Browse categories and answer follow-up questions to refine your symptom profile.
Approach to the Critical Patient
Triage priorities
High-risk age group
0 to 28 days with rectal temperature 38.0 C or higher
Serious bacterial infection risk even if well appearing
Treat as sepsis until proven otherwise
Immediate escalation triggers
Apnea
Cyanosis
Poor perfusion
Lethargy
Seizure
Hypotension
Initial monitoring
Continuous pulse oximetry
Cardiac monitor
Noninvasive blood pressure cycling
Temperature trend
Stabilization
Airway and breathing
Supplemental oxygen for SpO2 below local target
Bag-mask ventilation for apnea or inadequate ventilation
Early airway support for recurrent apnea or shock
Circulation
Vascular access within 5 minutes
Peripheral IV
If delayed, intraosseous
Fluid resuscitation
If shock, isotonic crystalloid 10 mL/kg bolus
Reassess after each bolus
Additional boluses up to 40 mL/kg in first hour if persistent shock and no fluid intolerance
Vasoactive support
If fluid-refractory shock, epinephrine infusion per local protocol
If cold shock with low cardiac output, epinephrine favored
If warm shock with low SVR, norepinephrine favored
Glucose and temperature
Hypoglycemia threshold 2.6 mmol/L
Dextrose bolus if 2.6 mmol/L or lower
D10W 2 mL/kg IV
Hypothermia and hyperthermia as sepsis markers
Sepsis bundle timing
Time zero
First documented rectal temperature 38.0 C or higher
First clinician recognition of sepsis physiology
Antibiotics
Within 60 minutes of sepsis recognition
After cultures if no delay
Lumbar puncture timing
Before antibiotics if stable and no delay
After antibiotics if unstable or delayed access
Key concepts
Neonatal fever framework
Immature immunity
Subtle early signs
Higher invasive bacterial infection risk than older infants
Common invasive pathogens
Escherichia coli
Group B Streptococcus
Listeria monocytogenes
Viral pathogens with high consequence
HSV risk highest in first weeks of life
Enterovirus consideration in season
History
Fever characterization
Fever details
Highest temperature
Method of measurement
Antipyretic exposure
Time course
Onset time
Duration
Trend
Vaccines
Immunization in prior 48 hours
Birth hepatitis B timing
Symptoms and functional change
Feeding and hydration
Intake decrease
Emesis
Wet diaper count
Respiratory
Cough
Tachypnea
Apnea
Neurologic
Lethargy
Irritability
Seizure activity
Gastrointestinal
Diarrhea
Blood in stool
Abdominal distension
Skin and soft tissue
Rash
Vesicles
Umbilical redness
Genitourinary
Foul urine
Poor feeding with no localizing signs
Perinatal and maternal risk
Birth history
Gestational age
NICU stay
Complications
Maternal infections
GBS status and intrapartum prophylaxis
Chorioamnionitis
HSV history
Peripartum genital lesions
Neonatal risk factors
Prematurity
Prolonged rupture of membranes
Central lines
Recent antibiotics
Exposure and environment
Sick contacts
Household viral illness
Daycare exposures
Travel and outbreaks
Known influenza or RSV circulation
Social risk
Barriers to return
Caregiver reliability
Physical Exam
Appearance and vitals
General appearance
Toxic appearance
Weak cry
Poor tone
Vital signs interpretation
Fever 38.0 C or higher
Hypothermia as sepsis marker
Tachycardia out of proportion to fever
Tachypnea
Hypotension late sign
Perfusion
Capillary refill
Central pulses
Mottling
Focused system exam
HEENT
Bulging fontanelle
Conjunctivitis
Otitis signs
Respiratory
Work of breathing
Focal crackles
Grunting
Cardiovascular
Murmur
Hepatomegaly
Differential pulses
Abdomen
Distension
Tenderness
Organomegaly
Skin
Petechiae or purpura
Vesicular lesions
Cellulitis
Omphalitis
MSK
Pseudoparalysis
Joint swelling
Long bone tenderness
Neuro
Tone abnormalities
Irritability
Seizure
PITFALLS
Misleading well appearance
Early meningitis may look well
Early bacteremia may have minimal signs
Partially treated infection
Antipyretics masking fever severity
Recent antibiotics masking culture yield
Temperature measurement error
Non-rectal measurements underestimating fever
Differential Diagnosis
Life-threatening
Invasive bacterial infection
Bacteremia
ICD-10 R78.81
Bacterial meningitis
ICD-10 G00.9
Neonatal sepsis
ICD-10 P36.9
HSV infection
Disseminated HSV
HSV CNS disease
Pneumonia
ICD-10 J18.9
Urinary tract infection
ICD-10 N39.0
Osteomyelitis or septic arthritis
Osteomyelitis ICD-10 M86.9
Septic arthritis ICD-10 M00.9
Other important causes
Viral illness
RSV
Influenza
SARS-CoV-2
Enterovirus
Congenital infection
TORCH considerations
Serious noninfectious
Congenital heart disease with decompensation
Inborn error of metabolism
Adrenal crisis
Localized bacterial
Omphalitis
Cellulitis
Abscess
Laboratory Tests
Core sepsis labs
Baseline evaluation set
Blood culture
Antibiotics after collection if feasible
Complete blood count with differential
ANC interpretation context dependent
WBC alone insufficient to rule out invasive infection
CRP
Early illness may be normal
Serial trend more informative
Procalcitonin
Higher specificity for invasive bacterial infection than WBC in many pathways
Interpretation limited in immediate neonatal period
Chemistry
Electrolytes
Creatinine and urea
Glucose mmol/L
Blood gas if ill
pH
Lactate mmol/L
PaCO2 mmHg
PaO2 mmHg
Urine testing
Urine assessment
Urinalysis
Leukocyte esterase
Nitrites
Microscopy WBC
Urine culture
Sterile collection method required
Catheter specimen
Suprapubic aspirate
Bag urine not acceptable for culture
CSF testing
Lumbar puncture panel
CSF cell count with differential
CSF glucose mmol/L
Paired serum glucose
CSF protein
CSF Gram stain and culture
CSF viral PCR as indicated
HSV PCR
Enterovirus PCR if available
Additional labs by presentation
Respiratory symptoms
Viral PCR panel per local availability
Diarrhea
Stool culture and PCR when bloody or severe
Hyperbilirubinemia or cholestasis
Total and direct bilirubin
Coagulopathy suspicion
INR
aPTT
Fibrinogen
Platelet trend
PITFALLS
False reassurance
Normal inflammatory markers early
Normal urinalysis with early pyelonephritis
Contamination risk
Blood culture contaminants in low-volume draws
Urine culture contamination with nonsterile collection
Diagnostic Tests
Scoring Systems
Risk stratification tools context
Many tools designed for older infants
Neonates 0 to 28 days generally managed as high risk regardless of score
Rochester criteria
Historical low-risk tool
Limited modern validation for neonates
Philadelphia and Boston criteria
Older criteria including routine LP
Not aligned with current biomarker era
Step-by-Step and PECARN febrile infant rules
Developed for infants up to 60 to 90 days in various cohorts
Youngest age groups typically treated as high risk in pathways
Guideline alignment
AAP guideline focuses on 8 to 60 days
Institutional pathways often treat 0 to 21 days as mandatory full sepsis evaluation and admission
MRI
CNS imaging indications
Focal neurologic deficit
Persistent seizures
Suspected HSV encephalitis with abnormal neuro exam
Practical limitations
Need for sedation in many neonates
Not first-line in initial ED sepsis evaluation
Interpretation pearls
HSV temporal involvement possible
Diffusion restriction in meningitis complications
CT
CT head indications
Concern for intracranial hemorrhage
Bulging fontanelle with focal deficits when MRI not available urgently
CT chest indications
Not routine for neonatal fever
Reserved for complications or unclear severe respiratory disease
Radiation considerations
Neonatal dose sensitivity
Strong preference for clinical evaluation and targeted imaging
Ultrasound
POCUS for unstable neonate
Cardiac function
Volume status
Pericardial effusion
Abdominal ultrasound indications
Suspected pyloric stenosis symptoms overlap with dehydration and fever
Suspected intraabdominal source
Renal ultrasound
Not acute ED test for initial febrile neonate evaluation
Consider after first febrile UTI per local guideline timing
Disposition
Admission and level of care
Default disposition
Inpatient admission for all febrile infants 0 to 28 days
Parenteral antibiotics pending cultures
PICU criteria
Shock
Need for vasoactives
Respiratory failure
Recurrent apnea
Seizure or altered mental status
Transfer criteria
No pediatric inpatient capability
Need for PICU not available
Need for lumbar puncture under specialist support
Observation endpoints
Culture monitoring
Blood culture time to positivity local lab dependent
Reassessment at 24 to 36 hours common inpatient practice
Clinical trajectory
Feeding improvement
Afebrile without antipyretics
Stable vitals and perfusion
Discharge exceptions
ED discharge generally not appropriate in 0 to 28 days
Consider only under specialist pathway
Requires full evaluation including CSF in most protocols
Requires reliable follow-up and return access
Treatment
Empiric antimicrobials
Initial empiric regimen for sepsis without focal source
Ampicillin
50 mg/kg IV every 6 hours for sepsis dosing
100 mg/kg IV every 6 hours if meningitis suspected
Listeria and Enterococcus coverage
Gentamicin
4 to 5 mg/kg IV every 24 hours
Therapeutic drug monitoring per local protocol
Nephrotoxicity and ototoxicity risk monitoring
Alternative regimen when meningitis suspected or Gram-negative meningitis risk
Cefotaxime
50 mg/kg IV every 6 to 8 hours depending on age and indication
Preferred cephalosporin in neonates when needed
Avoid ceftriaxone in neonates
Bilirubin displacement risk
Calcium precipitation risk
Vancomycin indications
Suspected MRSA
Central line infection
Severe skin and soft tissue infection
Local resistance patterns
15 mg/kg IV per dose with interval per gestational age and renal function
HSV coverage
Acyclovir indications
Vesicular rash
Seizure
Focal neurologic signs
CSF pleocytosis with negative Gram stain
Marked transaminitis
Severe sepsis with no source
Maternal HSV lesions near delivery
Acyclovir dosing
20 mg/kg IV every 8 hours
Renal adjustment per creatinine and gestational age
Hydration and renal monitoring
HSV diagnostic bundle while on acyclovir
CSF HSV PCR
Blood HSV PCR if available
Surface swabs PCR or culture per local protocol
ALT and AST
Supportive care
Fluids and perfusion targets
Capillary refill improving
Normalizing lactate trend
Adequate urine output per weight and age
Antipyretics
Acetaminophen 10 to 15 mg/kg per dose
Avoid ibuprofen in neonates
Respiratory support escalation
HFNC or CPAP per local neonatal protocols
Intubation for apnea or shock physiology
Source-directed therapy
UTI or pyelonephritis
Continue neonatal empiric coverage until culture susceptibilities
Narrowing once organism and sensitivities known
Meningitis
Antibiotic selection guided by Gram stain and culture
Duration guided by organism and specialist input
Omphalitis
Broad coverage including staphylococci and Gram-negatives
Surgical consult for necrotizing infection concern
Treatment adjustments
Narrowing strategy
De-escalation with negative cultures and improving course
Targeted therapy with identified pathogen
Stop criteria for antibiotics
Cultures negative at institutional time threshold
Clinical well-being and feeding
Specialist agreement for discharge planning
Special Populations
Pregnancy
Maternal postpartum context
Maternal fever and chorioamnionitis history relevance
Maternal HSV lesion history relevance
Medication exposure through breast milk
Generally compatible antibiotics used in neonates
Breastfeeding support during hospitalization
Geriatric
Not applicable group
Pediatric-only condition framework
Exclude from neonatal fever pathway use
Pediatrics
Neonatal specific factors
Corrected age consideration for prematurity
NICU discharge infants higher baseline risk
Febrile infant guideline context
Many national guidelines stratify 0 to 21 days as mandatory full evaluation and admission
22 to 28 days frequently treated similarly due to risk
Procedural considerations
Lumbar puncture positioning and analgesia
Blood culture volume optimization per local lab
Urine collection via catheter or suprapubic aspirate
Background
Epidemiology
Fever burden in neonates
Significant proportion viral
Nontrivial invasive bacterial infection risk compared with older infants
Most common serious bacterial infection
UTI among well-appearing febrile infants
Invasive bacterial pathogens in neonates
E coli
Group B Streptococcus
Listeria monocytogenes
Pathophysiology
Neonatal immune vulnerability
Reduced opsonization and complement activity
Limited neutrophil reserve in severe infection
Hematogenous spread propensity
Bacteremia seeding meninges
Rapid progression without obvious focus
HSV disease patterns
Skin eye mouth disease
CNS disease
Disseminated disease with hepatitis and shock
Therapeutic Considerations
Antibiotic selection rationale
Ampicillin for Listeria and Enterococcus
Aminoglycoside for Gram-negative synergy
Cefotaxime when meningitis suspected or high Gram-negative concern
Timing principle
Earlier antibiotics in shock improves outcomes
Cultures before antibiotics if no delay
Biomarker limitations
Single marker insufficient
Trend and clinical picture primary in 0 to 28 days
Patient Discharge Instructions
Copy discharge instructions
Post-hospital discharge guidance
Follow-up timing
Primary care visit within 24 to 48 hours after discharge
Specialty follow-up if meningitis or HSV
Feeding and hydration expectations
Normal feeding frequency for age
Wet diapers trending to baseline
Return immediately for
Temperature 38.0 C or higher
Difficulty breathing
Apnea
Blue or pale color
Poor feeding
Fewer wet diapers
Lethargy or unusual sleepiness
Persistent vomiting
New rash
Seizure or abnormal movements
Medication safety
Only medications prescribed at discharge
No ibuprofen unless specifically directed
Acetaminophen dosing only if instructed
Infection control
Hand hygiene
Limit sick contacts
References
Guidelines and society statements
Febrile young infants 0 to 90 days guidance
Canadian Paediatric Society position statement on well-appearing febrile infants 90 days or younger
American Academy of Pediatrics guideline on well-appearing febrile infants 8 to 60 days
NICE guideline NG143 fever in under 5s
TREKK fever in young children and young infants resources referenced in Canadian pathways
Neonatal HSV guidance
CDC STI Treatment Guidelines neonatal herpes acyclovir dosing
Canadian Paediatric Society neonatal HSV prevention and management statement
Evidence-based sources
Febrile infant pathway evidence base
AHRQ evidence review supporting AAP febrile infant guideline development
Studies evaluating inflammatory markers in febrile infants
Acyclovir dosing evidence
Neonatal HSV dosing standard 60 mg/kg/day divided every 8 hours
Safety literature on high-dose acyclovir in infants
SymptomDx is an educational tool for medical professionals. It does not replace clinical judgment. Verify all clinical data and drug dosages with authoritative sources.