I was told yesterday that I had a shunt, I do not know how to react, or if it was normal the reaction of my doctors, you can tell me the risks.

[@congratulation46]

Awesome!

[@UyenNguyen-vy4rx]

Thks u so much~~ I can understand shunting now

[@saifrafael5872]

thank u

[@MrAyousif]

MAGNIFICO

[@drpratik97]

I don't know who are those, who haven't not liked the video