VIRAL CROUP

Def.: heterogeneous group of mainly acute and infectious upper airway obstruction processes that are characterized by a barking like or brassy cough and may be associated with hoarseness, inspiratory stridor, and respiratory distress.

It is acute laryngotracheitis, Laryngotracheobronchitis!

Incidence:

·       The most common form of acute upper respiratory obstruction.

·       Affect about 15% of children.

·       It is most common between 6 m΄ and 6 years of age, with a peak prevalence in the 2^nd year of life, rare over the age of 10 years.

·       Boys > girls.

·       Season; a peak in autumn and winter is associated with parainfluenza virus but can occur throughout the year.

·       Croup is uncommon < 6 months of life.

·       Rarely lasts more than 10 to 14 days.

·       Approximately 15% of patients have a strong FHx of croup.

ETIOLOGY:

·       Parainfluenza viruses type 1 , 2 and 3 (account for ≈75% of cases(

·       Other viruses including RSV, adenovirus, influenza, and measles: Influenza has been associated with more severe cases.

Pathogenesis:

·       After inhalation of the virus, the cells of the local respiratory epithelium become infected.

·       There is marked edema of the lamina propria, submucosa, and adventitia accompanied by cellular infiltration with histiocytes, lymphocytes, plasma cells, and PNLs.

·       The infant’s glottis and subglottic region are normally narrow, and a small ↓ in diameter → large ↑ in airway resistance & ↓ in airflow.

- Assessment of severity of croup using Westley Clinical Scoring System.

 Assessment of severity of croup using Westley Clinical Scoring System

A variety of scoring systems have been developed to evaluate the severity of croup.The most commonly used scoring system has been that of Westley et al.(1).

Assessment of severity of croup using Westley (2) Clinical Scoring System in emergency department, as shown in following table is very useful to plan for staying at observation unit, hospital admission, ICU admission

• Mild croup—Score 0–2; 
•  Moderate croup—Score 3–5;
•  Severe croup—Score 6–11;
•  Impending respiratory failure—Score 12–17. 

 Ibrahim Samaha

References:

1. Cherry, James D. "Croup." New England Journal of Medicine 358.4 (2008): 384-391.
2. Westley CR, Cotton EK, Brooks JG. Nebulized racemic epicontents of this manuscript. nephrine by IPPB for the treatment of croup: a double-blind study. Am J Dis Child 1978 May; 132 (5): 484-7

- Lung Function Abnormalities in Bronchial Asthma.

Lung Function Abnormalities in Bronchial Asthma.

Spirometry (in clinic):

• Airflow limitation
• Low FEV1 (relative to percentage of predicted norms)
• FEV1:FVC ratio< 0.80

Bronchodilator response (to inhaled β-agonist):
o Improvement in FEV1 ≥12% and ≥200 mL
Exercise challenge: Worsening in FEV1 ≥15%
Daily peak flow or FEV1 monitoring: day to day and/or A.M.-to-P.M .variation ≥20%.

Ibrahim Samaha

- Understanding Bronchial Asthma Triggers.

 Understanding Bronchial Asthma Triggers.

1. Allergens: 

• Allergen exposures in sensitized individuals can initiate airways inflammation and hypersensitivity to other irritant exposures, and are strongly linked to disease severity and persistence. 
• Consequently, eliminating the offending allergen(s) can lead to resolution of asthma symptoms and can sometimes cure asthma.

- Clinical grades of stridor.

Clinical grades of stridor.

1.Grade 1 (Exertional stridor) :
Stridor appears during crying or exercise.
2.Grade 2 (Continuous stridor or stridor at rest) : 
Stridor is present at rest & become worse with exertion.
 3.Grade 3 (Stridor with retractions) : 
Stridor is continuous & accompanied with suprasternal& supraclavicular retractions. The patient looks anxious, irritable, struggling for breathing.
4.Grade 4 (Stridor with cyanosis) :
 In addition to continuous stridor & retractions, cyanosis& altered consciousness occur denoting severe respiratory failure. ET intubation may be considered.

- Causes of stridor In pediatrics.

Causes of stridor according to site of obstruction.

-Nose and pharynx: (by laryngeal compression)

• Lingual thyroid or thyroglossal cyst 
• Macroglossia(Beckwith-Wiedemann syndrome, hypothyroidism, Pompe disease, trisomy 21, hemangioma).
• Micrognathia (Pierre Robin syndrome, Treacher Collins syndrome,DiGeorge syndrome)
• Hypertrophic tonsils/adenoids
• Retropharyngeal or peritonsillar abscess / hematoma
• Tongue teratoma or dermoid 
• Masses: e.g. cystic hygroma or other malformation

-Larynx:
Not acute:

• Laryngomalacia
• Congenital subglottic stenosis
• Vocal cord paralysis
• Laryngeal atresia/web 
• Congenital Subglottic hemangioma
• Vascular ring compression syndrome.
• Laryngocele/cyst
• Laryngeal papillomas 
• GERD

- Infant girl with whooping cough (Video)

Infant girl with whooping cough

Mother holding infant girl in Intensive Care Unit. The baby has pertussis (whooping cough) and is coughing severely.

- Baby with viral croup (video).

2 years old female presenting with barking cough, stridor

The child have:

• stridor at rest 
• Subcostal and suprasternal retraction 

As classified by Westley score  minimally she has Moderate croup

- Pathogenesis of Acute Bronchiolitis.

Pathogenesis of Acute Bronchiolitis. 

RSV initially multiplies in the epithelium of the nasopharynx.
It then forms a syncytium and invades nearby cells.
 Hence, progression within few days of illness from an upper respiratory infection to a lower respiratory tract involvement is from cell to cell rather than hematogenous, extra-cellular fluid or any other route.
 The virus mainly multiplies within the bronchial epithelium and the alveolar macrophages.

 It finally results in:
o Destruction of the bronchiolar lining epithelium and loss of ciliated epithelial cells.
o Peribronchial infiltration of white blood cells.
o oedema of the submucosa and adventitia.
o ↑ Secretion
o Plugs of sloughed, necrotic epithelium and fibrin in the airways cause significant small airway obstruction (bronchospasm) resulting in hyperinflation, obstructive emphysema, atelectasis and ventilation/perfusion mismatch leading to hypoxemia.

N.b: Bronchial muscles are spared in bronchiolitis.

- Hospital and PICU admission criteria in cases of acute bronchiolitis.

Hospital and PICU admission criteria in cases of acute bronchiolitis.

Hospital Admission Criteria:

• Hypoxemia <90% on room air
• Dehydration with inability to maintain hydration
• Major comorbidity
• Need to rule out alternative diagnosis
• heart rate >180 bpm
• Moderate to Severe distress
• Inability to care for child at home.
• Strongly consider in infants with high-risk criteria:

- LBW
- age <6 wk,
- Prematurity
- Cardiac (Pulmonary hypertension,heart failure or cyanotic heart disease) .
- Pulmonary disease (BPD, cystic fibrosis or congenital anomalies of airway)
- Immunodeficiency
- neuromuscular disease

Critical care admission criteria:

• Recurrent apneas
• Concern regarding impending respiratory failure, increasing oxygen requirements
• High risk criteria…