Lactated Ringer’s Saline, IV
We give IV crystalloids almost every layer, and we discuss them almost as often. Some discussions have focused on Plasma Lyte, but it’s not readily available in most EDs, so we’ll focus on Lactated Ringer’s (LR) and Normal Saline (NS) in general. We owe the best of care to our patients, so it is time to finally put an end to the many false claims and myths that circulate in this debate. (EMCrit.org, February 27, 2018; https://bit.ly/3pHqM1J.)
With a pH of 5.5, NS is an acidic liquid. (Int. J. Med. Sci. 2013; 10: 747; https://bit.ly/3gdA3eI.) It has a 40 percent higher concentration of chloride than plasma and does not reflect the myriad components of human plasma. Many of us were trained in dealing with NS, so unfortunately it still stayed. It is a practical decision that we continue to make because no one is thinking of changing it. ED storage rooms and resuscitation bays are full of Nazi bags.
Large amounts of saline solution can be harmful to patients because NS causes a non-anion gap, hyperchloremic metabolic acidosis. For the hungover teenager or the gastrointestinal patient sent home after an IV liter, it probably doesn’t matter, but what about our critically ill patients? Many of them are initially acidotic (e.g., diabetic ketoacidosis, septic shock), so giving them NS and making their acidosis worse seems counterintuitive and downright negligent. Several animal models found that acidosis from NS caused earlier death, deterioration in kidney function, oliguria, and decreased oxygen levels in muscle tissue. (Anaesthesiology. 2016; 125: 744; Chest. 2004; 125: 243.) LR, on the other hand, is more alkaline and contains 28 mEq / l bicarbonate. (StatPearls. Jan 2021; PMID: 29763209.)
Animal testing may not be enough to change practice, so luckily the SMART-ED study provides more definitive evidence. A total of 15,802 critically ill patients in the emergency room were assigned a standard fluid (NS or balanced crystalloid) upon arrival and continued in the intensive care unit. The median amount of fluid administered was 1 liter. Those who received NS had a higher death rate (26.3% vs. 31.2%, CI 0.59–0.93) and kidney damage (35.4% vs. 40.1%, CI 0.63 -0.97). (Studies. 2017; 18: 178; https://bit.ly/3zkn3LS.)
A sister study at the same facility (SALT-ED) found that admitted patients who received a median of one liter of NS had a higher risk of kidney failure within 30 days (n = 13,347; 5.6% vs. 4.7%) , KI 0.70.). -0.95). (N Engl J Med. 2018; 378: 819; https://bit.ly/3veSSCs.) Even more stressful was the fact that those who already had kidney damage at the time of admission were more prone to further kidney damage from NS (37.6% vs. 28%, p <0.001).
Perhaps one of the most common myths about LR is hyperkalemia, which is interesting as no literature supports the claim that LR infusions significantly increase serum potassium. In fact, in an initially hyperkalemic patient, LR, who has a lower potassium concentration than the patient’s potassium concentration, will raise the patient’s potassium level to 4 mEq / L, thereby lowering it. (Surg Clin North Am. 2012; 92: 189; EMCrit.org. September 29, 2014; https://bit.ly/3cxWGrY.)
Ironically, NS is what is dangerous in hyperkalemia. Since it is acidic, NS causes potassium to be shifted into the blood in exchange for H + ions. Unfortunately, there are no direct ED studies on the subject, but four randomized controlled trials, each conducted during a kidney transplant, compared LR directly to NS. (Anesth Analg. 2005; 100: 1518; Ren fail. 2008; 30: 535; https://bit.ly/3xe6eAj; Saudi J Kidney Dis Transpl. 2012; 23: 135; https://bit.ly/3vdaxKY; Br. J. Anaesth. 2017; 119: 606; https://bit.ly/3cxfE28.) One study showed that 19 percent of the patients who received NS developed hyperkalemia compared to none in the LR group, and the patients in the NS group also had higher rates of metabolic acidosis. (Surg Clin North Am. 2012; 92: 189.) All four studies showed no evidence that LR caused hyperkalemia.
Another myth is that LR routinely increases serum lactate levels. LR contains sodium lactate, not lactic acid, and has been shown to increase lactate levels in healthy volunteers, but not significantly, even with large 30 ml / kg boluses. (J Emerg Med. 2018; 55: 313.) Compared to NS, LR does not cause a significant increase in lactate either. Mild to moderate liver damage should not be an absolute contraindication for LR. It is likely that the harm of a large volume crystalloid infusion in severe cirrhosis or patients with acute liver failure is more dangerous than a theoretical increase in lactate. With us, LR only costs about 25 cents more than NS. Most institutes report similar prices, so costs should not be considered when choosing between LR and NS.
LR should be the first choice for most medically ill patients, especially those in need of large IV crystalloid resuscitation (e.g., diabetic ketoacidosis, sepsis, rhabdomyolysis). Does it matter if we give a liter of NS to a non-sick patient who is likely to be discharged? Unlikely, but why create confusion about who gets LR or NS? Let’s make it easier for our fellow physicians, nurses, pharmacists, and other health care professionals to get started with IV crystalloids. If you want your business to run the most readily available go-to liquid in ED, then only a balanced crystalloid like LR should be used. Delivering the most advanced care that reduces the risk of harm to our patients begins with changing the way we administer IV crystalloids.
About clinical controversy
This is the first of a new monthly column attempting to resolve emergency medical practice disputes. Hit Dr. Briggs suggests subjects to investigate by writing to him [email protected].
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Dr. Briggsis Assistant Professor of Emergency Medicine at the University of South Alabama at Mobile. He is the founder, podcast co-host and editor-in-chief of EM Board Bombs (https://www.emboardbombs.com). Follow him on Twitter@blakebriggsmdxs.