Respiratory Distress
Esther M. Sampayo
INTRODUCTION
Respiratory distress is defined by increased work of breathing that can lead to respiratory failure, a state of inadequate oxygenation and/or ventilation. Symptoms and signs may include cough, tachypnea, retractions, grunting, stridor, wheezing, shortness of breath, chest tightness, chest pain, and altered mental status in later stages.
DIFFERENTIAL DIAGNOSIS LISTInfectious Causes
Peritonsillar abscess
Retropharyngeal abscess
Epiglottitis
Croup (viral laryngotracheobronchitis)
Bacterial tracheitis
Bronchiolitis
Meningitis
Pertussis
Pneumonia
Structural Lesions
Laryngeal lesions/masses
Laryngomalacia
Vocal cord paralysis
Subglottic stenosis
Tracheomalacia
Bronchomalacia
Lobar emphysema
Bronchogenic cyst
Vascular ring and other aberrant vessels
Mediastinal or other intrathoracic mass (cystic hygroma, teratoma, cystic adenomatoid malformation, neuroblastoma, diaphragmatic hernia, or eventration)
Toxic Causes
Carbon monoxide poisoning
Heavy metal poisoning
Methemoglobinemia
Organophosphate poisoning
Neoplastic Causes
Hemangioma
Papilloma
Brainstem tumor
Traumatic Causes
Foreign body aspiration
Aspiration caused by gastroesophageal reflux disease
Near drowning
Pneumothorax
Metabolic or Genetic Causes
Cystic fibrosis
Hypocalcemic tetany
Immune deficiency
Metabolic acidosis
Psychosocial Causes
Psychogenic hyperventilation
Neuromuscular Disorders
Respiratory muscle weakness, myopathy
Duchenne muscular dystrophy
Spinal muscle atrophy
Prune belly syndrome
Werdnig-Hoffmann disease
Miscellaneous Causes
Anaphylaxis
Asthma
Atelectasis
Cardiac disease (congestive heart failure, tamponade, myocarditis)
Central nervous system (increased intracranial pressure)
Pleural disease (effusion, empyema)
Pulmonary hemorrhage
Pulmonary edema
Pulmonary embolism
Sickle cell crisis—acute chest syndrome
Vocal cord dysfunction
DIFFERENTIAL DIAGNOSIS DISCUSSION
Infectious Causes
Infections causing respiratory distress may be bacterial or viral and may affect any part of the respiratory tract. Some infections are more common in different age groups, aiding in the diagnosis. In addition to the earlier-mentioned symptoms of respiratory distress, the patient may have congestion or rhinitis or a variety of constitutional symptoms such as fever, malaise, poor appetite, or body aches. The causative agent may be identified by cultures of the nasopharynx, pharynx, or sputum.
Epiglottitis
Etiology
Infection of the epiglottis is most commonly caused by Haemophilus influenzae type B and results in rapid swelling and airway compromise, creating a medical emergency. Fortunately, near universal use of the H. influenzae type B vaccine has dramatically reduced the incidence of this disease in children. Other pathogens that may cause epiglottitis include Streptococci, Staphylococci, and Candida albicans.
Clinical Features
Epiglottitis is most common in children between the ages of 3 and 6 years who have not been vaccinated against H. influenzae type B. Symptoms develop over several hours, which include high fever, dysphagia, drooling, inspiratory stridor, and holding the head in an upright “sniffing” position, with the neck extended and the jaw protruding.
Evaluation
When the history is suggestive, the child should not be excessively disturbed. Attempts to visualize the pharynx directly may result in complete occlusion of the airway and respiratory arrest. Vaccination status of a patient with suspected epiglottitis must be assessed, although a positive history of vaccination does not
rule out the possibility of epiglottitis. A lateral neck radiograph should not be attempted until a secure airway is established if the diagnosis is strongly suspected. A characteristic “thumbprint” epiglottis (the epiglottis is swollen) is diagnostic. A blood culture drawn after an airway is established may help determine the causative bacteria.
rule out the possibility of epiglottitis. A lateral neck radiograph should not be attempted until a secure airway is established if the diagnosis is strongly suspected. A characteristic “thumbprint” epiglottis (the epiglottis is swollen) is diagnostic. A blood culture drawn after an airway is established may help determine the causative bacteria.
Treatment
The most experienced staff available should establish an artificial airway under controlled circumstances, preferably by an otolaryngologist or anesthesiologist in an operating room. When intubation of the trachea cannot be accomplished, tracheostomy is indicated. Broad-spectrum antibiotics are then administered intravenously.
Croup (Viral Laryngotracheobronchitis)
Etiology
Most cases of croup are caused by parainfluenza virus types 1 and 3, although other pathogens have been described. Inflammation of the larynx, trachea, and bronchi results in increased airway resistance and obstruction. Rarely is airway obstruction so severe that cardiopulmonary arrest ensues. Clinical Features Patients are usually in the typical age range of 6 months to 6 years. The presence of symptoms in the first few months of life should prompt evaluation for congenital anomalies. Patients with mild cases may demonstrate a bark-like cough, nasal congestion, and fever. Typically, a mild cough with intermittent stridor progresses to continuous stridor, especially at night. Many patients improve after exposure to cool night air.
Evaluation
On physical examination, critical airway narrowing is denoted by severe retractions, inspiratory stridor, and decreased air entry. In patients with severe airway obstruction, cyanosis and fatigue may be noted. Cyanosis, tachycardia, and mental status changes may accompany hypoxia. Lateral and anteroposterior neck radiographs can help differentiate croup from epiglottitis, although radiographs should not be required in typical presentations. A characteristic “steeple sign” is often seen in the subglottic airway in croup, and the epiglottis is normal.
Treatment
An artificial airway should be established for patients with impending respiratory failure. Therapeutic strategies include the following:
Humidified oxygen. Cool, humidified oxygen is often provided for patients with mild-to-moderate cases of croup, although this practice is not clearly supported in randomized clinical trials.
Steroids. A single dose of oral dexamethasone is helpful in reducing respiratory symptoms even in mild cases with symptomatic relief within 4 to 6 hours.
Racemic epinephrine. Patients with severe cases may temporarily benefit from the inhalation of racemic epinephrine. These patients may need to be hospitalized
to observe for rebound effects, which may occur within 1 to 4 hours after the administration of racemic epinephrine.
Intravenous fluids. Fluids are helpful in maintaining adequate hydration in patients with severe tachypnea.
Antibiotics. Unless a secondary bacterial infection is suspected, antibiotics are not indicated.
Bronchiolitis
Etiology
Viruses (e.g., respiratory syncytial virus [RSV], human metapneumovirus, parainfluenza viruses, and adenoviruses) infect the lining of the small airways (bronchioles), resulting in mucosal edema and intraluminal accumulation of mucus and cellular debris. Infants less than 2 years are predominantly affected because the small caliber of their airways predisposes them to the development of increased airway resistance with even mild airway narrowing.
Clinical Features
A prodrome of nasal congestion and coryza lasting several days is usual. Fever and anorexia may be present, particularly in young infants with severe nasal congestion who may have difficulty feeding. Often, another family member has a mild upper respiratory tract infection. Respiratory distress usually develops gradually and is characterized by a worsening cough and wheezing. Typically, the symptoms are worse at night, especially days 3 to 5 of illness.
Evaluation
On physical examination, infants may be tachypneic, with a respiratory rate of 60 to 80 breaths/minute. The expiratory phase is usually prolonged, and diffuse wheezing, crackles, and rhonchi are often present. Breath sounds may be diminished in severe cases. Severe retractions and the use of accessory muscles are common. Lung hyperinflation and depression of the diaphragm may result in a palpable liver and spleen. Clinicians should diagnose bronchiolitis and assess disease severity on the basis of history and physical examination. Clinicians should not routinely order laboratory and radiologic studies for diagnosis unless there is concern for another disease entity. A chest radiograph, when obtained, may show hyperinflation, peribronchial thickening, and, in many patients, subsegmental atelectasis. The diagnosis of bronchiolitis is a clinical one, although nasopharyngeal swab or washing for RSV may help support the diagnosis in some cases.
Treatment
Supportive care entails administration of humidified oxygen for oxygen saturation less than 90%, and frequent nasal suctioning is often very helpful. Intravenous or nasogastric fluids are useful in maintaining hydration in the presence of tachypnea and decreased oral intake. The use of nebulized medications has been studied extensively, with inconclusive and variable results. A trial of nebulized albuterol may be administered although it is not effective in most cases. Nebulized racemic epinephrine has been shown to be beneficial in some studies. Systemic
corticosteroids also show variable results in clinical trials, although they are not currently recommended for routine use. Hypertonic normal saline may improve symptom scores. Sedatives should not be used, and antibiotics are generally not helpful. In infants with a severe course, or those with underlying cardiac or pulmonary disease, ribavirin may have a role in treating bronchiolitis caused by RSV.
corticosteroids also show variable results in clinical trials, although they are not currently recommended for routine use. Hypertonic normal saline may improve symptom scores. Sedatives should not be used, and antibiotics are generally not helpful. In infants with a severe course, or those with underlying cardiac or pulmonary disease, ribavirin may have a role in treating bronchiolitis caused by RSV.
HINT: Neonates and infants with a history of premature birth (with or without associated lung disease) or chronic heart or lung disease are at greater risk for apnea and poor outcome. A monoclonal antibody (Palivizumab), given in monthly intramuscular injections through the typical RSV season, is available for patients who meet high-risk criteria.Pertussis
Etiology
The classic causative organism is Bordetella pertussis, but Bordetella parapertussis and adenovirus infection can also cause pertussis, which is characterized by necrosis and desquamation of the superficial epithelium of the pharynx. Infants less than 2 months of age are most at risk, even if immunized. Adolescents and adults are often first affected because of waning immunity, and the diagnosis should be entertained in a younger child if an adult contact has a prolonged coughing illness.
Clinical Features
A catarrhal stage, consisting of symptoms of an upper respiratory tract infection, lasts 1 to 2 weeks.
A paroxysmal stage follows and is characterized by a distinctive, repeated, staccato cough that occurs during a single expiration, often emptying the lungs of all their vital capacity. In the following inspiration, a “whoop” sound is produced as the edematous, narrowed glottis oscillates between the open and the closed position, causing the column of inspired air to vibrate. Whoops are not always present; rather some patients demonstrate posttussive emesis at the end of a paroxysm. Patients are usually well between paroxysmal attacks. With repeated coughing, facial redness or cyanosis and neck vein distension may occur. Petechiae of the head and neck and conjunctival hemorrhages may develop after severe coughing. Infants may develop respiratory distress, apnea, or both.
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