Should labetalol and clonidine be held before general anesthesia?

Perioperative Management of Labetalol and Clonidine

Beta blockers like labetalol and centrally-acting agents like clonidine should be continued through the perioperative period and not held before general anesthesia. 1

Rationale for Continuing These Medications

Beta Blockers (Labetalol)

• Abrupt discontinuation of beta blockers preoperatively is potentially harmful (Class III: Harm, Level B-NR) 1
• Can cause rebound hypertension, tachycardia, and increased risk of perioperative cardiovascular events 1
• Patients who have been on beta blockers chronically should continue them throughout the perioperative period (Class I, Level B-NR) 1

Clonidine

• Abrupt discontinuation of clonidine can cause dangerous rebound hypertension (Class III: Harm, Level B-NR) 1
• Studies show that discontinuing clonidine before surgery can lead to hypertensive crisis in the recovery period 2
• The FDA label for clonidine specifically states: "Administration of clonidine should be continued to within four hours of surgery and resumed as soon as possible thereafter" 3

Clinical Evidence and Consequences

For Labetalol:

• Withdrawal can lead to:
  • Rebound hypertension
  • Tachycardia
  • Increased myocardial oxygen demand
  • Higher risk of perioperative ischemia and infarction 4
• The FDA label notes that abrupt discontinuation should be avoided 4

For Clonidine:

• Withdrawal syndrome can appear immediately after anesthesia if discontinued on the operation day 2
• Symptoms include nervousness, agitation, headache, tremor, and rapid rise in blood pressure 3
• Rare but serious consequences include hypertensive encephalopathy, cerebrovascular accidents, and death 3
• A study showed that 2 out of 10 patients who discontinued clonidine experienced hypertensive crisis during recovery 2

Perioperative Management Recommendations

1. Continue both medications up to the day of surgery (Class IIa, C-EO) 1
2. For clonidine: Continue administration to within four hours of surgery and resume as soon as possible afterward 3
3. For labetalol: Continue through the perioperative period, especially if the patient has been on it chronically 1
4. Intraoperative management: If needed, use intravenous medications to manage blood pressure until oral medications can be resumed 1

Potential Pitfalls and Caveats

• Do not start beta blockers on the day of surgery in beta blocker-naïve patients (Class III: Harm, Level B-NR) 1
• Monitor for hypotension during anesthesia induction, especially with labetalol, and have vasopressors readily available 5
• Consider dose adjustment rather than discontinuation if concerned about intraoperative hypotension 6
• For patients on both beta blockers and clonidine: Extra vigilance is required as the combination can potentiate bradycardia and hypotension 3

Special Considerations

• While ACE inhibitors and ARBs may be discontinued 24 hours before surgery (Class IIb, B-NR), this recommendation does not apply to beta blockers or clonidine 1, 7
• If severe hypertension exists (SBP ≥180 mmHg or DBP ≥110 mmHg), consider deferring elective surgery rather than adjusting chronic medications 1
• Ensure that these medications are resumed as soon as possible postoperatively 6

In summary, the evidence strongly supports continuing both labetalol and clonidine through the perioperative period to avoid potentially dangerous withdrawal syndromes and cardiovascular complications.