What are the management options for postoperative oliguria using intravenous (IV) fluids?

From the Guidelines

For postoperative oliguria, fluid therapy should not be initiated solely based on low urine output, as it is a normal physiological response during surgery and anesthesia, and the cause of oliguria should be investigated prior to additional fluid therapy. According to the most recent and highest quality study 1, oliguria should not trigger fluid therapy as low urine output is a normal physiological response during surgery and anesthesia and could be due to multiple factors. The study recommends that oliguria should not be managed in isolation but rather be investigated and the cause established prior to additional fluid therapy.

Key Considerations

• Postoperative oliguria is a common issue that requires careful assessment and management
• Fluid therapy should be individualized, taking into account the type of surgery and important patient factors, including intravascular volume status and acute and chronic comorbidities 1
• The use of 0.9% saline should be avoided due to the risk of salt and fluid overload 1
• Balanced crystalloids, such as Ringer’s lactate, are recommended for intraoperative fluid administration 1
• A mildly positive fluid balance (+1-2 L) by the end of the case should be aimed for to protect kidney function 1

Management Options

• Investigate the cause of oliguria before initiating fluid therapy
• Use balanced crystalloids, such as Ringer’s lactate, for intraoperative fluid administration
• Avoid the use of 0.9% saline due to the risk of salt and fluid overload
• Aim for a mildly positive fluid balance (+1-2 L) by the end of the case to protect kidney function
• Consider placing a urinary catheter if not already present to accurately measure output
• If oliguria persists despite adequate fluid resuscitation, further evaluation is necessary to rule out other causes such as acute kidney injury, urinary obstruction, or medication effects.

From the FDA Drug Label

DOSAGE AND ADMINISTRATION Adults: Parenteral therapy with Furosemide Injection should be used only in patients unable to take oral medication or in emergency situations and should be replaced with oral therapy as soon as practical. The usual initial dose of furosemide is 20 to 40 mg given as a single dose, injected intramuscularly or intravenously The intravenous dose should be given slowly (1 to 2 minutes). Ordinarily a prompt diuresis ensues. If needed, another dose may be administered in the same manner 2 hours later or the dose may be increased.

The management options for postoperative oliguria using intravenous (IV) fluids include:

• Administering furosemide at an initial dose of 20 to 40 mg IV, given slowly over 1 to 2 minutes 2
• Repeating the dose if needed, 2 hours after the previous dose, or increasing the dose until the desired diuretic effect is achieved
• Monitoring the patient's response to the medication and adjusting the dose as necessary to achieve the desired effect while minimizing potential side effects.

Note: The use of torsemide is not directly relevant to the management of postoperative oliguria using IV fluids, as the provided label does not discuss its use in this context 3.

From the Research

Management Options for Postoperative Oliguria using IV Fluids

• The use of IV fluids to manage postoperative oliguria has been studied in various clinical trials 4, 5, 6, 7, 8.
• A randomized controlled pilot trial compared the effect of a follow-up approach without fluid bolus to a 500 mL fluid bolus on urine output in hemodynamically stable critically ill patients with oliguria 4.
• The results showed that the fluid bolus group had a higher proportion of patients who doubled their urine output, and the median change in individual urine output was significantly higher in the fluid bolus group compared to the follow-up group 4.
• Another study found that the use of lactated Ringer's solution or normal saline for fluid replacement in surgical patients did not have a clinically meaningful difference in postoperative complications, including acute kidney injury 5.
• A cohort analysis of patients after intermediate and high-risk surgeries found that postoperative oliguria was common and increased the risk of acute kidney injury, but oliguria was largely unrelated to kidney dysfunction measured by serum creatinine 6.
• The importance of intraoperative oliguria during major abdominal surgery was studied, and the results showed that intraoperative oliguria was associated with an increased risk of postoperative acute kidney injury, but the predictive utility of oliguria for AKI was low 7.
• A trial protocol and statistical analysis plan for a randomized controlled trial comparing noninterventional follow-up to fluid bolus in response to oliguria in critically ill patients has been published, aiming to provide information on the potential effect of fluid bolus on oliguria in critically ill patients 8.

Key Findings

• Fluid bolus therapy may improve urine output in patients with postoperative oliguria 4.
• The type of IV fluid used (lactated Ringer's solution or normal saline) may not have a significant impact on postoperative complications, including acute kidney injury 5.
• Postoperative oliguria is common after intermediate and high-risk surgeries and increases the risk of acute kidney injury, but its relationship to kidney dysfunction is unclear 6.
• Intraoperative oliguria is associated with an increased risk of postoperative acute kidney injury, but its predictive utility is low 7.

IV Fluid Management

• The use of IV fluids to manage postoperative oliguria should be guided by the patient's hemodynamic status and urine output 4, 8.
• The choice of IV fluid (lactated Ringer's solution or normal saline) may not be critical in terms of postoperative complications, including acute kidney injury 5.
• Further research is needed to determine the optimal management of postoperative oliguria using IV fluids 4, 6, 7, 8.