Role of propofol in refractory status epilepticus

The Missing Piece? A Case for Microglia's Prominent Role in the Therapeutic Action of Anesthetics, Ketamine, and Psychedelics

There is much excitement surrounding recent research of promising, mechanistically novel psychotherapeutics - psychedelic, anesthetic, and dissociative agents - as they have demonstrated surprising efficacy in treating central nervous system (CNS) disorders, such as mood disorders and addiction. However, the mechanisms by which these drugs provide such profound psychological benefits are still to be fully elucidated. Microglia, the CNS's resident innate immune cells, are emerging as a cellular target for psychiatric disorders because of their critical role in regulating neuroplasticity and the inflammatory environment of the brain. The following paper is a review of recent literature surrounding these neuropharmacological therapies and their demonstrated or hypothesized interactions with microglia. Through investigating the mechanism of action of psychedelics, such as psilocybin and lysergic acid diethylamide, ketamine, and propofol, we demonstrate a largely under-investigated role for microglia in much of the emerging research surrounding these pharmacological agents. Among others, we detail sigma-1 receptors, serotonergic and γ-aminobutyric acid signalling, and tryptophan metabolism as pathways through which these agents modulate microglial phagocytic activity and inflammatory mediator release, inducing their therapeutic effects. The current review includes a discussion on future directions in the field of microglial pharmacology and covers bidirectional implications of microglia and these novel pharmacological agents in aging and age-related disease, glial cell heterogeneity, and state-of-the-art methodologies in microglial research.

Propofol inhibited apoptosis of hippocampal neurons in status epilepticus through miR-15a-5p/NR2B/ERK1/2 pathway

Although a previous study reported that propofol had a therapeutic effect in status epilepticus (SE), the mechanisms underlying the effect of propofol in SE remain unclear. The aim of this study was to explore the regulatory mechanisms underlying propofol-induced inhibition of SE.A rat SE model was established using the lithium-pilocarpine injection method. A qRT-PCR and Western blot were utilized to detect the expression of relative molecules. Cell apoptosis was evaluated by a flow cytometry assay. The interaction between miR-15a-5p and NR2B was assessed using a luciferase reporter assay.Propofol inhibited cell apoptosis and increased miR-15a-5p expression both in hippocampal tissues of SE rats and low Mg²⁺-induced hippocampal neurons. Propofol-induced attenuation of apoptosis of low Mg²⁺-induced hippocampal neurons was mediated by miR-15a-5p. miR-15a-5p targeted NR2B and negatively regulated its expression. Propofol downregulated NR2B expression, mediated by miR-15a-5p. In terms of the mechanism of action, propofol suppressed the apoptosis of Mg²⁺-induced hippocampal neurons through the miR-15a-5p/NR2B/ERK1/2 pathway. In vivo experiment suggested that propofol inhibited the apoptosis of hippocampal neurons in SE rats by upregulating miR-15a-5p.In terms of the molecular mechanism of propofol, it appears to inhibit apoptosis of hippocampal neurons in SE through the miR-15a-5p/NR2B/ERK1/2 pathway. The findings provide theoretical support for propofol treatment of SE.

Synergistic action of CB1 and 5-HT2B receptors in preventing pilocarpine-induced status epilepticus in rats

Endocannabinoids (eCBs) and serotonin (5-HT) play a neuromodulatory role in the central nervous system. Both eCBs and 5-HT regulate neuronal excitability and their pharmacological potentiation has been shown to control seizures in pre-clinical and human studies. Compelling evidence indicates that eCB and 5-HT systems interact to modulate several physiological and pathological brain functions, such as food intake, pain, drug addiction, depression, and anxiety. Nevertheless, there is no evidence of an eCB/5-HT interaction in experimental and human epilepsies, including status epilepticus (SE). Here, we performed video-EEG recording in behaving rats treated with the pro-convulsant agent pilocarpine (PILO), in order to study the effect of the activation of CB₁/5-HT₂ receptors and their interaction on SE. Synthetic cannabinoid agonist WIN55,212-2 (WIN) decreased behavioral seizure severity of PILO-induced SE at 2 mg/kg (but not at 1 and 5 mg/kg, i.p.), while 5-HT_2B/2C receptor agonist RO60-0175 (RO; 1, 3, 10 mg/kg, i.p.) was devoid of any effect. RO 3 mg/kg was instead capable of potentiating the effect of WIN 2 mg/kg on the Racine scale score. Surprisingly, neither WIN 2 mg/kg nor RO 3 mg/kg had any effect on the incidence and the intensity of EEG seizures when administered alone. However, WIN+RO co-administration reduced the incidence and the severity of EEG SE and increased the latency to SE onset after PILO injection. WIN+RO effects were blocked by the selective CB₁R antagonist AM251 and the 5-HT_2BR antagonist RS127445, but not by the 5-HT_2CR antagonist SB242084 or the 5-HT_2AR antagonist MDL11,939. These data revealed a synergistic interaction between CB₁R/5-HT_2BR in the expression of PILO-induced SE.

Does burst-suppression achieve seizure control in refractory status epilepticus?

Background

The general principles in the administration of anesthetic drugs entail not only the suppression of seizure activity but also the achievement of electroencephalography burst suppression (BS). However, previous studies have reported conflicting results, possibly owing to the inclusion of various anesthetic agents, not all patients undergoing continuous electroencephalography (cEEG), and the inclusion of anoxic encephalopathy. This study aimed to analyze the effects of midazolam-induced BS on the occurrence outcomes in refractory status epilepticus patients.

Methods

Based on a prospective database of patients who had been diagnosed with status epilepticus via cEEG, multivariate Poisson regression modules were used to estimate the effect of midazolam-induced BS on breakthrough seizure, withdrawal seizure, intra-hospital complications, functional outcome at 3 months, and mortality. Modules were based on a pre-compiled directed acyclic graph (DAG).

Results

We included 51 non-anoxic encephalopathy, refractory status epilepticus patients. Burst suppression was achieved in 26 patients (51%); 25 patients (49%) had non-burst suppression on their cEEG. Breakthrough seizure was less often seen in the burst suppression group than in the non-burst suppression group. The incidence risk ratio [IRR] was 0.30 (95% confidence interval = 0.13–0.74). There was weak evidence of an association between BS and increased withdrawal seizure, but no association between BS and intra-hospital complications, mortality or functional outcomes was observed.

Conclusion

This study provides evidence that BS is safe and associated with less breakthrough seizures. Additionally, it was not associated with an increased rate of intra-hospital complications or long-term outcomes.

Alpha-2 agonists for sedation of mechanically ventilated adults in intensive care units: a systematic review

BACKGROUND

Care of critically ill patients in intensive care units (ICUs) often requires potentially invasive or uncomfortable procedures, such as mechanical ventilation (MV). Sedation can alleviate pain and discomfort, provide protection from stressful or harmful events, prevent anxiety and promote sleep. Various sedative agents are available for use in ICUs. In the UK, the most commonly used sedatives are propofol (Diprivan(®), AstraZeneca), benzodiazepines [e.g. midazolam (Hypnovel(®), Roche) and lorazepam (Ativan(®), Pfizer)] and alpha-2 adrenergic receptor agonists [e.g. dexmedetomidine (Dexdor(®), Orion Corporation) and clonidine (Catapres(®), Boehringer Ingelheim)]. Sedative agents vary in onset/duration of effects and in their side effects. The pattern of sedation of alpha-2 agonists is quite different from that of other sedatives in that patients can be aroused readily and their cognitive performance on psychometric tests is usually preserved. Moreover, respiratory depression is less frequent after alpha-2 agonists than after other sedative agents.

OBJECTIVES

To conduct a systematic review to evaluate the comparative effects of alpha-2 agonists (dexmedetomidine and clonidine) and propofol or benzodiazepines (midazolam and lorazepam) in mechanically ventilated adults admitted to ICUs.

DATA SOURCES

We searched major electronic databases (e.g. MEDLINE without revisions, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE and Cochrane Central Register of Controlled Trials) from 1999 to 2014.

METHODS

Evidence was considered from randomised controlled trials (RCTs) comparing dexmedetomidine with clonidine or dexmedetomidine or clonidine with propofol or benzodiazepines such as midazolam, lorazepam and diazepam (Diazemuls(®), Actavis UK Limited). Primary outcomes included mortality, duration of MV, length of ICU stay and adverse events. One reviewer extracted data and assessed the risk of bias of included trials. A second reviewer cross-checked all the data extracted. Random-effects meta-analyses were used for data synthesis.

RESULTS

Eighteen RCTs (2489 adult patients) were included. One trial at unclear risk of bias compared dexmedetomidine with clonidine and found that target sedation was achieved in a higher number of patients treated with dexmedetomidine with lesser need for additional sedation. The remaining 17 trials compared dexmedetomidine with propofol or benzodiazepines (midazolam or lorazepam). Trials varied considerably with regard to clinical population, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded outcome assessors. Compared with propofol or benzodiazepines (midazolam or lorazepam), dexmedetomidine had no significant effects on mortality [risk ratio (RR) 1.03, 95% confidence interval (CI) 0.85 to 1.24, I (2) = 0%; p = 0.78]. Length of ICU stay (mean difference -1.26 days, 95% CI -1.96 to -0.55 days, I (2) = 31%; p = 0.0004) and time to extubation (mean difference -1.85 days, 95% CI -2.61 to -1.09 days, I (2) = 0%; p < 0.00001) were significantly shorter among patients who received dexmedetomidine. No difference in time to target sedation range was observed between sedative interventions (I (2) = 0%; p = 0.14). Dexmedetomidine was associated with a higher risk of bradycardia (RR 1.88, 95% CI 1.28 to 2.77, I (2) = 46%; p = 0.001).

LIMITATIONS

Trials varied considerably with regard to participants, type of comparators, dose of sedative agents, outcome measures and length of follow-up. Overall, risk of bias was generally high or unclear. In particular, few trials blinded assessors.

CONCLUSIONS

Evidence on the use of clonidine in ICUs is very limited. Dexmedetomidine may be effective in reducing ICU length of stay and time to extubation in critically ill ICU patients. Risk of bradycardia but not of overall mortality is higher among patients treated with dexmedetomidine. Well-designed RCTs are needed to assess the use of clonidine in ICUs and identify subgroups of patients that are more likely to benefit from the use of dexmedetomidine.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014014101.

FUNDING

The National Institute for Health Research Health Technology Assessment programme. The Health Services Research Unit is core funded by the Chief Scientist Office of the Scottish Government Health and Social Care Directorates.

Pharmacotherapy Overview of Seizure Management in the Adult Emergency Department

Seizures are a common cause of emergency department visits, and approximately 28% of epilepsy patients present to an emergency department annually for treatment. This article will provide an overview of the pharmacotherapeutic management of seizures and anticonvulsant therapy for patients who present to the adult emergency department, including practical information for pharmacists covering or cross-covering this practice area. The benzodiazepines are reviewed as a class, including dosing strategies, pharmacodynamic considerations, and advantages and disadvantages of lorazepam, diazepam, and midazolam. Indications for the use of phenytoin and fosphenytoin will be reviewed, as well as dosing, adverse effects, and cost-effectiveness data. In addition, dosing, administration, pharmacokinetics, and adverse effects of phenobarbital, carbamazepine, and valproate will be discussed. Clinical indications for serum anticonvulsant concentration monitoring and subsequent calculation of loading doses from serum concentrations are reviewed. Since status epilepticus is a life-threatening emergency, its therapeutic management is reviewed, including the use of continuous infusion midazolam, pentobarbital, and propofol. There are many opportunities for clinical pharmacists to collaborate with other members of the health care team to optimize efficacy and minimize adverse effects of anticonvulsant agents in the emergency department setting.

Treatment of drug-induced seizures

Seizures are a common complication of drug intoxication, and up to 9% of status epilepticus cases are caused by a drug or poison. While the specific drugs associated with drug-induced seizures may vary by geography and change over time, common reported causes include antidepressants, stimulants and antihistamines. Seizures occur generally as a result of inadequate inhibitory influences (e.g., gamma aminobutyric acid, GABA) or excessive excitatory stimulation (e.g. glutamate) although many other neurotransmitters play a role. Most drug-induced seizures are self-limited. However, status epilepticus occurs in up to 10% of cases. Prolonged or recurrent seizures can lead to serious complications and require vigorous supportive care and anticonvulsant drugs. Benzodiazepines are generally accepted as the first line anticonvulsant therapy for drug-induced seizures. If benzodiazepines fail to halt seizures promptly, second line drugs include barbiturates and propofol. If isoniazid poisoning is a possibility, pyridoxine is given. Continuous infusion of one or more anticonvulsants may be required in refractory status epilepticus. There is no role for phenytoin in the treatment of drug-induced seizures. The potential role of ketamine and levetiracetam is promising but not established.

Treatment of Generalized Convulsive Status Epilepticus in Pediatric Patients

Generalized convulsive status epilepticus (GCSE) is one of the most common neurologic emergencies and can be associated with significant morbidity and mortality if not treated promptly and aggressively. Management of GCSE is staged and generally involves the use of life support measures, identification and management of underlying causes, and rapid initiation of anticonvulsants. The purpose of this article is to review and evaluate published reports regarding the treatment of impending, established, refractory, and super-refractory GCSE in pediatric patients.

Propofol infusion syndrome in refractory status epilepticus

BACKGROUND AND PURPOSE

Propofol is used for treating refractory status epilepticus, which has high rate of mortality. Propofol infusion syndrome is a rare but often fatal syndrome, characterized by lactic acidosis, lipidemia, and cardiac failure, associated with propofol infusion over prolonged periods of time. We investigated the clinical factors that characterize propofol infusion syndrome to know the risk of them in refractory status epilepticus.

METHODS

This retrospective observation study was conducted in Samsung medical center from Jan. 2005 to Dec. 2009. Thirty two patients (19 males, 13 females, aged between 16 and 64 years), with refractory status epilepsy were included. Their clinical findings and treatment outcomes were evaluated retrospectively. We divided our patients into established status epilepticus (ESE) and refractory status epilepticus (RSE). And then the patients with RSE was further subdivided into propofol treatment group (RSE-P) and the other anesthetics treatment group (RSE-O). We analyzed the clinical characteristics by comparison of the groups.

RESULTS

There were significant differences of hypotension and lipid change between ESE and RSE (p<0.05). However, there was no significant difference between RSE-P and RSE-O groups. The hospital days were longer in RSE than in ESE (p=0.012) and treatment outcome was also worse in RSE than in ESE (p=0.007) but there were no significant differences of hospital stays and treatment outcome between RSE-P and RSE-O.

CONCLUSIONS

RSE is very critical disease with high mortality, which may show as many clinical changes as propofol infusion syndrome. Therefore propofol infusion syndrome might be considered as one of the clinical manifestations of RSE.

Guidelines for the evaluation and management of status epilepticus

Status epilepticus (SE) treatment strategies vary substantially from one institution to another due to the lack of data to support one treatment over another. To provide guidance for the acute treatment of SE in critically ill patients, the Neurocritical Care Society organized a writing committee to evaluate the literature and develop an evidence-based and expert consensus practice guideline. Literature searches were conducted using PubMed and studies meeting the criteria established by the writing committee were evaluated. Recommendations were developed based on the literature using standardized assessment methods from the American Heart Association and Grading of Recommendations Assessment, Development, and Evaluation systems, as well as expert opinion when sufficient data were lacking.

Toxin-related seizures

Toxin-related seizures result from an imbalance in the brain's equilibrium of excitation-inhibition. Fortunately, most toxin-related seizures respond to standard therapy using benzodiazepines. However, a few alterations in the standard approach are recommended to ensure optimal care and expedient termination of seizure activity. If 2 doses of a benzodiazepine do not terminate the seizure activity, a therapeutic dose of pyridoxine (5 g intravenously in an adult and 70 mg/kg intravenously in a child) should be considered. Phenytoin should be avoided because it is ineffective for many toxin-induced seizures and is potentially harmful when used to treat seizures induced by theophylline or cyclic antidepressants.

Propofol infusion syndrome in patients with refractory status epilepticus: an 11-year clinical experience

OBJECTIVES

Propofol is a sedative, anesthetic, and antiepileptic agent that is frequently used in patients with refractory status epilepticus. Propofol infusion syndrome is a feared complication of propofol use, especially at high infusion rates for prolonged periods. The present study describes the use of propofol and its associated complications in patients with refractory status epilepticus.

DESIGN

: Retrospective study with outcome assessment.

SETTING

Intensive care units at Mayo Clinic.

PATIENTS

Intensive care unit admissions with refractory status epilepticus.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

A computer-assisted search identified 41 consecutive patients from January 1997 to September 2008 admitted to our intensive care unit with refractory status epilepticus, defined by the need for continuous intravenous infusion of anesthetic agents to control seizures. Propofol infusion syndrome was defined per previously published criteria. The study population consisted of 24 males and 17 females with a median age of 51 yrs (range, 0.25- 80). Propofol was used in 31 (76%) of these patients (propofol group), and other agents like midazolam, lorazepam, and pentobarbital were used in the other ten (24%) patients (nonpropofol group). Median hospital (12 days; range, 2-112) and intensive care unit length of stay (9 days; range, 2-95) did not differ among the two groups. Propofol was used for a median of 63 hrs (range, 2-391) with a median cumulative dosage of 12,750 mg (range, 336-57,545). The median peak infusion rate was 67 microg/kg/min (range, 19-200). There were three sudden unexplained cardiorespiratory arrests in the propofol group (3 of 31, 10%), of which two were fatal. These three patients were aged 37, 46, and 55 yrs and had no prior cardiopulmonary disease. Eleven additional patients (11 of 31, 35%) had non-life-threatening features of propofol infusion syndrome. There were no such events noted in the nonpropofol group.

CONCLUSIONS

The prolonged use of large doses of propofol to treat refractory status epilepticus was associated with significant mortality and morbidity.

Critical care sedation for neuroscience patients

In 2000, the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) introduced the mandate for the implementation of standards for both pain assessment and need for therapy in hospitalized patients. The need for the appropriate titration of sedation and analgesia is particularly poignant in an intensive care unit (ICU) setting where iatrogenic discomfort often complicates patient management. Neurologically ill patients in ICUs present particularly complex sedation issues, owing to the need to monitor these patients with serial neurological exams. Hence, maximal comfort without diminishing neurological responsiveness is desirable. Here, we review the frequently applied methods of evaluating levels of pain and agitation in critically ill patients as well as discuss the appropriate classes of pharmaceutical agents common to this population, with particular emphasis on the potential neurophysiological impact of such therapy.

Comparative Efficacy and Safety of Antiepileptic Drugs for the Treatment of Status Epilepticus

Status epilepticus (SE) is a medical emergency with high mortality rate. Common causes of SE include noncompliance with antiepileptic medications, drug- and alcohol-related etiologies, and central nervous system (CNS) infections. Because prolonged seizures can cause neuronal damage, treatment should be initiated promptly to avoid potential complications. Previous studies support intravenous (IV) lorazepam as first-line therapy and IV phenytoin or fosphenytoin as a second-line medication. If first-and second-line medications fail to control SE, further treatment with propofol, pentobarbital, midazolam, or other medications should be considered. Many of the drugs currently used to control SE are associated with sedation, respiratory suppression, hypotension, cardiac dysrhythmia, and anaphylactic reactions. Therefore, IV valproate or other newer antiepileptic drugs may be considered as an alternative third-line therapy for those who cannot tolerate the hypotensive effects of other anticonvulsants. This paper reviews comparative effectiveness and safety concerns among frequently used medications for SE.

Hydroxyamide Analogs of Propofol Exhibit State-Dependent Block of Sodium Channels in Hippocampal Neurons: Implications for Anticonvulsant Activity

Although propofol is most commonly known for its general anesthetic properties, at subanesthetic doses, propofol has been effectively used to suppress seizures during refractory status epilepticus, a mechanism, in part, attributed to the inhibition of neuronal sodium channels. In this study, we have designed and synthesized two novel analogs of propofol, HS245 [2-(3-ethyl-4-hydroxy-5-isopropyl-phenyl)-3,3,3-trifluoro-2-hydroxy-propionamide] and HS357 [2-hydroxy-8-(4-hydroxy-3,5-diisopropyl-phenyl)-2-trifluoromethyl-octanoic acid amide], and determined their effects on sodium currents recorded from cultured hippocampal neurons. HS357 had greater affinity for the inactivated state of the sodium channel than propofol and HS245 (0.22 versus 0.74 and 1.2 microM, respectively) and exhibited the greatest ratio of affinity for the resting over the inactivated state. HS357 also demonstrated greater use-dependent block and delayed recovery from inactivation in comparison with propofol and HS245. Under current-clamp conditions, action potentials from hippocampal CA1 neurons in slices were evoked by current injection, or following perfusion with a zero Mg(2+)/7 mM K(+) artificial cerebrospinal fluid solution. Propofol and HS357 reduced the number of current-induced action potentials; however, HS357 caused a greater reduction in the number of spontaneous action potentials. Consistent with these electrophysiology studies, propofol and HS357 protected mice against acute seizures in the 6-Hz (22-mA) partial psychomotor model. Efficacious doses of propofol were associated with an impairment of motor coordination as assessed in the rotorod toxicity assay. In contrast, HS357 demonstrated a 2-fold greater protective index than propofol. Thus, propofol analogs represent an important structural class from which not only effective, but also safer, anti-convulsants may be developed.

[Refractory status epilepticus: diagnosis, therapy, course, and prognosis]

Status epilepticus (SE) is a frequent neurological emergency with an annual incidence of 10-20/100,000 individuals. The overall mortality is about 10-20%. Patients present with long-lasting fits or series of epileptic seizures or extended stupor and coma. Furthermore, patients with SE can suffer from a number of systemic complications possibly also due to side effects of the medical treatment. In the beginning, standardized treatment algorithms can successfully stop most SE. A minority of SE cases prove however to be refractory against the initial treatment and require intensified pharmacologic intervention with nonsedating anticonvulsive drugs or anesthetics. In some partial SE, nonpharmacological approaches (e.g., epilepsy surgery) have been used successfully. This paper reviews scientific evidence of the diagnostic approach, therapeutic options, and course of refractory SE, including nonpharmacological treatment.

Airway management in neurological emergencies

Several neurological conditions may present to the emergency department (ED) with airway compromise or respiratory failure. The severity of respiratory involvement in these patients may not always be obvious. Proper pulmonary management can significantly reduce the respiratory complications associated with the morbidity and mortality of these patients. Rapid sequence intubation (RSI) is the method of choice for definitive airway management in the ED and is used for the majority of intubations. The unique clinical circumstances of each patient dictates which pharmacological agents can be used for RSI. Several precautions must be taken when using these drugs to minimize potentially fatal complications. Noninvasive positive pressure ventilation may obviate the need for intubation in a select population of patients. This article reviews airway management, with a particular emphasis on the use of RSI for common neurological problems presenting to the ED.

Inhibition of Persistent Sodium Current Fraction and Voltage-gated L-type Calcium Current by Propofol in Cortical Neurons: Implications for Its Antiepileptic Activity

PURPOSE

Although it is widely used in clinical practice, the mechanisms of action of 2,6-di-isopropylphenol (propofol) are not completely understood. We examined the electrophysiologic effects of propofol on an in vitro model of epileptic activity obtained from a slice preparation.

METHODS

The effects of propofol were tested both on membrane properties and on epileptiform events consisting of long-lasting, paroxysmal depolarization shifts (PDSs) induced by reducing the magnesium concentration from the solution and by adding bicuculline and 4-aminopyridine. These results were integrated with a patch-clamp analysis of Na(+) and high-voltage activated (HVA) calcium (Ca(2+)) currents from isolated cortical neurons.

RESULTS

In bicuculline, to avoid any interference by gamma-aminobutyric acid (GABA)-A receptors, propofol (3-100 microM) did not cause significant changes in the current-evoked, sodium (Na(+))-dependent action-potential discharge. However, propofol reduced both the duration and the number of spikes of PDSs recorded from cortical neurons. Interestingly, relatively low concentrations of propofol [half-maximal inhibitory concentration (IC(50)), 3.9 microM) consistently inhibited the "persistent" fraction of Na(+) currents, whereas even high doses (< or =300 microM) had negligible effects on the "fast" component of Na(+) currents. HVA Ca(2+) currents were significantly reduced by propofol, and the pharmacologic analysis of this effect showed that propofol selectively reduced L-type HVA Ca(2+) currents, without affecting N or P/Q-type channels.

CONCLUSIONS

These results suggest that propofol modulates neuronal excitability by selectively suppressing persistent Na(+) currents and L-type HVA Ca(2+) conductances in cortical neurons. These effects might cooperate with the opening of GABA-A-gated chloride channels, to achieve depression of cortical activity during both anesthesia and status epilepticus.

Propofol treatment of refractory status epilepticus: a study of 31 episodes

PURPOSE

Refractory status epilepticus (RSE) is a critical medical condition with high mortality. Although propofol (PRO) is considered an alternative treatment to barbiturates for the management of RSE, only limited data are available. The aim of this study was to assess PRO effectiveness in patients with RSE.

METHODS

We retrospectively considered all consecutive patients with RSE admitted to the medical intensive care unit (ICU) between 1997 and 2002 treated with PRO for induction of EEG-monitored burst suppression. Subjects with anoxic encephalopathy showing pathological N20 on somatosensory evoked potentials were excluded.

RESULTS

We studied 31 RSE episodes in 27 adults (16 men, 11 women; median age, 41.5 years). All patients received PRO, and six also subsequently thiopental (THP). Clonazepam (CZP) was administered with PRO, and other antiepileptic drugs (AEDs) concomitant with PRO and THP. RSE was successfully treated with PRO in 21 (67%) episodes and with THP after PRO in three (10%). Median PRO injection rate was 4.8 mg/kg/h (range, 2.1-13), median duration of PRO treatment was 3 days (range, 1-9), and median duration of ICU stay was 7 days (range, 2-42). In 24 episodes in which the patient survived, shivering after general anesthesia was seen in 10 episodes, transient dystonia and hyperlipemia in one each, and mild neuropsychological impairment in five. The seven deaths were not directly related to PRO use.

CONCLUSIONS

PRO administered with CZP was effective in controlling most of RSE episodes, without major adverse effects. In this setting, PRO may therefore represent a valuable alternative to barbiturates. A randomized trial with these drug classes could definitively assess their respective role in RSE treatment.

The safe and effective use of propofol sedation in children undergoing diagnostic and therapeutic procedures: experience in a pediatric ICU and a review of the literature

OBJECTIVES

To describe our experience using propofol sedation to facilitate elective diagnostic and therapeutic procedures, and to document the safety profile of propofol in this setting.

DESIGN

Retrospective consecutive case series and review of the literature.

SETTING

Pediatric intensive care unit of a United States Navy tertiary care medical center.

PATIENTS

Children receiving propofol for procedural sedation over an 18-month period.

OUTCOME MEASURES

Descriptive features of sedation including adverse events.

RESULTS

During the study period, 91 children received propofol to facilitate the performance of 110 medical procedures. The mean induction dose was 2.41 mg/kg, the mean infusion rate was 179.3 microg/kg/min, and the mean total dose of propofol administered was 4.23 mg/kg. In all cases, sedation was successfully achieved. The average length of stay in the PICU was 108.4 minutes. Three children (3.3%) had transient episodes of oxygen desaturation that improved with repositioning of the airway. No child required placement of an endotracheal tube. Three (3.3%) children experienced hypotension requiring a decrease in the infusion rate of propofol and a 10-mL/kg bolus infusion of normal saline. No cardiac arrhythmias or adverse neurologic effects secondary to propofol infusion were identified.

CONCLUSIONS

Pediatric intensivists can safely and effectively administer propofol to facilitate the performance of diagnostic and therapeutic procedures outside the operating room setting.

Treatment of status epilepticus: a survey of neurologists

BACKGROUND

New antiepileptic drugs (AEDs) have provided alternatives to traditional treatment paradigms for status epilepticus (SE).

METHODS

To determine current treatment preferences for generalized convulsive status epilepticus (GCSE), we surveyed 106 members of the Critical Care or Epilepsy sections of the American Academy of Neurology.

RESULTS

Most respondents initially treat patients with intravenous (IV) lorazepam (76%), followed by phenytoin or fosphenytoin (95%) if first-line therapy fails. Preferences for GCSE refractory to two AEDs (RSE) varied: 43% would give phenobarbital, 19% would give one of three continuous-infusion (cIV) AEDs (pentobarbital, midazolam, propofol), and 16% would give IV valproic acid. About half indicated "burst suppression" (56%) and half indicated "elimination of seizures" (41%) as the titration goal for cIV-AED therapy. About half (42%) would add a new cIV-AED, and the other half (41%) would not add another agent to treat electrographic SE refractory to four AEDs.

DISCUSSION

In accordance with published trials and general guidelines, neurologists most often use lorazepam followed by phenytoin or fosphenytoin as first-line and second-line therapies for GCSE. There is no consensus for third-line or fourth-line treatment for RSE. The treatment of RSE needs to be studied in a large, prospective, randomized, multicenter trial.

Comparison of conscious sedation and general anesthesia for motor mapping and resection of tumors located near motor cortex

Object

The surgical treatment of tumors located near eloquent cortex carries a high risk of inducing worsening neurological deficits. Intraoperative electrocorticography techniques have been developed to help identify these areas at the time of surgery in an effort to minimize such risks. The optimal anesthetic technique for conducting these procedures, however, has never been determined.

Methods

The authors conducted a retrospective study to compare patients who underwent intraoperative motor mapping between September 2000 and May 2002. Demographic and neurophysiological monitoring data were collected from the hospital records. Patients were divided into two groups based on the anesthetic technique used for surgery: in Group 1 general anesthesia was used, and in Group 2 conscious sedation.

Group 1 comprised 24 patients (mean age 47 years) with 16 right- and eight left-sided lesions. Group 2 consisted of 21 patients (mean age 46 years) with 18 right- and three left-sided lesions. Pathological diagnoses were similar between the two groups. Motor stimulation was elicited in 12 patients (50%) in Group 1 and in 21 patients (100%) in Group 2 (p < 0.001). In addition, the mean stimulation amplitude required was significantly higher (13 mA) in patients in whom conscious sedation was used as opposed to general anesthesia (5 mA, p < 0.0001). Electrographic evidence of seizures was seen in 29% of Group 1 cmpared with 10% of Group 2 patients (p > 0.05).

Conclusions

The use of conscious sedation as an anesthetic technique for motor mapping not only improves the chances of achieving successful stimulation and identification of motor cortex in relationship to the lesion, but it also allows for repetitive monitoring of the patient's motor function during resection of the lesion.

Progress in clinical neurosciences: Status epilepticus: a critical review of management options

Although generalized tonic-clonic status epilepticus (SE) is frequently seen, an evidence-based approach to management is limited by a lack of randomized clinical studies. Clinical practice, therefore, relies on a combination of expert recommendations, local hospital guidelines and dogma based on individual preference and past successes. This review explores selected and controversial aspects of SE in adults and provides a critical appraisal of currently recommended management strategies.

The current state of treatment of status epilepticus

There have been many important developments in the diagnosis and treatment of status epilepticus in the recent past. Earlier treatment, including at home by caregivers and in the field by paramedics, has been shown to be safe and effective. Rapid-acting anesthetic agents, such as midazolam and propofol, are being used more often for refractory status epilepticus, though clinical trials are lacking. Nonconvulsive status epilepticus is being considered and recognized more often, including in ambulatory patients with a confusional state, after convulsive status epilepticus, and in critically ill patients. Modern technology and continuous digital electroencephalogram (EEG) recordings have taught us many things, but have raised at least as many questions. Much work needs to be done regarding the significance of certain EEG patterns (particularly periodic discharges) and when and how to treat them. This article reviews these issues, concentrating on recent advances and practical issues related to the clinical care of patients with status epilepticus.

Treatment of refractory status epilepticus with pentobarbital, propofol, or midazolam: a systematic review

BACKGROUND

New continuous infusion antiepileptic drugs (cIV-AEDs) offer alternatives to pentobarbital for the treatment of refractory status epilepticus (RSE). However, no prospective randomized studies have evaluated the treatment of RSE. This systematic review compares the efficacy of midazolam (MDL), propofol (PRO), and pentobarbital (PTB) for terminating seizures and improving outcome in RSE patients.

METHODS

We performed a literature search of studies describing the use of MDL, PRO, or PTB for the treatment of RSE published between January 1970 and September 2001, by using MEDLINE, OVID, and manually searched bibliographies. We included peer-reviewed studies of adult patients with SE refractory to at least two standard AEDs. Main outcome measures were the frequency of immediate treatment failure (clinical or electrographic seizures occurring 1 to 6 h after starting cIV-AED therapy) and mortality according to choice of agent and titration goal (cIV-AED titration to "seizure suppression" versus "EEG background suppression").

RESULTS

Twenty-eight studies describing a total of 193 patients fulfilled our selection criteria: MDL (n = 54), PRO (n = 33), and PTB (n = 106). Forty-eight percent of patients died, and mortality was not significantly associated with the choice of agent or titration goal. PTB was usually titrated to EEG background suppression by using intermittent EEG monitoring, whereas MDL and PRO were more often titrated to seizure suppression with continuous EEG monitoring. Compared with treatment with MDL or PRO, PTB treatment was associated with a lower frequency of short-term treatment failure (8 vs. 23%; p < 0.01), breakthrough seizures (12 vs. 42%; p < 0.001), and changes to a different cIV-AED (3 vs. 21%; p < 0.001), and a higher frequency of hypotension (systolic blood pressure <100 mm Hg; 77 vs. 34%; p < 0.001). Compared with seizure suppression (n = 59), titration of treatment to EEG background suppression (n = 87) was associated with a lower frequency of breakthrough seizures (4 vs. 53%; p < 0.001) and a higher frequency of hypotension (76 vs. 29%; p < 0.001).

CONCLUSIONS

Despite the inherent limitations of a systematic review, our results suggest that treatment with PTB, or any cIV-AED infusion to attain EEG background suppression, may be more effective than other strategies for treating RSE. However, these interventions also were associated with an increased frequency of hypotension, and no effect on mortality was seen. A prospective randomized trial comparing different agents and titration goals for RSE with obligatory continuous EEG monitoring is needed.

Status epilepticus and acute serial seizures in children

Status epilepticus is defined as a seizure that persists for a sufficient length of time or is repeated frequently enough to produce a fixed and enduring epileptic condition of 30 minutes or longer. Status epilepticus is a life-threatening condition that often occurs in children. The degree of mortality and neurologic morbidity, as well as the risk for recurrence, is highly dependent on the etiology and duration of the seizures. Although much has been written about pediatric status epilepticus, many issues remain unresolved. A better understanding of the different types of seizures and their etiologies may help in the prevention and treatment of status epilepticus. The vast extent of status epilepticus in both children and adults mandates that new options for prevention and treatment be given a close scrutiny and high priority. This article will review the most current information on convulsive and nonconvulsive status epilepticus, including the potential for neurologic damage, changes in magnetic resonance imaging after status epilepticus, risk for recurrence, and current treatment options available for treating status epilepticus in children.

Inefficacy of burst-suppression anesthesia in medication-resistant major depression: a controlled trial

Burst-suppression anesthesia (BSA) has been previously compared with electroconvulsive therapy (ECT) in drug-resistant depression, with promising results. We have carried out a double-blind randomized clinical trial comparing BSA with sham-BSA in 20 patients meeting DSM-IV criteria for major depression with inadequate response to antidepressant drugs and who chose BSA as an alternative to ECT. After withdrawing antidepressant drugs, patients were randomized to receive four sessions of either BSA (induction with propofol followed by the anesthetic agent sevoflurane, achieving BSA for 1 hour) or sham-BSA (induction with propofol until loss of consciousness, followed by spontaneous awakening in 5-10 minutes). Decrease in the Hamilton Rating Depression Scale was larger with BSA (-6.0 +/- 7.3) than with sham-BSA (-2.5 +/- 4.5), but differences did not reach statistical significance ( t = -1.08, p = 0.3). In our sample, we have not found BSA to be superior to sham-BSA and therefore cannot consider BSA as an alternative to ECT.

The etiology and diagnosis of status epilepticus

Status epilepticus (SE) is a common, serious, potentially life-threatening, neurologic emergency characterized by prolonged seizure activity. Generalized convulsive status epilepticus (GCSE) is the most widely recognized form of SE. Direct consequences of convulsive movements from SE can result in injury to the body and brain. Nonconvulsive status epilepticus (NCSE) is underrecognized, with controversy surrounding the consequences and treatment. High mortality rates with GCSE have been noted in the past. New treatments for SE are emerging with new parenteral drug formulations as well as new agents for refractory SE, offering an opportunity to improve outcome. Special drug delivery systems, drug combinations, and neuroprotective agents that prevent the subsequent development of epilepsy may soon emerge as future options for treating SE.

Status epilepticus

Status epilepticus is a medical emergency that requires rapid and vigorous treatment to prevent neuronal damage and systemic complications. Failure to diagnose and treat status epilepticus accurately and effectively results in significant morbidity and mortality. Cerebral metabolic decompensation occurs after approximately 30 min of uncontrolled convulsive activity, and the window for treatment is therefore limited. Therapy should proceed simultaneously on four fronts: termination of seizures; prevention of seizure recurrence once status is controlled; management of precipitating causes of status epilepticus; management of the complications. This article reviews current opinions about the classification, aetiology and pathophysiology of adult generalised convulsive status epilepticus and details practical management strategies for treatment of this life-threatening condition.

Status epilepticus

Status epilepticus is a serious medical emergency that requires prompt and appropriate intervention. Maintenance of adequate vital function with attention to airway, breathing, and circulation; prevention of systemic complications; and rapid termination of seizures must be coupled with investigating and treating any underlying cause. In most patients with SE, the use of adequate dosages of first-line antiepileptic agents allows for the successful and rapid termination of SE and avoidance of potential neurologic complications. Refractory SE requires more aggressive treatment, often the use of intravenous anesthetic agents and intense monitoring, and therefore must be managed in a pediatric intensive care unit with a multidisciplinary approach. Large, controlled, multicenter, comparative studies are needed urgently to clarify better the optimal management of these patients.

Activation of interictal spiking in mesiotemporal lobe epilepsy by propofol-induced sleep

The objective of this study was to test whether low-dose propofol increases the number of interictal spikes in patients with mesiotemporal lobe epilepsy, and to determine whether this is the result of intrinsic properties and is restricted to the primary epileptogenic focus. Controlled infusion of propofol in step-up/-down target concentrations of 0, 0.3, 0.6, and 0.8 mg/L was administered to 10 patients during a 3.5-hour daytime EEG registration. The number of spikes were counted and related to propofol concentration and sleep level. Results were compared with a spontaneous, nocturnal first sleep cycle in 9 of 10 patients. All patients entered nonrapid eye movement 1 sleep during propofol administration, and 8 reached nonrapid eye movement 2 sleep. In 7 patients who showed spikes, spikes were related to sleep (P < 0.05) and not to increasing (P = 0.1) or decreasing (P = 0.5) propofol concentration. Six of nine patients showed more spikes during spontaneous (nocturnal) sleep than during propofol-induced sleep. Contralateral spiking was not suppressed selectively. Low-dose propofol is a safe means of increasing spiking in these patients because it induces sleep. There were no signs of an intrinsic epileptogenicity of propofol or a selective effect on ipsilateral spikes. Controlled sleep induction will increase the yield of interictal spikes during short interictal recordings such as in magnetoencephalography.

Treatment of status epilepticus

The approach to treatment of status epilepticus has changed because of the demonstration of decreased mortality with rapid intervention, completion of a randomized, double-blind VA Cooperative study comparing first-line agents, and further understanding of the pathophysiologic changes discovered in experimental animal studies. This article reviews the treatments of generalized convulsive status epilepticus in the prehospital, emergency department, and intensive care unit settings.

[Status epilepticus: pharmacokinetic basis of anticonvulsant treatment in adults]

In status epilepticus, the optimal efficacy of the antiepileptic drugs depends notably on effective, quickly reached and sufficiently lasting cerebral concentrations and the optimal tolerability notably on the lack of excessive storage in the brain and other tissues. So, the best efficacy-tolerability ratio of these drugs is largely determined by their pharmacokinetic properties. A linear kinetics, a not too short distribution half-life, a neither too brief nor too long elimination half-life, a fast and easy crossing of the blood-brain barrier and the lack of long-lasting accumulation in fat tissues are among the main ideal pharmacokinetic properties. Any of the antiepileptic drugs currently used in status epilepticus has all these properties together. An accurate knowledge of the pharmacokinetics is absolutely crucial to rationally decide the route of administration, the loading dose and the maintenance doses. However, pharmacokinetics must only complete, but cannot replace, the clinical experience and judgement, especially because some limitations: kinetic equations are mathematically exact but theoretical; individual kinetics in a given patient is exceptionally known in clinical practice; finally the pharmacokinetics may be significantly modified during a status epilepticus, especially of the generalized convulsive type, due to systemic consequences and complications of the seizures. In the emergency situation of status epilepticus, the correlation between the clinical efficacy and the so-called "therapeutic" plasma levels remains ill defined. The reported values are often very high and their range appears very large. Nevertheless plasma levels are useful, especially for the monitoring of the evolution; they are mandatory for nonlinear-kinetics drugs.

The anticonvulsant effects of volatile anesthetics on penicillin-induced status epilepticus in cats

Volatile anesthetics may be used to treat status epilepticus when conventional drugs are ineffective. We studied 30 cats to compare the inhibitory effects of sevoflurane, isoflurane, and halothane on penicillin-induced status epilepticus. Anesthesia was induced and maintained with one of the three volatile anesthetics in oxygen. Penicillin G was injected into the cisterna magna, and the volatile anesthetic discontinued. Once status epilepticus was induced (convulsive period), the animal was reanesthetized with 0.6 minimum alveolar anesthetic concentration (MAC) of the volatile anesthetic for 30 min, then with 1.5 MAC for the next 30 min. Electroencephalogram and multiunit activity in the midbrain reticular formation were recorded. At 0.6 MAC, all anesthetics showed anticonvulsant effects. Isoflurane and halothane each abolished the repetitive spike phase in one cat; isoflurane reduced the occupancy of the repetitive spike phase (to 27%+/-22% of the convulsive period (mean +/- SD) significantly more than sevoflurane (60%+/-29%; P < 0.05) and halothane (61%+/-24%; P < 0.05), and the increase of midbrain reticular formation with repetitive spikes was reduced by all volatile anesthetics. The repetitive spikes were abolished by 1.5 MAC of the anesthetics: in 9 of 10 cats by sevoflurane, in 9 of 9 cats by isoflurane, and in 9 of 11 cats by halothane. In conclusion, isoflurane, sevoflurane, and halothane inhibited penicillin-induced status epilepticus, but isoflurane was the most potent.

IMPLICATIONS

Convulsive status epilepticus is an emergency state and requires immediate suppression of clinical and electrical seizures, but conventional drugs may be ineffective. In such cases, general anesthesia may be effective. In the present study, we suggest that isoflurane is preferable to halothane and sevoflurane to suppress sustained seizure.

Anesthesia and epilepsy

The patient with epilepsy is an anesthetic challenge. New drugs and surgical procedures are being used to treat epilepsy. Certain anesthetics have been reported to cause perioperative seizures. This discussion will focus on advances in the treatment of epilepsy, as well as the pro- and anti-convulsant effects of the newer anesthetic agents.

Convulsive Status Epilepticus

Generalized convulsive status epilepticus (GCSE) is a medical emergency that must be treated rapidly and aggressively to prevent neuronal damage. Treatment should be initiated with intravenous lorazepam, 0.1 mg/kg, given at a rate of no more than 2 mg/min. If convulsions persist for more than 10 minutes or recur more than 20 minutes after lorazepam therapy is started, then fosphenytoin (20 mg of phenytoin equivalents per kilogram) should be infused at a rate of no more than 150 mg/min. If convulsions still continue, intravenous general anesthesia with pentobarbital, benzodiazepine drip, or propofol should be initiated after respiratory support has been established. All patients with GCSE who do not recover consciousness should be monitored with electroencephalography (EEG), and any residual epileptiform activity on EEG, including periodic epileptiform discharges (PEDs), should be considered evidence of continuing GCSE and treated aggressively.