How do you manage positive and negative fluid balance in patients?

Managing Positive and Negative Fluid Balance in Patients

Context-Dependent Fluid Balance Targets

Fluid balance management must be tailored to the clinical context, with perioperative patients requiring mildly positive balance (+1-2 L) to protect renal function, while critically ill patients with sepsis or heart failure require strategies that minimize fluid accumulation and promote euvolemia. 1

Perioperative Setting

Target a mildly positive fluid balance of +1-2 liters by the end of major surgery, then transition rapidly to early oral intake while minimizing IV fluids postoperatively. 1, 2

• A large multicenter RCT of 3,000 patients undergoing major abdominal surgery demonstrated that stringently restrictive "zero-balance" fluid regimens resulted in significantly higher acute kidney injury rates compared to modestly liberal regimens (body weight increase of 1.6 kg vs 0.3 kg in first 24 hours). 1

• Use buffered crystalloid solutions (Ringer's Lactate or Plasmalyte) as first-line therapy, avoiding 0.9% saline which causes hyperchloremic metabolic acidosis and renal dysfunction. 1, 3, 2

• Administer fluids intraoperatively at 1-2 ml/kg/hour to minimize postoperative lung injury risk. 2

• Avoid fluid overload exceeding 2.5 kg perioperative weight gain, as this significantly increases complications including anastomotic leak, pulmonary complications, ventilator dependence, gut edema, and poor wound healing. 3, 2

Critical Illness and Sepsis

In critically ill patients, particularly those with sepsis, persistent positive fluid balance is independently associated with increased mortality and should be avoided after initial resuscitation. 4

• A prospective study of 173 septic patients found that daily fluid balance was more than twice as large in non-survivors versus survivors (29 ± 22 vs 13 ± 19 ml/kg, p <0.001), with persistence of positive balance over time strongly associated with higher mortality. 4

• Use strategies that minimize risk of fluid accumulation and promote maintenance of intravascular normovolemia (98% expert agreement). 1

• Buffered crystalloid solutions are recommended over 0.9% saline in critical illness (98% expert agreement). 1, 3

• Avoid routine use of synthetic colloids (97% expert agreement) or albumin (96% expert agreement) in critically ill patients. 1

Heart Failure Patients

Patients with heart failure require aggressive diuresis to achieve euvolemia before hospital discharge, as unresolved edema attenuates diuretic response and increases readmission risk. 1

• Progressive increments in loop diuretic doses are often required, frequently necessitating addition of a second diuretic with complementary action (e.g., metolazone). 1

• If volume overload persists despite high-dose diuretics, hospitalization for IV dopamine or dobutamine may be needed, though this frequently causes worsening azotemia. 1

• Small or moderate elevations of BUN and creatinine should not lead to minimizing therapy intensity, provided renal function stabilizes. 1

• If edema becomes resistant to treatment with severe renal dysfunction, ultrafiltration or hemofiltration may be needed to achieve adequate fluid control and can restore responsiveness to conventional diuretic doses. 1

• Patients should not be discharged until a stable diuretic regimen is established and euvolemia is achieved, as premature discharge leads to high readmission rates. 1

• Restrict dietary sodium to ≤2 g daily and consider fluid restriction to 2 liters daily in patients with persistent fluid retention despite sodium restriction and high-dose diuretics. 1

Monitoring Strategies

Fluid balance monitoring requires integration of intake/output records with physical assessment, daily weights, and electrolyte monitoring rather than relying on any single parameter. 5

• Monitor serum electrolytes (particularly potassium), CO2, creatinine, and BUN frequently during initial months of diuretic therapy and periodically thereafter. 6

• Define the patient's dry weight once euvolemia is achieved and use this as a continuing target for diuretic dose adjustment. 1

• Many patients can modify their own diuretic regimen in response to weight changes exceeding a predefined range. 1

• In critically ill patients, monitor cardiac output continuously, targeting low/normal values to avoid fluid overload and excessive vasopressor use. 3

• Volumetric monitoring technologies are useful during resuscitation phases in critically ill patients. 3

Patient-Specific Considerations

Patients with congestive heart failure, chronic kidney disease, and acute or chronic lung disease have lower fluid tolerance and require more conservative fluid administration strategies. 1, 3

• These patients are at higher risk of fluid accumulation and associated complications. 1

• Conversely, patients with severe intravascular hypovolemia may require larger volumes to restore euvolemia and tissue perfusion. 1

Critical Pitfalls to Avoid

• Never use large volumes of 0.9% saline, as it causes hyperchloremic acidosis, renal vasoconstriction, and acute kidney injury. 3, 2

• Avoid overly restrictive "zero-balance" strategies in perioperative patients, as they increase AKI risk. 1

• Do not allow persistent positive fluid balance in septic or critically ill patients beyond initial resuscitation, as this independently predicts mortality. 4

• In hepatic cirrhosis with ascites, sudden alterations in fluid and electrolyte balance may precipitate hepatic coma; initiate diuretic therapy in hospital with strict observation and supplemental potassium chloride. 6, 7

• If increasing azotemia and oliguria occur during treatment of severe progressive renal disease, discontinue furosemide. 6, 7

• Avoid rapid IV furosemide injection (use controlled infusion not exceeding 4 mg/minute in adults) to prevent ototoxicity, especially with concurrent aminoglycosides or in patients with severe renal impairment. 6, 7