Management of Shivering (Rigors) and Vomiting in a 2-Month-Old in PICU

A 2-month-old presenting with rigors and vomiting in the PICU should be treated as late-onset neonatal sepsis / serious bacterial infection (SBI) until proven otherwise. At this age, the rate of SBI in febrile infants is 6-10%, and the presentation is often non-specific.

Step 1 - Immediate Assessment (ABC)

Priority	Action
Airway	Assess patency; intubate if altered consciousness or apnea
Breathing	Oxygen by mask/CPAP; monitor SpO2
Circulation	IV/IO access; HR, BP, capillary refill, skin color
Disability	GCS, fontanel bulge, seizures, pupil response
Exposure	Full skin exam - rash, petechiae, vesicles

Shock signs (poor perfusion, hypotension, altered mentation): start fluid resuscitation immediately - 20 mL/kg isotonic crystalloid IV/IO bolus; repeat up to 60 mL/kg over 60 minutes if shock persists.

Step 2 - Investigations (Before Antibiotics If Possible)

Blood culture (mandatory before antibiotics)
CBC with differential, CRP, procalcitonin
Blood glucose (hypoglycemia is common in septic neonates)
Serum electrolytes, creatinine, LFTs
Urine culture (catheter specimen)
Lumbar puncture + CSF analysis (can defer if hemodynamically unstable)
Chest X-ray (if respiratory symptoms)
Blood gas (metabolic acidosis = early septic shock)

Step 3 - Drug Management

A. Empiric Antibiotics (START WITHIN 1 HOUR)

At 2 months of age, organisms to cover: Group B Streptococcus, E. coli, Listeria monocytogenes, H. influenzae, N. meningitidis, S. pneumoniae

Drug	Dose	Route	Frequency	Indication
Ampicillin	50-100 mg/kg	IV	Every 6-12 hrs (adjust for renal function)	GBS, Listeria coverage
Cefotaxime	50 mg/kg	IV	Every 6-12 hrs	Gram-negative meningitis (preferred over gentamicin if meningitis suspected)
Gentamicin	4-5 mg/kg	IV	Every 24-48 hrs	Alternative to cefotaxime for gram-negatives
Ceftriaxone	50 mg/kg	IV	Every 12 hrs	For 29-90 day infants (NOT neonates <28 days - displaces bilirubin, risk of kernicterus)
Vancomycin	10-20 mg/kg	IV	Every 6-8 hrs	Add if penicillin/cephalosporin-resistant S. pneumoniae suspected

Key rule: Avoid ceftriaxone in neonates (< 28 days) - it displaces bilirubin and can cause kernicterus. At 2 months of age it can be used.

Preferred regimen for 29-90 day old (including 2 months):

Ampicillin + Cefotaxime (if meningitis possible) OR
Ampicillin + Ceftriaxone (if meningitis less likely)

B. Antiviral (Acyclovir) - Add If:

Indication	Dose
Maternal history of genital herpes	20 mg/kg IV every 8 hours
Vesicular rash on skin/mucosa	Same
CSF pleocytosis with lymphocytes + RBCs	Same
Ill-appearing neonate with fever + seizure	Same
Transaminitis or coagulopathy	Same

C. Anti-shivering / Antipyretics

In a 2-month-old, "shivering" most likely represents rigors from fever or sepsis, not true thermoregulatory shivering. Treat the underlying infection. Symptomatic fever management:

Drug	Dose	Route	Note
Paracetamol (Acetaminophen)	10-15 mg/kg	IV/PR	Preferred antipyretic; every 4-6 hrs
Ibuprofen	Avoid	-	Not recommended < 3 months
Aspirin	Avoid	-	Contraindicated in children

D. For Vomiting

At 2 months of age, vomiting is likely from sepsis, increased intracranial pressure, or ileus. Treat the cause. Symptomatic management:

Keep NPO (nil per os) initially
IV fluid maintenance (Dextrose 10% + Normal Saline at maintenance rates) - neonates are at risk of hypoglycemia
Nasogastric tube if abdominal distension or aspiration risk
Avoid metoclopramide (risk of extrapyramidal effects); ondansetron has limited safety data at this age and is not routinely recommended

E. Vasopressors (If Septic Shock Persists After Fluids)

Drug	Dose	Indication
Dopamine	1-20 mcg/kg/min IV infusion	First-line vasopressor in pediatric septic shock
Norepinephrine	0.05-2 mcg/kg/min IV infusion	Add if dopamine insufficient

F. Other Supportive Drugs

Drug	Use
Dextrose 10% IV	Correct/prevent hypoglycemia (bolus 2 mL/kg if glucose < 40 mg/dL)
Phenobarbitone	20 mg/kg IV loading dose if seizures occur
Vitamin K	0.5-1 mg IM if intracranial hemorrhage suspected and not yet given

Step 4 - Differential Diagnoses to Rule Out

Condition	Key Features
Neonatal sepsis/meningitis	Most common - treat empirically
Congenital heart disease	Cyanosis, murmur, shock without fever
Inborn error of metabolism	Metabolic acidosis, hypoglycemia, family history
Pyloric stenosis	Projectile non-bilious vomiting, olive mass on palpation
Intracranial hemorrhage	Bulging fontanel, seizures
Congenital adrenal hyperplasia	Hyponatremia, hyperkalemia, ambiguous genitalia
Intussusception	Colicky pain, currant jelly stool (rare at 2 months)

Summary Algorithm

2-month-old: Rigors + Vomiting → PICU
         ↓
ABC stabilization + IV access
         ↓
Blood culture + urine culture + CBC + CRP + glucose + LP (if stable)
         ↓
Ampicillin IV + Cefotaxime IV (+ Acyclovir if HSV risk)
         ↓
Paracetamol for fever, IV dextrose-saline for maintenance
         ↓
If shock → 20 mL/kg NS bolus → repeat → Dopamine if no response
         ↓
Review cultures at 48-72 hrs → de-escalate/target antibiotics

Sources:

Tintinalli's Emergency Medicine, Neonatal Sepsis section
Rosen's Emergency Medicine, Pediatric Fever and Febrile Infant management
Red Book 2021, AAP Committee on Infectious Diseases

Clinical note: At 2 months (approx. 29-60 days), these infants fall in the "late neonatal" risk window. All ill-appearing infants of this age warrant full sepsis evaluation, empirical antibiotics, and hospital admission regardless of how well they look initially. Do not delay antibiotics for lumbar puncture if the child is hemodynamically unstable.

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