What is the recommended approach for postoperative fluid management?

Postoperative Fluid Management

The recommended approach for postoperative fluid management is to administer an adequate volume of buffered crystalloid solutions, generally aiming for a 1-2 L positive fluid balance by the end of surgery to protect kidney function, while avoiding both hypovolemia and fluid overload. 1

General Principles of Postoperative Fluid Management

• Fluid management should be viewed as a continuum through preoperative, intraoperative, and postoperative phases, with the goal of maintaining adequate tissue perfusion without causing harm 2
• Both intravascular hypovolemia and fluid overload are harmful and associated with organ dysfunction 1
• Patient's ability to tolerate fluids varies based on comorbidities - patients with congestive heart failure, chronic kidney disease, and lung disease have lower fluid tolerance and higher risk of fluid accumulation 1

Recommended Fluid Type

• Buffered crystalloid solutions are strongly recommended over 0.9% saline in most surgical patients (98% agreement among experts) 1
• Buffered solutions help avoid hyperchloremic metabolic acidosis, renal vasoconstriction, and acute kidney injury that can occur with large volumes of 0.9% saline 1
• Specific exceptions where 0.9% saline is preferred:
  • Patients with hypochloremia 1
  • Patients with traumatic brain injury 1

Fluid Volume Management

• Aim for a mildly positive fluid balance (1-2 L) by the end of surgery to protect kidney function 1
• Avoid both insufficient and excessive fluid administration, as both are associated with increased hospital stay and morbidity 1
• A large multicenter RCT in 3000 patients showed that a stringently restrictive fluid regimen resulted in higher incidence of acute kidney injury compared to a modestly liberal regimen 1

Colloids vs. Crystalloids

• Strong recommendation against routine use of albumin or synthetic colloids for intraoperative fluid administration (90% agreement among experts) 1
• Despite some studies showing potential benefits of hydroxyethyl starch (HES) in specific surgical settings, the consensus is to avoid synthetic colloids due to potential risks 1
• In critically ill patients, both synthetic colloids and albumin are not recommended for routine use 1

Special Surgical Considerations

• Kidney transplantation: Buffered crystalloid solutions are strongly recommended over 0.9% saline (99% agreement among experts) 1
• Lung resection surgery: Avoid positive fluid balance in the first 24 hours following surgery (88% agreement) 1
• Neurosurgical patients: Avoid both albumin and hypotonic solutions (88% and 100% agreement, respectively) 1
• Minor noncardiac surgery: A mildly positive fluid balance is recommended to reduce postoperative nausea and vomiting (93% agreement) 1, 3

Postoperative Phase Management

• Early initiation of oral intake and cessation of intravenous therapy are recommended 4
• Once oral fluid intake is established, intravenous fluid administration can be discontinued and restarted only if clinically indicated 5
• "Permissive oliguria" can be tolerated in the absence of other concerns to avoid detrimental postoperative fluid overload 5

Goal-Directed Fluid Therapy (GDFT)

• For high-risk surgical patients, individualized goal-directed fluid therapy may provide benefits through continuous monitoring of circulatory status 3
• In elective surgery, a "zero-balance" approach (avoiding fluid overload) has shown to reduce postoperative complications and is simpler to apply than GDFT 3

Common Pitfalls to Avoid

• Relying on central venous pressure measurement to predict fluid responsiveness is ineffective and should be avoided 2
• Prolonged fasting and routine mechanical bowel preparation should be avoided preoperatively to prevent dehydration 5
• Excessive crystalloid administration can lead to tissue inflammation, edema formation, and compromised tissue healing 3
• Hyperchloremic acidosis from large volumes of 0.9% saline can lead to renal vasoconstriction and acute kidney injury 1

By following these evidence-based recommendations, postoperative fluid management can be optimized to improve patient outcomes while minimizing complications related to both hypovolemia and fluid overload.