What causes breathing problems in children?
A child’s breathing passages (pediatric airway) have many characteristics that render it more prone to obstruction (airway compromise). Newborns and infants breathe primarily through their nose. This is especially true when they are asleep. Oral breathing is a learned response that may take weeks or even months to develop. During this early stage of life, nasal obstruction presents a serious and potentially life-threatening problem. Blockage of the back part of the nose (figure 1) (choanal atresia and stenosis) represents common forms of congenital nasal obstruction.
Infants and children have small airways with loose lining. As a result, the airway is inherently vulnerable to narrowing by mucosal swelling (edema) from any source, be it infective (croup), chemical or traumatic. Although partial narrowing may be of little significance in an adult, the same degree of narrowing in a child’s airway may result in serious compromise.
Finally, the supporting cartilage of the newborn and infant airway is less rigid than in adults. It is very common for the supporting structures to collapse during respiration, producing noisy breathing, a condition known as laryngomalacia (figure 2). The larynx and trachea are also more susceptible to compression from outside its lumen that may twist, kink or collapse the airway. Congenital vascular benign neoplasm (lymphangiomas and hemangiomas) are common pathologies that could be responsible for airway compression.
What is stridor?
Narrowed areas in the upper airway provide distinctive vibratory patterns (noisy breathing) that are transmitted to the surrounding soft tissues of the neck and chest. Depending on where the obstruction is present different sounds are emitted. Snoring is a low pitch sound coming from the nasal passages. Stridor is a high pitch musical sound coming from the pharynx, larynx, trachea & main bronchi. Wheeze is an expiratory musical whistling coming from the small airways (bronchioles), like the sound produced by asthmatics.
What is the significance of stridor?
The presence of stridor creates much anxiety and concern. It is a frightening symptom for parents and diagnostic challenge for the clinician.
If its onset is sudden and associated with severe airway obstruction, intervention must be immediate. If the patient’s stridor is severe, the attending doctor should promptly inform the anesthesiologist and the Otolaryngologist and the patient should be taken to the operating room and under anesthesia secure the airway by intubation (passing a tube through the mouth into the trachea), bronchoscopy (examining the airway through the normal passages), or tracheotomy (performing a hole outside the neck bypassing the obstructed airway).
However, if the patient condition is stable, it must be thoroughly investigated. The general practitioners and pediatricians will evaluate meticulously every case of stridor by performing a thorough history and physical examination. The history includes information concerning the pregnancy and birth especially intubation & prematurity. In addition, information pertinent to the stridor must be obtained, including its onset, severity, its relation to child’s position, its relationship to the phases of respiration, its association to crying and feeding. An immediate onset of stridor after a choking spell, foreign body aspiration must be ruled out. The physician physical examination looks for the severity of stridor by the presence of drooling, dysphagia and dysphonia, cyanosis, nasal flaring, the use of accessory muscles of respiration, chest wall retractions, patient position (sitting with neck hyper-extended) and characterization of any cough. He may order some imaging (radiology). The most common x rays are soft tissue of the neck and chest. Depending on the case he will refer to an Otolaryngologist for further evaluation.
The Otolaryngologist will complement the examinations by performing flexible endoscopy and video examination of the airway from the nose to the larynx. He may have to evaluate the full extent of the airway under general anesthesia with a rigid laryngoscopy and bronchoscopy.
Depending on the case he may also order more imaging as CT scan of chest and neck to evaluate the trachea, MRI for the chest for intrathoracic vascular anomalies compressing the airway. A complete evaluation of GE reflux (gastric acid fro stomach regurgitates into the upper airways causing swelling and airway obstruction), by performing two probe 24 hours pH monitoring (a small probe passing from the nose to the esophagus). Other tests could be sleep study (polysomnography) to evaluate sleep apnea, electrocardiography and echocardiography to evaluate the heart function, pulmonary function tests to evaluate objectively respiratory obstruction, and voice evaluation by using stroboscopy and acoustic analysis (especial digital recording of child’s voice).
What is the most common cause of stridor in infants?
The most common cause of stridor in infant is laryngomalacia (figure 2). It is caused by collapse of the supraglottic (above the vocal cords) structures during inspiratory phase of breathing due to abnormal softening of its cartilage. In mild cases no treatment is required as the condition resolves over time of 12 months. However, gastro esophageal reflux is present in 25 to 80% of cases which needs to be treated with antireflux medication for 3-6 months. Severe cases (10-25%) can cause serious life-threatening complications, which require endoscopic supraglottoplasty (mild trimming of collapsing tissues) which is both safe and very effective treatment.
What is the most common cause of stridor in preschool-aged children?
The most common cause of stridor in preschool-aged children (age 2- 5) is croup. Croup is caused inflammation and swelling of the subglottis (region in the larynx below the vocal cords) resulting from a viral infection. Patient with croup have hoarse voice, harsh barking cough, and inspiratory stridor. The incidence per year is about 2% of preschool-aged children. Of these patients 1 -2 % required hospitalization. Contributing factors for recurrent croup (more than 3 times) could be secondary to allergy, gastro esophageal reflux disease, or underlying airway abnormalities (e.g. mild subglottic stenosis). Treatment is supportive like humidification by cool mist, or short course of oral steroids for few days. However, moderate cases will need hospital outpatient O2 therapy with mask inhalation therapy using topical vasoconstrictor (racemic epinephrine). In very few severe cases, short term nasotracheal intubation to bypass the obstructed site for few days may be needed.