Pulmonary Function Tests (PFT): Lesson 4 - DLCO

A description of how the DLCO (diffusing capacity of carbon monoxide) is measured, and how it is used in the diagnosis of various forms of lung disease.

[@DoctorKnowDoctorKnow]

Saw your videos before a major exam...sometimes repeated them 3 or 4 times...took my test on PFTs and got a 100%....Your Video's Saved Me...

[@StrongMed]

+DoctorKnow956 DoctorKnow956 I'm glad the videos helped you out!

[@nickgowen7737]

Great job as usual Eric. I am continuously amazed at how well you explain these concepts.

[@gerryzavorsky]

At 2:37, where the instructor mentions that the DLCO is a measurement of the overall function of the alveolar-capillary membrane, this is technically is incorrect. The overall function of the alveolar-capillary membrane is DmCO, which is alveolar-membrane diffusing capacity. The Roughton and Forster equation states that 1/DLCO = 1/DmCO + 1/(thetaCO x Vc), which is the total resistance to CO transfer is equally divided into membrane resistance and red cell resistance. Thus, DLCO is a function of both alveolar-membrane diffusing capacity (DmCO, mL/min/mmHg), and the hemoglobin concentration (ThetaCO) and the pulmonary capillary blood volume (mL). ALL these things represent DLCO.

[@sunving]

Thank you Dr Eric Strong. I may need to watch again to understand but as yet this might not relevant to me much since it hardly be ordered this test either.

[@davidzane3372]

I appreciate your lectures very much. You mention that DLCO may be decreased with anemia and increased with polycythemia. Later you mention DLCO may be adjusted downward for anemia and upwards for polycythemia. I looked at abstract of Am J Respir Crit Care Med, 1997 Jan: 155 (1). 236-41 which notes DLCO may be adjusted upward for anemia. I thank you for any clarification. I'm likely not seeing something clearly. Thank you again for your efforts. I really appreciate your lectures.

[@AshishSharma-bb7or]

I hope I'm interpretating this correctly - the slides refer to adjustment of 'predicted' DLCO, ie, the expected *reference* range which is patient specific. So if the patient is anemic, then the reference range/value for that specific patient will be adjusted downward and the observed DLCO value will be compared to this reference value instead of a one-size-fits-all sort of value.

[@AnomiEj]

Great video as always Dr. Strong! At 8:51 I would add that DLCO is used when considering surgical treatment of lung cancer (in conjunction with FEV1).

[@dionnawalton6069]

Hello Brian. Thank You so much for responding to my question. Now it makes sice why the it affects the DLCO.

[@Suzan_Baddar]

Thank you Sir, it is a great presentaion, very simple and clear

[@sanjd6882]

Very nice video. Thank you. Would have been helpful to explain reasons for any discordance with AAO2 gradient.

[@sunving]

Thank you Dr Strong

[@johnheathcote9032]

Thank you for placing your presentations under the creative commons license noted.

[@ianwalker6378]

You list Pulmonary HTN as a cause of Low DLCO, but I don't see how that fits into Fick's Law of Diffusion. By itself PHTN doesnt change partial pressure gradient, the thickness of membrane or surface area. Is this association due to chronic damage to the pulmonary vasculature due to PHTN?

[@drsabitayograj4571]

wonderful videos,well explained

[@rxx3081]

Great video, thank you so much!!

[@MOhamedFAthi87]

جزاك الله خيرا

[@lizasandilands6054]

Hi there, may I use this video in our training material for the company, or where can I purchase it. We train employees what the effects of CO gas are and how it works

[@2100zain]

Thank you that was very helpful

[@kkarantanou]

6:29 when you refer to low lung volumes you mean ERV,IRV,TV and not RV? because in the case of Pseudorestrictive ERV,IRV,TV are reduced but RV is increased. In this case what should be done with DLCO adjustment?

[@farisalshboul998]

you are genius sir , may the GOD preserve u :)

[@afnanalnajar865]

thanks!

[@jkahn5350]

Really, really useful, thank you.

[@ryuhyobosa2465]

hello sir. would please in the future lectures use the pointer in explanation the slides and please use the light background instead the blue one because its more comfortable to the eye.

[@StrongMed]

Ryu, thanks for the feedback. I know that many on-line educational videos (e.g. Khan Academy) use a pointer function during their video capture. I use different software for my videos (Adobe Premeire), which I think allows for greater readability and versatility, but unfortunately, does not have a pointer available. Regarding the background, I try to mix up the background colors such that each topic gets its own color scheme (chest X-rays are white on black, electrolytes are black on light blue, antibiotics are dark brown on beige, etc...) I understand that some viewers may have different preferences than my choices. For consistency, I'm planning on sticking with current color schemes when completing unfinished series (e.g. video #5 of PFTs, videos #8-10 of CXRs), but will consider your comment when starting new series in the future.

[@sarikab5845]

Sir my DLCO is 40 is there any thing to worry please reply 🙏

[@StrongMed]

I'm very sorry, but unfortunately I cannot give specific, individualized medical advice on here. I recommend speaking with the physician who ordered the test for you about your concerns.

[@MrSkaja001]

Marvelous

[@dianagae3024]

very good explanations

[@ramshaarshad8823]

THANK YOU

[@poojapatwal6525]

Thank you so much

[@facebook6771]

Why is dlco increased in obesity, and during morning

[@ryuhyobosa2465]

hello sir, l wish u to be in good heath and ask the God to help u in your hard fantastic work. May i ask u where can i find lesson about FIO2 and Base deficient. regards

[@StrongMed]

Ryu, in the ABG interpretation playlist, there is a video entitled "Effect of supplemental oxygen" - I think it's lesson 17. I generally don't use, or recommend use, of the base deficit, but a brief discussion of it is in a video, also in the ABG playlist, entitled "Alternate approaches to acid base analysis (Lesson 15)" at 6:45.

[@shoger8]

So helpful Thanks

[@hereiswherethereisnt]

excellent

[@reemaz1024]

Love your vids but the intro music u use makes me anxious

[@twominuteanaesthesia]

Interesting

[@MyCold1]

I had a PLCO test recently with 88% of predicted.....is that any good?

[@StrongMed]

I'm sorry but I can't offer specific, individualized medical advice here. However, I will say that one can't conclude anything from a DLCO alone - it only helps with diagnosis or prognosis in the presence of additional data (e.g. lung volumes, spirometry, etc...)

[@Mohanj83777]

Excellent talk.. thank you

[@ryuhyobosa2465]

hello sir we don't have lesson 5 in PFTs. regards.

[@StrongMed]

Ryu, I'm sorry I haven't completed this yet. I'm working on several series in overlapping fashion (so that subscribers who aren't interested in a specific topic don't need to wait too long for something that they might be interested in). I've got a couple of other videos in the works ahead of the last PFT lesson, but it's still coming! Thanks for watching!

[@dionnawalton6069]

hello. how exactly does Pulmonary HTN effect DLCO?

[@bswgd8]

+Dionna Walton Pulmonary HTN leads acutely to pulmonary edema due to increased hydrostatic pressure in the pulmonary vasculature which will inhibit diffusion, and chronically leads to thickened vascular walls which further limits the gas diffusion.

[@memescometrue88]

🧬