Prehospital Management of Seizures
A seizure is a surge of abnormal electrical activity in the brain that temporarily alters body movement, sensation, or awareness [1.8.5]. While many seizures resolve on their own within minutes, a seizure lasting longer than five minutes is considered status epilepticus, a medical emergency requiring prompt intervention to prevent long-term brain damage or death [1.2.4]. When Emergency Medical Services (EMS) respond, their initial priority is to ensure patient safety and perform a rapid assessment using the ABCDE (Airway, Breathing, Circulation, Disability, Exposure) approach [1.5.1]. This includes protecting the patient from injury, ensuring the airway is clear, providing oxygen if needed, and checking for reversible causes, with a blood glucose check being a critical step [1.5.1, 1.5.4].
First-Line Medications: The Role of Benzodiazepines
Benzodiazepines are the cornerstone of prehospital seizure treatment [1.3.4]. These medications work by enhancing the effect of the neurotransmitter GABA (gamma-aminobutyric acid), which has an inhibitory or calming effect on the brain's electrical activity [1.3.2, 1.3.4]. Guidelines from the American Epilepsy Society recommend benzodiazepines as the first-line treatment for status epilepticus [1.3.6].
The three most common benzodiazepines used by paramedics are:
- Midazolam (Versed): This is a very common choice in the prehospital setting due to its effectiveness and multiple administration routes [1.2.7]. It can be given intramuscularly (IM), intravenously (IV), or intranasally (IN) [1.4.2].
- Lorazepam (Ativan): Considered a drug of choice for status epilepticus, lorazepam is highly effective when given intravenously [1.3.4]. It has a longer duration of action in the central nervous system compared to diazepam [1.4.2]. However, its use in the prehospital setting can be limited by the need for refrigeration [1.4.3].
- Diazepam (Valium): This drug has a very rapid onset when given IV but is also highly lipid-soluble, meaning it redistributes quickly out of the brain, leading to a shorter duration of clinical effect [1.3.4]. It can also be administered rectally (Diastat), a common form prescribed for at-home use [1.2.3, 1.3.4].
Routes of Administration: A Critical Choice
The method of drug delivery is just as important as the drug itself. The goal is to stop the seizure as quickly and safely as possible.
- Intravenous (IV): Administering medication directly into a vein provides the fastest onset of action [1.3.4]. However, establishing IV access on a convulsing patient can be difficult and time-consuming [1.4.3].
- Intramuscular (IM): Injecting medication into a large muscle is often faster to perform than starting an IV on a seizing patient [1.4.3]. The RAMPART study, a major clinical trial, found that IM midazolam was non-inferior and even superior in some outcomes to IV lorazepam for stopping seizures before hospital arrival, largely because it could be administered more quickly [1.4.1, 1.4.3]. This has made IM midazolam a preferred first-line treatment in many EMS systems, especially when IV access is not already established [1.6.4].
- Intranasal (IN): Spraying atomized medication into the nose is a less invasive option that allows for rapid absorption through the nasal mucosa [1.6.5]. It's a particularly useful route in pediatric patients or when an injection is difficult [1.6.1, 1.6.3]. However, some studies suggest IN midazolam may be associated with a higher need for a second rescue dose compared to IV or IM routes [1.6.1].
Comparison of First-Line Benzodiazepines
| Feature | Midazolam (Versed) | Lorazepam (Ativan) | Diazepam (Valium) |
|---|---|---|---|
| Common Routes | IM, IV, IN, Buccal [1.4.2] | IV [1.4.2] | IV, Rectal [1.4.2] |
| Onset (IV) | < 3 minutes [1.3.4] | ~2 minutes [1.3.4, 1.4.2] | ~1-3 minutes [1.4.2] |
| Onset (IM) | ~5-15 minutes [1.4.2] | Not recommended (erratic) [1.4.2] | N/A |
| Onset (IN) | ~3-10 minutes [1.4.2] | N/A | N/A |
| Duration | 2-6 hours [1.4.2] | 4-6 hours [1.4.2] | 15-30 minutes [1.4.2] |
| Prehospital Notes | Often preferred for IM use due to rapid administration and effectiveness [1.4.3]. | Very effective IV, but storage can be an issue for EMS (requires refrigeration) [1.4.3]. | Fast-acting IV but has a high rate of seizure recurrence due to short duration [1.3.4]. |
Second-Line and Refractory Seizure Treatment
Unfortunately, up to a third of patients in status epilepticus do not respond to initial benzodiazepine treatment [1.7.2]. This is known as refractory status epilepticus. In these cases, paramedics, often with guidance from online medical control, may move to second-line medications. Options for second-line therapy include anticonvulsant drugs like Levetiracetam (Keppra), Fosphenytoin, or Valproic Acid [1.7.2, 1.7.6].
More recently, some EMS systems have adopted protocols for using Ketamine as a rescue drug for seizures that are resistant to benzodiazepines [1.3.3]. Ketamine works on a different receptor in the brain (NMDA receptor) and has been shown to be effective in terminating ongoing seizures when first-line drugs have failed [1.3.3, 1.7.6].
Conclusion
The primary medications paramedics use to stop seizures are benzodiazepines, with midazolam, lorazepam, and diazepam being the most common [1.5.5]. The choice of which drug to use is guided by EMS protocols, patient factors, and the available routes of administration. The ability to administer midazolam intramuscularly has been a significant advancement, allowing for rapid treatment without the delay of establishing IV access [1.4.3]. For seizures that persist despite these first-line treatments, paramedics may utilize second-line agents like other anticonvulsants or ketamine to bring the medical emergency under control [1.7.5].
For more information on seizure management guidelines, you can visit the American Epilepsy Society. [1.3.1]
