ACVC 2019: Managing status epilepticuswhat are you waiting for?

leungchopan/stock.adobe.comThe key to managing patients with status epilepticus, according to Armi Pigott, DVM, DACVECC, a criticalist at Lakeshore Veterinary Specialists in Glendale, Wisconsin, is early and very aggressive seizure control. “The longer a patient seizes,” he said this week at the 2019 Atlantic Coast Veterinary Conference, “the more it propagates and the harder it's going to be to control.”

Status epilepticus has been redefined as a seizure that lasts five or more minutes, Dr. Pigott told the audience. “They don't have to seize and cook for 30 minutes anymore,” he said. That means if a patient brings in a pet that began seizing at home and is still seizing upon arrival at the hospital, that pet is in status epilepticus.  

The best first-line drugs for treating these patients are benzodiazepines, specifically midazolam due to its ease of administration. “Midazolam just needs to go intradog,” Dr. Pigott said. It can be given intravenously, intramuscularly, intranasally, transmucosal, orally, subcutaneously or rectally. Diazepam is also useful for these patients, but it requires intravenous, nasal or rectal administration. “And in a shaking dog you want to go for the easiest route possible,” he said.

The dose is the same for both drugs: 0.5 to 1 mg/kg. For fastest action and best effect in the hospital setting, Dr. Pigott advised, administer midazolam either intravenously or intramuscularly. “We should be hitting these guys hard,” he said, “and we shouldn't be starting with less than 0.5 mg/kg if they're still actively seizing when they arrive at your hospital.”

Benzodiazepines are short-acting drugs, he cautioned. “You're going to get about 15 or 20 minutes of seizure control on the initial dose, if that,” he said. “We need to be thinking about what we're going to do for a long-acting plan.” And that plan will be different for first-time seizure patients vs. known seizure patients.

All dogs that present with status epilepticus, even if it's their first time having a seizure, should be put on antiseizure medications. The only animals that don't need to be treated immediately are those that had a brief seizure (less than two minutes) at home but are now neurologically normal. For these animals you can adopt a wait-and-see approach, he said. (Bonus tip: According to Dr. Pigott, 50% of these “wait-and-see” patients will have another seizure in 24 hours.)

For long-term management, Dr. Pigott's first-line choice is phenobarbital, which will take 30 to 60 minutes to reach peak effect. Levetiracetam (Keppra) is also a very reasonable choice, he said, and this drug reaches peak effect in about 15 to 30 minutes. Both are administered intravenously. 

Dosing these drugs will be different for patients that have just had their first seizure, Dr. Pigott said. For these patients, he gives 4 mg/kg of phenobarbital or 30 mg/kg of levetiracetam. For dogs experiencing new-onset seizures presenting with status epilepticus, he said, "I will probably load them at 16 mg/kg of phenobarbital over 4 to 24 hours, depending on the animal, in 4-mg/kg doses." He balances how frequently he gives the doses with how sedate the patient is and whether they continue to seize. "[If the drug is administered] too fast, the patient may need to be intubated or even ventilated if their respirations are really depressed by the medications," he said. 

He gives midazolam as an injection, which can be repeated five or more times for seizure control while waiting for other medications to take effect. “If I have to give more than two injections [of midazolam],” he said, “the next time they seize they're going on a constant-rate infusion (CRI, 1 mg/kg/hr). 

"You could keep going [with midazolam doses], but it's more effective for the patient to go on a CRI," he said. "Generally I want to do that as early as possible since earlier control is associated with better outcomes." They typically stay on the CRI for six to 12 hours before tapering them off.