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Approach to the Critical Patient
Initial stabilization
Immediate priorities
Airway patency
If ongoing convulsions, lateral positioning and suction readiness
Breathing adequacy
Oxygen if hypoxemia or respiratory depression after benzodiazepine
Circulation status
If shock, isotonic fluid bolus 20 mL/kg and reassess
Bedside glucose
If glucose <3.0 mmol/L, dextrose
D10W 5 mL/kg IV
D25W 2 mL/kg IV
D50W 1 mL/kg IV for adolescents
Seizure time and response
Time since onset
If >5 minutes, benzodiazepine pathway
Return to baseline mental status
If persistent altered mental status, expanded evaluation and admission pathway
Fever and infection risk stratification
Signs of CNS infection
If meningeal signs, petechiae, toxic appearance, or persistent encephalopathy, meningitis encephalitis pathway
Immunization status
If underimmunized for Hib or pneumococcus, lower threshold for lumbar puncture when indicated
Classification and key decision points
Febrile seizure phenotypes
Simple criteria
Generalized onset
Duration <15 minutes
Single seizure in 24 hours
No prior neurologic deficit
Complex criteria
Focal features
Duration 15 minutes or more
More than one seizure in 24 hours
Postictal deficit
Febrile status epilepticus
Continuous seizure 30 minutes or more
Recurrent seizures without return to baseline
Escalation triggers
High risk features
Persistent focal neurologic deficit
Neuroimaging consideration
Persistent altered mental status
Lumbar puncture consideration
Concern for trauma
Neuroimaging consideration
Severe dehydration or inability to tolerate oral intake
IV fluids and observation or admission consideration
Unreliable follow up or caregiver concern
Observation or admission consideration
History
Focused elements
Event characteristics
Duration estimate
Greater than 5 minutes
Greater than 15 minutes
Semiology
Generalized tonic clonic features
Focal onset or asymmetry
Number of seizures in 24 hours
Single
Multiple
Recovery course
Time to baseline
Persistent confusion
Fever and illness context
Maximum temperature
Fever at seizure onset
Fever after seizure
Fever duration before seizure
Less than 1 hour
One hour or more
Infectious symptoms
Upper respiratory symptoms
Gastrointestinal symptoms
Otalgia
Urinary symptoms
Rash
Risk modifiers
Age in months
6 to 60 months typical range
Prior febrile seizures
Number of prior episodes
Family history
Febrile seizures
Epilepsy
Developmental history
Baseline neurologic deficits
Immunization history
Hib series completion
Pneumococcal series completion
Recent antibiotics
Partially treated meningitis risk consideration
Toxin ingestion risk
Access to medications
Exposure to recreational substances in home
PITFALLS
Common misses
Rigors misclassified as seizure
Preserved awareness during shaking suggests rigors
Syncope with convulsive movements misclassified as seizure
Prodrome and rapid recovery suggests syncope
Meningitis signs absent early
Persistent altered mental status as key discriminator
Physical Exam
Core exam
General and vitals
Temperature
Persistent high fever
Heart rate and perfusion
Signs of shock
Respiratory status
Work of breathing
Oxygen saturation
Hydration
Mucous membranes
Capillary refill
Neurologic
Mental status
Return to baseline
Persistent encephalopathy
Focal deficits
Asymmetric strength
Gaze deviation
Unilateral tone abnormality
Postictal findings
Todd paresis
Meningitis encephalitis screen
Nuchal rigidity
Neck stiffness
Rash pattern
Petechiae or purpura
Bulging fontanelle in infants
Increased intracranial pressure concern
Source of fever
Otitis media
Tympanic membrane findings
Pharyngitis
Tonsillar exudate
Pneumonia
Focal crackles
Skin and soft tissue infection
Cellulitis
Urinary tract infection
Suprapubic tenderness
PITFALLS
Examination limitations
Transient postictal sleepiness
Reassess mental status over time
Subtle focality
Recheck symmetry after full recovery
Differential Diagnosis
Seizure with fever mimics and alternatives
Life threatening diagnoses
Bacterial meningitis
ICD-10 G00.9
Viral encephalitis
ICD-10 G04.90
Sepsis
ICD-10 A41.9
CNS hemorrhage
ICD-10 I61.9
Toxic ingestion
ICD-10 T50.901A
Neurologic diagnoses
First unprovoked seizure
ICD-10 R56.9
Epilepsy
ICD-10 G40.909
Febrile status epilepticus
ICD-10 R56.00
Metabolic diagnoses
Hypoglycemia
ICD-10 E16.2
Hyponatremia
ICD-10 E87.1
Hypocalcemia
ICD-10 E83.51
Non seizure paroxysms
Rigors
Fever associated shivering
Breath holding spell
Triggered by crying
Syncope
Presyncopal prodrome
Differentiating clues
Febrile seizure supportive pattern
Age 6 to 60 months
Peak incidence 12 to 18 months
Generalized seizure with rapid recovery
Baseline normal development
CNS infection supportive pattern
Toxic appearance
Persistent altered mental status
Meningeal signs
Petechiae or purpura
Laboratory Tests
Targeted testing strategy
Minimal testing for simple febrile seizure
No routine blood tests
Focus on fever source evaluation
Bedside glucose if not rapidly recovering
Persistent altered mental status
Indications for labs
Persistent altered mental status
Glucose
Electrolytes
Venous blood gas if respiratory compromise
Prolonged seizure or status epilepticus
Glucose
Sodium
Calcium
Magnesium
CBC if sepsis concern
Dehydration or poor intake
Electrolytes
Toxicology considerations
Exposure concern
Acetaminophen level
Salicylate level
Targeted tox screen per local pathways
Interpretation pearls
Electrolyte abnormalities
Mild hyponatremia common in illness
Profound hyponatremia as seizure trigger
Hypoglycemia
Ongoing seizure risk if untreated
Infection markers
CBC and inflammatory markers
Poor specificity for CNS infection
PITFALLS
Over testing harms
Incidental abnormalities
Unnecessary interventions
Delayed disposition
Low value in simple phenotype
Diagnostic Tests
Scoring Systems
Operational criteria tools
Simple febrile seizure criteria
Generalized onset
Duration <15 minutes
Single in 24 hours
Baseline normal neurologic status
Complex febrile seizure criteria
Focal features
Duration 15 minutes or more
Multiple in 24 hours
Postictal focal deficit
Lumbar puncture decision framework
Clinical concern for meningitis encephalitis
Persistent altered mental status
Meningeal signs
Bulging fontanelle
Underimmunized Hib pneumococcus in young infant
Antibiotics prior to presentation with ongoing concern
MRI
MRI brain indications
Persistent focal neurologic deficit
Concern for structural lesion
Febrile status epilepticus
Consider hippocampal injury assessment depending on local practice
Abnormal development or abnormal exam baseline
Structural evaluation
MRI brain limitations
Limited acute availability
Not a first line test in stable simple phenotype
Need for sedation in young children
Airway risk consideration
CT
CT head indications
Signs of increased intracranial pressure
Persistent vomiting
Papilledema
Concern for trauma
Scalp hematoma with high risk mechanism
Persistent focal deficit not resolving
Intracranial hemorrhage concern
CT head limitations
Low yield in typical simple febrile seizure
Radiation risk
Ultrasound (or US)
Bedside ultrasound adjuncts
Lung ultrasound for pneumonia suspicion
Consolidation pattern
Bladder ultrasound for urine retention before catheterization
Sampling facilitation
IVC or cardiac POCUS for shock evaluation
Volume status estimation
Disposition
ED observation vs discharge vs admission
Discharge pathway
Simple febrile seizure phenotype
Returned to neurologic baseline
Normal exam
Fever source identified or low risk appearance
No CNS infection concern
Caregiver capability
Reliable supervision
Return precautions understood
Observation pathway
Uncertain baseline recovery timeline
Reassessment after antipyretic and fluids as needed
First episode with high caregiver anxiety
Education and reassurance time
Admission pathway
Complex febrile seizure with concerning features
Persistent altered mental status
Persistent focal deficit
Febrile status epilepticus
Ongoing monitoring and further workup
Suspected meningitis encephalitis
Lumbar puncture and IV antimicrobials per pathway
Inability to maintain hydration
IV therapy requirement
Consultation triggers
Neurology
Complex features
Focality
Recurrent seizures in 24 hours
Prolonged duration
Abnormal developmental baseline
Epilepsy risk evaluation
Pediatrics
Admission candidate
Ongoing monitoring needs
Treatment
Acute seizure termination
First line benzodiazepines
Lorazepam IV
0.1 mg/kg
Maximum 4 mg per dose
Repeat once after 5 minutes if ongoing seizure
Respiratory depression monitoring
Diazepam IV
0.2 mg/kg
Maximum 10 mg per dose
Repeat once after 5 minutes if ongoing seizure
Respiratory depression monitoring
Midazolam intranasal
0.2 mg/kg
Maximum 10 mg per dose
Repeat once after 5 minutes if ongoing seizure
Ventilation monitoring
Midazolam IM
0.2 mg/kg
Maximum 10 mg per dose
Repeat once after 5 minutes if ongoing seizure
Hypotension monitoring
Second line antiseizure therapy for refractory seizures
Levetiracetam IV
60 mg/kg
Maximum 4500 mg
Infusion time per local protocol
Monitoring for agitation
Fosphenytoin IV
20 mg PE/kg
Maximum 1500 mg PE
If persistent seizure, additional 5 to 10 mg PE/kg
Cardiac monitoring
Valproate IV
40 mg/kg
Maximum 3000 mg
Avoid known mitochondrial disease
Avoid significant hepatic disease
Phenobarbital IV
20 mg/kg
Respiratory depression monitoring
Refractory status pathway
If ongoing convulsions after second line agent, ICU escalation
Continuous infusion pathway per institutional protocol
Fever and comfort
Antipyretics for comfort
Acetaminophen PO
15 mg/kg
Every 4 to 6 hours as needed
Ibuprofen PO
10 mg/kg
Every 6 to 8 hours as needed
Avoid dehydration with renal risk
Counseling on recurrence prevention limits
Antipyretics do not reliably prevent febrile seizure recurrence
Comfort benefit only
Long term prophylaxis
No routine daily antiseizure prophylaxis for simple febrile seizure
Adverse effects outweigh benefit
Education and reassurance preferred
Intermittent rescue medication
Consideration for recurrent prolonged febrile seizures based on clinician judgment
Rectal diazepam or intranasal midazolam prescription pathways
Special Populations
Pregnancy
Pregnancy considerations
Febrile seizure age range mismatch
Pregnancy section not applicable to typical phenotype
Seizure with fever in pregnancy
Alternate etiologies
CNS infection
Toxic ingestion
Eclampsia if hypertensive context
Geriatric
Geriatric considerations
Febrile seizure definition age mismatch
Consider seizure provoked by infection or metabolic derangement
High risk differentials
CNS infection
Stroke with seizure
Medication toxicity
Pediatrics
Age based approach
Typical age 6 to 60 months
Peak 12 to 18 months
Under 6 months with fever and seizure
Lower threshold for CNS infection evaluation
Lumbar puncture considerations
Clinical concern for meningitis encephalitis
Persistent altered mental status
Meningeal signs
Underimmunized Hib pneumococcus
Consideration when clinically indicated
Antibiotics prior to presentation with ongoing concern
Consideration when clinically indicated
Recurrence risk counseling
Higher recurrence risk
First episode before 18 months
Family history of febrile seizures
Lower fever at seizure onset
Short fever duration before seizure
Background
Epidemiology
Frequency
Occurs in a minority of children
Approximate lifetime risk 2 to 5 percent in typical populations
Recurrence
About one third have recurrence after first episode
Epilepsy risk
Simple febrile seizure
Slightly above baseline population risk
Complex febrile seizure
Higher risk than simple phenotype
Pathophysiology
Mechanism concepts
Fever as trigger in susceptible immature brain
Genetic contribution in some families
Cytokine mediated neuronal excitability changes
Infection driven inflammatory response
Natural history
Benign course for simple phenotype
Normal neurodevelopment in most cases
Therapeutic Considerations
Benzodiazepines
Rapid seizure termination
Greatest benefit when seizure exceeds 5 minutes
Key harms
Respiratory depression risk
Excess sedation risk
Neurodiagnostic testing
Routine EEG not indicated in simple phenotype
Low impact on management
Routine neuroimaging not indicated in simple phenotype
Low yield and potential harm
Prophylaxis balance
Daily antiseizure therapy generally not recommended in simple phenotype
Adverse effect burden
Intermittent prophylaxis rarely indicated
Select high burden recurrent prolonged episodes
Patient Discharge Instructions
copy discharge instructions
Home guidance
If another seizure occurs
Place on side on a safe surface
Nothing in mouth
Time the event
Fever care
Acetaminophen or ibuprofen for comfort
Fluids to prevent dehydration
Return to emergency care now
Seizure lasting more than 5 minutes
Call emergency services
Trouble breathing or persistent blue color
Emergency services
Not waking up or not acting back to normal after a reasonable recovery period
Emergency assessment
Stiff neck, severe headache, persistent vomiting, or new rash with purple spots
Emergency assessment
Weakness on one side or trouble speaking after recovery
Emergency assessment
Follow up
Primary care visit
Fever source review
Recurrence counseling
Neurology follow up
If complex features or recurrent prolonged events
References
Clinical guidelines and evidence sources
Key guidance documents
American Academy of Pediatrics guideline on neurodiagnostic evaluation of simple febrile seizures
Lumbar puncture indications based on clinical concern
American Academy of Pediatrics febrile seizure management statements
Routine EEG and neuroimaging not recommended in simple phenotype
International League Against Epilepsy definitions for febrile seizures and status epilepticus
Phenotype terminology standardization
Evidence synthesis
Meta analyses on epilepsy risk after febrile seizures
Risk stratification by simple vs complex features
Emergency seizure termination pathways
Benzodiazepine first line for seizures exceeding 5 minutes
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.