Domino_5-Minute Clinical Consult, 33e

CROUP (LARYNGOTRACHEOBRONCHITIS) Afsha Rais Kaisani, MD • Tasaduq Hussain Mir, MD, FAAFP • Amulya Sajja, MD

HISTORY Croup is primarily a clinical diagnosis characterized by abrupt onset of barking cough, inspiratory stridor, and hoarseness (2). PHYSICAL EXAM • Vital signs can demonstrate tachypnea and tachycardia. • Pulse oximetry often is normal as there is no distur bance of alveolar gas exchange; however, oxygen saturation might be decreased in severe cases. • Visual inspection: Nasal flaring, retraction, and/or cyanosis indicate high suspicion for croup. • Breathing sounds and voice are important for diagno sis; typically, the patient will present with hoarseness, stridor, and/or inspiratory wheezing to auscultation. – Stridor can be present at rest and aggravated by agitation. – Substantial wheezing, rhonchi, and rales should prompt alternative diagnosis. • Decreased breath sounds and respiratory effort may indicate the child is progressing into respiratory fail ure and less able to mount an effort to move air (2). DIFFERENTIAL DIAGNOSIS • Foreign body aspiration • Bacterial tracheitis: high fever, barking cough, respiratory distress, and rapid deterioration • Retropharyngeal or peritonsillar abscess: similar septic appearance with dysphonia • Allergic reaction (acute angioneurotic edema) includes spasmodic croup with classic nocturnal exacerbations. • Epiglottitis: rapid onset, high fever, dysphonia, drool ing, and prototypical posture of extended chin and leaning forward; the incidence of epiglottitis has significantly decreased with widespread vaccination against H. influenzae being replaced by strep and staph organisms. • Others: subglottic stenosis, thermal injury/smoke inhalation, hemangioma, airway anomalies (e.g., tracheo-/laryngomalacia), neoplasm, other anatomic obstructions (2) • SARS-CoV-2 presents with more severe symptoms, and response to treatment is not as rapid as expected (3). DIAGNOSTIC TESTS & INTERPRETATION • Croup is a clinical diagnosis and does not require confirmatory testing. • Blood work is not required; if done, WBC counts may be mildly elevated with a predominance of lymphocytes. – An elevated WBC shift to the left (bandemia) would suggest bacterial etiology (epiglottitis, bacterial tracheitis, peritonsillar, and/or retropha ryngeal abscess). • Rapid antigen or viral culture tests should be reserved for patients in whom initial treatment is ineffective.

BASICS Croup is a self-limited upper respiratory tract infection causing inflammation and edema, leading to obstruc tion of the larynx and subglottic airway. It presents with barking cough and inspiratory stridor. Although usually mild, croup can cause significant respiratory distress and even death. DESCRIPTION • The spectrum of croup includes laryngotracheitis (LT), laryngotracheobronchitis (LTB), and laryngo tracheobronchopneumonitis. It is often a result of a viral infection and most common cause of airway obstruction in young children. • May occur in absence of viral prodrome, known as spasmodic croup, occurring in older children; rapid onset and resolution and often has a recurrent course EPIDEMIOLOGY • Most commonly affects children aged 6 months to 3 years of age, peaks at 18 months; although rare, croup can affect children as young as 3 months and as old as 6 to 7 years. • Predominant sex: male . female • Most often occurs in the fall and early winter but may present year-round Incidence • Accounts for 1.3% of emergency department cases • The vast majority are considered mild cases, but 3–7% of cases require hospitalization. • , 3% require laryngoscopic or airway procedures. • 4.4% of children returned to the emergency depart ment within 48 hours (1). Prevalence 60% of barking cough are resolved within 48 hours, and only 2% have symptoms persisting for . 5 nights (1). ETIOLOGY AND PATHOPHYSIOLOGY • Infection of the larynx, trachea, and bronchi, causing narrowing of the airway secondary to inflammation and edema • Children have narrow airway, and negative-pressure inspiration pulls airway walls closer together, creating inspiratory stridor. • Typically, caused by viruses that infect oropharyngeal mucosa and migrates inferiorly; most common pathogen is parainfluenza virus, responsible for . 80% of cases – Types 1 and 2 are the most common. – Type 3 is affiliated with bronchiolitis and pneumonia in young infants and children. – Type 4 (subtypes 4A and 4B) are associated with milder illness. • Other viruses: RSV, paramyxovirus, influenza virus type A or B, adenovirus, rhinovirus, enteroviruses (coxsackie and echo), reovirus, measles virus where vaccination is not common, and metapneumovirus • Mycoplasma pneumoniae and Corynebacterium diphtheriae have been reported but are rare.

• Bacterial croup is commonly caused by Staphylococcus aureus , Streptococcus pneumoniae , Haemophilus influenzae , and Moraxella catarrhalis . • Spasmodic croup cause is unclear, possibly allergy, airway hyperactivity, and gastroesophageal reflux. Genetics Congenital subglottic stenosis, which is a narrowing of the lumen of the cricoid region, can present as recurrent croup. RISK FACTORS Prior intubations, structural airway abnormality, prematurity, and age , 3 years increase the risks for recurrent croup (more than two episodes per year) (2). GENERAL PREVENTION Croup spreads through droplets. Children should be considered contagious up to 3 days after the start of illness and/or until afebrile. There is no specific vaccine for croup, but seasonal influenza vaccine may contribute to decreased risk. COMMONLY ASSOCIATED CONDITIONS • Some evidence suggests croup hospitalization may be associated with future development of asthma. • If recurrent (more than two episodes in a year) or during the first 90 days of life, consider host factors or allergic factors. • Underlying anatomic abnormality (e.g., subglottic stenosis, paradoxical vocal cord dysfunction) • Consider gastroesophageal reflux disease diagnostic consideration for patients with recurrent croup symptoms. • COVID-19—a potential viral agent in patients with croup DIAGNOSIS • Croup is a clinical diagnosis; most children present with acute onset of classic “seal-like” barking cough, inspiratory stridor, hoarseness, and chest wall indrawing. • Low-to-moderate grade fever but absence of fever should not reduce suspicion for croup. • Severity is determined by clinical inspection for signs of respiratory distress: nasal flaring, retractions, tripoding, sniffing position, abdominal breathing, and tachypnea. Although uncommon, hypoxia, cyanosis, and fatigue are late signs of severity. • For cases presenting with more severe symptoms or not improving as rapidly as expected, SARS-CoV-2 testing should be considered (3). • Westley Croup Severity Score is the commonly used scoring system. It looks at five clinical features, and the scores are as follows: # 2 mild; 3 to 7 moderate; 8 to 11 severe; $ 12 impending respiratory failure. – Level of consciousness: normal, including sleep 5 0; disoriented 5 5 – Cyanosis: none 5 0; with agitation 5 4; at rest 5 5 – Stridor: none 5 0; with agitation 5 1; at rest 5 2 – Air entry: normal 5 0; decreased 5 1; markedly decreased 5 2 – Retractions: none 5 0; mild 5 1; moderate 5 2; severe 5 3

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