PE25.1-6 | Respiratory System — Glossary

Rapid inward-and-upward thrusts delivered just above the navel to generate a sudden increase in intrathoracic pressure, used to expel a foreign body in conscious children over 1 year of age.

An acute bacterial or viral infection of the middle-ear cavity presenting with rapid onset of otalgia, fever, and a bulging erythematous tympanic membrane with middle-ear effusion.

An aminopenicillin antibiotic; the first-line oral antibiotic for non-severe childhood pneumonia per IAP guidelines, dosed at 40 mg/kg/day in 3 divided doses for 5 days.

Second-line antibiotic for AOM treatment failure, combining amoxicillin with the beta-lactamase inhibitor clavulanate to cover beta-lactamase-producing NTHi and M. catarrhalis; dose 90 mg/kg/day (amoxicillin component).

Severe, systemic hypersensitivity reaction with laryngeal oedema causing acute inspiratory stridor plus urticaria, angioedema, and haemodynamic instability; first-line treatment is intramuscular adrenaline 0.01 mg/kg (1:1000) into the anterolateral thigh.

The period following the initial choking phase of FBA during which the child appears clinically well, creating a diagnostic trap that leads to dangerous delays in management.

Lobar or segmental collapse resulting from complete bronchial obstruction (stop-valve mechanism) with absorption of trapped air distal to the foreign body.

Firm blows delivered with the heel of the hand between the shoulder blades, used as part of the first-aid sequence for choking in both infants and children over 1 year.

A rare but severe bacterial infection of the trachea (usually S. aureus) that mimics croup but causes a toxic, febrile child who fails to respond to nebulised adrenaline; characterised by pseudomembrane formation; requires IV antibiotics and often intubation.

A partial bronchial obstruction that allows air entry on inspiration (bronchial dilation) but prevents exit on expiration (bronchial constriction around the FB), causing progressive air-trapping and hyperinflation distal to the obstruction.

The characteristic brassy, harsh cough of croup, resembling a seal's bark; produced by vibration of the inflamed subglottic mucosa and is pathognomonic of croup on clinical pattern recognition.

Noisy breathing heard on both inspiration and expiration; indicates a fixed or tracheal-level obstruction that is not mitigated by the airway pressure dynamics of either phase; examples include subglottic stenosis, tracheal foreign body, and vocal cord paralysis.

Irreversible pathological dilatation of the bronchi resulting from chronic infection and inflammatory destruction of bronchial walls; a late complication of prolonged untreated foreign body aspiration.

Acute viral infection of the bronchioles, predominantly caused by RSV, affecting infants under 2 years; characterised by epithelial necrosis, mucus plugging, air-trapping, hyperinflation, and diffuse bilateral wheeze.

Outward displacement of the tympanic membrane due to pressure from a suppurative middle-ear effusion; the single most specific otoscopic sign of AOM.

A small lithium disc battery that, when lodged in the airway or oesophagus, generates a localised electric current causing liquefactive tissue necrosis within 2 hours; constitutes a separate, higher-urgency emergency than other FBs.

The ridge at the bifurcation of the trachea (at T4–T5 level) into the right and left main bronchi; the anatomical landmark at which the right main bronchus diverges at a smaller angle.

A third-generation cephalosporin that is first-line IV antibiotic for epiglottitis; dosed at 50-100 mg/kg/day IV once daily (maximum 2 g); covers Hib (including beta-lactamase-producing strains), S. pyogenes, and S. pneumoniae.

The inward drawing of the lower chest wall during inspiration; a sign of increased inspiratory effort against reduced lung compliance or increased airway resistance; the IMNCI criterion for severe pneumonia.

Sharp compressions delivered to the lower sternum (two-finger technique) in an infant under 1 year of age as part of choking first aid; replace abdominal thrusts which are contraindicated in this age group.

Chronic middle-ear infection with persistent tympanic membrane perforation and otorrhoea lasting more than 6 weeks; a complication of inadequately treated or recurrent AOM.

Endotracheal intubation performed under gas-induction general anaesthesia in an operating theatre, with ENT surgeon present for emergency tracheotomy if needed; the correct airway-securing procedure for epiglottitis — distinct from emergent bedside intubation.

A viral infection of the subglottic larynx, trachea, and bronchi causing acute inspiratory stridor, barking cough, and hoarse voice; most common in children aged 6 months to 3 years, primarily caused by parainfluenza virus.

Clinical features indicating very severe pneumonia or general danger requiring urgent referral: unable to drink or breastfeed, persistent vomiting, convulsions, lethargy or unconsciousness, stridor in calm child, severe acute malnutrition.

A potent glucocorticoid used as adjunct therapy in epiglottitis at 0.6 mg/kg IV to reduce supraglottic oedema; also the standard systemic steroid for croup, though evidence is strongest for croup.

Inability to swallow saliva, producing visible salivary dripping from the mouth; a cardinal sign of epiglottitis reflecting severe dysphagia due to supraglottic oedema.

Accumulation of purulent exudate in the pleural space as a complication of bacterial pneumonia; caused most commonly in children by S. aureus and S. pneumoniae; requires drainage in addition to antibiotics.

An acute bacterial infection of the epiglottis and supraglottic structures causing rapidly progressive airway obstruction; a paediatric emergency requiring immediate controlled airway management in OT.

The pharyngotympanic tube connecting the middle ear to the nasopharynx; in infants it is shorter, more horizontal, and more flaccid than in adults, predisposing them to AOM following URTI.

Chest radiograph obtained at the end of expiration; used to demonstrate unilateral hyperinflation or failure of the affected lung to deflate in bronchial foreign body aspiration with a ball-valve mechanism.

A fibre-optic bronchoscope used for diagnostic evaluation and certain therapeutic manoeuvres; less suited than rigid bronchoscopy for initial FB removal in children due to smaller working channel and limited forceps options.

Inhalation of a solid object into the lower airway; most common in children aged 6 months-3 years; presents with sudden onset of cough, stridor, or unilateral wheeze without fever; bronchial FB causes unilateral air trapping; managed with urgent rigid bronchoscopy.

An encapsulated Gram-negative bacterium whose polysaccharide (PRP) capsule enables invasive bacteraemic disease; the classical cause of epiglottitis, now rare in vaccinated populations due to PRP-containing pentavalent vaccine.

The pathological process of alveolar filling with fibrin-rich inflammatory exudate during bacterial pneumonia, making the affected lung lobe firm and liver-like in consistency.

Vaccine against Haemophilus influenzae type b, part of the pentavalent vaccine in India's Universal Immunization Programme; has dramatically reduced Hib pneumonia and meningitis incidence in immunised cohorts.

Amoxicillin at 80-90 mg/kg/day (versus the standard 40-45 mg/kg/day) used for AOM to achieve middle-ear fluid concentrations above the MIC of relatively penicillin-resistant S. pneumoniae.

Maintenance fluid calculation: 100 mL/kg/day for first 10 kg + 50 mL/kg/day for next 10 kg + 20 mL/kg/day for each additional kg; used to calculate IV or nasogastric maintenance fluids in children with LRTI who cannot take adequate oral feeds.

WHO Integrated Management of Neonatal and Childhood Illness age-specific respiratory rate thresholds for diagnosing pneumonia: ≥60/min for under 2 months, ≥50/min for 2–12 months, ≥40/min for 1–5 years.

A harsh, high-pitched respiratory noise on inspiration produced by turbulent airflow through a narrowed extrathoracic (upper) airway, as in croup or epiglottitis; stridor at rest indicates moderate-severe obstruction.

Inflammatory pattern of lung disease affecting the alveolar walls and interstitium rather than alveolar airspaces; typically caused by viral pathogens (RSV, influenza) and producing a bilateral hazy pattern on chest X-ray.

Agents such as urokinase instilled via a chest drain into a fibrinopurulent pleural collection to dissolve fibrin loculations and improve drainage; used in empyema not adequately drained by chest tube alone.

The most common cause of chronic inspiratory stridor in infants; caused by prolapse of floppy (hypotonic) supraglottic structures (omega epiglottis, aryepiglottic folds) into the airway during inspiration; onset in first 2 weeks of life; self-limiting, resolving in 90% by 18-24 months; supraglottoplasty for refractory cases.

Chest radiograph taken with the patient lying on one side; the dependent (lower) lung is compressed by gravity, mimicking expiration; used to detect air-trapping when expiratory cooperation is impossible in toddlers.

Inflammatory lung consolidation caused by aspiration of lipid-containing material (e.g. oily nose drops, organic FB fatty acids); overlaps pathologically with the reaction to vegetable FBs.

Radiological filling of an entire lobe or lung segment with inflammatory exudate, appearing as homogeneous opacity on chest X-ray; characteristic of bacterial (pneumococcal) pneumonia.

Suppurative infection of the mastoid air cells, the commonest intratemporal complication of AOM; characterised by post-auricular tenderness, erythema, swelling, and anterior displacement of the pinna.

The third principal bacterial pathogen in AOM (15-20%), most likely to resolve spontaneously and highly likely to be beta-lactamase positive; coverage by amoxicillin-clavulanate.

A characteristic voice quality in epiglottitis caused by supraglottic swelling muffling phonation; the child sounds as if speaking with food in the mouth; distinct from the hoarse voice of subglottic croup.

L-epinephrine 1:1000 solution (5 mL) or racemic epinephrine delivered by nebulisation for moderate-severe croup; acts within 10-30 minutes via alpha-adrenergic subglottic vasoconstriction; effect lasts 1-2 hours with rebound possible at 2-3 hours.

IMNCI severity tier characterised by fast breathing for age without chest indrawing or danger signs; managed at home with oral amoxicillin 40 mg/kg/day for 5 days.

The second most common bacterial cause of AOM (20-30%); non-encapsulated strains of H. influenzae distinct from the typeable Hib that causes epiglottitis; commonly produces beta-lactamase, causing amoxicillin resistance.

Unilateral or lobar hyperinflation resulting from air-trapping due to a ball-valve foreign body obstruction, visible on expiratory or lateral decubitus chest radiography.

Non-infectious accumulation of fluid in the middle ear (glue ear) presenting with hearing loss and a retracted, non-erythematous tympanic membrane, without acute pain or fever; does not require antibiotics.

Discharge from the external ear canal; in AOM it signifies tympanic membrane perforation with drainage of middle-ear suppuration and automatically qualifies for antibiotic treatment.

A single-stranded RNA paramyxovirus; type 1 is the most common cause of croup (LTB), responsible for approximately 75% of cases; peaks in autumn-early winter; also causes pharyngitis and bronchiolitis.

Otoscopic examination with a sealed speculum that delivers a puff of air to assess tympanic membrane mobility; gold-standard technique for diagnosing middle-ear effusion.

A conjugate vaccine targeting 13 serotypes of Streptococcus pneumoniae included in India's Universal Immunization Programme; the most important preventive intervention for bacterial childhood pneumonia.

The physical law describing flow through a cylinder: resistance is inversely proportional to the fourth power of the radius (R ∝ 1/r⁴); explains why 1 mm of subglottic oedema in an infant with a 4 mm lumen increases resistance 16-fold, while the same oedema in an adult causes minimal effect.

The polysaccharide capsular antigen of Haemophilus influenzae type b; the key virulence determinant enabling immune evasion; the antigen targeted by Hib conjugate vaccines to generate protective anti-PRP antibodies.

Epiglottitis occurring in vaccinated populations, caused increasingly by S. pyogenes, S. pneumoniae, or S. aureus rather than Hib; may present in older children or adults with a less classical clinical picture.

A non-selective beta-blocker used as first-line medical treatment for subglottic haemangioma at 2-3 mg/kg/day orally; induces vasoconstriction and promotes involution of proliferating haemangiomas; requires monitoring of heart rate and blood glucose during initiation; contraindicated in reactive airway disease.

Non-invasive measurement of oxygen saturation (SpO2) by photoplethysmography; the key bedside monitoring tool for respiratory severity in paediatric LRTI; SpO2 <92% indicates need for supplemental oxygen.

The return of croup symptoms to pre-treatment severity 2-3 hours after nebulised adrenaline as its vasoconstrictor effect wanes; mandates a minimum 2-4 hours of observation before discharge in any child who has received nebulised adrenaline.

Three or more distinct AOM episodes in 6 months, or four or more episodes in 12 months; an indication for ENT referral and consideration of tympanostomy tubes.

The single most common cause of bronchiolitis, responsible for up to 80% of cases; a negative-sense single-stranded RNA paramyxovirus with seasonal winter peaks.

Chemoprophylaxis given to unvaccinated household contacts of a Hib epiglottitis case to eradicate nasopharyngeal Hib carriage and prevent secondary invasive disease in susceptible contacts.

The shorter, wider, more vertically-oriented main bronchus arising from the carina, predisposing it to receive aspirated foreign bodies compared to the left.

The gold-standard procedure for airway foreign body removal, performed under general anaesthesia; provides superior optics, a larger working channel, and the ability to ventilate the patient during the procedure.

IMNCI severity tier characterised by fast breathing AND lower chest-wall indrawing; requires hospital admission, IV antibiotics (ampicillin + gentamicin), and oxygen if SpO2 <92%.

A recurrent variant of croup occurring in atopic children, typically without an infectious prodrome; presents identically to infectious croup but resolves faster and recurs; thought to have an allergic or reactive airway component.

The radiological appearance of croup on AP neck or chest X-ray: symmetric subglottic narrowing producing a pointed (steeple or pencil-tip) shape below the glottis; present in approximately 50-60% of cases; the AP view counterpart to epiglottitis' lateral-view thumbprint sign.

Complete bronchial obstruction by a foreign body that prevents airflow in both directions, leading to rapid absorption of trapped air and resultant atelectasis or lobar collapse.

The most common and most virulent bacterial cause of AOM; responsible for approximately 30-40% of bacterial AOM cases and the most likely to cause treatment failure and suppurative complications.

A high-pitched, harsh respiratory noise produced by turbulent airflow through a narrowed airway segment; a symptom, not a diagnosis; classified by phase (inspiratory, expiratory, biphasic) as a localising sign for the level of obstruction.

A proliferating vascular lesion of the subglottic mucosa presenting at 4-6 weeks with progressive biphasic stridor; associated with beard-distribution cutaneous haemangiomas in 50% of cases; treated with oral propranolol 2-3 mg/kg/day which induces involution.

Mucosal swelling of the subglottic space (below the vocal cords), the narrowest fixed segment of the paediatric airway; in croup, parainfluenza-driven inflammation produces this oedema, and by Poiseuille's law, even 1 mm of narrowing dramatically increases airway resistance in infants.

Narrowing of the subglottic airway at the level of the cricoid cartilage, either congenital (narrow cricoid ring) or acquired (post-prolonged intubation); presents with biphasic stridor and recurrent croup-like episodes triggered by minor viral URTIs; managed with laryngotracheal reconstruction.

The airway above the glottis, comprising the epiglottis, aryepiglottic folds, and arytenoids; the region affected in epiglottitis, in contrast to the subglottic involvement in croup.

Endoscopic surgical procedure for refractory laryngomalacia; involves division of shortened aryepiglottic folds and/or excision of redundant arytenoid mucosa to relieve supraglottic inlet obstruction; reserved for the 10% with failure to thrive, recurrent apnoea, or severe hypoxia.

The radiological appearance of epiglottitis on lateral neck X-ray: the swollen, rounded epiglottis projects from the base of the tongue resembling an adult's raised thumb, replacing the normal thin crescent epiglottic silhouette.

The characteristic posture adopted by a child with epiglottitis — sitting upright, leaning forward with hands on knees or bed, neck hyperextended, and mouth open — to maximise airway patency; must be preserved and never forced to lie down.

An objective test of tympanic membrane compliance and middle-ear pressure using an air-pressure probe; a flat (type B) curve indicates middle-ear effusion.

Small ventilation tubes surgically inserted into the tympanic membrane to equalise middle-ear pressure and drain effusion; indicated for recurrent AOM (≥3 episodes in 6 months) or persistent OME with hearing loss.

An anomaly of the aortic arch system (double aortic arch, right-sided aortic arch with aberrant left subclavian) forming a complete or partial ring around the trachea and oesophagus, causing biphasic stridor and dysphagia; diagnosed on CT angiography; treated with surgical division.

An intense inflammatory reaction of bronchial mucosa caused by fatty acids released from organic foreign bodies (peanuts, seeds), leading to progressive mucosal oedema, granulation tissue, and secondary infection.

Unilateral (left RLN injury — birth, cardiac surgery, mediastinal mass) or bilateral (CNS — Arnold-Chiari, birth asphyxia) vocal cord immobility; presents with weak cry and biphasic stridor; bilateral paralysis is a more serious airway emergency.

A period of 48-72 hours of analgesic therapy without antibiotics for non-severe, unilateral AOM in children ≥6 months, with a safety net for re-evaluation; reduces antibiotic prescriptions without increasing complication rates.

A validated 5-parameter clinical severity scoring tool for croup (total 0-17); assesses stridor, retractions, air entry, cyanosis, and level of consciousness; categorises into mild (<3), moderate (3-7), and severe (≥8) to guide management.

Lower respiratory infection in young children characterised by viral-triggered bronchospasm, overlapping with early asthma; shows partial bronchodilator responsiveness unlike classic bronchiolitis.