By Dr. Abdolghader Pakniayt, peer-reviewed by Dr. S. Berdouk.

Status Epilepticus — Shift Cheat Sheet (ED)

Mantra: Right drug. Right dose. Right now.
Targets: Benzo ≤5–10 min → Second-line ≤20 min → cEEG ≤60 min

0–2 min — Stabilize & Screen

• Airway position/suction, O₂; monitors; temp.
• Access: 2 IVs; IO if no IV by 2–3 min.
• Check glucose; treat if low. Consider pregnancy test when relevant.
• Prep RSI if vomiting, apnea, or failure to protect airway.

≤5 min — First-line benzodiazepine (full dose)

• No IV: Midazolam 10 mg IM (adult); repeat same dose once in 5–10 min if needed.
• IV present: Lorazepam 0.1 mg/kg IV (max 4 mg) or Midazolam 10 mg IV; may repeat once in 5–10 min.
• Pearl: Respiratory risk from underdose + ongoing SE > risk from proper dose.

5–20 min — Second-line (pick ONE, load fully)

• Levetiracetam 60 mg/kg IV (max 4.5 g) over 5–15 min.
• Valproate 20–40 mg/kg IV (max 3 g), up to 10 mg/kg/min.
• Fosphenytoin 20 mg PE/kg IV (max 1.5 g PE), ≤150 mg PE/min; cardiac monitor.
  Choosing: LEV (few interactions/renal), VPA (avoid if severe liver disease/pregnancy), FOS-PHT (Na⁺ channel effect; watch hypotension/arrhythmias).

20–40 min — Refractory SE (RSE) → Polytherapy bundle + cEEG

• Intubate if not already; start continuous infusions targeting electrographic control.
• GABA infusion:
  • Midazolam: e.g., 0.1–0.2 mg/kg bolus, then 0.05–2 mg/kg/h (titrate; tachyphylaxis common).
  • Propofol: e.g., 1–2 mg/kg load, then 50–200 mcg/kg/min (watch BP/PRIS).
• Add NMDA block: Ketamine 2 mg/kg IV load → 1.5–10 mg/kg/h (hemodynamics friendly).
• Add a long-acting ASM not yet used:
  • Lacosamide 200–400 mg IV load (watch PR prolongation), or
  • Phenobarbital 20 mg/kg IV (anticipate hypotension/resp depression, esp. with benzos).
• Maintain suppression 24–48 h before weaning.

NCSE — Don’t miss the silent fire

• If not waking 30–60 min after motor stop, assume NCSE → cEEG ASAP (≤60 min).
• Subtle signs: ocular deviation, eyelid/facial myoclonus, small automatisms, fluctuating coma.

Diagnostics (don’t delay meds)

• Labs: glucose first; Na⁺, Ca²⁺, Mg²⁺, PO₄, CBC, LFTs, renal, tox as indicated; ASM levels if on therapy.
• CT head if trauma/focal deficit/anticoagulation/immunocompromise/fever/cancer/age >40/persistent altered state.
• LP if encephalitis/meningitis suspected (after CT when indicated).

Special etiologies & antidotes (treat in parallel)

• INH toxicity: Pyridoxine 5 g IV (or gram-for-gram vs. INH dose).
• Eclampsia: MgSO₄ 4–6 g IV load → 1–2 g/h; obstetrics/ICU.
• Severe hypoNa⁺/hypoCa²⁺: correct promptly (e.g., 3% saline bolus for hyponatremic seizures; CaCl₂/CaGluconate for hypocalcemia).
• Theophylline, TCA, cocaine: avoid phenytoin/fosphenytoin; prefer LEV/VPA + sedation ± ketamine.

Airway & safety

• Anticipate hypotension with propofol/barbiturates; have vasopressors ready.
• If paralyzing, ensure EEG (avoid masking ongoing seizures).
• Manage hyperthermia, rhabdo (fluids, CK), lactic acidosis; prevent pressure injuries.

Do / Don’t (common pitfalls)

• Do: full-dose benzo by ≤5–10 min; one full second-line by ≤20 min; early IO if access fails.
• Don’t: stack partial doses of multiple second-lines; wait for CT before treating; forget cEEG when not waking.

KPIs (track monthly)

• Benzo given ≤5 min; correct adult dose (IM midazolam 10 mg).
• Second-line ≤20 min after inadequate benzo, If the patient is still seizing, start the second medication immediately.
• cEEG ≤60 min if persistent encephalopathy/RSE suspected.

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Pocket doses (adult quick refs):

• Midazolam IM 10 mg; Lorazepam 0.1 mg/kg IV (max 4 mg).
• LEV 60 mg/kg (max 4.5 g); VPA 20–40 mg/kg (max 3 g); FOS-PHT 20 mg PE/kg (max 1.5 g PE).
• Ketamine 2 mg/kg → 1.5–10 mg/kg/h; Lacosamide 200–400 mg; Phenobarbital 20 mg/kg.

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Deep Dive

Status epilepticus (SE) is a dynamic neurotoxic emergency in which synaptic mechanisms evolve over minutes, changing the pharmacology required for control. The International League Against Epilepsy (ILAE) emphasizes two treatment anchors: T1 ≈ 5 minutes (start therapy) and T2 ≈ 30 minutes (risk of neuronal injury) for generalized convulsive SE (GCSE). Early, weight-based benzodiazepines remain first-line, followed rapidly by one full-dose second-line antiseizure medication (ASM). Contemporary data support parity among levetiracetam, valproate, and fosphenytoin; selection should be pragmatic. If seizures persist (refractory SE, RSE), physiology and clinical series support multi-mechanism polytherapy—typically a GABAergic anesthetic plus NMDA antagonism (ketamine) and an additional long-acting ASM—titrated by continuous EEG (cEEG). Novel neurosteroid ganaxolone (extrasynaptic and synaptic GABA-A potentiation) shows promise in early clinical trials; phase 3 is in progress. In NORSE/FIRES, early immunotherapy is reasonable while ruling out infection. This review translates these updates into an ED-first algorithm with concrete dosing, safety checks, and systems KPIs.

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Clinical Snapshot — the First Five Minutes Decide the Next Five Days

A 79-year-old with atrial fibrillation arrives convulsing; EMS gave 5 mg IM midazolam en route. At minute 9, he remains in tonic–clonic activity; glucose 108 mg/dL, BP 168/92, SpO₂ 89% on NRB, no IV access.

The ILAE T1/T2 framework clarifies why speed matters: treat by 5 minutes to avoid the ~30-minute injury window in convulsive SE.

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1) Pathophysiology in Three Phases—Why Timing Changes the Drug You Need

Phase A: Impending SE (0–5 min)
Glutamatergic surge (AMPA/NMDA) drives synchronized firing; GABA-A receptors are still abundant → benzodiazepines have high effect. (Framework consistent with ILAE timing rationale.)

Phase B: Established SE (~5–30 min)
With ongoing seizures, GABA-A receptors internalize, while NMDA currents sustain excitotoxicity; benzos lose potency → weight-based, non-benzo second-line ASMs are required. (Guidelines reflect earlier start of treatment and escalating therapy in this window.)

Phase C: Refractory/Super-Refractory (>30–60 min)
Network injury pathways predominate; clinical motor activity may wane despite electrographic seizures—cEEG is essential.

Take-home: Treat SE as a moving target: early GABAergic therapy, then rapid mechanism-diverse escalation (Na-channel agents, NMDA antagonism, neurosteroids) with EEG guidance.

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2) Recognition & Classification—Don’t Miss the Silent Half

Operational definition: Seizure ≥5 min or recurrent without recovery = SE; for generalized convulsive SE, T1 = 5 min, T2 ≈ 30 min.

Nonconvulsive SE (NCSE): In older adults, NCSE often presents as persistent altered mentation with subtle motor signs; mortality is high (≈27–52%), and overtreatment can harm via hypotension/arrhythmias/sedation—hence the need for EEG to titrate “enough, not too much.” Trinka underscores that NCSE has become more visible with validated EEG criteria and carries worse outcomes than promptly-treated convulsive forms.

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3) ED Workflow by the Clock—What to Do and When

Mantra: Right drug. Right dose. Right now. The biggest failures are underdosing and delays.

0–2 minutes — Stabilize + Screen

Airway/oxygen/monitor; suction; obtain two IVs or IO (if IV not in ≤2–3 min); check glucose; prepare RSI when indicated. (ED practice primer)

≤5 minutes — Benzodiazepine (full dose)

• No IV: Midazolam 10 mg IM; repeat once in 5–10 minutes if needed.
• IV present: Lorazepam 0.1 mg/kg IV (max 4–8 mg; many experts favor higher initial IV dose in the critically ill) or Midazolam 10 mg IV.
  Pearl: Treat early; adequate benzo dosing reduces respiratory harm versus ongoing SE.

5–20 minutes — Second-Line (pick one, load fully)

• Levetiracetam 60 mg/kg IV (max 4500 mg), 5–15 min.
• Valproate 20–40 mg/kg IV (practice-based ranges; see guideline variability).
• Fosphenytoin 20 mg PE/kg IV, ≤100–150 mg PE/min, with monitoring.
  ESETT-era guidance: these agents have similar efficacy; choose by patient factors, interactions, and logistics.

20–40 minutes — Refractory SE (RSE)

• Secure airway if needed; start continuous infusions and cEEG.
• GABAergic anesthetic (midazolam/propofol) ± ketamine (see §5) and add a mechanistically distinct ASM (e.g., lacosamide, phenobarbital) not already used—this is polytherapy guided by EEG.
• Many ongoing seizures here are nonconvulsive—EEG is the only way to know you’ve won.

By 60 minutes — cEEG running; maintain electrographic control (often 24–48 h) before weaning in RSE.

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4) Pharmacology—Practical Doses & When to Prefer Which

Benzodiazepines (first line)

• Midazolam 10 mg IM (preferred if no IV).
• Lorazepam 0.1 mg/kg IV (max 4–8 mg); higher initial IV dose is reasonable in the critically ill.
• Avoid IM/IN diazepam in the ED due to erratic absorption/delay.

Second-line ASMs (choose one, load fully)

• Levetiracetam 60 mg/kg IV (max 4.5 g), 5–15 min; favored for minimal interactions, hepatic safety.
• Valproate 20–40 mg/kg IV; consider in myoclonus or where Na-channel blockade is undesirable.
• Fosphenytoin 20 mg PE/kg IV (≤150 mg PE/min); monitor for hypotension/arrhythmias; avoid IM for GCSE.

Refractory SE (infusions and add-ons)

• Midazolam/Propofol infusions with vasopressor readiness; beware PRIS with high-dose/long duration propofol. (Comprehensive RSE reviews summarized in your sources.)
• Ketamine: 2 mg/kg IV load → 1.5–10 mg/kg/h, titrate to electrographic control; hemodynamically friendlier than other anesthetics.
• Lacosamide and phenobarbital are useful adjuncts in RSE; mind conduction effects (PR prolongation) with lacosamide and cumulative respiratory depression with benzos + barbiturates. (Adjunct strategy reflected across ED/RSE guidance.)

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5) Polytherapy—What’s New and How to Do It Safely

Why polytherapy? As SE persists, GABA-A internalizes while NMDA currents dominate; single-mechanism escalation underperforms. Preclinical work shows synergy with midazolam + ketamine, simultaneous triple therapy, and early polytherapy for benzo-refractory SE.

What your clinical sources support now:

• RSE: Combine a GABAergic infusion (midazolam/propofol) ± ketamine, and add a long-acting ASM not already used (e.g., lacosamide or phenobarbital) under cEEG.
• Early simultaneous multi-drug loading (before RSE) is physiology-plausible but remains a field for clinical trials, not current standard of care. (Guidelines still recommend one full-dose second-line, then escalate decisively.)

Safety notes: Expect hypotension with sedative combinations; plan airway and vasopressors. Avoid fosphenytoin/phenytoin in suspected toxicologic etiologies or in patients already on these agents due to cardiovascular risk.

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6) Innovations That Change Practice

A) Ketamine (NMDA antagonism)
Mechanistically ideal as minutes pass; 2 mg/kg load → 1.5–10 mg/kg/h; series and systematic reviews support efficacy in RSE/SRSE, with favorable hemodynamics.

B) Ganaxolone (neurosteroid)
Potentiates synaptic and extrasynaptic GABA-A → may bypass benzo resistance. Phase 2 open-label RSE data reported; phase 3 RAISE ongoing and case experiences in SRSE exist.

C) AMPA antagonism / newer agents
Perampanel has growing, though heterogeneous, support in systematic review for SE cessation; consider as an adjunct in SRSE with expert input.

D) NORSE/FIRES—immunotherapy
When autoimmune/inflammatory SE is suspected, initiate steroids/IVIG/PLEX early; cohort data associate earlier anakinra/tocilizumab with shorter SE duration.

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7) Airway & Sedation Strategy in SE

When to intubate: recurrent apnea/hypoxia, failure to protect airway, need for continuous anesthetics, or to facilitate imaging safely. Induction: propofol or propofol + ketamine (synergistic GABA/NMDA), then short-acting paralytic if needed—avoid prolonged paralysis until EEG is available.

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8) Diagnostics You Can’t Skip (but Don’t Let Them Delay Drugs)

Labs: POC glucose first; electrolytes (Na⁺, Ca²⁺, Mg²⁺), renal/liver panel, tox as indicated; ASM levels if on therapy.
Imaging: Noncontrast head CT when red flags present (trauma, focal deficit, anticoagulation, immunocompromise, cancer, age >40, persistent altered state) and in SE generally—but treat first.
EEG: If mental status does not normalize rapidly, assume NCSE and obtain cEEG within ~1 h, as a significant fraction of “improved” patients still seize electrographically.

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9) Special Populations—Older Adults

NCSE is common, often without prior epilepsy; mortality 27–52% in critically ill older patients; balance adequate therapy with iatrogenic risks (hypotension, arrhythmia, prolonged sedation). Clinical vigilance for subtle facial twitching, nystagmus, or minor automatisms is essential; confirm with EEG.

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10) One-Page ED Algorithm (Text)

1. 0–2 min: ABCs, oxygen, suction; IV/IO; check glucose; prepare RSI as needed.
2. ≤5 min (T1): Midazolam 10 mg IM (if no IV) or Lorazepam 0.1 mg/kg IV (max 4–8 mg); repeat once in 5–10 min if needed.
3. 5–20 min: Load one: LEV 60 mg/kg (max 4.5 g), VPA 20–40 mg/kg, FOS-PHT 20 mg PE/kg; choose pragmatically.
4. 20–40 min (RSE): Intubate as needed; start midazolam/propofol infusion; add ketamine (2 mg/kg → 1.5–10 mg/kg/h) and add another ASM not yet used (e.g., lacosamide or phenobarbital) under cEEG.
5. ≤60 min: cEEG on; titrate to electrographic control 24–48 h before wean. Consider immunotherapy for NORSE/FIRES and discuss ganaxolone via trial/compassionate access at capable centers.

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11) Quality & Systems—Make It Hard to Do the Wrong Thing

Key Performance Indicators (KPIs)

• First benzodiazepine ≤5–10 min from onset/arrival.
• Appropriate benzo dose (e.g., adult midazolam 10 mg IM).
• Full-dose second-line ASM ≤20 min after inadequate benzo response.
• cEEG ≤60 min when encephalopathy persists or RSE suspected.

Implementation Tips

• Build an SE order set with weight-based defaults and nurse-driven timers.
• Stock IM/IN midazolam at triage/EMS; reinforce 10 mg IM adult dosing.
• Run mock codes; audit KPI performance and feedback monthly.

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12) Dosing Rails (quick-reference)

(Keep tables for numbers only; give prose above for context.)

Drug	Adult initial dosing (ED/RSE context)
Midazolam	10 mg IM once; may repeat ×1 if needed.
Lorazepam	0.1 mg/kg IV (max 4–8 mg); may repeat ×1.
Levetiracetam	60 mg/kg IV (max 4500 mg), 5–15 min.
Valproate	20–40 mg/kg IV (guideline range).
Fosphenytoin	20 mg PE/kg IV, ≤100–150 mg PE/min; monitor.
Ketamine (RSE)	2 mg/kg IV load → 1.5–10 mg/kg/h infusion, cEEG-guided.

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13) Limitations & Future Directions

• Evidence gaps remain for simultaneous early polytherapy in humans; preclinical synergy and physiology justify trials.
• Ganaxolone is promising but not yet standard of care outside trials/compassionate pathways.
• Optimal cEEG targets (burst suppression vs. seizure-free) and weaning strategies need prospective definitions.

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14) Bottom Line

SE therapy must track the biology over time. Dose full benzos by ≤5 min, fully load one second-line ASM by ≤20 min, and do not linger—if refractory, pivot to polytherapy that mixes GABA and NMDA mechanisms under cEEG. In older or persistently encephalopathic patients, assume NCSE until proven otherwise. This is how we turn a nine-minute seizure in triage into a neurologically intact discharge a week later.

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