Should diuretics, such as furosemide (loop diuretic) or hydrochlorothiazide (thiazide diuretic), be held on the morning of surgery to prevent hypovolemia and hypotension?

Management of Diuretics on the Day of Surgery

For patients with hypertension, diuretics should be discontinued on the day of surgery, while for patients with heart failure, diuretics should be continued up to the day of surgery and resumed intravenously perioperatively. 1

Diuretic Management Algorithm Based on Underlying Condition

For Patients with Hypertension:

• Discontinue low-dose diuretics on the morning of surgery 1
• Resume oral diuretics when possible postoperatively
• If blood pressure control is needed before oral therapy can be restarted, consider alternative IV antihypertensive agents 1

For Patients with Heart Failure:

• Continue diuretic treatment up to the day of surgery 1
• Switch to intravenous administration perioperatively
• Resume oral administration as soon as possible 1
• Monitor volume status carefully during the perioperative period 1
• Consider dosage adjustments based on:
  • Increase dose if signs of fluid retention are present
  • Reduce dose if risk of hypovolemia, hypotension, or electrolyte disturbances 1

Rationale and Evidence Quality

The European Society of Cardiology (ESC) guidelines provide clear Class I recommendations (Level C evidence) for diuretic management, differentiating between hypertension and heart failure patients 1. This approach balances the risks of perioperative hypovolemia against the need for ongoing volume management in heart failure.

A randomized controlled trial by Rosenman et al. found that administering furosemide on the day of surgery in chronic users did not significantly increase the risk of intraoperative hypotension compared to placebo (49% vs 51.9%, RR 0.95) 2. However, the ESC guidelines still recommend withholding diuretics in hypertensive patients, likely due to the theoretical risk of hypovolemia and the lack of necessity for acute blood pressure control during surgery.

Electrolyte Considerations

• Evaluate potassium and magnesium homeostasis preoperatively 1
• Pay special attention to patients on diuretics who are prone to arrhythmias 1
• Correct any electrolyte disturbances (especially hypokalemia and hypomagnesaemia) before surgery 1
• Minor, asymptomatic electrolyte disturbances should not delay acute surgery 1

Potential Complications and Pitfalls

1. Hypovolemia risk: Continuing diuretics in hypertensive patients may lead to relative hypovolemia during anesthesia induction
2. Electrolyte imbalances: Diuretics can cause hypokalemia, which increases risk of ventricular arrhythmias 1
3. Renal dysfunction: Preoperative diuretic use has been associated with increased risk of postoperative renal dysfunction in cardiac surgery patients 3

Special Considerations

• In patients with significant fluid overload or advanced renal failure, loop diuretics may still be necessary on the day of surgery 4
• For patients on multiple diuretic agents (e.g., combination therapy for resistant hypertension), prioritize discontinuation of thiazides while considering continuation of potassium-sparing agents if hyperkalemia risk is low 5

Remember that these recommendations apply to elective surgeries. For emergency procedures, the benefits of proceeding with surgery generally outweigh the risks of diuretic-related complications, and minor electrolyte disturbances should not delay urgent surgery 1.