Management of Ketamine Infusion in Status Epilepticus After 48 Hours of Seizure Freedom
Ketamine infusion should be gradually tapered over 24-48 hours rather than abruptly discontinued to prevent seizure recurrence in a patient who has been seizure-free for 48 hours. 1, 2
Tapering Protocol for Ketamine Infusion
- Begin tapering by reducing the infusion rate by 25% of the original dose every 6-8 hours while monitoring for seizure recurrence 2
- Continue the taper over 24-48 hours depending on the patient's clinical stability and initial ketamine dose 1, 2
- Consider slower tapering (10-20% reduction every 8-12 hours) if the patient has a history of difficult-to-control seizures or if status epilepticus was refractory to multiple agents 2, 3
Monitoring During Tapering
- Maintain continuous EEG monitoring throughout the tapering process to detect subclinical seizure activity 2
- Monitor vital signs including blood pressure, as both hypertension (39.3%) and hypotension (31.8%) have been reported during ketamine infusion 2
- Assess for emergence reactions which may occur during tapering, especially at higher doses 1, 4
Considerations for Antiepileptic Management
- Ensure therapeutic levels of maintenance antiepileptic drugs before and during ketamine tapering 1
- If midazolam was previously used and withheld, do not reintroduce it unless seizures recur, as benzodiazepines may increase the risk of respiratory depression when combined with ketamine 1
- Consider introducing a non-benzodiazepine antiepileptic drug if not already in place before complete ketamine discontinuation 5
Special Considerations
- Ketamine has a unique mechanism as an NMDA receptor antagonist, which is particularly effective in refractory status epilepticus where NMDA receptors are upregulated 3
- Early initiation of ketamine (within 5 hours of seizure onset) has been associated with better response rates (80% more likely to respond) 2
- Patients who have been seizure-free for 48 hours on ketamine have a good prognosis for successful weaning 2
Potential Complications to Monitor
- Watch for delirium during and after ketamine tapering, as ketamine use has been associated with increased delirium rates (22% vs 7.6% in non-ketamine patients) 6
- Monitor for hypersecretion, which has been reported in 14 out of 73 patients in a pediatric study 6
- Be vigilant for hepatobiliary dysfunction with prolonged ketamine use, especially with a cholestatic pattern 4
If Seizures Recur During Tapering
- Immediately return to the previous effective ketamine infusion rate 2
- Consider adding a benzodiazepine such as midazolam if seizures are not controlled with ketamine alone 1
- Reassess the underlying cause of status epilepticus and optimize treatment of any precipitating factors 1
Ketamine has shown efficacy in terminating refractory status epilepticus, even after failure of GABAergic anesthetics 3. The successful management of ketamine discontinuation requires careful monitoring and gradual tapering to prevent seizure recurrence while minimizing potential adverse effects.