Table of Contents
Work of Breathing (WOB) — clinical parameters
Work of breathing is assessed mainly by respiratory effort, chest movement, and signs of respiratory distress.
According to Nelson Textbook of Pediatrics, work of breathing (WOB) refers to the effort required to breathe—i.e., the amount of respiratory muscle activity needed to move air into and out of the lungs.
Clinically, Nelson assesses increased WOB by looking for signs of respiratory distress, particularly:
- Tachypnea
- Nasal flaring
- Retractions/recessions — intercostal, subcostal, suprasternal
- Grunting
- Accessory muscle use
- Head bobbing in infants
- Paradoxical/see-saw breathing
- Changes in respiratory pattern or effort
Exam definition
Work of breathing = the effort required to generate ventilation and move air through the respiratory system.
Increased WOB means the child must generate greater-than-normal respiratory effort to maintain adequate ventilation.
High-yield distinction:
WOB ≠ respiratory rate alone. A child can have severe increased WOB even with a relatively normal RR, particularly when respiratory muscle fatigue is developing.
Parameters to assess work of breathing
| Parameter | What to look for | Significance |
|---|---|---|
| Respiratory rate | Tachypnea for age | Early sign of increased WOB |
| Nasal flaring | Alae nasi widening during inspiration | ↓ upper-airway resistance |
| Retractions / recession | Suprasternal, intercostal, subcostal, substernal | Increased negative intrathoracic pressure |
| Grunting | Expiratory grunt | Maintains end-expiratory pressure; important neonatal distress sign |
| Head bobbing | Especially infants | Severe respiratory effort |
| Tracheal tug | Downward movement of trachea on inspiration | Increased inspiratory effort |
| See-saw/paradoxical breathing | Chest moves inward while abdomen moves outward, or vice versa | Severe distress/fatigue |
| Accessory muscle use | SCM, scalene, abdominal muscles | Increased WOB |
| Abnormal chest movement | Asymmetry, poor expansion | Airway/lung pathology |
| Breath sounds | Wheeze, stridor, crackles, diminished/absent air entry | Identifies cause/severity |
| Expiratory phase | Prolonged expiration | Particularly obstructive disease |
| Grunting | Especially in neonates | Suggests significant respiratory distress |
| Posture | Tripod/sniffing position | Compensatory increase in airway patency |
| Ability to speak/feed | Full sentences vs words; feeding interruption in infants | Functional measure of WOB |
| Mental status | Irritability → lethargy → exhaustion | Late/severe respiratory compromise |
| Oxygenation | SpO₂, cyanosis | Consequence rather than direct measure of WOB |
Quick severity framework
Mild ↑ WOB
- Tachypnea
- Mild nasal flaring
- Mild intercostal/subcostal recession
- Child alert and feeding reasonably well
Moderate ↑ WOB
- Marked retractions
- Nasal flaring
- Accessory muscle use
- Grunting
- Difficulty feeding/speaking
- Persistent tachypnea
Severe ↑ WOB / impending failure
- Severe recession
- Head bobbing
- Paradoxical/see-saw breathing
- Poor air entry or “quiet chest”
- Exhaustion, altered consciousness
- Apnea/bradypnea
- Cyanosis despite oxygen
Important: A falling respiratory rate is not necessarily improvement. In a tiring child, tachypnea may progress to a normal or low RR as respiratory muscles fatigue—often a dangerous sign.
For bedside pediatric assessment, the highest-yield things to document are RR + retractions + nasal flaring + grunting + accessory muscle use + air entry + SpO₂ + mental status/feed/speech ability.