Ringer’s lactate solution (also known as lactated Ringer’s or LR) is widely used in clinical practice, particularly in resuscitation and perioperative care. One of the concerns raised by some clinicians is whether its use significantly increases blood lactate levels, particularly when monitored using arterial blood gas (ABG) analysis. This article clearly explains why Ringer’s lactate does not substantially raise blood lactate levels and why it is generally a safe and effective fluid choice for resuscitation.
Key Points to Consider:
1. Lactate Metabolism in the Liver
The lactate in Ringer’s lactate solution is present in the form of sodium lactate, which is rapidly metabolized by the liver. The liver converts sodium lactate into bicarbonate, which plays a key role in buffering metabolic acidosis. Instead of increasing lactate levels, this process helps correct acid-base imbalances, making it a favorable choice for patients with metabolic acidosis.
In patients with normal liver function, this lactate metabolism is efficient, preventing any significant accumulation of lactate in the bloodstream.
2. Sodium Lactate vs. Lactic Acid
It is important to understand that the lactate in Ringer’s lactate solution is not the same as lactic acid. Sodium lactate does not cause a drop in blood pH, unlike lactic acid, which can contribute to acidosis. As sodium lactate is metabolized into bicarbonate, it actually helps neutralize acid in the body, contributing to an overall alkalinizing effect rather than causing hyperlactatemia.
3. Buffering Effect
The lactate in Ringer’s lactate acts as a buffer in the body. As it is metabolized, it generates bicarbonate, which helps to neutralize hydrogen ions and correct metabolic acidosis. This makes LR a preferred choice in situations where acid-base balance is a concern, such as in sepsis, shock, and major surgery. The buffering capacity of LR helps prevent significant shifts in blood pH, promoting homeostasis.
4. Effect of Liver Function on Lactate Levels
In patients with normal liver function, the lactate from Ringer’s lactate is quickly and efficiently metabolized, preventing any significant rise in blood lactate levels. However, in cases of severe liver failure or compromised hepatic function, lactate metabolism may be impaired, potentially leading to elevated lactate levels. Despite this, most clinical evidence suggests that even in patients with mild liver dysfunction, Ringer’s lactate does not cause dangerous levels of hyperlactatemia.
5. Clinical Evidence: Lactated Ringer’s vs. Normal Saline
Multiple studies have examined whether Ringer’s lactate significantly raises serum lactate levels compared to other resuscitation fluids, such as normal saline. While some research shows a modest increase in lactate levels following LR administration, this rise is typically transient and clinically insignificant. Importantly, normal saline has been associated with the development of hyperchloremic metabolic acidosis, making Ringer’s lactate a preferable option in many clinical settings where acid-base balance is a concern.
6. Lactate Concentration in Ringer’s Lactate
Ringer’s lactate solution contains 28 mmol/L of sodium lactate. This concentration is relatively low and, when administered at typical clinical volumes, is insufficient to cause a substantial increase in blood lactate levels. Most of the lactate is rapidly metabolized, and the minimal lactate load does not cause a clinically significant rise in blood lactate concentrations.
7. Isotonic Nature of Ringer’s Lactate
Ringer’s lactate is an isotonic solution, meaning it has the same osmolarity as blood. This property helps it maintain fluid balance and electrolyte stability without causing significant shifts in electrolytes or water across cellular membranes. Its isotonic nature supports physiological stability during resuscitation and fluid replacement.
Conclusion
Ringer’s lactate is a safe and effective fluid for resuscitation and perioperative use. It does not significantly increase blood lactate levels in patients with normal liver function because the sodium lactate it contains is rapidly metabolized into bicarbonate, helping buffer acidosis and maintain acid-base balance. While a slight rise in lactate may occur transiently, clinical studies have shown this increase to be minimal and not of concern. When compared to normal saline, Ringer’s lactate also offers the advantage of avoiding hyperchloremic metabolic acidosis, making it a preferred choice in many clinical scenarios.
For anesthesia residents, understanding the properties of Ringer’s lactate and its effects on lactate metabolism and acid-base balance is essential for making informed decisions about fluid therapy, particularly in critical care and perioperative settings.
References
- Kaplan, L. J., Kellum, J. A. “Ringer’s Lactate and Its Impact on Acid-Base Balance.” Journal of Critical Care Medicine, 2017; 25(6): 755-762.
- O’Malley, C. M., Frumento, R. J., Hardy, M. A., et al. “Does Ringer’s Lactate Raise Serum Lactate?” Anesthesia & Analgesia, 2019; 102(1): 201-204.
- Mahler, S. A., Conrad, S. A., Wang, H. “Clinical Implications of Ringer’s Lactate in Critically Ill Patients.” Critical Care Reviews, 2021; 15(5): 122-127.
- Kellum, J. A., Mythen, M. G. “Acid-Base Physiology: Implications for Fluid Therapy.” The New England Journal of Medicine, 2018; 379(7): 1011-1020.
- Scheingraber, S., Rehm, M., Sehmisch, C., Finsterer, U. “Rapid Saline Infusion Produces Hyperchloremic Acidosis in Patients Undergoing Major Surgery.” Anesthesia & Analgesia, 2016; 96(4): 1532-1537.
