Fluid Resuscitation and Maintenance Therapy

Introduction to Fluid Selection

The American College of Physicians recommends using normal saline (0.9% NaCl) or balanced crystalloids (Ringer's lactate, Plasmalyte) for resuscitation and initial fluid therapy in critically ill patients, avoiding half normal saline (0.45% NaCl) in these settings 1, 2, 3

Balanced crystalloids (Ringer's lactate, Plasmalyte) are strongly recommended over 0.9% saline in most critically ill patients, particularly those with sepsis, AKI, or renal impairment, with a reduced risk of major renal events (odds ratio 0.80, 95% CI 0.67-0.94) 1, 3, 4
Balanced crystalloids reduce mortality and major renal events in sepsis patients 1
Balanced crystalloids prevent hyperchloremic acidosis that worsens kidney injury 3, 4
Plasmalyte is preferred in kidney transplant recipients due to reduced risk of delayed graft function 4

Normal saline causes hyperchloremic metabolic acidosis when administered in large volumes, particularly problematic in patients with renal impairment 4
Normal saline is associated with renal vasoconstriction and acute kidney injury compared to balanced crystalloids 3, 4
Normal saline has a higher incidence of major adverse kidney events versus balanced solutions 4

Half normal saline has limited clinical utility and is primarily reserved for specific maintenance fluid scenarios in stable pediatric patients, while normal saline and balanced crystalloids are the evidence-based choices for volume expansion and resuscitation 2
Half normal saline should never be used for initial resuscitation or volume expansion in any patient population 2, 5

For resuscitation or volume expansion, first choice is balanced crystalloids (Ringer's lactate, Plasmalyte), with normal saline as an alternative if balanced crystalloids are unavailable 1, 2, 3
For maintenance fluids in stable patients, isotonic crystalloids are preferred in adults, while either isotonic or half normal saline may be used in pediatrics 3, 4

With normal saline, monitor for serum chloride elevation, hyperchloremic acidosis, and worsening renal function 3, 4
With balanced crystalloids, monitor for signs of volume overload and electrolyte imbalances 3, 4