[0:00]All right, let's talk about normal saline versus LR or any other fluid resuscitation for that matter. Which one should you be using and which one is best for your patient? To be completely honest, I would basically never use normal saline. I don't think it's a good fluid to give at all, except in maybe a few specific scenarios like hyponatremia potentially or traumatic brain injury, but in all other cases, I think lactated ringers is definitely the better solution. And let's go over why I think that. So first of all, I think it's a good idea to look at the different composition of the different solutions we're looking at. So here we have normal saline right here at the top. Then we have lactate ringers and plasmalite here. These are going to be our balanced crystalloid solutions. And then over here, albumin, dextran, hetastarch, these are going to be colloids. If we want to break it down even further, then all of these solutions up here are actually going to be crystalloid solutions, which basically means compared to colloids, they don't have as much protein within them as colloids do. The first question that we should ask is, is there any benefit of giving colloid over crystalloid in terms of survival benefit or preventing adverse outcomes? Because one of the things we know about colloids is that they have a lot more proteins within them. They're actually able to expand the intravascular space much better than crystalloid is. Crystalloid when you infuse a bunch of normal saline or lactated ringers, it'll help increase the intravascular volume temporarily, but then a lot of it will start leaking out into the extravascular space and people can get very edematous. Colloid has been proven not only to improve the intravascular space better than crystalloid, but also improves cardiac output and tissue perfusion and oxygen delivery. But does this really translate to a mortality benefit? And this is where we have a couple of good studies that really help guide us with this. So in 2004, there was this trial called the SAFE trial. And it asked, among ICU patients, does albumin compared to normal saline for fluid resuscitation improve clinical outcomes? The bottom line was that albumin and normal saline resulted in similar clinical outcomes when administered to ICU patients for volume resuscitation. And then in 2013, we had this CRISTAL trial, which asked among ICU patients with hypovolemic shock, does fluid resuscitation with colloids reduce mortality at 28 days when compared to crystalloids? And there was no mortality benefit at 28 days with colloids over crystalloids for fluid resuscitation. Notably, in this trial, they did actually see a reduction in all cause mortality at 90 days, but again, we did not see any evidence of mortality benefit at 28 days. So both of these trials really have led us to suggest that infusing colloid for patients for volume resuscitation, in general, is really just kind of giving them very expensive fluids that doesn't actually improve their mortality. Even though there's a lot of benefits and physiologically you might think that colloids are better than crystalloid, we haven't really seen evidence in that in the trials that have been done so far. And that's why we don't really fluid resuscitate with colloids. Next, I wanted to briefly look at the different compositions of normal saline compared to LR and plasma light. So normal saline, if you look here, is very acidic compared to LR and plasma light. And not only that, but it's got very, very super physiologic concentrations of sodium and chloride. Whereas lactated ringers and plasmalite are much more physiologic and balanced solutions, hence why they're called balanced crystalloid solutions. So what are the downsides of these different chemical compositions on actual patient outcomes? So normal saline is actually very, very well known to cause a metabolic acidosis. Particularly because of the high chloride levels, it causes a hyperchloremic metabolic acidosis. In addition, we see higher rates of acute kidney injury with normal saline. Also thought to be due to chloride-mediated vaso constriction. Normal saline also does tend to extravasate more and lead to more interstitial edema due to its higher sodium content. And actually in animal models looking at the metabolic acidosis caused by normal saline, they found that there was not only a decrease in blood pressure, but also in cardiac index, tissue perfusion, and also increased rates of acute kidney injury as well. Thirdly, because of the metabolic acidosis, this actually leads to hyperkalemia, which is seen less frequently in lactated ringers. One of the criticisms a lot of times people have of lactated ringers is lactated ringers contains a little bit of potassium. As you can see here, as does plasmalite. And so people are afraid to give lactated ringers and plasmalite in patients who have high potassium. But actually giving normal saline, which theoretically has no potassium in it, really has a worse chance of causing hyperkalemia, because you're inducing such a severe acidosis that there is intracellular shift of potassium into the bloodstream. This is just a graph from Marino's ICU book, showing the difference in pH over time when a patient was receiving 30 cc's per kilogram per hour of lactated ringers versus isotonic saline. And just look how the lactated ringers really stays right at that perfect 7.4 pH, while the longer you were infusing isotonic saline or normal saline, their pH drops almost from 7.4 to 7.3. So imagine all of the physiological effects that acidosis is going to cause when your body is processing all of that, because all of the proteins in our body do not work as well when you're in a more acidemic state. So now I've explained all the reasons that normal saline is not really a good option, except maybe in hyponatremia because you're trying to get the sodium back up. and traumatic brain injury because you want to reduce cerebral edema. So you're giving a hypertonic solution with more sodium in it, so it's kind of drying out all of that fluid and water that's causing swelling in the brain. So with lactated ringers, the things people are afraid of are, like I mentioned earlier, hyperkalemia, which is actually a worse situation with normal saline than lactated ringers, as I said earlier. Um, and also with the lactate that's contained in lactated ringers. And some people are worried that if you elevate the lactate levels, the patients actually going to look and become more sick. The problem with this is that the lactate in lactated ringers is not lactic acid, which is kind of the byproduct of anaerobic metabolism. It's actually sodium lactate.
[5:44]So while this can lead to an increased serum value of lactate when you're measuring it in your patients, this is not going to contribute to a lactic acidosis, because sodium lactate is completely separate from the lactic acid that's seen in anaerobic metabolism. In fact, there's actually thoughts that the sodium lactate can be metabolized by cells and actually be used for energy, which actually helps in shock and hypoperfusion states. Another con that some people have with lactated ringers is that it does contain some calcium, and a lot of times this is a good thing. It's nice to have, make sure your patients have enough calcium, but sometimes when you're infusing blood products, there is a fear that the calcium may interfere and bind some of that blood and you're not going to get as much bang for your buck with your blood transfusions. So that's another thing to consider, although I think this is very theoretical, and it's not really something that's been proven. Briefly touching on plasmalite, plasmalite, I've seen a lot in our ICU, and I think the reason is because the pH of plasmalite is actually 7.4, which is pretty good if you see that because a lot of our ICU patients are going to lead towards the acidemic side. Also the sodium is 140, also very helpful, and there's actually a little bit of magnesium in plasmalite as well. Now one more last thing that people might bring up is that, oh, normal saline is significantly cheaper than lactated ringers or plasmalite. But actually everything that I've looked up so far shows that lactated ringers is only like 25 cents more per liter compared to normal saline, and plasmalite is only a few dollars more at most institutions. Obviously, this varies between institutions, and you may have plasmalite be very expensive, but in general, lactated ringers is a very cheap alternative to normal saline. not really associated with a cost increase at all. So now that we've kind of gone over a lot of the downsides of normal saline and some of the upsides and also debunking some of the myths about lactated ringers and plasmalite, let's actually look at some of the trials which actually compared balanced crystalloids versus normal saline. The ones you really should know about are the SMART-MED and the SMART-SURG trials, as well as the SALT-ED trial. So in the SMART trials, they tested among medical and surgical ICU patients, normal saline versus balanced crystalloids, and they checked for rates of death, need for renal replacement therapy, or dialysis, or persistent renal dysfunction. And what they found was that balanced crystalloids reduced the rate of death, reduced the need for dialysis, and they reduced the rates of acute kidney injury compared to normal saline. This was a very large and fairly well-conducted study, and so if that doesn't convince you, then we have the SALT-ED trial, which was also released in 2018. And it asked, among non-critically ill adults in the ED, does fluid management with balanced crystalloid result in earlier hospital discharge compared to isotonic crystalloids? And what they found is that it does not reduce the duration of hospitalization. However, balanced crystalloid use was associated with a reduction in major kidney related events. So, those are basically all the reasons that I favor using lactated ringers over normal saline in like 99% of scenarios. In fact, I very rarely ordered normal saline at all, and honestly, I just think it's not a very good thing that we should order be ordering frequently in the hospital at all. If to be honest, every time somebody orders normal saline, I think there should be a pop-up that literally says, are you sure you want to order normal saline? It's associated with higher rates of AKI, associated with higher mortality in ICU and critically ill patients, and basically it's just a worse version of balanced crystalloid. You know, actually that would be a pretty good QI project. Maybe I should think about doing something like that. So just to sum things up really quickly, first we talked about crystalloids versus colloids and how colloids actually expand the intravascular space better and increase cardiac output, but the the reason we don't use it for fluid resuscitation is because we've never really seen a clear mortality benefit and it's just basically infusing really expensive fluid in order to resuscitate somebody with no mortality benefit. And then secondly, we compared balanced crystalloids versus isotonic or normal saline and talked about how normal saline has all of these downsides. Acidosis, decreased blood pressure, increased mortality, increased rates of kidney injury, hyperkalemia, whereas all of these effects are really, really mitigated by balanced crystalloid solutions, like lactated ringers and plasmalite, and there is no really significant cost increase to doing those two different solutions. We have several large trials like the SMART trial and the SALT trial, which showed a big mortality benefit and reduction in AKI with these fluids. I hope this video was useful. Let me know in the comments what your preferred fluid of choice is, and I'd love to hear your comments on this subject. If you like this content, please like and subscribe for more content like this in the future. I'll see you in the next video, and thanks for watching. Peace.
