Potential consequences of high-dose infusion of ketamine for refractory status epilepticus: case reports and systematic literature review

A Comparison of Ketamine and Midazolam as First-Line Anesthetic Infusions for Pediatric Status Epilepticus

BACKGROUND

Pediatric refractory status epilepticus (RSE) often requires management with anesthetic infusions, but few data compare first-line anesthetics. This study aimed to compare the efficacy and adverse effects of midazolam and ketamine infusions as first-line anesthetics for pediatric RSE.

METHODS

Retrospective single-center study of consecutive study participants treated with ketamine or midazolam as the first-line anesthetic infusions for RSE at a quaternary care children's hospital from December 1, 2017, until September 15, 2021.

RESULTS

We identified 117 study participants (28 neonates), including 79 (68%) who received midazolam and 38 (32%) who received ketamine as the first-line anesthetic infusions. Seizures terminated more often in study participants administered ketamine (61%, 23/38) than midazolam (28%, 22/79; odds ratio [OR] 3.97, 95% confidence interval [CI] 1.76-8.98; P < 0.01). Adverse effects occurred more often in study participants administered midazolam (24%, 20/79) than ketamine (3%, 1/38; OR 12.54, 95% CI 1.61-97.43; P = 0.016). Study participants administered ketamine were younger, ketamine was used more often for children with acute symptomatic seizures, and midazolam was used more often for children with epilepsy. Multivariable logistic regression of seizure termination by first-line anesthetic infusion (ketamine or midazolam) including age at SE onset, SE etiology category, and individual seizure duration at anesthetic infusion initiation indicated seizures were more likely to terminate following ketamine than midazolam (OR 4.00, 95% CI 1.69-9.49; P = 0.002) and adverse effects were more likely following midazolam than ketamine (OR 13.41, 95% CI 1.61-111.04; P = 0.016). Survival to discharge was higher among study participants who received midazolam (82%, 65/79) than ketamine (55%, 21/38; P = 0.002), although treating clinicians did not attribute any deaths to ketamine or midazolam.

CONCLUSIONS

Among children and neonates with RSE, ketamine was more often followed by seizure termination and less often associated with adverse effects than midazolam when administered as the first-line anesthetic infusion. Further prospective data are needed to compare first-line anesthetics for RSE.

Impact of Continuous Infusion Ketamine Compared to Continuous Infusion Benzodiazepines on Delirium in the Intensive Care Unit

Purpose: The purpose of this study was to evaluate rates of delirium or coma-free days between continuous infusion sedative-dose ketamine and continuous infusion benzodiazepines in critically ill patients. Materials and Methods: In this single-center, retrospective cohort adult patients were screened for inclusion if they received continuous infusions of either sedative-dose ketamine or benzodiazepines (lorazepam or midazolam) for at least 24 h, were mechanically ventilated for at least 48 h and admitted to the intensive care unit of a large quaternary academic center between 5/5/2018 and 12/1/2021. Results: A total of 165 patients were included with 64 patients in the ketamine group and 101 patients in the benzodiazepine group (lorazepam n = 35, midazolam n = 78). The primary outcome of median (IQR) delirium or coma-free days within the first 28 days of hospitalization was 1.2 (0.0, 3.7) for ketamine and 1.8 (0.7, 4.6) for benzodiazepines (p = 0.13). Patients in the ketamine arm spent a significantly lower proportion of time with RASS -3 to +4, received significantly higher doses and longer durations of propofol and fentanyl infusions, and had a significantly longer intensive care unit length of stay. Conclusions: The use of sedative-dose ketamine had no difference in delirium or coma-free days compared to benzodiazepines.

Ketamine in the treatment of refractory and super-refractory status epilepticus: Experience from two centres

PURPOSE

There is insufficient evidence on the management of refractory status epilepticus (RSE) and super-RSE (SRSE). Ketamine is a N-methyl-d-aspartate receptor antagonist in the treatment of these entities. Our objectives were to study the effectiveness and safety of ketamine in the treatment of adult patients with RSE and SRSE, to determine the factors that can influence the response to ketamine, and to explore its use in patients without mechanical ventilation.

METHODS

Adult patients who had received intravenous ketamine for the treatment of RSE or SRSE at Hospital Universitario Clínico San Carlos (Madrid, Spain) or Hospital Universitari Vall d'Hebron (Barcelona, Spain) from 2017 to 2023 were retrospectively analysed.

RESULTS

This study included 58 adult patients, mean (standard deviation) age 60.2 (15.7) years, of whom 41 (70.7 %) were male; 33 (56.9 %) patients responded to ketamine without recurrence, with a low rate of adverse effects (8.6 %). The presence of SRSE at the time of ketamine initiation (OR 0.287, p = 0.028) and the time elapsed between status epilepticus onset and ketamine administration (OR 0.991, p = 0.034) were associated with worse response to ketamine. Patients treated without mechanical ventilation had similar rates of response without recurrence (62.5% vs 56.9 %) and lower mortality (37.5% vs 53.5 %) compared to the overall group.

CONCLUSION

Ketamine is an effective drug with few adverse effects. Prompt administration should be considered in patients with RSE requiring anaesthesia, in patients with SRSE, and in patients with RSE who do not respond to standard antiseizure drugs and in whom mechanical ventilation is not advised.

Ketamine for Super-Refractory Status Epilepticus in Palliative Care. A Case Report and Review of the Literature

We report a case of super refractory status epilepticus uncontrolled by multiple anti-seizure medications in an individual with acute liver failure due to hepatic cirrhosis and an obstructive ileocecal mass plus multiple bilateral lung lesions presumed to be metastatic. A ketamine infusion was initiated late in his hospitalization which eliminated the convulsive seizures in less than an hour. The abatement of convulsive seizures allowed his grieving wife to return to her husband's bedside to witness the withdrawal of life sustaining treatment and be present during the final 24 hours of his life. We review the medical literature on the role of Intravenous (IV) Ketamine in the treatment of super refractory status epilepticus.

Use of Continuous Ketamine Infusion as an Adjunctive Agent in Young Infants With Refractory and Super Refractory Status Epilepticus: A Case Series

Continuous ketamine infusions have been studied as an adjunctive agent for refractory status epilepticus (RSE) and super refractory status epilepticus (SRSE) in older children and adults. However, minimal information exists on the efficacy, safety, and dosing for continuous ketamine in young infants. We present the clinical course of 3 young infants with RSE and SRSE who received continuous ketamine in conjunction with other antiseizure medications. The condition of these patients was refractory to an average of 6 antiseizure medications before initiation of continuous ketamine infusion. For each patient, a continuous ketamine infusion was initiated at a rate of 1 mg/kg/hr with 1 patient requiring titration to a maximum of 6 mg/kg/hr. In 1 case, the concomitant use of continuous ketamine allowed for a reduction in the benzodiazepine continuous infusion rate. In all cases, ketamine was well tolerated especially in the setting of hemodynamic instability. Ketamine may provide a safe adjunct in the acute setting in severe RSE and SRSE. This is the first case series to document the use of continuous ketamine as a treatment modality in young infants with RSE or SRSE secondary to various underlying etiologies, without adverse events. Further studies are needed to evaluate the long-term safety and efficacy of continuous ketamine in this patient population.

Ketamine for Management of Neonatal and Pediatric Refractory Status Epilepticus

BACKGROUND AND OBJECTIVES

Few data are available regarding the use of anesthetic infusions for refractory status epilepticus (RSE) in children and neonates, and ketamine use is increasing despite limited data. We aimed to describe the impact of ketamine for RSE in children and neonates.

METHODS

Retrospective single-center cohort study of consecutive patients admitted to the intensive care units of a quaternary care children's hospital treated with ketamine infusion for RSE.

RESULTS

Sixty-nine patients were treated with a ketamine infusion for RSE. The median age at onset of RSE was 0.7 years (interquartile range 0.15-7.2), and the cohort included 13 (19%) neonates. Three patients (4%) had adverse events requiring intervention during or within 12 hours of ketamine administration, including hypertension in 2 patients and delirium in 1 patient. Ketamine infusion was followed by seizure termination in 32 patients (46%), seizure reduction in 19 patients (28%), and no change in 18 patients (26%).

DISCUSSION

Ketamine administration was associated with few adverse events, and seizures often terminated or improved after ketamine administration. Further data are needed comparing first-line and subsequent anesthetic medications for treatment of pediatric and neonatal RSE.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence on the therapeutic utility of ketamine for treatment of RSE in children and neonates.

Cortical Spreading Depolarizations in Aneurysmal Subarachnoid Hemorrhage: An Overview of Current Knowledge and Future Perspectives

Despite significant advances in the management of aneurysmal subarachnoid hemorrhage (SAH), morbidity and mortality remain devastating particularly for high-grade SAH. Poor functional outcome usually results from delayed cerebral ischemia (DCI). The pathogenesis of DCI during aneurysmal SAH has historically been attributed to cerebral vasospasm, but spreading depolarizations (SDs) are now considered to play a central role in DCI. During SAH, SDs may produce an inverse hemodynamic response leading to spreading ischemia. Several animal models have contributed to a better understanding of the pathogenesis of SDs during aneurysmal SAH and provided new therapeutic approaches including N-methyl-D-aspartate receptor antagonists and phosphodiesterase inhibitors. Herein we review the current knowledge in the field of SDs' pathogenesis and we detail the key experimental and clinical studies that have opened interesting new therapeutic approaches to prevent DCI in aneurysmal SAH.

Use of Unconventional Therapies in Super-refractory Status Epilepticus: A Case Report and Literature Review

Super-refractory status epilepticus (SRSE) is a life-threatening condition characterized by the persistence or recurrence of seizures despite the use of first- and second-line antiepileptic drugs and the continuous infusion of anesthetics for more than 24 hours. This has always been a challenge for the physician, given the high mortality and morbidity related to this condition. Unfortunately, there are currently no definitive data to guide the therapy, since most of the therapeutic approaches regarding SRSE come from anecdotal evidence. Here, we present a case report of long-persisting new-onset SRSE treated with unconventional therapies recently reported to be successful such as ketamine, ketogenic diet, and tocilizumab, that could have played an important role in the management of this patient. A review of the literature regarding those is also included. SRSE has been reported to have long hospital length of stay, with a small percentage of patients returning to baseline functional status. Moreover, recent evidence showed that functional and cognitive outcome could depend on seizure duration, so prolonged duration of epileptic activity with abnormalities on the magnetic resonance imaging (MRI) could be seen as a reason to discontinue treatment. However, despite many weeks of seizures and a noncomforting MRI, our patient was discharged with a good functional status.

Ketamine to treat super-refractory status epilepticus

OBJECTIVE

To test ketamine infusion efficacy in the treatment of super-refractory status epilepticus (SRSE), we studied patients with SRSE who were treated with ketamine retrospectively. We also studied the effect of high doses of ketamine on brain physiology as reflected by invasive multimodality monitoring (MMM).

METHODS

We studied a consecutive series of 68 patients with SRSE who were admitted between 2009 and 2018, treated with ketamine, and monitored with scalp EEG. Eleven of these patients underwent MMM at the time of ketamine administration. We compared patients who had seizure cessation after ketamine initiation to those who did not.

RESULTS

Mean age was 53 ± 18 years and 46% of patients were female. Seizure burden decreased by at least 50% within 24 hours of starting ketamine in 55 (81%) patients, with complete cessation in 43 (63%). Average dose of ketamine infusion was 2.2 ± 1.8 mg/kg/h, with median duration of 2 (1-4) days. Average dose of midazolam was 1.0 ± 0.8 mg/kg/h at the time of ketamine initiation and was started at a median of 0.4 (0.1-1.0) days before ketamine. Using a generalized linear mixed effect model, ketamine was associated with stable mean arterial pressure (odds ratio 1.39, 95% confidence interval 1.38-1.40) and with decreased vasopressor requirements over time. We found no effect on intracranial pressure, cerebral blood flow, or cerebral perfusion pressure.

CONCLUSION

Ketamine treatment was associated with a decrease in seizure burden in patients with SRSE. Our data support the notion that high-dose ketamine infusions are associated with decreased vasopressor requirements without increased intracranial pressure.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that ketamine decreases seizures in patients with SRSE.

Antiseizure medications in critical care: an update

PURPOSE OF REVIEW

Seizures and status epilepticus are very common diagnoses in the critically ill patient and are associated with significant morbidity and mortality. There is an abundance of research on the utility of antiseizure medications in this setting, but limited randomized-controlled trials to guide the selection of medications in these patients. This review examines the current guidelines and treatment strategies for status epilepticus and provides an update on newer antiseizure medications in the critical care settings.

RECENT FINDINGS

Time is brain applies to status epilepticus, with delays in treatment corresponding with worsened outcomes. Establishing standardized treatment protocols within a health system, including prehospital treatment, may lead to improved outcomes. Once refractory status epilepticus is established, continuous deep sedation with intravenous anesthetic agents should be effective. In cases, which prove highly refractory, novel approaches should be considered, with recent data suggesting multiple recently approved antiseizure medications, appropriate therapeutic options, as well as novel approaches to upregulate extrasynaptic γ-aminobutyric acid channels with brexanolone.

SUMMARY

Although there are many new treatments to consider for seizures and status epilepticus in the critically ill patient, the most important predictor of outcome may be rapid diagnosis and treatment. There are multiple new and established medications that can be considered in the treatment of these patients once status epilepticus has become refractory, and a multidrug regimen will often be necessary.