Approach to lower airway obstruction (pediatrics): Clinical sciences

Lower airway obstruction occurs when any part of the airway below the thoracic inlet is blocked or narrowed, resulting in flow limitation and expiratory prolongation. Clinically, this typically presents with symptoms related to lung overinflation and air trapping, such as wheezing and a prolonged expiratory phase. Underlying causes of lower airway obstruction can be differentiated by the symptom onset as well as an assessment of triggers.

Now, if your patient presents with a chief concern suggesting lower airway obstruction, first perform an ABCDE assessment to determine if they are unstable or stable. If unstable, stabilize their airway, breathing, and circulation. You might even need to intubate your patient. Additionally, obtain IV access, and begin continuous vital sign monitoring, including respiratory rate, pulse oximetry, and cardiac monitoring. Finally, if needed, don’t forget to provide supplemental oxygen. Once you stabilize the patient, obtain a focused history and physical examination.

Unstable presentation is typically associated with anaphylaxis. In this case, history usually reveals a rapid onset of facial swelling and dyspnea, without a fever. They may also have a known allergy with exposure to a specific food like peanuts or another allergen like insect venom. Physical exam may reveal hypotension with audible stridor and wheezing. Additionally, you may notice facial edema and a diffuse urticarial rash. These findings are highly suggestive of anaphylaxis.

Now, let’s return to the ABCDE assessment and go over stable patients. Again, obtain a focused history and physical exam and check the patient’s pulse oximetry. Patients often report difficulty breathing and may have a cough.

Physical exam findings might include tachypnea and signs of labored breathing, like suprasternal, intercostal, and subcostal retractions, while lung auscultation commonly reveals wheezing. Finally, in some cases, oxygen saturation might be below 90%. With these findings, you should consider conditions that cause lower airway obstruction. To start your evaluation, first assess the onset of your patient’s symptoms.

If your patient’s symptoms were present from birth, you should consider the possibility of a congenital anomaly. History often reveals a hypoechoic pulmonary lesion that was identified on prenatal ultrasound, and affected infants might experience recurrent pulmonary infections.

Physical examination often reveals tachypnea and increased work of breathing starting shortly after birth. These findings are highly suggestive of a congenital anomaly, such as a congenital pulmonary adenomatous malformation or congenital lobar overinflation. In this case, you may need to order additional imaging to confirm and define the specific lesion.

On the other hand, if your patient’s symptoms had an abrupt onset, you should consider foreign body aspiration. Affected children typically have a rapid onset of a cough, and caregivers may describe a witnessed choking event.

Physical exam commonly reveals localized wheezing and the unilateral absence of breath sounds. However, a higher level obstruction may present with stridor. Next, consult the surgical team for a diagnostic and therapeutic bronchoscopy. If bronchoscopy identifies a foreign body, you can confirm foreign body aspiration.

Here’s a high-yield fact! Foreign body aspiration most commonly occurs in the right lung, because the right mainstem bronchus is wider and runs more vertically than the left, making it easier for objects to enter and become trapped.

Alright, if your patient’s symptoms had a subacute onset, consider bronchiolitis. History typically reveals a patient less than 2 years old, with symptoms of upper respiratory infection, like cough, rhinorrhea, and fever. In young infants, history might even reveal intermittent apneic episodes.

Physical exam reveals diffuse wheezing and crackles. These findings are highly suggestive of bronchiolitis, which you can usually diagnose clinically. However, if there’s uncertainty about the diagnosis, you can order a chest X-ray, which classically demonstrates hyperinflation and peribronchial thickening in the perihilar region.

Now, let’s consider patients whose symptoms had a gradual onset. In this case, you should assess the triggers of your patient’s symptoms to determine the underlying cause. First, let’s discuss premature infants who developed symptoms after treatment for respiratory distress syndrome. For these patients, you should consider the possibility of bronchopulmonary dysplasia.

Affected infants are typically born before 34 weeks of gestation, and have a history of respiratory distress syndrome requiring mechanical ventilation and supplemental oxygen. On physical examination, you are likely to detect a prolonged expiratory phase and diffuse wheezing, occasionally with crackles and rhonchi. Your next step is to order a chest x-ray.

X-ray results would show hyperinflated lungs with scattered cystic spaces among coarsened, reticular opacities. In addition, chest x-ray may help determine the severity of bronchopulmonary dysplasia and its complications. Based on these findings, you can diagnose bronchopulmonary dysplasia.

Next, lets look at patient’s whose symptoms are triggered by certain positional changes. In this case you should consider structural abnormalities of the airway, such as tracheobronchomalacia and vascular rings and slings. First, let’s discuss tracheobronchomalacia.

Tracheobronchomalacia commonly presents in infancy, with a cough and intermittent cyanotic episodes. Symptoms tend to be worse after bronchodilator use and improve with prone positioning.