Can Lactated Ringer's Be Used as Maintenance Fluid for Extended Periods?
Yes, lactated Ringer's (LR) solution can be safely used as maintenance fluid for extended periods in most patients, and is generally preferred over normal saline due to superior outcomes including reduced acute kidney injury, lower mortality, and avoidance of hyperchloremic acidosis—however, it must be avoided in patients with severe traumatic brain injury (TBI) due to its hypotonic nature. 1, 2
Primary Recommendation Based on Highest Quality Evidence
The 2023 World Journal of Emergency Surgery guidelines establish that balanced crystalloids like LR result in improved patient outcomes and reduced morbidity and mortality compared to normal saline, based on the landmark SMART trial (15,802 patients) and SALT trial (974 patients). 1 Patients receiving balanced crystalloids had:
- Lower incidence of major adverse kidney events (14.3% vs 15.4%) 1
- Reduced 30-day in-hospital mortality 1
- Lower rates of renal replacement therapy 1
- Decreased vasopressor requirements 1
Critical Contraindication: Severe Head Trauma
LR must be avoided in patients with severe traumatic brain injury (GCS <8) because it is hypotonic when measured by real osmolality (273-277 mOsm/L vs plasma 275-295 mOsm/L), which risks worsening cerebral edema. 1, 2 The 2023 European trauma guidelines explicitly state that "hypotonic solutions such as Ringer's lactate should be avoided in patients with severe head trauma." 1
- For TBI patients, use 0.9% saline as the isotonic crystalloid of choice (308 mOsm/L) 2
- Maintain mean arterial pressure ≥80 mmHg in severe TBI 1
Advantages of LR for Extended Maintenance Use
Metabolic Benefits
LR prevents the hyperchloremic metabolic acidosis that occurs with prolonged normal saline administration. 1, 3 In kidney transplant recipients, 31% of patients receiving normal saline required treatment for metabolic acidosis versus 0% receiving LR. 3
Renal Protection
The balanced electrolyte composition of LR (Na⁺:Cl⁻ ratio closer to plasma) protects kidney function during extended use. 1 Normal saline causes:
- Decreased kidney perfusion 1
- Reduced urine output 1
- Increased extravascular fluid accumulation 1
- Higher risk of acute kidney injury 1
Coagulation Profile
LR preserves coagulation function better than normal saline during resuscitation. 4 In hemorrhagic shock models, normal saline resulted in significantly lower fibrinogen levels (99 mg/dL vs 123 mg/dL) and dilutional coagulopathy. 4
Electrolyte Management
LR reduces hyperkalemia risk compared to normal saline. 3 In renal transplant patients, 19% receiving normal saline developed potassium >6 mEq/L requiring treatment versus 0% receiving LR. 3
Specific Clinical Scenarios for Extended LR Use
Burns Management
LR is recommended as first-line balanced fluid resuscitation solution for burns victims despite being slightly hypotonic, due to its electrolyte composition closely matching plasma. 1, 2 Continue LR for maintenance after initial resuscitation. 1
Perioperative Care
For emergency laparotomy patients, target postoperative fluid balance of 0-2 L using balanced crystalloids like LR. 1 Avoid normal saline especially in higher-risk patients with existing acidosis or hyperchloremia. 1
DKA Management
Recent evidence supports LR over normal saline for DKA treatment, with faster resolution times (17.1 vs 20.6 hours) and shorter insulin drip duration (16.0 vs 21.4 hours). 5 This challenges traditional DKA protocols favoring normal saline. 5
Severe Dehydration
For severe dehydration with shock, use isotonic crystalloids like LR until pulse, perfusion, and mental status normalize. 1 Continue LR for maintenance fluid replacement of ongoing losses. 1
Common Pitfall: The Lactate Misconception
Elevated serum lactate after LR administration does not indicate tissue hypoperfusion or acidosis. 4 In hemorrhagic shock resuscitation, LR-treated animals had higher lactate levels (4.7 vs 1.7 mEq/L) but better pH (7.45 vs 7.28) and superior survival compared to normal saline. 4 The lactate in LR is metabolized to bicarbonate by the liver, improving acid-base balance. 1
Practical Implementation
Volume Requirements
LR requires significantly less volume than normal saline for equivalent resuscitation (125.7 mL/kg vs 256.3 mL/kg in uncontrolled hemorrhage). 4 This reduces risk of volume overload complications including organ dysfunction, ventilator dependence, and gut edema. 1
Monitoring Parameters
- Track fluid balance carefully throughout treatment 1
- Monitor electrolytes, particularly in patients with renal dysfunction 1
- Assess for signs of volume overload (peripheral edema, pulmonary congestion) 1
- In TBI patients, use normal saline instead and monitor intracranial pressure 1, 2
Avoid Hydroxyethyl Starch
Do not use hydroxyethyl starch (HES) solutions due to increased risk of kidney failure and mortality without demonstrated benefit. 1