What is the recommended maintenance fluid for surgical patients?

Maintenance Fluid Therapy in Surgical Patients

Balanced crystalloids should be used as first-line maintenance fluid therapy for surgical patients to reduce mortality and adverse renal events compared to 0.9% saline. 1

Recommended Fluid Type

• Balanced crystalloid solutions (such as Ringer's Lactate or Plasmalyte) are preferred over 0.9% saline for maintenance fluid therapy in most surgical patients due to their lower risk of hyperchloremic metabolic acidosis and adverse renal events 1
• Balanced solutions have an electrolyte composition closer to plasma, which helps maintain acid-base balance and reduces the risk of hyperchloremia 1, 2
• The SMART trial demonstrated that balanced crystalloids resulted in lower rates of major adverse kidney events compared to saline in critically ill patients 2

Volume Considerations

• A mildly positive fluid balance (+1-2 L) by the end of surgery is recommended to protect kidney function 1
• Excessive fluid administration should be avoided as it can lead to complications such as organ dysfunction, pulmonary complications, ventilator dependence, gut edema, and poor wound healing 1
• Intraoperative fluid administration rates of 1-2 ml/kg/h are recommended to minimize the risk of postoperative lung injury 1

Special Considerations

Neurosurgical Patients

• 0.9% saline is recommended as first-line fluid therapy in patients with traumatic brain injury 1
• Hypotonic solutions should be avoided in neurosurgical patients due to the risk of cerebral edema 1
• Albumin is not recommended in neurosurgical patients or those with traumatic brain injury 1

Colloids vs. Crystalloids

• Routine use of albumin or synthetic colloids for intraoperative fluid administration is not recommended 1
• Crystalloid solutions should be preferred over colloids due to the reported risks of renal failure and hemostasis disorders with colloids 1
• Despite colloids having greater volume expansion capacity than crystalloids (mean ratio of 1.5), this does not translate to improved outcomes in terms of mortality or postoperative complications 1

Monitoring and Administration

• Fluid administration should be individualized based on objective measures of hypovolemia 1
• Goal-directed fluid therapy using flow measurements is recommended for open surgery and high-risk patients with comorbidities, blood loss >7 ml/kg, or prolonged procedures 1
• Postoperative intravenous fluids should be minimized to maintain normovolemia and avoid fluid excess 1
• The enteral route should be used as early as possible, and intravenous fluids should be discontinued as soon as practicable 1

Pitfalls and Caveats

• Avoid using hypotonic solutions in patients with (impending) cerebral edema 3
• Be cautious with 0.9% saline in patients requiring large volumes as it may lead to hyperchloremic metabolic acidosis 1
• In patients with hemorrhagic shock requiring large volume resuscitation, balanced solutions may be particularly beneficial compared to 0.9% saline 1
• Patients with reduced cardiac function or comorbidities may benefit most from goal-directed fluid therapy to optimize cardiac output and end-organ perfusion 1

By following these evidence-based recommendations for maintenance fluid therapy in surgical patients, clinicians can help reduce complications, improve outcomes, and enhance recovery after surgery.