Is Lactated Ringer's (LR) solution better than Normal Saline (NS) as a maintenance intravenous fluid?

From the Guidelines

Lactated Ringer's (LR) is generally preferred over Normal Saline (NS) as a maintenance fluid for most patients. This recommendation is based on the most recent and highest quality study available, which suggests that LR more closely resembles the electrolyte composition of human plasma with a balanced pH and lower chloride content, making it less likely to cause metabolic acidosis with prolonged use 1. When administering maintenance fluids, LR is typically given at rates of 1-2 mL/kg/hr for adults or calculated using the 4-2-1 rule for pediatric patients (4 mL/kg/hr for first 10kg, 2 mL/kg/hr for next 10kg, and 1 mL/kg/hr for each additional kg).

Some key points to consider when choosing a maintenance fluid include:

• The risk of hyperchloremic metabolic acidosis associated with NS, particularly with large volume administration 1
• The potential negative impact of solutions with high chloride content on renal function, resulting in decreased kidney perfusion and urine output, increased extravascular fluid accumulation, increased vasopressor requirements and acute kidney injury (AKI) 1
• The importance of regular monitoring of electrolytes, acid-base status, and fluid balance, regardless of which solution is chosen 1

It's worth noting that NS may still be appropriate in specific situations, such as hypercalcemia, severe metabolic alkalosis, or when administering blood products. However, for most patients, LR is the preferred choice for maintenance fluid therapy due to its more physiologic composition and lower risk of complications 1.

From the Research

Comparison of Lactated Ringer's and Normal Saline as Maintenance Fluids

• The choice between Lactated Ringer's (LR) and Normal Saline (NS) as maintenance fluids has been debated, with some studies suggesting that LR may be superior due to its balanced electrolyte composition 2, 3, 4.
• A study on patients with diabetic ketoacidosis found that LR was associated with faster resolution of high anion gap metabolic acidosis compared to NS, with no difference in complications or length of stay 2.
• Another study on patients undergoing kidney transplantation found that LR was associated with less hyperkalemia and acidosis compared to NS, although there was no difference in renal function 3.
• A meta-analysis of randomized controlled trials on patients with acute pancreatitis found that LR may be superior to NS in reducing the incidence of intensive care unit admission, although there was no difference in other outcomes such as mortality or length of hospital stay 4.
• A study on patients with reduced kidney function found that LR was not independently associated with the development of hyperkalemia, and that serum potassium levels prior to LR use were highly correlated with serum potassium levels after LR use 5.

Electrolyte and Acid-Base Responses

• A study on fetal sheep found that amnioinfusion with NS increased fetal plasma sodium and chloride concentrations, resulting in a hyperchloremic acidosis, whereas amnioinfusion with LR resulted in minimal changes in fetal electrolytes and acid-base balance 6.
• The study suggests that LR may be a better choice than NS for maintaining acid-base balance and preventing electrolyte imbalances, particularly in vulnerable populations such as patients with kidney disease or those undergoing surgery 3, 5, 6.

Clinical Implications

• The available evidence suggests that LR may be a better choice than NS as a maintenance fluid in certain clinical situations, such as in patients with diabetic ketoacidosis or acute pancreatitis 2, 4.
• However, more research is needed to fully understand the benefits and risks of using LR versus NS in different patient populations, and to determine the optimal choice of maintenance fluid in various clinical contexts 2, 3, 5, 4, 6.