A Hunt for the Right Reference 2

I believe I have located the right reference. While I was reading another article, I have found the reference which looks almost alike, but not identical.

"Mahan G, Dabestani A, Gardin J, Allfie A, Burn C, Henry W (1983) Estimation of pulmonary artery pressure by pulsed Doppler echocardiography [abstr].Circulation [Suppl 3]68:367"

Look at the words "[abstr]" and "Suppl 3". So it is NOT an article, but an abstract, my friends. We should be able to find it in the supplemental edition of Circulation in 1983 but for sure I could not find it in Circulation 1983;68:367, since it does not exist.

Finally, I guess I have located the right reference, but I use the term "guess" since I have not confirmed this abstract in print. This supplement is unfortunately too old to locate in my university's library in Print, but I would pursue it anyway.

Now I feel better as I have found the "right" reference for the equation: mean PA = 79 - (0.45 x AT), but also am amazed to find this famous equation is based on an abstract, not even on an article which has been taught for many years in the guidelines, review course, and textbooks.

A Hunt for the Right Reference

I recently taught at Advanced Critical Care Echocardiography course at the CHEST headquarter in Glenview, IL when I realized this while reading a guideline from ASE.

This famous (?) equation of estimating mean pulmonary artery (PA) pressure by using pulmonary arterial acceleration time (AT) does not have the right reference:

mean PA pressure  = 79 - (0.45 x AT)

Where is it from? This equation is based upon which article? Research? Well, when you read the guideline from the American Society of Echocardiography (ASE), the reference for this equation is written so clearly.

(Reference 81)
Mahan G, Dabestani A, Gardin J, Allfie A, Burn C, Henry W. Estimation of pulmonary artery pressure by pulsed Doppler echocardiography. Circulation 1983;68:367.

The problem is that I could not locate this article. There is no such article in Circulation 1983; 68:367. I know, I know, I did my homework. I went to the Circulation website, went to the past issues, went to the one published on August 1, 1983 Volume 68 Issue 2, and alas, there was no such article. One article ends on page 367, then the next one starts on page 368, neither of which carries this title nor the authors.

https://www.ahajournals.org/toc/circ/68/2

Maybe there might be typos, the year might be wrong, or pages might be wrong. I guess I should be able to find the right reference just googling the equation. After spending hours googling, I gave up. There is some web info about this equation, but no clear mentioning of the reference. Now what? Contact ASE, which I did. First by sending an email like below, then by calling them. Guess what, the staffs at ASE are so kind as to contact the writing group for the 2010 Right Heart guideline immediately upon my calling. Thank you so much. So, I guess I wait for their answer. Stay tuned.

My email to ASE
"While reading your guideline published in 2010 as below, I could not find the reference (81) as shown below.

Rudski LG, Lai WW, Afilalo J, Hua L, Handschumacher MD, Chandrasekaran K, Solomon SD, Louie EK, Schiller NB. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010 Jul;23(7):685-713; quiz 786-8. doi:10.1016/j.echo.2010.05.010. PubMed PMID: 20620859.

(Reference 81)
Mahan G, Dabestani A, Gardin J, Allfie A, Burn C, HenryW. Estimation of pulmonary artery pressure by pulsed Doppler echocardiography. Circulation 1983;68:367.

I am afraid there might be an error. Kindly suggest me the right reference. Appreciate your inputs in advance."

IVC and right atrial pressure

Another heated topic. Well, things seem to be clear. When you read the guideline, say the one from ASE in 2010 below, they are quite clear:

(1) IVC diameter is normal (<2.1 cm) and collapses  >50% with a sniff: 3 mm Hg (0 - 5 mm Hg)
(2) IVC diameter is large (>2.1 cm) and collapses <50% with a sniff: 15 mm Hg (10-20 mm Hg)
(3) Either IVC diameter is normal (<2.1 cm) but collapses <50%, OR IVC diameter is large (>2.1 cm) but collapses >50%, 8 mm Hg (5-10 mm Hg)

Lang RM, Badano LP, Mor-Avi V, Afilalo J, Armstrong A, Ernande L, Flachskampf FA, Foster E, Goldstein SA, Kuznetsova T, Lancellotti P, Muraru D, Picard MH, Rietzschel ER, Rudski L, Spencer KT, Tsang W, Voigt JU. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr. 2015 Jan;28(1):1-39.e14. doi:10.1016/j.echo.2014.10.003. PubMed PMID: 25559473.

Questions

Which one could have higher RAP?
a. Large IVC diameter (>2.1 cm) but collapses > 50%
b. Normal IVC diameter (<2.1 cm) but collapses < 50%

When you read the article below, an impression is that b has a higher RAP. 

Brennan JM, Blair JE, Goonewardena S, Ronan A, Shah D, Vasaiwala S, Kirkpatrick JN, Spencer KT. Reappraisal of the use of inferior vena cava for estimating right atrial pressure. J Am Soc Echocardiogr. 2007 Jul;20(7):857-61. PubMed PMID: 17617312.

Two historical articles worth mentioning:

(1) Moreno FL, Hagan AD, Holmen JR, Pryor TA, Strickland RD, Castle CH.  Evaluation of size and dynamics of the inferior vena cava as an index of right-sided cardiac function. Am J Cardiol. 1984 Feb 1;53(4):579-85. PubMed PMID: 6695787.

(2) Kircher BJ, Himelman RB, Schiller NB. Noninvasive estimation of right atrial pressure from the inspiratory collapse of the inferior vena cava. Am J Cardiol. 1990 Aug 15;66(4):493-6. PubMed PMID: 2386120.

You are right, evidence has been there for more than 30 years. Yet, there seems to be some confusion about this. Why is that? I plan to talk more about IVC. Stay tuned.  

IVC: How to measure?

One of the most common questions I receive while teaching at various POCUS courses, either in the US or in Japan, is "Where should we measure the diameter of the inferior vena cava (IVC)?"

Well, there are recommendations from the guidelines, but they are slightly different from one to another. Let us first take a look at this guideline from ASE in 2010.

Rudski LG, Lai WW, Afilalo J, Hua L, Handschumacher MD, Chandrasekaran K, Solomon SD, Louie EK, Schiller NB. Guidelines for the echocardiographic assessment of the right heart in adults: a report from the American Society of Echocardiography endorsed by the European Association of Echocardiography, a registered branch of the European Society of Cardiology, and the Canadian Society of Echocardiography. J Am Soc Echocardiogr. 2010 Jul;23(7):685-713; quiz 786-8.
doi: 10.1016/j.echo.2010.05.010. PubMed PMID: 20620859.

When you read the guideline above, they say (page 692, figure 4) "The diameter (solid line) is measured perpendicular to the long axis of the IVC at end-expiration, just proximal to the junction of the hepatic veins that lie approximately 0.5 to 3.0 cm proximal to the ostium of the right atrium (RA)."

Given above, we could divide the way we measure IVC diameter into four components.

(1) timing of the measurement (2) Axis of the measurement (3) point of the measurement (4) point of the measurement 2

So I guess the article above explains these four points as below:

(1) Timing: End-expiration
(2) Axis: Perpendicular to the long axis of the IVC
(3) Point1: Just proximal to the junction of the hepatic veins
(4) Point2: 0.5 to 3.0 cm proximal to the ostium of the right atrium

Then let us take a look at the next guideline, again from ASE, but in 2015.

Lang RM, Badano LP, Mor-Avi V, Afilalo J, Armstrong A, Ernande L, Flachskampf FA, Foster E, Goldstein SA, Kuznetsova T, Lancellotti P, Muraru D, Picard MH, Rietzschel ER, Rudski L, Spencer KT, Tsang W, Voigt JU. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the  American Society of Echocardiography and the European Association of Cardiovascular Imaging. J Am Soc Echocardiogr. 2015 Jan;28(1):1-39.e14. doi: 10.1016/j.echo.2014.10.003. PubMed PMID: 25559473.

When you read this article, then the point of measurement is slightly different.

"the diameter of the IVC should be measured in the subcostal view with the patient in the supine position at 1.0 to 2.0 cm from the junction with the right atrium, using the long-axis view."

(4) Point4: 1.0 to 2.0 cm from the junction with the right atrium

Last, not the least, a recent article from again ASE, published this year (note Epub is in 2018).

Mitchell C, Rahko PS, Blauwet LA, Canaday B, Finstuen JA, Foster MC, Horton K, Ogunyankin KO, Palma RA, Velazquez EJ. Guidelines for Performing a Comprehensive  Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2019 Jan;32(1):1-64. doi: 10.1016/j.echo.2018.06.004. Epub 2018 Oct 1. PubMed PMID: 30282592.

Now, when you read this most recent guideline from the article, the point of the measurement is the same as the guideline in 2015, but the timing is slightly different. 

"The measurement should be made 1 to 2 cm proximal to the junction of the IVC and right atrium. The IVC diameter should be measured at its maximum dimension, usually during expiration."

(1) Timing: should be measured at its maximum dimension, usually during expiration

So, with all these said, I would summarize the guidelines as follows

(1) Timing: measure when it is at its maximum dimension, usually during expiration
(2) Axis: Perpendicular to the long axis of the IVC
(3) Point: 1 to 2 cm proximal to the ostium of the right atrium

Transducer Manipulation: What is "Tilt", "Rock", or "Angle"?

There seems to be a confusion in this area. For example, when you open up a textbook of echocardiography, one term may be explained in a completely different way from another textbook of POCUS. I once had a heated discussion with my colleague about the definition of each term since I learned from one textbook, whereas I believe he got the information somewhere else and to confess, now I believe he was right, and I was wrong. So where is the "GOLD" standard? The American Institute of Ultrasound in Medicine (AIUM) published a statement in 1999 where they define each maneuver, which could be used as a "GOLD" standard.

AIUM technical bulletin. Transducer manipulation. American Institute of Ultrasound in Medicine. J Ultrasound Med. 1999 Feb;18(2):169-75. PubMed PMID: 10206813.

American Society of Echocardiography has recently published an article on how to perform a comprehensive transthoracic echocardiographic examination, in which they also specifically define these terms which are essentially the same with AIUM.

Mitchell C, Rahko PS, Blauwet LA, Canaday B, Finstuen JA, Foster MC, Horton K, Ogunyankin KO, Palma RA, Velazquez EJ. Guidelines for Performing a Comprehensive Transthoracic Echocardiographic Examination in Adults: Recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2019 Jan;32(1):1-64. doi: 10.1016/j.echo.2018.06.004. Epub 2018 Oct 1. PubMed PMID: 30282592.

The video below (I have found it on YouTube) might be helpful for you to understand the difference between each maneuver.

Advanced Critical Care Echocardiography: Complete Examination

As you may know, the National Board of Echocardiography (NBE) has launched a new Examination of Special Competence in Critical Care Echocardiography (CCEeXAM). The very first examination was performed in January 2019, and they have already received the pass (or fail) results. Congratulations to those who have passed! Me? I did take Examination of Special Competence in Adult Echocardiography (ASCeXAM). Boy, it was really a tough exam (particularly for me being a pulmonologist to take an exam for cardiologists!) and am so glad I have passed!

Passing the examination is required, but not sufficient to be the Diplomate of the board. You have to submit 150 complete advanced critical care echocardiography (ACCE) examination. But what is exactly the "complete" examination? This YouTube video below, by my mentor Dr. Paul Mayo, and my dear colleague Dr. Yonatan Greenstein explains this very nicely. For those who are new to this concept, I suggest you review this video to get an idea of what is the "Complete" examination.


https://www.youtube.com/watch?v=OJB8ZNtVAvA

Speaking of which, CHEST has a great course of advanced critical care echocardiography in the end of May to June. Dr. Mayo is a co-chair and I have been teaching there this year (Yes, just came back) and last year.

Point-of-Care Ultrasound and Me

Hello there,

I am a pulmonary and critical care physician in the United States and an associate professor of medicine at the Warren Alpert Medical School of Brown University, teaching Point-of-Care Ultrasound (POCUS) to medical students, medical residents, and fellows. For some reasons, I - all of a sudden, not sure how or why - thought of writing about POCUS - more or less for my personal memorandum. I teach POCUS in the US more than a decade at American College of Chest Physicians (ACCP - CHEST) and have been teaching at my medical school as well. I have also started teaching it in Japan as well since 2017. Again, this article is more or less for my personal memo, but hope you also find it helpful. Note also I may keep editing each article, so you may notice some changes when you come back to read the "same" article.

(1) Point-of-Care Ultrasound in General
(1-a) Paper
Moore CL, Copel JA. Point-of-care ultrasonography. N Engl J Med. 2011 Feb 24;364(8):749-57. doi: 10.1056/NEJMra0909487. Review. PubMed PMID: 21345104.

So, what exactly is this "Point-of-Care Ultrasound"? How different is it from a conventional ultrasound examination? Any special technique? This article defines POCUS as follows: "Point-of-care ultrasonography is defined as ultrasonography brought to the patient and performed by the provider in real time. "

For those who use ultrasound for your daily practice, like in Japan where you can find ultrasound machines on every medicine floor, you might be puzzled to learn this concept. "So what is this POCUS thing? How is it different from my everyday practice? I perform ultrasound examinations for my patients at the bedside every day". Well, you are performing POCUS. No difference.

But for those who practice in the US, you may understand this concept better, since ultrasound was traditionally NOT performed by physicians at the bedside, and the results were NOT interpreted and applied to the patients in front of you in real-time. We order an ultrasound, then the technicians may come at the bedside, perform ultrasound examinations, then, later on, radiologists read the findings stored in the machines or servers, then upload the reports. Most often we only read the reports, and not the images or least, movies. Sometimes we receive the reports on the same day hours later, and sometimes we do not and may wait for them for days. For those of us, POCUS is indeed a new and brilliant concept. This article explains the concept very nicely. A nice introductory paper I recommend you all read to get the grasp of this concept.

(1-b) Textbook
Point-of-Care ULTRASOUND by Nilam Soni (Second edition)
If I choose one textbook for point-of-care ultrasound, I have no doubt to pick up this one. The first edition is truly a fantastic textbook written by my dear friend Nilam (I started the program in Japan with him and Dr. Toru Yamada at Tokyo Medical and Dental Univ, so every year we work together), and please note 2nd edition is now out!

Ultrasound in the Intensive Care Unit

I wrote a few chapters including diaphragm ultrasound and abdominal ultrasound. While I still recommend Nilam's amazing textbook, this unique textbook might be still the only textbook published in English which explains diaphragm ultrasound in one chapter. A good read.

For those who can read Japanese fluently, I highly recommend this book.
レジデントノート 2018年8月 Vol.20 No.7 エコーを聴診器のように使おう! POCUS〜ここまでできれば大丈夫! ベッドサイドのエコー検査

I have edited this book with Dr. Toru Yamada at TMDU and Dr. Hiromizu Takahashi at Juntendo University. I hate to recommend something I wrote, but I believe this is quite a good one as long as you can read Japanese!

(2) Focused Cardiac Ultrasound (FoCUS)
Spencer KT, Kimura BJ, Korcarz CE, Pellikka PA, Rahko PS, Siegel RJ. Focused cardiac ultrasound: recommendations from the American Society of Echocardiography. J Am Soc Echocardiogr. 2013 Jun;26(6):567-81. doi:10.1016/j.echo.2013.04.001. PubMed PMID: 23711341.

I believe one of the significances of FoCUS comes from the fact it is written by the group of cardiologists, and Dr. Kirk Spencer is indeed the pioneer of this field.

Via G, Hussain A, Wells M, Reardon R, ElBarbary M, Noble VE, Tsung JW, Neskovic AN, Price S, Oren-Grinberg A, Liteplo A, Cordioli R, Naqvi N, Rola P, Poelaert J, Guliĉ TG, Sloth E, Labovitz A, Kimura B, Breitkreutz R, Masani N, Bowra J, Talmor D, Guarracino F, Goudie A, Xiaoting W, Chawla R, Galderisi M, Blaivas M, Petrovic T, Storti E, Neri L, Melniker L; International Liaison Committee on Focused Cardiac UltraSound (ILC-FoCUS); International Conference on Focused Cardiac UltraSound (IC-FoCUS). International evidence-based recommendations for focused cardiac ultrasound. J Am Soc Echocardiogr. 2014 Jul; 7(7):683.e1-683.e33. doi: 10.1016/j.echo.2014.05.001. Review. PubMed PMID: 24951446.

International guideline for FoCUS: a very nice summary of FoCUS (and I like how they define FoCUS, which embodies the spirit of POCUS).

(3) Lung Ultrasound
Lichtenstein DA, Mezière GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest. 2008 Jul;134(1):117-25. doi:10.1378/chest.07-2800. Epub 2008 Apr 10. Erratum in: Chest. 2013 Aug;144(2):721. PubMed PMID: 18403664; PubMed Central PMCID: PMC3734893.

Lichtenstein is a genius who has founded this field of lung ultrasound almost all by himself - my dear mentor and I am so fortunate to learn this directly from him.

(4) Abdominal Ultrasound
Scalea TM, Rodriguez A, Chiu WC, Brenneman FD, Fallon WF Jr, Kato K, McKenney MG, Nerlich ML, Ochsner MG, Yoshii H. Focused Assessment with Sonography for Trauma (FAST): results from an international consensus conference. J Trauma. 1999 Mar;46(3):466-72. Review. PubMed PMID: 10088853.

(5) DVT
Kory PD, Pellecchia CM, Shiloh AL, Mayo PH, DiBello C, Koenig S. Accuracy of ultrasonography performed by critical care physicians for the diagnosis of DVT. Chest. 2011 Mar;139(3):538-542. doi: 10.1378/chest.10-1479. Epub 2010 Oct 28. PubMed PMID: 21030490.

My then senior fellow Pierre wrote this excellent article.

(6) POCUS in the evaluation of Shock
Perera P, Mailhot T, Riley D, Mandavia D. The RUSH exam: Rapid Ultrasound in SHock in the evaluation of the critically lll. Emerg Med Clin North Am. 2010 Feb;28(1):29-56, vii. doi: 10.1016/j.emc.2009.09.010. PubMed PMID: 19945597.

There are SO many protocols to assess hemodynamic instability by POCUS, such as RUSH, FALLS, or FEEL. I think as long as you stick to keep four major differential diagnosis of shock (hypovolemic, cardiogenic, obstructive, and distributive) in mind and figure out how you rule them in or out, you should not miss too much. I believe they have almost the same or similar content with different faces. Pick one of your preference, and we teach RUSH at the medical school.