Fluid Resuscitation and Maintenance with Saline and Lactated Ringer's Solution

Composition and Clinical Considerations

Normal saline (0.9% NaCl) contains 154 mmol/L of both sodium and chloride, making it hyperchloremic compared to plasma 1
Lactated Ringer's is a balanced solution with near-physiological concentrations of electrolytes and contains lactate as a buffer 1, 2
LR has lower chloride content than normal saline, which reduces the risk of hyperchloremic metabolic acidosis 2
Reduced risk of hyperchloremic acidosis compared to normal saline 1, 2
Potentially lower rates of acute kidney injury and renal replacement therapy 1, 3
A large RCT in critically ill patients (n=15,802) showed balanced crystalloids resulted in lower rates of major adverse kidney events compared to saline 1, 4

European guidelines recommend either 0.9% sodium chloride or balanced crystalloid solutions for initial fluid therapy in hypotensive bleeding trauma patients 1, 5
ERAS guidelines for emergency laparotomy suggest balanced crystalloids may result in improved patient outcomes 2
The SMART trial showed lower rates of major adverse kidney events with balanced crystalloids versus saline 1, 2
The SALT trial demonstrated lower 30-day in-hospital mortality and lower incidence of renal replacement therapy with balanced crystalloids versus saline 2
For most patients requiring fluid resuscitation, balanced crystalloid solutions like LR are preferred first-line 1, 2
If normal saline is used, limit to 1-1.5 L maximum 1
In patients with traumatic brain injury, use normal saline rather than LR 6, 1
Both colloids and crystalloids are effective for fluid resuscitation, but crystalloids are recommended initially due to lower cost and similar outcomes 4, 3

The KDIGO guidelines recommend isotonic crystalloids for volume expansion in patients at risk for or with established AKI, with emerging evidence favoring balanced solutions 7
The Kidney Disease: Improving Global Outcomes (KDIGO) guidelines and other evidence suggest using balanced crystalloids, such as Lactated Ringer's (LR), rather than normal saline (NS) for initial fluid resuscitation in AKI patients to reduce the risk of major adverse kidney events, hyperchloremic metabolic acidosis, and potentially mortality 7, 8

High chloride loads in NS cause renal afferent arteriolar vasoconstriction, reducing glomerular filtration rate, whereas LR's balanced electrolyte composition avoids these deleterious effects 8

The European Society of Intensive Care Medicine and other guidelines suggest avoiding excessive fluid administration regardless of crystalloid type, as both LR and NS can cause volume overload and worsen AKI outcomes 7, 9
Fluid administration should be guided by frequent hemodynamic reassessment, targeting tissue perfusion markers (lactate clearance, urine output, MAP) rather than fixed volumes 9

The French guidelines suggest balanced crystalloids, such as LR, reduce mortality and adverse renal events in hemorrhagic shock, although evidence is less robust than in other AKI settings 8

The American College of Anaesthesia recommends using balanced crystalloids, such as lactated Ringer's solution, as the first-line fluid for resuscitation in most adult patients, reserving normal saline for specific indications like severe traumatic brain injury 10
The Annals of Internal Medicine suggests that crystalloids should be used rather than colloids for volume expansion in critically ill patients because colloids offer no mortality benefit, are significantly more expensive, and current evidence does not justify their routine use 11, 12

A Cochrane systematic review found no difference in mortality between critically ill patients who received colloids versus crystalloids for fluid resuscitation, with a relative risk of 0.98, 95% CI 0.92 to 1.06 11, 12
The SAFE study showed that albumin administration was not associated with improved outcomes compared to crystalloids in 6,997 ICU patients 13

The Anaesthesia journal recommends using balanced crystalloids, such as lactated Ringer's or Plasma-Lyte, preferentially over 0.9% normal saline to reduce the risk of hyperchloremic metabolic acidosis, acute kidney injury, and potentially mortality 10
The SMART trial demonstrated that balanced crystalloids resulted in fewer major adverse kidney events compared to normal saline, with an odds ratio of 0.91, 95% CI 0.84 to 0.99 11, 12

In patients with cirrhosis, albumin may be preferred over crystalloids for managing ascites-related hypovolemia and supporting colloid osmotic pressure, according to the Anaesthesia journal 10
The Surviving Sepsis Campaign suggests that albumin may be added to crystalloids in sepsis or septic shock, though this remains controversial 10
In acute kidney injury, balanced crystalloids should be used rather than normal saline to reduce major adverse kidney events and avoid worsening hyperchloremic acidosis, as recommended by the Anaesthesia journal 10