Stridor Theresa Laguna, MD, MSCS
Transcription
Stridor Theresa Laguna, MD, MSCS
http://www.us.elsevierhealth.com/Medicine/Pediatrics/book/9780323054058/Bermans-Pediatric-Decision-Making/ Stridor Theresa Laguna, MD, MSCS Stridor is a vibratory noise caused by turbulent air flow and airway obstruction. Stridor can be heard on inspiration (extrathoracic obstruction), expiration (intrathoracic obstruction), or during both phases of the respiratory cycle (fixed obstruction) depending on the location of the lesion. Stridor can be classified as acute, chronic, or recurrent in nature. CAUSATIVE FACTORS Inflammation, edema, compression, or intraluminal obstruction of the respiratory tract above the larynx (uvula, epiglottis, and arytenoid cartilages), at the level of the larynx (false cords, vocal cords, and arytenoepiglottic folds), or in the trachea causes narrowing of the airway and signs of airway obstruction. 1. Infection is a main cause of acute stridor in children. Croup is the most common cause of acute inspiratory stridor in children between 6 months and 3 years of age. Croup is a clinical respiratory syndrome characterized by the sudden onset of a barky cough, respiratory distress, and inspiratory stridor usually secondary to viral pathogens, most commonly parainfluenza types 1 and 3, respiratory syncytial virus, influenza virus, adenovirus or human metapneumovirus. In unimmunized children, laryngeal diphtheria and measles are important infectious causative factors of croup to consider. Spasmodic croup is similar to viral croup; however, its symptoms usually occur without a viral prodrome and tend to be more short-lived. A rare cause of inspiratory stridor, epiglottitis, is usually caused by Haemophilus influenzae type b, although Streptococcus pneumoniae and Streptococcus pyogenes can rarely cause acute epiglottitis. Immunization against H. influenzae type b has dramatically decreased the cases of epiglottitis seen in the United States. Bacterial tracheitis, either caused by Staphylococcus aureus, S. pneumoniae, H. influenzae or influenza viruses has emerged as a leading cause of life-threatening airway infection in children, surpassing epiglottis and viral croup. 2. Acute stridor can also be secondary to noninfectious causes. Etiologies to consider include angioedema, foreign body aspiration, peritonsillar abscess, retropharyngeal abscess, and trauma. 3. Recurrent or chronic stridor can be caused by intrinsic lesions such as laryngomalacia, tracheomalacia, masses and foreign bodies, or extrinsic lesions such as vascular rings or slings. MEDICAL MANAGEMENT AND APPROACH A. In the patient’s history, ask the following questions: When did the stridor begin? Does the child have symptoms of an upper respiratory infection or cold, such as coughing or rhinitis? When did the cold symptoms 404 begin? Is it difficult for the child to breathe? Is there fast breathing? Did the child recently choke on something and have difficulty breathing or turn blue? Does the child have a sore throat, hoarseness, or a change in voice? Can the child swallow? Is there drooling or fever? B. In the physical examination, count the respiratory rate, note the heart rate, and assess the oxygen saturation for signs of impending respiratory failure. Listen for stridor at rest when the child is calm or an increase in stridor during crying or coughing. Note the phase of the breathing cycle that stridor is heard (during inspiration, expiration, or both). Most cases of acute stridor are inspiratory in nature. Listen for hoarseness, a barky cough, or a muffled voice. Look for retractions, cyanosis, extreme anxiety or confusion, restlessness, drooling, or a sniffing-type posture. With a stethoscope, note air exchange, wheezing, and rales. Determine whether the stridor is acute or chronic. C. Angioedema usually presents with facial swelling, urticaria, and a history of similar allergic reactions. Foreign body aspiration can cause stridor, asymmetric breath sounds, or wheezing. The onset is sudden, and upper respiratory infection symptoms and fever are not usually present. An ingested foreign body can rarely lodge in the esophagus and cause upper airway obstruction. A forced expiratory chest film may demonstrate air trapping and possibly a shift of the mediastinum. Bronchoscopy is diagnostic and therapeutic, and should be performed if foreign body is suspected. Assess carefully for tonsillitis or peritonsillar abscess. D. Assess the degree of respiratory distress and determine whether it is mild/moderate, severe, or very severe (Table 1). Antibiotics play no role in uncomplicated viral croup. Early corticosteroid treatment appears to modify the course of even mild/moderate viral croup and should be used to reduce the progression of the inflammation and to prevent return for care and/or hospitalization. Corticosteroids may be given orally, intramuscularly, or parenterally. Nebulized corticosteroids may be useful, although oral or intramuscular routes are preferred. E. Encourage parents to give fluids to the child with uncomplicated, mild/severe viral croup. Instruct the parents to call or seek medical care if the child develops stridor at rest, has evidence of respiratory distress (retractions), or becomes too ill to drink. Children with croup whose stridor resolves after treatment with nebulized racemic epinephrine in an ambulatory setting should be observed for at least 3 hours before returning home because stridor and respiratory distress frequently recur. F. When stridor is moderate to severe and does not respond to traditional therapy, hospitalization in a pediatric ward or pediatric intensive care unit (ICU) should be considered. If acute epiglottitis is suspected, it should be http://www.us.elsevierhealth.com/Medicine/Pediatrics/book/9780323054058/Bermans-Pediatric-Decision-Making/ http://www.us.elsevierhealth.com/Medicine/Pediatrics/book/9780323054058/Bermans-Pediatric-Decision-Making/ Patient with STRIDOR A History B Physical exam C Identify: Impending respiratory failure Angioedema Aspiration/foreign body ingestion Tonsillitis/peritonsillar abscess Assess pattern Recurrent/chronic stridor Acute stridor D Assess degree of respiratory distress (Table 1) Consult: Pulmonologist or otolaryngologist for laryngoscopy or bronchoscopy Consider airway visualization Mild-moderate Severe Very severe Treat: Racemic epinephrine Corticosteroids E Consider discharge Hospitalize, consider after ≥3 hrs of pediatric ICU admission observation after last F racemic epi nebulizer Consider airway visualization (Table 2) (Cont’d on p 407) considered an airway emergency and airway visualization should be considered (Figure 1). It is important to assess the risk for acute airway obstruction before attempting to visualize the epiglottis in any patient suspected of having acute epiglottitis to allow for adequate preparation (Table 2). When there is severe distress, inspection of the epiglottis should be done in the operating room by an anesthesiologist whenever possible, with an otolaryngologist or pediatric surgeon available for emergency intubation and/or tracheostomy. In visualizing the epiglottis, it is important to have oxygen, a self-inflating Ambu bag, a laryngoscope, and an appropriately sized endotracheal tube (0.5–1 mm less than expected for the child’s age) available in case the examination precipitates acute upper airway obstruction. Never force a distressed sitting child to lie down. This may compromise the airway and cause immediate obstruction. Lateral neck radiographs should not be taken initially in patients at high risk for acute epiglottitis because of the danger of acute obstruction in the radiology department and the delay in diagnosis and treatment while waiting for the film. The value of lateral neck films as an alternative to direct visualization in cases with a moderate risk for epiglottitis is controversial. http://www.us.elsevierhealth.com/Medicine/Pediatrics/book/9780323054058/Bermans-Pediatric-Decision-Making/ 405 http://www.us.elsevierhealth.com/Medicine/Pediatrics/book/9780323054058/Bermans-Pediatric-Decision-Making/ G. Suspect bacterial tracheitis when croup is complicated by high fever, purulent tracheal secretions, and increasing respiratory distress. This may be the presenting pattern (resembling epiglottitis), or it may present after several days of stridor (secondary bacterial tracheitis). Endotracheal intubation is often necessary. Tracheal secretions should be cultured to allow for appropriate antibiotic therapy. Abundant purulent secretions and pseudomembrane formation require aggressive pulmonary toilet. H. In hospitalized children, manage respiratory distress and stridor associated with viral croup with racemic epinephrine and corticosteroids. Corticosteroid treatment shortens the hospital stay. Although humidified mist therapy is used routinely in many centers, its efficacy has not been documented, and tents are a barrier to observation. Viral croup rarely requires endotracheal intubation, although extreme vigilance is required. Heliox (70% helium and 30% oxygen) may prevent intubation in severe cases, although there is not enough evidence to recommend its regular use. Ribavirin therapy is not indicated for viral croup. Always continue to reassess the patient if incomplete response to therapy for secondary infections such as bacterial tracheitis. I. Manage acute epiglottitis with intubation in a controlled setting because of the high risk for acute airway obstruction. Initiate antibiotic therapy with an appropriate cephalosporin antibiotic (Table 3). Blood cultures will be positive in more than 50% of the cases caused by H. influenzae type b. Identify extraepiglottic foci of infections, such as pneumonia, septic arthritis, pericarditis, and meningitis. Consider bacterial pathogens other than H. influenzae in a child immunized against H. influenzae type b. J. Causes of stridor identified by direct laryngoscopy or bronchoscopy include laryngomalacia, laryngeal web, laryngeal papilloma, redundant folds in the glottic area, and supraglottic masses. Diagnoses associated with pharyngeal or retropharyngeal masses include enlarged adenoids; abscess or cellulitis; benign neoplasms, such as cystic hygroma, hemangioma, goiter, and neurofibroma; and malignant neoplasms, such as neuroblastoma, lymphoma, and histiocytoma. Bronchoscopy can further identify tracheomalacia and/or tracheal compression from a variety of lesions including vascular malformations. Esophagram or barium swallow can also aid in the diagnosis of intrathoracic lesions, which often are characterized by expiratory or fixed stridor. K. Discharge children from the hospital when stridor at rest and respiratory distress has resolved and they no longer need oxygen. They should be afebrile, eating well, and appropriately active. Schedule a follow-up visit 24 to 48 hours after discharge. Consider a visiting nurse referral. Instruct the parents to call the physician immediately if stridor or signs of respiratory distress (fast breathing or chest indrawing) return. (Continued on page 408) Table 1. Degree of Respiratory Distress Mild/Moderate Severe Volume status Intermittent stridor with crying and/or coughing, no audible stridor at rest Good air exchange with minimal or no retractions No signs of dehydration Ability to take PO Mental status Able to drink without drooling Normal mental status Stridor at rest, often both inspiratory and expiratory Decreased air entry with marked retractions Signs of dehydration including increased heart rate and decreased urine output Impaired ability to drink Altered mental status Oxygen saturation Normal Normal or slightly decreased Stridor Air exchange Very Severe Stridor at rest, cyanosis Minimal air exchange with severe retractions Signs of dehydration including increased heart rate and decreased urine output Inability to drink Agitation and anxiety secondary to air hunger, or lethargic Hypoxemic Table 2. Risk for Acute Airway Obstruction and Guidelines for Visualization of the Epiglottis in Children with Stridor and Suspected Epiglottitis Risk for Acute Obstruction High Moderate Low Minimal Clinical Manifestations Location and Personnel for Visualization Drooling, muffled voice, severe sore throat, sniffing posture, high fever, dehydration, anxiety, toxicity, no URI or cough Stridor (intermittent or constant) with minimal URI signs, high fever, age .5 years old without other signs of epiglottitis Stridor at rest associated with URI symptoms for 3–4 days, low-grade fever Operating room with airway specialist (anesthesia, otolaryngologist, pulmonologist) and surgeons Emergency department with airway specialist Intermittent stridor with 2–4 days of URI, low-grade to absent fever, no toxicity, no respiratory distress Visualization usually not necessary; if done in emergency department or in patient ward, have physician present experienced with pediatric resuscitation Visualization not necessary URI, upper respiratory infection. 406 http://www.us.elsevierhealth.com/Medicine/Pediatrics/book/9780323054058/Bermans-Pediatric-Decision-Making/