Respiratory Complications in Down Syndrome - An Overview

Introduction

Down syndrome is a common chromosomal abnormality caused due to full or partial trisomy of chromosome 21. It is manifested with several anomalies such as hypotonia, craniofacial abnormalities, congenital malformations, cognitive impairment, auto-immune disorders, dysmorphic features, and respiratory, cardiac, and pulmonary system abnormalities. Other systems commonly involved are gastrointestinal malformations, hematological disorders, and thyroid dysfunctions. The incidence of Down syndrome occurs around one in 800 live births. The occurrence of lung disease with hospitalization accounts for 54 percent.

What Are the Respiratory Diseases Associated With Down Syndrome?

• In children under three years of age, respiratory disorders are the common cause of hospitalization and death in persons with Down syndrome.

• A high incidence of significant morbidity and mortality happens due to a combination of cardiopulmonary disease in Down syndrome.

• Respiratory and pulmonary morbidity results in frequent hospitalization in intensive care admission.

• Respiratory illness in Down syndrome involves the airways and the pulmonary vasculature.

• Pulmonary edema and pulmonary embolism are commonly seen in Down syndrome and are associated with pulmonary vascular diseases such as pulmonary artery hypertension. The lung vasculature of Down syndrome patients is immature, with double capillary networks and bronchopulmonary anastomoses.

The typical respiratory problems associated with Down syndrome include:

• Pneumonia: Pneumonia is the predominant cause of mortality in adults with Down syndrome. Pneumonia and respiratory infections associated with Down syndrome are more common and severe than in normal healthy individuals. It refers to the inflammation of air sacs filled with fluid, mucus, or phlegm in one or both lungs. It can manifest with fever, cough with phlegm, chills, and difficulty breathing. Various microorganisms, such as bacteria, fungi, and viruses, are responsible for causing pneumonia. Antibiotics and antiviral medications are commonly used to treat pneumonia. Different causes involved in causing pneumonia-associated Down syndrome include:

• Sleep Apnea: It is commonly seen in Down syndrome patients. It may increase the risk of gastroesophageal reflux disease (GERD).

• Impaired Immunity: A certain degree of impairment in the immune system can be seen commonly in patients with Down syndrome.

• Gastroesophageal Reflux Disease (GERD) - It is more familiar in Down syndrome patients. The gastric contents are pushed back into the esophagus and sometimes reach the throat during sleep. It can cause aspiration of gastric contents into the lungs, resulting in pneumonia or bronchospasm. Gastroesophageal reflux disease can also cause constriction of the esophagus.

• Dysphagia (Difficulty in Swallowing)- It is more commonly seen in patients with Down syndrome. It may be due to physiologic, anatomic, or psychological.

Physiologic causes include:

• The swallowing mechanisms can be impaired by certain neurologic conditions such as seizures or Alzheimer's disease.

• Some of the debilitating conditions, such as weakness, impaired fitness, or conditions that lead to increased time in bed, can worsen or increase the difficulty in swallowing.

• Swallowing dysfunction is more common in Down syndrome patients due to nervous system impairment.

• Inflammations, infections, or injuries in the throat can cause a higher risk of swallowing activity.

Anatomic reasons include:

• Presence of Large Tonsils: Large tonsils can obstruct the airway and cause difficulty in swallowing and breathing mechanisms.

• Atlantoaxial Instability: It is more familiar in Down syndrome patients. In a severe case of subluxation of cervical vertebrae, the vertebrae displace or slip forward and press against the back of the throat, which obstructs air and food passages.

• Foreign Bodies: When a foreign body is swallowed and gets stuck in the throat or pharynx, it causes impairment in swallowing. In addition, this foreign object, then passed onto the lungs, can result in recurrent pneumonia.

Behavioral or psychological causes include:

• Some people develop a fear of swallowing by choking episodes (throat pain, pain during swallowing noticed).

• Fast eating, inadequate chewing, lack of drinking between bites, and taking larger bites rapidly can lead to swallowing problems.

• Depression can also cause impaired swallowing.

• Laryngomalacia: Laryngomalacia refers to softening of tissues in the larynx. Laryngomalacia associated with Down syndrome is more common.

• The occurrence of both laryngomalacia and gastroesophageal reflux disease together results in upper airway obstruction and stridor.

• It occurs most commonly in children younger than two years of age. It is generally associated with neurological disorders, especially hypotonia.

• Children with Down syndrome usually present with generalized hypotonia, flaccidity of the supraglottis, high incidence of gastroesophageal reflux disease, and anatomical changes in the arytenoids, epiglottis, and aryepiglottic folds.

• Therefore, children with Down syndrome present with these features have a high prevalence of laryngomalacia, leading to upper airway obstruction.

• Obstructive Sleep Apnea: In children above two years of age, obstructive sleep apnea is the most common cause of upper airway obstruction. The incidence rate of his condition in children is found to be around three percent in the general population.

• The characteristic feature of Down syndrome, such as macroglossia, generalized hypotonia, mandibular hypoplasia, and adenotonsillar hypertrophy, may present with constriction of the pharyngeal airway during inspiration.

• Clinically, this condition may present with behavioral problems, daytime somnolence, developmental delay, and poor school performance in young children.

What Are the Respiratory Complications in Children With Down Syndrome?

Respiratory problems are the common reason infants and children are hospitalized in the intensive care unit. The typical anatomical features of Down syndrome that contribute to respiratory concerns in children are:

• Craniofacial features such as flattened midface, macroglossia, and narrowed nasopharynx.

• Adenotonsillar hypertrophy (abnormal growth of the pharyngeal tonsil and palatine tonsil).

Other features that may contribute to respiratory concerns in Down syndrome patients include:

• Hypotonia (low tone)- Caused due to dysphagia (upper airway muscles involved), and malacia (obstruction of the airway)

• Cardiac diseases.

• Obesity.

• Gastroesophageal reflux results in airway inflammation and adenotonsillar hypertrophy.

What Are the Anatomical Anomalies Specific to Down Syndrome Leading To Malacia?

• Malacia refers to the change or loss of consistency in the organs or tissues.

• Anatomic dysmorphia may present as laryngomalacia, tracheomalacia, bronchomalacia, and airway malacia.

What Are the Respiratory Infections Associated With Down Syndrome?

In children, respiratory infections such as bronchiolitis, pneumonia, upper respiratory tract infection, and lower respiratory tract infections occur. In addition, chronic aspiration may result in these infections.

What Are the Symptoms of Chronic Aspiration?

Common symptoms of chronic aspiration include:

• Pneumonia.

• Chronic cough.

• Wheezing.

• Radiographic findings reveal the presence of bronchiectasis and right middle lobe syndrome.

What Are the Symptoms of Airway Problems Associated With Down Syndrome?

The presence of airway issues is manifested in the following symptoms:

• Wheezing: The presence of expiratory wheeze that suggests lower airway disease (asthma).

• Dyspnea: It refers to shortness of breath.

• Stridor: Inspiratory wheeze that is suggestive of upper airway obstruction.

What Are the Upper Airway Abnormalities?

The upper airway abnormalities are manifested as:

• Macroglossia (enlarged tongue).

• Narrowing of the nasopharyngeal passages.

• Laryngomalacia (a condition that refers to the softening of tissues of the larynx).

What Are the Lower Airway Abnormalities?

The lower airway abnormalities are manifested as:

• Subglottic stenosis (narrowing of the subglottis, the area below the vocal cords and above the trachea).

• Tracheal stenosis (refers to the narrowing of the trachea that obstructs the breathing process).

• Tracheobronchomalacia ( a condition in which the tissues of the windpipe and trachea become soft and weak).

What Are the Investigations of Airway Issues?

• Careful Examination - A careful physical examination and detailed history help in diagnosing the condition clearly.

• Chest Radiograph - It reveals the findings of reticulonodular opacities or patchy consolidations in the case of pneumonia.

• Bronchoscopy - It is a highly useful diagnostic procedure in the diagnosis of various respiratory complications associated with Down syndrome.

• Sleep Study - Children with Down syndrome reported obstructive sleep apnea are confirmed by monitoring full night polysomnography. Even children without sleep apnea problems also reported sleep fragmentation with frequent arousals and awakenings.

How To Treat Respiratory Complications Associated With Down Syndrome?

• In the case of pneumonia associated with Down syndrome, antibiotics, and antiviral medications are recommended.

• Aryepiglottoplasty is a procedure performed for treating laryngomalacia. It is a safe and effective procedure for children without significant complications.

• Adenotonsillectomy is performed in children suffering from adenotonsillar hypertrophy.

• Tracheotomy is carried out in the case of tracheomalacia and patients with severe aspiration. It is one of the effective methods of surgical therapy.

• In the case of asthma associated with Down syndrome, bronchodilators are prescribed to relieve the symptoms and decrease breathing difficulty.

Conclusion

Respiratory illness can contribute to difficult, life-threatening situations. The cause of upper airway obstruction, especially in children with Down syndrome, is age-related. However, preventive measures can be followed, such as reducing exposure to viral respiratory infections, maintaining a healthy lifestyle to boost the immune system, and avoiding exposure to environmental tobacco smoke. The administration of vaccines helps in preventing certain infectious diseases.