HFNC: The Physiologic Effects

Physiologic Effects of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure

I have extensively covered high flow nasal cannula, HFNC on this page due to a talk I'm creating on the matter. We've witnessed it first hand keep patients off of the ventilator. This article published in the American Journal of Respiratory and Critical Care Medicine, which as an aside is the highest impact factor publication in the Critical Care world, looked at 15 patients to determine the physiologic effects of the HFNC system. The reason why they performed the study was because those physiologic effects that we all know are beneficial were just not defined at the time of the publication. The ambitious authors wanted to go ahead and define them. Although this study was published in May 2017, one can grasp more or less the time it takes to get one of these important studies published by noting that it was initially submitted in May 2016. Imagine having this data and not being able to get it out. I would lose my mind.
The authors used patients with a P/F ratio of less than or equal to 300. They performed a number of measurements which I will not cover here for the sake of it being Sunday morning and you do not want to be put into another nap.
In a quick and dirty recap, here are their findings:
1. less inspiratory effort
2. lighter metabolic work of breathing
3. less minute ventilation (due to decreased respiratory rate)
4. improved oxygenation
5. no change in PCO2 nor pH
6. increased lung volume in dependent and non-dependent lung regions
- this may be a huge key towards understanding the possible PEEP that the HFNC system may provide. The authors state that increasing the EELI with an improvement in oxygenation while not having a change in tidal volume may explain the PEEP effect
There are other findings which I will defer to the authors to describe in the article. Check it out in the link below.

- EJ






Link to Abstract

Mauri, T., Turrini, C., Eronia, N., Grasselli, G., Volta, C. A., Bellani, G., & Pesenti, A. (2017). Physiologic Effects of High-Flow Nasal Cannula in Acute Hypoxemic Respiratory Failure. American Journal of Respiratory and Critical Care Medicine, 195(9), 1207–1215.

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

Normal Saline: A History Lesson for the Inappropriate Name

A little history lesson, my friends, regarding the origins of us calling 0.9% saline solution, aka 0.9% sodium chloride, "normal saline".

We are all disappointed in ourselves. You've been calling it normal saline, I've been calling it normal saline, we just can't stop ourselves! Of course you know I am referring to 0.9% sodium chloride solution used so commonly, and many times inappropriately, in our everyday practice. Why is it not normal? Well, I have covered this many times on my Instagram page and YouTube videos. First of all, the sodium concentration in serum is 140meq/L. The reference range in the labs are usually 135-145meq/L. What's the sodium concentration in "Normal Saline"? 154meq/L. How much chloride is in serum? 98-109meq/L. What about in "normal saline"? 154meq/L because it's equal parts sodium and chloride. We can continue talking about strong ion difference and all the adverse effects of the 0.9% saline but that will take me forever. It's Saturday and I have a birthday party to go to. Where in the world did the associate with "normal" come from? The inspiration for this post came from @anursingnote and her discussion with @med.life.crisis, two RN's who are trying to kick butt and get smarter every day. You go girl(s)!
This article is not free, unfortunately, but they do make a couple key points, all of which show that even though they used the word "normal", it's not in the appropriate way. You're never going to think about a Hamburger now without thinking about 0.9% saline solution. Sorry I ruined that for you.
Here's how all this went down in chronological order:
I credit the authors of this paper for doing much of this heavy lifting, by the way. I can't actually get my hands on many of these papers. I'm going to do my best to briefly summarize.
1888: Hamburger. This Dutch physiologic chemist performed in vitro studies (not in vivo, take a second to let that process) where he found that there was less hemolysis with 0.92% saline than other concentrations.
1888: Dr Churton. "he was ordered transfusion of ‘normal saline’ solution in order to replace the fluid thus lost". That fluid was nothing like the saline we know and are still trying to understand to this day. That particular fluid had 150meq/L of Na and 128meq/L of chloride. It also had some bicarb in it.
1892: Dr Spencer used the term "normal salt solution" but the composition of the fluid was not defined.
There are plenty more goodies in the article which I recommend you try to get your hands on. The article is going to definitely be included in my lecture regarding intravenous fluids that I will be giving to the anesthesia department in my shop next month and on various lectures I have scheduled nationally next year. It's that important. A great job by the authors!
All in all, can we really stop saying "normal saline"? I think it's too embedded in our vernacular and it'll be too challenging to fix. I am always trying to make a conscious effort to stop but it's challenging because I have been hearing it for over a decade now. I'm getting old.

-EJ





Link to Abstract


Citation:
Awad S, Allison SP, Lobo DN. The history of 0.9% saline. Clin Nutr Edinb Scotl. 2008;27:179–188.
Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

10,000 Followers on Instagram: THANK YOU!

THANK YOUUUUUU!

It finally happened; my instagram account reached 10,000 followers. I could not have done it without your support. Yeah, you. You're one of those 10,000. Thank YOU for following along in my craziness.

First of all, I know there are plenty of Instagram accounts with many more followers than mine, but I have created a niche type account which is mostly specific to Critical Care. There aren't many dedicated Intensivists in this world, unfortunately. To me, this means that 10,0000 people have the potential to learn what I am learning and be able to either utilize this information directly, or share it with the medical community they work with. There's nothing that makes me happier than a nurse or respiratory therapist who makes a great suggestion on how to help me better manage the patient. That shows interest and passion in what they are doing. In addition, when those suggestions are made, it also means that I have created an environment where the staff is not fearful of what I am going to say or think about them. After all, I say plenty of silly things just to keep the mood light and lively in an environment which is filled with critically ill patients. If I teach one medical student about fluids, and they go on to take care of thousands of patients throughout their career and potentially train other students and residents along the way. Exposing 10,000+ people to the same article at once is far more powerful. It would be an exponential effect and you bet that that keeps me incredibly motivated. I am not in academics although I obviously love to teach. At this juncture of my career, I struggle with giving up control, it's the Intensivist in me where I want to be in charge and managing as much as humanly possible. This medium of teaching on social media provides me with a release. I get immediate feedback from you all. In addition, I provide the citations for everything I post so that you don't, as you shouldn't, trust me. Sorry if the articles aren't always free. After all, I frequently say that I'm not someone who actually does clinical research and do not take credit for being the one who discovers anything I post. I have one publication and, for the moment, that's all I am going to have.

Ulterior motives

As some of you already know, I am going to be speaking at several conferences this year. I have not disclosed that publicly just yet, though. No, it's not Chest, ATS, nor SCCM, but I will be sharing the stage with certain notable clinicians who regularly present at those conferences. I have pursued this opportunity to speak because it is something I have never done before and I really wanted to push myself to be very uncomfortable. A new challenge. Do I need to do this? Absolutely not. But presenting at these conferences has lit a fire underneath my behind because I don't need to bring my A game, rather, I need to bring my A++ game. My reputation is on the line, I will be standing in front of hundreds of clinicians influencing their practice. It will be in front of a live audience of several hundred individuals who paid some good, hard earned, money for some CME credits. I do not get to hide behind my Instagram account. My information will be crucial to the care of their patients and their communities. That's a big challenge! Bring it! This ends up benefitting my IG and YouTube audience because I have shared many articles of some of talks that I am preparing. My research is getting directly to you after being masticated a bit. As always, I leave some of the lifting to you all as I cannot bear the responsibility of digesting all the data for you. If the article I share stimulates your interest, I will also provide the links to where I got the data or explain how I came to that conclusion.

Financial Compensation/Multiple Streams of Income

I am writing the following for the sake of transparency. I hope you appreciate it as such. I am disclosing that I am earning some money off of all this. No one wants to work for free. This may motivate some of you to do the same, potentially use the same or similar model, or just wonder why I am investing so much time into it all. Achieving 10,000 followers is a big part of monetizing this whole ordeal. By no means am I going to quit my job and live off of this, but it does provide incentive. The good thing is that none of this will cost you one cent. For the sake of full disclosure, here's how all this works. First of all, the swipe up feature is going to allow me to send you to a couple different locations.

My Website: eddyjoemd.com

I have this website that runs ads. Google Adsense sends me a check every month for the website. At the time of this writing, I earned $0.63 yesterday and $0.72 the day before. Let's say $20 a month. How's that for transparency? I don't have any expectations for the website to blow up but I enjoy doing it. I enjoy typing out with my improper grammar and run-on sentences what I'm thinking as I go through the articles. I have learned a lot about the google algorithms, SEO, keywords and the like. Many cool people on YouTube such as Income School and Miles Beckler for those who are interested in going down that rabbit hole. I really like to learn and expand my knowledge. This was something cool and it's rewarding.

The YouTube channel: www.youtube.com/eddyjoemd

This has been my longest running side gig. My channel is over four years old now. I had to stop and think about it. It feels newer than that. Oh well. This was a very successful and much more profitable venue to discuss medicine things with you all but recently YouTube changed their algorithm because of the vaccination and misinformation which destroyed my audience and leads. I was no longer being recommended. This is why I ask for some thumbs up during my videos because it helps YouTube see that I'm legit and not someone pretending to be a physician. I plan on making many more videos as time allows in the near future. I just need more feedback as to whether the videos are any good or if I can do better. At the moment spending 15 minutes shooting a video and 5 minutes editing it for 400 views isn't worth my time. I may have to change strategies. I just may not be that good or I may be too niche. I'll figure this out. It's also challenging to record myself. Do I really have to stress that hearing the sound of my own voice when I'm editing irks me?

Amazon Affiliates

I may start plugging in a book that I am enjoying and think it's a good value which will be helpful for you all. I may do this on a story, a blog post, or a link to my Amazon store. The fun part for me is that you don't even need to buy that particular book or item for me to earn a commission. I'm always reading something that's not medicine related. At this time I am reading this book by Dale Carnegie Titled: Public Speaking for Success. If you click on that link, it will open up the book on Amazon. In the next 24 hours, if you purchase that book OR anything else whatsoever on amazon, I will get a commission. It doesn't make your price higher. I earn something like 1-5% of the price of the item. Definitely won't make me wealthy but it pays for Netflix. I also have an Amazon Store. For those interested, creating an Amazon Affiliate account is really easy.

Tips for those who are trying to find any type of success around here.

Provide value. The results I have experienced speak for themselves. I even created a graph about it. People who know me aren't the least bit surprised that I've kept peripheral track of my follower count and more recently have kept track almost daily. At first I was naive enough to think that I could get there on just posting random things. That my life would be sufficiently interesting to carry some weight. Harsh reality struck. Truth is, as an individual, I am not that interesting. I had to come up with a way to get there without butt pics. The day I decided to start sharing what I was already doing on my free time, i.e. reading a bunch of articles, is the day my account starting making a drastic upswing.




I need to shout out to everyone who has ever shared my page. Without these kind people who did this for me and my page out of the goodness of their own heart, I would potentially never be writing this post. Apologies if you shared my page and you're not on this list. Call me out on it like Sean Dent did! I will go in alphabetical order:

@afibflutter
@amandasximd
@ambcarerx
@anishathemd
@ashleyadkinsrn
@austinchiangmd
@bedsideroundz
@breatheeasy_rrt
@brendalee_figurepro
@combatmidwife
@corporatenutritionist
@doctor.charlesclinton
@doctorwarsgame
@drbuckparker
@drcindylou
@drhakman
@drkmitchell
@drkoriashner
@drmanuelroman
@drmcsaucy84
@dr.tommymartin
@elisewitz
@grepmed
@hayleykrayburn
@herbsandfood
@icuphysiotherapist
@ingriddborges
@jacquicormier_rn
@kettyelena
@kristinyatesdo
@leahem09
@me.girlincognito
@michaelgalvezmd
@nicolekupchik
@nikiz11
@npstudentmagazine
@nurseannrn
@oneinamelon.co
@pagethepa
@paramedicpractitioner
@physiciandoodles
@plan.film.medical.memes
@poojalakshminmimd
@pre_stethoscope_life
@rn_ratched
@seanpdent
@the_resuscitationist
@thedoughnutdiary
@theencouragingdoc
@thefacetiousmurse
@themedicnurse
@xray.doctor
@yournursingeducator

That's enough for today! Hope this helps. Again, thank you all for your support!
-EJ

Check out some resources I have personally found value in and recommend over at my My Amazon Store. This is an affiliate link which means that I may make a small commission if you make any purchase on Amazon after clicking on a product, you do not even have to purchase something I recommended. Thank you for supporting my work.

Ionized Calcium in the Critically Ill

Ionized Calcium in the ICU

I have to credit Dr. Rishi Kumar for inspiring me on this ionized calcium post this today. His post on instagram regarding total versus ionized calcium made me recall this article that was transformative for me when it was published in CHEST in December of 2015. I know that the official article was published in March 2016 but cool people like me get their hands on the manuscripts from time to time. Okay, fine, I'm not cool. CHEST sends pre-release articles out all the time. As mentioned, this article was formative for me and I hope it has the same effect for you all.

ICU practitioners, nurses, doctors, respiratory therapists are all obsessed with perfection. We want the MAP to be 65, the ABG to be perfect, and for there not to be any red numbers on the labs. What happens very often in our labs is that the calcium comes back low. Then we check an albumin and correct the calcium. Then it's still low so we check an ionized calcium. We get that number and do whatever we choose with it. I rarely check ionized calcium in my practice after reading this article. This is unfortunately not a free article but when there's a will there's a way.

I'll update this blog post later when I have a little more time.

- EJ



Link to Abstract

Link to PDF

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

BiPAP (NIV) vs. High Flow Nasal Cannula

High-flow nasal cannula oxygen therapy in patients undergoing thoracic surgery: current evidence and practice

Always give credit when credit is due and cite your sources. The article below isn't free, but if you can get your hands on it, it has some really nice tables. In particular, there is one table where they compare non-invasive ventilation to high-flow nasal cannula with regards to comfort, airway pressure and PEEP (see more on my post about that yesterday), anatomical dead space, CO2 washout, mucociliary function, pulmonary effects, extra pulmonary effects, skin breakdown and sores. It's worth checking out if you have access to this journal.

- EJ

Link to Abstract

Wittenstein, J., Ball, L., Pelosi, P.; Gama de Abreu, M. (2018). High-flow nasal cannula oxygen therapy in patients undergoing thoracic surgery. Current Opinion in Anaesthesiology, 1.

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

HFNC/High Flow Nasal Cannula: Does it generate "PEEP"?

Please note that I have sorted out this issue and the following rant is a rant on my thought process leading up to my eventual resolution. 

I was trained, or maybe even made it up in my head, that for every 10L of flow increase on the high flow nasal cannula, HFNC, you get 1cmH2O of "PEEP". Is this accurate? The short answer in my opinion is no. At least not the way you're thinking about it. I've been digging pretty deep into the topic because although much data is suggestive of it, but I can't find something that I can clearly understand. Maybe it's just my lack of intelligence or lack of direct pulmonary training. Positive end-expiratory pressure (PEEP) is defined by UpToDate as the alveolar pressure above atmospheric pressure that exists at the end of expiration. Therefore, we need to look at alveolar pressure directly. In particular, we need to look at extrinsic PEEP. Without a closed system, we cannot obtain that data. I have run into several papers cited below that discuss methodologies used to estimate what PEEP should be in the HFNC system. The 2009 Parke study looked at the mean nasopharyngeal airway pressure and deemed it to be 2.7cmH2O with a flow of 35L and the mouth closed. That's not the alveolar pressure. The Corley study utilized electrical impedance tomography along with a transducer placed nasally that ran down into the esophagus that measured the airway pressure. With the flow in the study between 35-50L on the HFNC system, the authors found that there was an increase in the airway pressure by 3cmH2O. Is this what's being considered as PEEP? Lastly, Parke performed another study in CVICU patients where she and her team measured nasopharyngeal pressures at 30L, 40L, and 50L, and concluded that the HFNC system provided 3-5cmH2O of PEEP. I guess that's where the numbers I was taught came from. But in reality does that translate to PEEP? Do we just need to accept that we are comparing apples and oranges? Do we just need to change our language since we are just so comfortable of saying "PEEP" because we're used to it on our ventilators? Am I just going to have to delete this post after I am exposed as being a moron when a number of people just comment about how silly am I that I do not know this stuff? Why are we even trying to compare the two? We know that pharyngeal pressure is increased by the HFNC system. That's fine and dandy. Patients do well on HFNC when used in the correct setting. Plenty of data to support that. But this system uses flow rather than pressure and we are comparing apples to oranges. The three articles are all FREE! Links below.

Addendum: tonight is 9/24/19 and it's 4:34 in the am. I am currently working a night shift. I have run into additional data that has provided me with some perspective as to the whole PEEP/Paw discussion. Parke performed a study that was published in 2015 using Electrical Impedance Tomography where there was a marked improvement in the end-expiratory lung volumes. Then Frat, the main author of the FLORALI trial, commented on the mechanism of how this happens by stating that the large nasal prongs create a resistance to the exhaled air by continuously pushing high flow air and in turn this causes positive pressure. The issue lies when the patient opens their mouth. This could be highly variable. Anyway, I still take issue with the numerical measurement of it.

-EJ

Link to Abstract

Link to FREE Article

Parke R, McGunness S, Eccleston M. Nasal high-flow therapy delivers low level positive airway pressure. Br J Anaesth 2009;103:886–90.

Link to Abstract

Link to FREE Article

Corley A, Caruana L, Barnett A, Tronstad O, Fraser J. Oxygen delivery through high-flow nasal cannulae increase end- expiratory lung volume and reduce respiratory rate in post-cardiac surgical patients. Br J Anaesth. 2011;107(6):998- 1004.

Link to Abstract

Link to FREE Article

Parke RL, McGuinness SP: Pressures delivered by nasal high flow oxygen during all phases of the respiratory cycle. Respir Care 2013; 58:1621–1624.
Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

Do Not Resuscitate/Do Not Intubate does NOT mean Do Not Do Anything.

Nasal high flow oxygen therapy in do-not-intubate patients with hypoxemic respiratory distress

This topic is very dear to me because I am a huuuuuuuge proponent for appropriate end of life care. I'm an Intensivist after all and people unfortunately die on my service. We all are going to have our day. My goal with the patients I take care of is to make their passing to the next life as comfortable as possible with as much love surrounding the individual as humanly possible. It irks me at times when clinicians write patients off just because they have a DNR/DNI order written. For the non-medical people around here that means do not resuscitate/do not intubate. Also, what are you doing around here? Those patients also need our best efforts as they are already cognizant of their impending mortality. That usually means their friends and family members are also aware and would rather be around when the inevitable to all of us occurs and they pass. In this article, the authors attempted to avoid utilizing non-invasive ventilation, or as most of us just call it, BiPAP, by placing patients on high flow nasal cannula. Small study, 50 patients. Can you imagine the difficulty in enrolling patients into a study like this? It must have been quite challenging. In short, although mortality in hospital was appropriately high, they found that they were able to avoid placing patients on BiPAP in 82% of patients. To me, this is particularly important because that means these patients were able to comfort eat, speak to their families, say their goodbyes, give them unobstructed hugs (due to the BiPAP mask), kisses, and smiles without a NIV mask in the way. The decreased RR as a clinician to me is significant because if there's one thing that makes me uncomfortable, it's a patient who is in frank respiratory distress sucking wind to survive. A respiratory rate decrease from 30.6 to 24.7 is something I'd take any day. This is something I do in my practice. I was very happy to run into their article and find some data to support what I anecdotally believed.

A hat tip to the authors.

-EJ

Peters S, Holets S, Gay P. Nasal high flow oxygen therapy in do-not-intubate patients with hypoxemic respiratory distress. Respir Care. 2013 ; 58(4): 597-600.

Link to abstract

Link to full FREE article

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

Soft drinks: are they associated with increased mortality?

Association between soft drink consumption and mortality in 10 European countries

This study is trying to tell me that soft drinks, whether they are diet or sweetened by sugar are associated with higher mortality? I honestly can't say I'm surprised. Glad I'm not investing in the Coca Cola company. I personally do not drink sodas but I do indulge on a Diet Dr Pepper every now and then. Guess I'll be cutting that out soon. But you're here for the data. I am omitting some of the data because I can't analyze and cover it all. Let's take a good look at this study.

They started off by stating that sugar sweetened drinks could cause approximately 184000 deaths due to cardiovascular issues, cancer, and diabetes. To look at the numbers in Europe, where this study took place, they used the European Prospective Investigation into Cancer and Nutrition cohort that has followed up patients from the general population of 10 European countries which include Denmark, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, and the UK. In America we tend to think that these countries are healthier than ours. This "EPIC" cohort, pun intended, had 521330 patients in it. They ruled out a number of patients for reasons specified in the paper and ended up with 451743 patients. The famously large Framingham heart study has been going on for 70 years now and doesn't have anything remotely close to that many patients involved. 451743 to be exact. WOW!

They figured out if and how many soft drinks these people consumed by different methods including interviews and questionnaires. People lie. That's a limitation of the study in my opinion but with almost half a million patients, the liars could be mitigated. They also asked many other questions, like smoking and exercise habits, in the questionnaires, etc, so this data isn't only for soft drink consumption. They used ICD-10 codes to figure out for what reasons the 41693 patients died. The researchers did a bunch of statistical jumping jacks that I am not going to go through. I'm am honestly going to lump together the patients who were drinking both soft drinks with sugar and soft drinks without sugar for the sake of simplicity. Again, read the article for yourself.

Here are the results that I find interesting about the groups:
1. Amongst all the patients, 43.2% of patients died from cancer.
2. Women made up 76.5% of the group that drinks less than 1 glass per months vs 60.9% of the group that drinks greater than or equal to 2 glasses per day.
3. The BMI is 1 point higher in those who drink greater than or equal to 2 glasses per day (median)
4. People who drink greater than or equal to 2 glasses per day claimed to be more physically active than with 27.8% of them saying they are physically active versus 15.5% in the
5. The greater than or equal to 2 glasses per day group also ate more red meat, fewer fruits and vegetables, more coffee, and more fruit and vegetable juices. No notable difference in alcohol consumption in my humble opinion.

Let's talk mortality
Higher all cause mortality with greater than or equal to glasses per day of soft drinks. That includes sugar sweetened and artificially sweetened. That also includes if you're male or female.

Regarding circulatory diseases
Same thing here. Higher circulatory mortality risks for those consuming greater than or equal to 2 glasses of soft drinks per day. If you break it down between the sugar vs artificial sweetener groups, however, the sugar group was not statistically significant. I guess that can be interpreted as don't drink the diet stuff.

Regarding Cancer
This was interesting because they only found an association in colorectal cancer deaths. I expected them to find a risk with overall cancer.

There was an association with soft drinks, both types, and risk of Parkinson disease mortality.

All in all, the researchers found that higher risks were observed when people would consume more than 125ml (that's just half a glass!!) of diet stuff and 250ml (just one glass!!) of the not diet stuff. I wonder what they considered high fructose corn syrup to be? They were also perplexed as to why artificial sweeteners caused the increase in mortality despite being "zero calorie". They don't have an answer to that and are seeking more data.

As with every other study, this one has some notable limitations such as the fact that it is an observational study. There's no other way, honestly, to be able to perform a study of this scale. They also cannot identify causality. They also only asked the people in the study only once (upon enrollment) if they consumed soft drinks. That means that patients could have changed their habits, either started consuming soft drinks or stopped. Or switched to diet or switched to regular. No way of knowing.

Overall I know the media is on a frenzy right now with this study and I thought it was pretty cool so I hope that you all gained something from it.

As always, a big hat tip to the authors!

-EJ

Mullee A, Romaguera D, Pearson-Stuttard J, et al. Association between soft drink consumption and mortality in 10 European countries [published online September 3, 2019]. JAMA Intern Med.

Link to Abstract

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

Lactic Acidosis: Does it really mean Hypoperfusion?

Understanding lactatemia in human sepsis: potential impact for early management

Having an elevated lactate in septic acid on admission is bad. Trending it, as studies that I have shown on this page does not change mortality. Seeing the numbers downtrend do give us that warm and fuzzy feeling inside, though. We give off a sigh of relief when that number becomes "euboxic". This article was published in April 2019 and authors explained the different mechanisms by which lactic acid is elevated in septic patients.
1. a deficit in oxygen delivery or extraction
2. shunting
3. stress
4. increased adrenergic stimulation

Notice that none of these mean that we have to drown the lactates with a bunch of fluids thereby diluting the value. We need to go after the etiology of it in a more specific manner. The authors of this study looked at the patients enrolled in the ALBIOS study (you know, the 2014 study where they sorted out that giving patients in septic shock albumin was good for depleting hospital resources but not a survival benefit? I guess I need to cover that trial on here) and used more than 1700 patients in whom lactate and central venous oxygen saturation were measured. They did a bunch of calculations and statistics that I am not going to cover here but you can click on the link for the article and go to town on it if you so wish.

Something really interesting was found in this study. The authors found that 1017 patients had a lactic acidosis but 57% of those patients had a normal serum pH. I would've thought that the number would have been lower. And it's not because these patients were on bicarbonate drip band-aids either.

The Early Goal Directed Therapy trial made us infatuated with checking central venous oxygen sats and our target was to get that to be over 70%. This study showed us that only 35% of that patients they looked at had a value less than 70%. 65% of patients with an elevated lactic acid had a normal or high ScVO2. Strange. We do know that the extremes of ScVO2 are bad and that ultimately ScVO2 has a number of limitations within itself. Anyway, I'm not going to dive too deep into all that, I'll leave it for the authors to explain.

All in all their main conclusion in this study, and the important takeaway is that lactate is not primarily created in sepsis by of the cells not receiving enough oxygen, but rather by impaired tissue oxygen utilization. This is a game changer. In my opinion, it doesn't mean that fluids are the answer, but rather, to find a way to help the tissues use said oxygen. Now let's all change our practice.

Don't take my word as gospel on all this, I could be wrong. Read the article for yourself. A hat tip to the authors.

-EJ



Link to Abstract

Gattinoni, L., Vasques, F., Camporota, L., Meessen, J., Romitti, F., Pasticci, I., … Marini, J. J. (2019). Understanding Lactatemia in Human Sepsis: Potential Impact for Early Management. American Journal of Respiratory and Critical Care Medicine.

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Does using Balanced Crystalloids vs. Saline improve mortality in sepsis?

Balanced Crystalloids Versus Saline in Sepsis: A Secondary Analysis of the SMART Trial

Sometimes we need to make minor adjustments in what we do in the ICU to see a difference. I have been going off for several years now on my instagram account as well as YouTube channel regarding the importance of utilizing balanced crystalloids such as lactated ringers or plasma-lyte and I keep on hearing "there's no mortality benefit". Well, now there's data showing that there is. I knew it was just a matter of time. It just makes sense. This analysis is a piggyback on the SMART trial performed by the good people over at Vanderbilt published last year in the NEJM. In that study and therefore this study, they looked at using saline solution versus either lactated ringers or plasma-lyte. You may be asking yourself "but I thought that study didn't show any mortality benefit". You are correct, it didn't, but that finding was regarding all critically ill patients.

This study looked at 30 day mortality in patients in the MICU who were septic. All in all, they looked at 1641 patients with the diagnosis of sepsis. Note: not necessarily septic shock. 34.1% of patients were on vasopressors and 40% were on the vent.

Here are the outcomes:
30 day mortality: 26.3% in the balanced crystalloids group vs. 31.2% in the saline group (p=0.01)
Patients who received balanced crystalloids had more days free of vasopressors, free of dialysis days, lower plasma lactate concentrations after ICU admission.
Debate settled? Well, no. But check out the article for yourself before taking my opinion as gospel.

-EJ




Link to Abstract

Link to FULL FREE Article

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.