A seizure that lasts longer than 5 minutes, or multiple seizure episodes with no intervening periods of consciousness is the current accepted definition of status epilepticus. Observe carefully for seizure activity in the patient in coma. Signs of convulsive status epilepticus (CSE) may be subtle (deviation of head or eyes; repetitive jerking of fingers, hands, or one side of the face).
Use a nasopharyngeal airway. Administer 100% oxygen by nasal cannula or non-rebreathing face mask and monitor with pulse oximetry. Be prepared for possible endotracheal intubation if anticonvulsants therapy fails to terminate the seizure or causes respiratory depression after seizure termination (see Chapter 9).
INSERT AN INTRAVENOUS CATHETER
Obtain blood specimens for glucose, electrolytes, magnesium, and phosphate determinations; hepatic and renal function tests; and complete blood count; as well as additional tubes of blood for possible toxicology screen or measurement of anticonvulsant levels if the patient is known or suspected to be on these medications. Consider blood and urine cultures as needed based on the presentation.
Obtain bedside glucose and administer 2.5 mL/kg of 10% dextrose solution if the patient is hypoglycemic. If an intravenous (IV) line cannot be established, hypoglycemia can be treated with glucagon, given intramuscularly or subcutaneously at a dose of 0.03 mg/kg, maximum of 1 mg.
PHARMACOLOGICAL TREATMENT PROTOCOL
Administer lorazepam, 0.1 mg/kg IV (max dose 5 mg) over 1 minute. Repeat lorazepam dose in 5 minutes if the seizure has not terminated. Diazepam 0.2 mg/kg is an alternative. The two drugs have been shown to be equally effective as first-line choices. Lorazepam has a longer duration of action compared with diazepam. Because of this property, lorazepam is currently considered the drug of choice. If venous access cannot be obtained, midazolam, 0.2 mg/kg, can be administered by several routes: intramuscularly, intranasal, or buccal. Alternatively, diazepam can be given rectally 0.2-0.5 mg/kg (Figure 20–1).
Pharmacological treatment for status epilepticus.
Phenytoin or Fosphenytoin
If the seizure persists after two adequate doses of benzodiazepine, administer phenytoin or fosphenytoin as the second-line anticonvulsant drug. Infusion of phenytoin at rapid rates can precipitate cardiac arrhythmias and hypotension. These unwanted side effects can be avoided by the use of fosphenytoin (a prodrug of phenytoin) which can be given faster than phenytoin. Fosphenytoin dosage is expressed as phenytoin equivalent (PE). The dose is 25-30 mg PE/kg IV at a rate up to 150 PE/min. Administer phenytoin 25-30 mg/kg by IV infusion at a maximum rate of 50 mg/min.
There is no consensus on the definition for refractory status epilepticus (RSE). Recent literature is supporting a definition of RSE to be any seizure that continues for 60 minutes after the administration of both first- and second-line agents. Consider administration of one of the following anticonvulsant drugs for patients with RSE (levetiracetam, valproic acid, phenobarbital). Intubation may be required with the administration of these drugs. Continuous electroencephalography (EEG) monitoring should be considered if it is readily available while using these drugs in patients with RSE. If seizure activity persists for 5 minutes after completion of administration of a third-line agent, consider administration of an additional third-line agent, or proceed to induction of coma.
Levetiracetam has shown to be effective in termination of RSE. Administer a dose of 40 mg/kg IV at a rate of 5 mg/kg/min. The drug has attractive features for RSE with almost no drug interactions, rare allergic reactions, and minimal respiratory and cardiovascular effects with IV dosing. In addition, it is safe in patients with metabolic and liver disease.
Valproic acid is reported to be effective in termination of RSE. Administer a dose of 40 mg/kg IV at a rate of 5 mg/kg/min. Advantages of the drug are excellent safety profile and ease of administration. It is contraindicated in patients with metabolic and liver disease and in patients with thrombocytopenia.
Administer phenobarbital at a dose of 20-30 mg/kg. Common complications with phenobarbital at this dose include hypotension and respiratory depression. Endotracheal intubation is often necessary. Patients with hemodynamic instability should not receive this drug.
Failure to terminate seizure activity after administration of a third-line agent is the indication for general anesthetics to induce coma. The selection of agent should be based on availability, physician familiarity with the drugs, and side effects. Consultation with a neurologist and continuous EEG monitoring are indicated. Endotracheal intubation will typically be required.
Administer midazolam in a loading dose of 0.2 mg/kg (10 mg max) given over 2 minutes followed by an infusion of 0.1 mg/kg/hr. If seizure activity persists, administer a second bolus dose of 0.2 mg/kg and continue the infusion. If the seizure is not terminated, administer a third bolus and increase infusion to 0.2 mg/kg/hr. Side effects are minimal, and hypotension is rare. There seems to be increased risk of seizure recurrence with midazolam compared with other agents.
Administer pentobarbital at a loading dose of 3-5 mg/kg followed by infusion of 1 mg/kg/hr titrated to burst suppression on EEG with maximum infusion dose of 10 mg/kg/hr. Hypotension and myocardial depression are prominent side effects.
Evidence exists that propofol is superior to midazolam and the shorter-acting barbiturates to terminate RSE. Administer propofol at a dose of 1-2 mg/kg load followed by infusion of 1-15 mg/kg/hr. Propofol infusion syndrome in children is well described and limits use of the drug for RSE. Clinical features are acute refractory bradycardia leading to asystole with at least one of the following: hyperlipidemia, rhabdomyolysis, metabolic acidosis, or fatty infiltration of the liver. It is strongly associated with prolonged use greater than 48 hours and dose greater than 4 mg/kg/hr.
Patients in status epilepticus or those given anticonvulsant medications that are strong respiratory depressants often require endotracheal intubation to protect the airway and maintain adequate ventilation. Monitor pulse oximetry and blood gas measurements to follow the adequacy of oxygenation and ventilation.
Noncontrast head computed tomography (CT) scan should not be performed routinely for patients with status epilepticus. After termination of the seizure and stabilization, the following should undergo CT scan.
Patients presenting with partial seizures
Patients with a focal neurological examination
Patients suspected to have intracranial hypertension
Patients with a head injury
Neonates and infants
Lumbar puncture should not be performed routinely on a patient with status epilepticus. The decision should be driven based on the clinical presentation. Perform lumbar puncture if fever is greater than 38.5°C (101.2°F) or nuchal rigidity is present. Muscle activity of status epilepticus may produce transient fever. Neonates that present with status epilepticus should have a lumbar puncture. Status epilepticus may produce a mild transient cerebrospinal fluid pleocytosis in up to 20% of patients.
Patients with CSE should be admitted to the hospital. Admission to intensive care unit (ICU) is required for patients who received large doses of antiepileptic agents, and those requiring continuous EEG and respiratory monitoring or support.
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