Upper airway obstruction is a frequent and serious cause of respiratory difficulty in children, addressed with urgency in Pediatric Advanced Life Support (PALS) protocols. This obstruction involves a blockage or narrowing in the respiratory tract located above the trachea, encompassing the nose, pharynx, and larynx. Because the airways of infants and young children are significantly smaller than those of adults, they are more susceptible to obstruction from conditions like infection, foreign objects, or swelling. Prompt recognition of specific signs is paramount, as respiratory distress can rapidly progress to respiratory failure and cardiac arrest. Identifying the earliest indicators of a compromised airway allows for timely intervention to support breathing and prevent catastrophic outcomes.
Distinct Auditory Clues
The sound a child makes while breathing often provides the first evidence of an upper airway problem, resulting from turbulent airflow passing through a narrowed passage. Stridor is the most recognized auditory sign, characterized by a high-pitched, harsh sound primarily heard during inspiration. This sound is generated when air is forcibly drawn past a restriction in the rigid structures of the larynx or upper trachea. Inspiratory stridor is the classic presentation of a partial upper airway obstruction, indicating sufficient air movement is maintained.
The intensity of stridor indicates the severity of the obstruction. Stridor audible only when the child is agitated suggests a milder issue. As narrowing worsens, stridor becomes audible even at rest. In severe cases, it may become biphasic, heard during both inhalation and exhalation, reflecting a highly compromised airway.
A sudden decrease or absence of stridor in a previously noisy patient is an alarming sign of impending respiratory failure, suggesting critically low air movement.
Laryngotracheobronchitis (croup) produces a distinct “seal-like” or “barking” cough. This is caused by inflammation and swelling around the vocal cords and subglottic area, reliably indicating laryngeal involvement.
Changes in the quality of the child’s voice or cry are also significant. A muffled or hoarse voice suggests swelling or dysfunction at the vocal cords. In cases of severe swelling, such as epiglottitis, the voice may become entirely absent or a weak, whispering cry may be all that is possible.
Visible Signs of Increased Respiratory Effort
When the upper airway is narrowed, the body must exert increased physical effort to overcome resistance and move air into the lungs, leading to several visible signs of distress. Tachypnea, an abnormally fast breathing rate, is an early compensatory mechanism to maintain adequate oxygen delivery. This increased work of breathing results in the use of accessory muscles, which are not typically engaged for quiet respiration.
The most noticeable sign of muscle use is retractions, visible indentations of the chest wall and neck. Retractions specific to upper airway obstruction are often seen in the suprasternal notch, the supraclavicular areas, and sometimes the intercostal spaces. These occur because the strong negative pressure generated during labored inspiration pulls the soft tissues inward.
Nasal flaring is another indicator of increased effort, where the nostrils widen during inhalation to decrease airway resistance. Infants and small children often instinctively adopt specific positions to help open their compromised airways. The sniffing position, or sitting bolt upright and leaning forward, are common compensatory stances that help align the oral, pharyngeal, and laryngeal axes to optimize airflow. Attempting to move the child from their position of comfort may worsen their distress.
As the obstruction progresses and oxygen delivery remains insufficient, changes in skin color and mental status become apparent. Pallor is an early sign of poor tissue perfusion. Cyanosis, a bluish discoloration, is a late sign of severe hypoxemia. The child’s behavior changes dramatically, moving from early anxiety and agitation to lethargy and decreased responsiveness as the brain becomes oxygen-deprived.
Differentiating Between Partial and Complete Obstruction
The interpretation of auditory and visible signs is crucial in PALS for determining the severity of the obstruction and guiding the urgency of intervention.
Partial Obstruction (Compensated Distress)
A partial obstruction is considered mild or compensated respiratory distress, characterized by the child being generally alert and interactive. The patient’s heart rate is typically elevated (tachycardia) and their skin color is good, reflecting successful compensation for reduced airflow. In this state, stridor is generally loud and heard mainly on inspiration, and retractions may be mild or moderate. Air movement is sufficient to maintain oxygenation, allowing for a more controlled approach to treatment.
Complete Obstruction (Decompensated Failure)
Conversely, a severe or complete obstruction represents decompensated respiratory failure, a life-threatening emergency where compensatory mechanisms are failing. The child’s compensatory mechanisms are failing, leading to rapid deterioration. A critical sign is the “silent chest,” where loud stridor is replaced by minimal or no audible breath sounds despite continued, frantic respiratory effort. This paradoxical silence means almost no air is moving past the obstruction.
Decompensation is also evidenced by a significant change in mental status, progressing from agitation to profound lethargy or unresponsiveness as brain hypoxia worsens. The respiratory effort itself may decrease as the child becomes exhausted, leading to bradypnea or apnea. Late signs of impending cardiac arrest include cyanosis and bradycardia, which is the most reliable indicator of severe, prolonged hypoxia in a child. Recognizing this progression from noisy, compensated distress to a silent, decompensated state is the core of the PALS assessment.