Perioperative Management of Diuretics
The Critical Distinction: Indication Matters Most
For hypertensive patients on low-dose diuretics, discontinue diuretics on the day of surgery; for heart failure patients, continue diuretics up to the day of surgery and resume intravenously perioperatively. 1, 2
Algorithm for Diuretic Management
Step 1: Identify the Primary Indication
Hypertension (Low-Dose Diuretics):
- Discontinue on the morning of surgery 1, 2
- Resume orally when the patient can tolerate oral intake 1
- If blood pressure control is needed before oral resumption, use alternative IV antihypertensive agents rather than IV diuretics 1
Heart Failure (High-Dose Diuretics):
- Continue up to and including the day of surgery 1, 2
- Resume intravenously in the perioperative period to control volume overload 1
- Carefully monitor volume status throughout the perioperative period 1
- Transition back to oral diuretics when feasible 1, 2
The Rationale Behind This Approach
Why Hold Diuretics in Hypertensive Patients
Volume depletion and electrolyte disturbances are the primary concerns. 2
- Diuretics cause hypokalemia in up to 34% of surgical patients 1, 2
- Hypokalemia independently increases perioperative mortality risk in cardiac disease patients undergoing non-cardiac surgery 1
- Volume depletion increases the risk of intraoperative hypotension and hemodynamic instability 2
- Diuretics increase the risk of ventricular tachycardia and ventricular fibrillation, particularly in patients with cardiac disease 1
Why Continue Diuretics in Heart Failure Patients
The risk of fluid overload and decompensation outweighs the risks of continuing therapy. 1, 2
- Abrupt discontinuation can precipitate acute heart failure exacerbation 1
- Volume status must be carefully monitored, with dosage adjustments based on clinical assessment 1
- If signs of fluid retention are present, consider dosage increase 1
- If there is risk of hypovolemia, hypotension, or electrolyte disturbances, consider dosage reduction 1
Critical Preoperative Electrolyte Management
Mandatory Preoperative Assessment
Check potassium and magnesium levels in all patients on diuretics before surgery. 1, 2
- Correct any electrolyte disturbances—especially hypokalemia and hypomagnesemia—before surgery 1, 2
- Target potassium levels of 4.0-5.0 mEq/L for optimal perioperative safety 1
- Minor, asymptomatic electrolyte disturbances should not delay acute surgery 1
Strategies for Electrolyte Correction
Use a multimodal approach to correct deficiencies: 1
- Provide dietary advice to increase potassium and magnesium intake 1
- Reduce potassium-depleting drugs if possible 1
- Add or prefer potassium-sparing diuretics (spironolactone, eplerenone) 1
- Provide supplementation when necessary 1
- Acute preoperative repletion is recommended even in asymptomatic patients 1
Special Considerations for Specific Diuretic Classes
Loop Diuretics (Furosemide, Bumetanide, Torsemide)
The evidence on holding loop diuretics is nuanced. 3
- A randomized controlled trial of 193 patients found no significant difference in intraoperative hypotension risk between continuing furosemide (49%) versus placebo (51.9%) on the day of surgery 3
- Vasopressor and fluid requirements were similar between groups 3
- Postoperative cardiovascular event rates were not significantly different 3
- However, this study was conducted in elective, non-cardiac surgeries in chronic furosemide users 3
Despite this evidence, guideline recommendations still favor holding low-dose diuretics for hypertension. 1, 2
Thiazide Diuretics (Hydrochlorothiazide, Chlorthalidone)
Thiazides have distinct pharmacokinetic properties that affect perioperative management: 4
- Chlorthalidone has an extremely long half-life (40-60 hours) and large volume of distribution 4
- Hydrochlorothiazide has a shorter duration of action 4
- Both cause electrolyte disturbances including hypokalemia, hyponatremia, and metabolic abnormalities 4
- The same hold/continue algorithm based on indication (hypertension vs. heart failure) applies 1, 2
Potassium-Sparing Diuretics (Spironolactone, Eplerenone)
These agents reduce mortality in severe heart failure and should generally be continued. 1
- Aldosterone antagonists are now well-established to reduce mortality in severe heart failure 1
- They help prevent hypokalemia and hypomagnesemia 1
- Monitor for hyperkalemia, particularly in patients with renal impairment or those on ACE inhibitors/ARBs 1
Common Pitfalls and How to Avoid Them
Pitfall #1: Treating All Diuretics the Same
The indication for the diuretic—not the drug class—determines perioperative management. 1, 2
- A patient on furosemide 20 mg daily for hypertension should have it held 1
- A patient on furosemide 80 mg twice daily for heart failure should continue it 1
Pitfall #2: Ignoring Electrolyte Disturbances
Failing to check and correct electrolytes preoperatively increases perioperative mortality. 1, 2
- Hypokalemia in cardiac disease patients undergoing non-cardiac surgery is independently associated with perioperative mortality 1
- Always check potassium and magnesium levels before surgery in diuretic users 1, 2
- Correct deficiencies to target ranges (K+ 4.0-5.0 mEq/L) before elective procedures 1
Pitfall #3: Abruptly Stopping Diuretics in Heart Failure
This can precipitate acute decompensation and pulmonary edema. 1
- Heart failure patients require continued diuretic therapy perioperatively 1, 2
- Transition to IV administration if oral intake is not possible 1
- Monitor volume status closely and adjust dosing accordingly 1
Pitfall #4: Resuming Diuretics Too Early After High-Bleed-Risk Surgery
Early diuresis does not reduce length of stay and may worsen outcomes. 5
- A randomized trial of 123 patients undergoing colon and rectal surgery found that early furosemide administration (postoperative days 1-2) did not reduce length of hospital stay 5
- Time to return of bowel function was actually significantly longer in the furosemide group (48.8 vs 45.4 hours) 5
- Resume diuretics based on clinical need for volume management, not as a routine measure 5
Pitfall #5: Not Recognizing Increased Risk in Cardiac Surgery
Preoperative diuretic use is associated with increased major adverse events after cardiac surgery. 6
- A study of 12,593 cardiac surgery patients found that preoperative diuretic use was associated with increased risk of major adverse events (48% vs 43%), postoperative renal dysfunction (19% vs 14%), and atrial fibrillation (34% vs 32%) 6
- This association persisted after propensity score matching 6
- Despite this, heart failure patients still require continued diuretic therapy—the key is optimizing volume status and electrolytes preoperatively 1
Practical Perioperative Timeline
5-7 Days Before Surgery
- Check electrolytes (potassium, magnesium) in all diuretic users 1
- Begin correction of any deficiencies 1
- Optimize volume status in heart failure patients 1