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.

[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.

[johnheathcote]

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

[reemaz]

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

[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...

[nickgowen]

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

[davidzane]

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.

[sarikab]

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

[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.

[Suzan_Baddar]

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

[ianwalker]

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?

[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?

[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).

[lizasandilands]

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

[sanjd]

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

[MyCold]

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

[dionnawalton]

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

[facebook]

Why is dlco increased in obesity, and during morning

[dionnawalton]

hello. how exactly does Pulmonary HTN effect DLCO?

[ryuhyobosa]

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

[ryuhyobosa]

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.