I'm grateful for your effective and succinct explanations. I prefer the reliability of your explanations to any amount of graphics or humorous non-sequiturs. You've been a tutor from afar - thank you!
This is an amazing video, Dr Eric. Thank you for uploading it. I would like to point out a mathematical error regarding FRC. FRC = [(Initial conc. of He - Final conc. of He) / Final conc. of He] - Volume of Reservoir.
Ahmed Khattab Thanks for the message. However, I do think the original math is correct. It's worked out more explicitly here: samples.jbpub.com/9780763781187/81187_CH02_FF.pdf (page 90 of the book, or page 22 of the uploaded pdf) Please let me know if it still seems in error.
Eric's Medical Lectures I don't know how to thank you for your reply. It turns out that it's just a matter of rearranging the equation. My mistake. Thank you for the clarification.
I have always wondered whether the lung capacity measured in a living animal would be different from the lung capacity measured in post mortem, ex situ lungs. I see lots of pubs report excised lung volumes but haven't found any that can compare these two measurements. I study marine mammals, which have extremely compliant chest walls and lung volumes, but am curious whether the post mortem ex situ values for lung capacity could be overestimates. Thanks for your help, this video is inspiring (pun intended)! :-) Another thing I was hoping you could clear up is whether helium dilution or nitrogen washout techniques can be used to estimate total lung capacity...based on this video it seems like they can only be used to measure FRC, but I just wanted to ask in case I misunderstood. Thank you again for making this video, it's great!
In moderate to severe COPD the patient may never "washout." The duration of testing encourages fatigue related errors. TGV by Body Plethysmography with good technique is a better alternative in most patient groups.
Dear Dr Strong, Thanks for the very informative series on pulmonary function tests. Would you consider an additional lecture on interpreting the validity of each of each type of PFT to complete the series. Thank you. Sincerely, Raleigh
By validity, are you asking about how accurately the tests are in discriminating different forms of pulmonary disease? Or how reproducible they are? Or how much clinicians actually use them in practice? (I'm happy to discuss any of these in the final video in the series.)
Eric's Medical Lectures Dear Dr Strong, By validity, I am refering to the criteria for acceptability for each test. For example, for spirometry, is there maximal effort; no cough or glottic closure during the first second ;good start-of-test; back-extrapolated volume less than 5% of FVC or 150 mL,tracing shows 6 seconds of exhalation or an obvious plateau, 3 acceptable spirograms obtained; 2 largest FVC values within 150 mL; 2 largest FEV1 values within 150 mL and finally reporting the highest FVC and highest FEV1, even if they come from separate maneuvers and that the FEV1/FVC ratio is derived from these values. There are criteria for acceptability for dilutional lung volumes, body box and the different techniques for diffusion capacity. Would you be able to elaborate on these in a separate lecture on pulmonary function test. Thank you. Sincerely, Raleigh
Raleigh Lee Raleigh, I'm very sorry, but I think you just exhausted my own knowledge on this particular issue. This level of detail is critical in the PFT lab, but by the time I see a PFT report, the technicians have already taken care of this. Thus, I don't know more about it. However, unless you are working as a PFT technician, it seems unlikely you'll need this information in routine clinical care. (though I can imagine one might potentially need to know this for pulmonary boards...)
Amazing-- well thought out and clearly explained lectures which have impacted greatly on my confidence and practice. Thank you from the bottom of my heart. This is an invaluable resource. Any chance of some CSF interpretation or pleural fluid interpretation lectures?
Thanks for the feedback, and that's a great suggestion! I'm super behind in fulfilling requests, so I can't guarantee when I'll be able to get to it, but will add CSF, pleural fluid, and ascites fluid analysis to the list of upcoming topics.
You sound like the guy out of Friends. Good videos. I can across theses asI have had and still getting my energy from pneumonia / plurisy. Bloody bugs.
I'm struggling with the eqution a bit. I get FRC = (initial concentration x initial volume / end concentration) - initial volume after solving the equation. Looking in some books I can see that the s is apparently correct but that it can be solved further through some likely clever maths? Is there any way of explaining this please?
Thank you for the video, it is indeed very helpful. I have a question though about the "pseudorestriction" case. Can you explain why if we only measure the lung volumes by spirometry will that be inaccurate ? you mean that we only measure IRV, TV and ERV which are reduced so we think of a restrictive disease??
Yes, you are correct. If only spirometry is ordered without a lung volume test, one might intepretate the result as "restrictive lung disease" based on the reduced vital capacity measured by sprometry.
I've been wanting to do a video on breath sounds for a while, but unfortunately, I've been dissatisfied with the quality of the breath sound recordings I've made. They are much harder to clean up than heart sounds were, and I've put it on hold until I either get a better recording stethoscope or manage to make cleaner recordings with what I have.
No and I'll explain why! For example, in the helium test, the patient begins to breathe the air containing helium at the end of tidal exhalation (i.e. when the FRC is contained in his lungs). When the stopcock is closed it is true that helium is distributed throughout the lung but in an air volume that corresponds only to the FRC. I got it?
@nada amraoui Try to think that when the patient begins to breathe the circuit is closed and a single environment (reservoir + lungs [FRC]) is created in which the helium is distributed homogeneously. That's why the final helium concentration is the same in the reservoir and lungs. Clear?
In the absence of a pneumothorax (air in the pleural space around the lung), any air located within the thorax would necessarily be within the lung (with the exception of air in the esophagus, which is negligible in volume).
@@StrongMed Thank you for your response. The reason I'm asking is because I'm interested in measuring air volume within inflated lungs using CT. I am just curious whether quantifying the volume of the lungs=quantifying the volume of the air. Seems like this is true given your response, but if you have anything to add please do! Thank you again.
@@hollyhermann-sorensen5974 Yes, the volume of the lungs on CT is close enough to the air volume that these can be assumed to be equal for any common clinical application. (i.e. the volume of lung tissue
@@StrongMed Thank you SO MUCH for this response. This sets my mind at ease. I'm quantifying the air spaces of some anesthetized animals using CT at known inflated conditions. Someone recently asked me whether this method was comparable to whole body plethysmography as I'm quantifying tissue + air versus just changes in air volume. I feel now like I can say that they are basically the same thing. Thank you again!
Plz dont use that sculpture... Its hard to concentrate on ur words while thinking about that art and why u used it and what kind of person u r and blah blah...
I'm grateful for your effective and succinct explanations. I prefer the reliability of your explanations to any amount of graphics or humorous non-sequiturs. You've been a tutor from afar - thank you!
thank you so much!!! incredible how logical things can be explained.More doctors like you are needed.
Boy, you are a star. Thank you and wish you lots of health and wealth and happiness
Probably this channel is for medical students but I have to say that I have learned a lot from here.
This is an amazing video, Dr Eric. Thank you for uploading it. I would like to point out a mathematical error regarding FRC. FRC = [(Initial conc. of He - Final conc. of He) / Final conc. of He] - Volume of Reservoir.
Ahmed Khattab Thanks for the message. However, I do think the original math is correct. It's worked out more explicitly here: samples.jbpub.com/9780763781187/81187_CH02_FF.pdf (page 90 of the book, or page 22 of the uploaded pdf) Please let me know if it still seems in error.
Eric's Medical Lectures I don't know how to thank you for your reply. It turns out that it's just a matter of rearranging the equation. My mistake. Thank you for the clarification.
Ahmed Khattab No problem! I do make mistakes in these videos, and I honestly appreciate viewers pointing them out. Thanks for watching!
I did not get that calculation
I'm a new NP. Love your videos. Very clear. Helping me study for board certification. Thank you!!
Wooooow. I can't describe this video because is more than just great. Thank you so much
I have always wondered whether the lung capacity measured in a living animal would be different from the lung capacity measured in post mortem, ex situ lungs. I see lots of pubs report excised lung volumes but haven't found any that can compare these two measurements. I study marine mammals, which have extremely compliant chest walls and lung volumes, but am curious whether the post mortem ex situ values for lung capacity could be overestimates. Thanks for your help, this video is inspiring (pun intended)! :-)
Another thing I was hoping you could clear up is whether helium dilution or nitrogen washout techniques can be used to estimate total lung capacity...based on this video it seems like they can only be used to measure FRC, but I just wanted to ask in case I misunderstood. Thank you again for making this video, it's great!
In moderate to severe COPD the patient may never "washout." The duration of testing encourages fatigue related errors. TGV by Body Plethysmography with good technique is a better alternative in most patient groups.
thank you very much for these helpful videos.
Thanks dr. Eric.
So nice & informative video.
Dear Dr Strong,
Thanks for the very informative series on pulmonary function tests. Would you consider an additional lecture on interpreting the validity of each of each type of PFT to complete the series.
Thank you.
Sincerely,
Raleigh
By validity, are you asking about how accurately the tests are in discriminating different forms of pulmonary disease? Or how reproducible they are? Or how much clinicians actually use them in practice? (I'm happy to discuss any of these in the final video in the series.)
Eric's Medical Lectures
Dear Dr Strong,
By validity, I am refering to the criteria for acceptability for each test.
For example, for spirometry, is there maximal effort; no cough or glottic closure during the first second ;good start-of-test; back-extrapolated volume less than 5% of FVC or 150 mL,tracing shows 6 seconds of exhalation or an obvious plateau, 3 acceptable spirograms obtained; 2 largest FVC values within 150 mL; 2 largest FEV1 values within 150 mL and finally reporting the highest FVC and highest FEV1, even if they come from separate maneuvers and that the FEV1/FVC ratio is derived from these values.
There are criteria for acceptability for dilutional lung volumes, body box and the different techniques for diffusion capacity.
Would you be able to elaborate on these in a separate lecture on pulmonary function test.
Thank you.
Sincerely,
Raleigh
Raleigh Lee Raleigh, I'm very sorry, but I think you just exhausted my own knowledge on this particular issue. This level of detail is critical in the PFT lab, but by the time I see a PFT report, the technicians have already taken care of this. Thus, I don't know more about it. However, unless you are working as a PFT technician, it seems unlikely you'll need this information in routine clinical care. (though I can imagine one might potentially need to know this for pulmonary boards...)
Amazing-- well thought out and clearly explained lectures which have impacted greatly on my confidence and practice. Thank you from the bottom of my heart. This is an invaluable resource. Any chance of some CSF interpretation or pleural fluid interpretation lectures?
Thanks for the feedback, and that's a great suggestion! I'm super behind in fulfilling requests, so I can't guarantee when I'll be able to get to it, but will add CSF, pleural fluid, and ascites fluid analysis to the list of upcoming topics.
thank you!! super useful!
great lecture
our proffesor using your videos at lectures 😆 amazing
I hope he/she properly attributed them!
Thank you Dr Strong,
Thank you so much!Do keep making more videos. 💕
thank you, Eric
You sound like the guy out of Friends. Good videos. I can across theses asI have had and still getting my energy from pneumonia / plurisy. Bloody bugs.
so easy to understand , THANK YOU !!!!!!
I'm struggling with the eqution a bit. I get FRC = (initial concentration x initial volume / end concentration) - initial volume after solving the equation. Looking in some books I can see that the s is apparently correct but that it can be solved further through some likely clever maths? Is there any way of explaining this please?
In pseudorestriction is it possible that FEV1 / FVC is normal? I think yes because FVC is reduced.
Thank you for the video, it is indeed very helpful. I have a question though about the "pseudorestriction" case. Can you explain why if we only measure the lung volumes by spirometry will that be inaccurate ? you mean that we only measure IRV, TV and ERV which are reduced so we think of a restrictive disease??
Yes, you are correct. If only spirometry is ordered without a lung volume test, one might intepretate the result as "restrictive lung disease" based on the reduced vital capacity measured by sprometry.
Thanks Dr.
You have great lectures. Can you do one on Breath Sounds?
I've been wanting to do a video on breath sounds for a while, but unfortunately, I've been dissatisfied with the quality of the breath sound recordings I've made. They are much harder to clean up than heart sounds were, and I've put it on hold until I either get a better recording stethoscope or manage to make cleaner recordings with what I have.
Great video
Currently studying to be a PFT lab technician, skips over the steps relevant to me. Frick.
yeah its like the only reason I watched the video lol. "ok, pleth, here it comes, and its skipped."
Why does He dilution not measure FRC + TV? Wouldn’t the person still be breathing in tidal volume after the stopcock is closed? Confused...
No and I'll explain why! For example, in the helium test, the patient begins to breathe the air containing helium at the end of tidal exhalation (i.e. when the FRC is contained in his lungs). When the stopcock is closed it is true that helium is distributed throughout the lung but in an air volume that corresponds only to the FRC. I got it?
@@giuseppevallese4153 Thank you!! Yes this makes more sense now
@nada amraoui
Try to think that when the patient begins to breathe the circuit is closed and a single environment (reservoir + lungs [FRC]) is created in which the helium is distributed homogeneously. That's why the final helium concentration is the same in the reservoir and lungs. Clear?
This is awesome!
Thanks.. great video.
Very descriptive
Using the radiographic technique, how do you separate the lung tissue from the air? Or do you? Are the two considered to be one and the same?
In the absence of a pneumothorax (air in the pleural space around the lung), any air located within the thorax would necessarily be within the lung (with the exception of air in the esophagus, which is negligible in volume).
@@StrongMed Thank you for your response. The reason I'm asking is because I'm interested in measuring air volume within inflated lungs using CT. I am just curious whether quantifying the volume of the lungs=quantifying the volume of the air. Seems like this is true given your response, but if you have anything to add please do! Thank you again.
@@hollyhermann-sorensen5974 Yes, the volume of the lungs on CT is close enough to the air volume that these can be assumed to be equal for any common clinical application. (i.e. the volume of lung tissue
@@StrongMed Thank you SO MUCH for this response. This sets my mind at ease. I'm quantifying the air spaces of some anesthetized animals using CT at known inflated conditions. Someone recently asked me whether this method was comparable to whole body plethysmography as I'm quantifying tissue + air versus just changes in air volume. I feel now like I can say that they are basically the same thing. Thank you again!
Merci Dr.
How do you measure RV?
I like this video
awesome
Thanks !
Thanks btw your sound like Joey from Friends tv series :)
Plz dont use that sculpture...
Its hard to concentrate on ur words while thinking about that art and why u used it and what kind of person u r and blah blah...