Should phenobarbital be continued on the day of surgery in a patient with a seizure disorder?

Perioperative Management of Phenobarbital in Seizure Disorder Patients

Continue phenobarbital on the day of surgery to prevent potentially life-threatening withdrawal seizures, which can occur even weeks after discontinuation and pose far greater risk than the manageable sedative effects during anesthesia. 1

Primary Rationale for Continuation

• Withdrawal seizures from phenobarbital represent a severe, potentially fatal complication that can persist for several weeks after discontinuation, even in patients who have been seizure-free for years 1
• Patients with established seizure disorders who are on chronic antiepileptic therapy should continue their medications perioperatively to maintain seizure control 2
• The risk of perioperative seizures—including status epilepticus, aspiration, and neurological deterioration—far outweighs the additive sedative effects that can be managed by anesthesiologists 1

Clinical Algorithm for Perioperative Phenobarbital Management

For Patients on Chronic Phenobarbital:

• Continue the medication through the morning of surgery with a small sip of water 3
• Document the patient's baseline phenobarbital dose and serum levels if available
• Alert the anesthesia team to adjust anesthetic dosing to account for CNS depression 4
• Resume oral phenobarbital as soon as the patient can tolerate oral intake postoperatively 2

If NPO Status Prevents Oral Administration:

• Consider intravenous phenobarbital at equivalent dosing if oral route is unavailable for extended periods
• Monitor for signs of withdrawal: autonomic instability, tremor, agitation, or seizure activity 1

Anesthetic Considerations

• Phenobarbital enhances CNS depression when combined with general anesthetics, requiring careful titration of anesthetic agents to avoid profound sedation and respiratory depression 4
• The anesthesia team should anticipate delayed emergence and prolonged recovery time due to additive sedative effects 4
• This additive sedation is manageable and expected—it does not constitute a contraindication to continuing the medication 4

Critical Pitfalls to Avoid

• Never abruptly discontinue phenobarbital perioperatively: Withdrawal seizures can emerge even 3 weeks after stopping the medication and may continue despite reinitiation of therapy 1
• Do not assume that patients who have been seizure-free for years can safely skip doses—one case report documented withdrawal seizures in a patient seizure-free for 3 years following temporal lobe surgery 1
• Withdrawal seizures may require weeks to resolve even after phenobarbital is restarted, and aura frequency can remain elevated for months 1
• In patients with preoperative epilepsy, antiepileptic drugs must be continued after surgery to maintain seizure control 2

Special Populations

Elderly Patients (≥65 years):

• While the American Geriatrics Society Beers Criteria advise against barbiturates due to cognitive impairment and fall risk, the risk of withdrawal seizures supersedes these concerns in established users 4
• Increase monitoring for delirium and cognitive changes postoperatively
• Ensure fall precautions are in place during recovery

Patients with Hepatic Impairment:

• Exercise caution but do not discontinue—adjust postoperative dosing based on hepatic function 4
• Monitor phenobarbital levels more closely in the perioperative period

Postoperative Monitoring

• Assess for excessive sedation, respiratory depression, and delayed emergence from anesthesia 4
• Monitor for breakthrough seizures if oral intake is delayed
• Document time to resumption of oral phenobarbital and any missed doses
• If weaning is ever planned, it must occur over at least 2 weeks in a controlled outpatient setting—never in the perioperative period 3