How should an infant with subcostal retractions be evaluated and managed?

Evaluation and Management of Subcostal Retractions in Infants

An infant with subcostal retractions requires immediate assessment for signs of severe respiratory distress (grunting, nasal flaring, head nodding, tracheal tugging, intercostal retractions, severe tachypnea ≥70 breaths/min) and pulse oximetry measurement, as isolated subcostal retractions in children under 2 years may represent simple nasal obstruction, but when combined with danger signs indicate serious lower respiratory tract disease requiring hospitalization. 1, 2

Age-Specific Interpretation

In infants under 2 years, subcostal retractions are less specific for pneumonia because their chest walls are nearly 3 times more compliant than their lungs due to immature bone ossification. 1 This creates a mechanically disadvantageous respiratory state requiring more negative intrapleural pressures even during healthy breathing. 2

Benign Causes in Young Infants:

• Mild upper airway obstruction from nasopharyngeal inflammation (common cold) can cause isolated subcostal retractions without lower respiratory disease 1, 2
• Febrile illnesses with high metabolic demands that increase minute ventilation 1
• These typically present with mild, isolated retractions without additional danger signs 2

Critical Assessment: Identifying Severe Respiratory Distress

Immediately evaluate for these danger signs that indicate serious disease requiring hospitalization: 1

Signs of Severe Respiratory Distress:

• Grunting: Repetitive "eh" sounds during early expiration, indicating attempt to maintain lung volume 1
• Nasal flaring: Consistent outward movement of nostrils during inspiration 1, 2
• Head nodding: Head moves up/down with breathing from sternocleidomastoid/scalene muscle use 1
• Tracheal tugging: Soft tissue above sternum pulls inward during inspiration 1
• Intercostal retractions: Tissue between ribs pulls inward during inspiration 1
• Severe tachypnea: ≥70 breaths/min in infants 2-11 months, or ≥60 breaths/min in children 12-59 months 1, 3

Mandatory Pulse Oximetry

Measure oxygen saturation immediately in all infants with subcostal retractions. 1, 2 SpO2 <90% is a key predictor of mortality and mandates immediate hospitalization regardless of underlying cause. 1, 2 SpO2 <93% at sea level requires supplemental oxygen and hospitalization. 2

Diagnostic Approach

When Subcostal Retractions Are ISOLATED (No Danger Signs):

Consider benign upper airway obstruction if: 2

• No grunting, nasal flaring, head nodding, tracheal tugging, or intercostal retractions present
• Respiratory rate <70 breaths/min
• SpO2 ≥93%
• Infant feeding adequately

Management: Gentle external nasal suctioning (bulb suction) when visible nasal congestion affects breathing or feeding, positioning with head slightly elevated, frequent small feedings. 3, 2

When ANY Danger Signs Are Present:

This indicates lower respiratory tract disease (pneumonia, bronchiolitis) requiring different management: 1, 4

Distinguish Bronchiolitis from Pneumonia:

Bronchiolitis features: 3, 4

• Viral upper respiratory prodrome followed by wheezing, crackles, increased respiratory effort
• Age typically <2 years
• Diffuse findings on exam
• No chest radiography needed if all four pneumonia criteria absent 4

Pneumonia criteria requiring chest X-ray: 4

• Tachycardia (HR >100)
• Tachypnea (RR >24 in older infants)
• Fever >38°C
• Focal findings on examination

High-Risk Factors Requiring Lower Threshold for Hospitalization

Assess for these factors that substantially increase mortality risk: 3, 2

• Age <12 weeks (especially <3 months)
• History of prematurity
• Chronic lung disease
• Hemodynamically significant congenital heart disease
• Immunodeficiency

Management Algorithm

Immediate Actions:

1. Measure pulse oximetry 1, 2
2. Count respiratory rate for full 60 seconds 1
3. Assess for danger signs systematically 1
4. Apply high-flow oxygen to face if any respiratory distress present 1

Decision Points:

HOSPITALIZE immediately if: 3, 2

• SpO2 <90% (or <93% at sea level)
• Any signs of severe respiratory distress present
• Inability to maintain adequate oral intake
• Age <12 weeks with any respiratory distress
• High-risk factors present with moderate distress

Outpatient management acceptable if: 3, 2

• Isolated mild subcostal retractions only
• SpO2 ≥93%
• Feeding adequately
• No high-risk factors
• Reliable caregiver with clear return precautions

Common Pitfalls to Avoid

Do not assume all subcostal retractions indicate pneumonia in infants under 2 years—assess for accompanying danger signs. 1

Do not rely on single examination—serial observations over time provide more valid assessment, as signs can be subtle and variable. 1

Avoid deep nasal suctioning—use only gentle external bulb suctioning, as deep suctioning associates with longer illness duration. 3

Do not use OTC cough/cold medications or topical decongestants in children under 1 year due to documented fatalities and cardiovascular/CNS side effects. 2

Do not obtain routine chest X-rays for suspected bronchiolitis without pneumonia criteria present. 4