HERMES Paediatric Respiratory key terms

An abnormally fast breathing rate for age. In children the threshold is age-specific: above 60/min in infants under 2 months, 50/min at 2–12 months, 40/min at 1–5 years, and 30/min over 5 years.

The visible signs that breathing is costing a child excessive effort, including recession, nasal flaring, grunting, head bobbing and tracheal tug. It signals increased work of breathing and need for assessment, not a diagnosis in itself.

The effort required to move air into and out of the lungs. It rises when airways narrow, lungs stiffen, or the chest wall is compliant, and is estimated clinically from recession, accessory muscle use, and the child's ability to speak or feed.

Inward drawing of the chest wall during inspiration because high negative intrathoracic pressure pulls on a compliant chest. Intercostal, subcostal, suprasternal and sternal recession indicate increased work of breathing in children.

A short expiratory sound made by partially closing the glottis at end-expiration. It creates positive end-expiratory pressure that helps keep small airways and alveoli open, and in an infant is a worrying sign of respiratory distress.

A harsh, predominantly inspiratory sound caused by turbulent airflow through a narrowed upper airway, from the larynx upward. It is a sign of obstruction such as croup, laryngomalacia or an inhaled foreign body, not a diagnosis.

A continuous musical sound, usually expiratory, produced by turbulent flow through narrowed lower airways. In children it suggests bronchiolitis, asthma or another cause of intrathoracic airway narrowing, and can be heard or felt on the chest.

Discontinuous, short, explosive lung sounds heard on auscultation, formerly called crepitations or rales. Fine crackles suggest alveolar fluid or collapse, as in pneumonia or pulmonary oedema; coarse crackles suggest airway secretions.

Listening with a stethoscope to the sounds made by the lungs, heart and airways. In children it is used to confirm air entry, identify wheeze, crackles or stridor, and detect asymmetry suggesting collapse, effusion or foreign body.

A non-invasive method of estimating arterial oxygen saturation by measuring light absorption through a pulsatile vascular bed. It is a core monitoring tool in paediatric respiratory illness, but is unreliable with poor perfusion, motion or abnormal haemoglobin.

An abnormally low oxygen content or partial pressure in arterial blood, detected clinically by cyanosis or by oximetry. It indicates impaired gas exchange from causes such as airway obstruction, lung disease, hypoventilation or shunt.

A blood sample taken from a warmed heel or fingertip to estimate pH, carbon dioxide and bicarbonate when arterial sampling is impractical. It is useful in children for assessing ventilation and acid-base status, though oxygen values are less reliable.

Inability of the respiratory system to maintain adequate oxygenation or carbon dioxide clearance. Type 1 has low oxygen with normal or low carbon dioxide; type 2 adds carbon dioxide retention, and in children suggests exhaustion or hypoventilation.

A viral lower respiratory infection of infants, most often caused by respiratory syncytial virus, producing bronchiolar inflammation and obstruction. It presents with coryza, cough, tachypnoea, wheeze and crackles, typically peaking around days three to five.

A paramyxovirus that is the commonest cause of bronchiolitis and a major cause of infant respiratory admission. Infection gives incomplete immunity, so reinfection occurs throughout life, usually as a mild upper respiratory illness in older children.

A pause in breathing lasting long enough to be clinically significant, conventionally 20 seconds or more, or shorter if accompanied by bradycardia or desaturation. In infants it can be the presenting feature of bronchiolitis or of prematurity.

Acute inflammation of the larynx, subglottis and trachea, usually viral, causing a barking cough, hoarse voice and inspiratory stridor. Symptoms are typically worse at night and improve with corticosteroids and, when severe, nebulised adrenaline.

Acute bacterial inflammation of the epiglottis and supraglottic structures, classically from Haemophilus influenzae type b. It causes rapid-onset fever, drooling, muffled voice and a toxic child who prefers to sit upright; the airway must be secured urgently.

Congenital floppiness of supraglottic structures causing inspiratory stridor that worsens when lying supine, feeding or crying. It is the commonest cause of stridor in infancy and usually resolves without surgery by 12–18 months.

A chronic inflammatory disorder of the airways with variable airflow obstruction, bronchial hyperresponsiveness and symptoms of wheeze, cough and breathlessness. Diagnosis in children relies on characteristic pattern and response to bronchodilators or corticosteroids.

A lung function test measuring how much and how quickly air can be forcibly exhaled. In children it supports asthma diagnosis and monitoring, with bronchodilator reversibility or a positive exercise challenge adding evidence of variable obstruction.

A drug, usually a short-acting beta-2 agonist such as salbutamol, that relaxes airway smooth muscle and relieves bronchoconstriction. In children it is given by inhaler with spacer or nebuliser and is central to acute asthma and wheeze management.

An anti-inflammatory asthma preventer delivered directly to the airways, reducing symptoms and exacerbations. Children need correct technique, mouth rinsing and growth monitoring, and the dose should be stepped down once control is achieved.

A valved holding chamber placed between a pressurised metered-dose inhaler and the child's mouth. It removes the need for perfect coordination, improves lung deposition and reduces oropharyngeal side effects, and is preferred to nebulisation in most acute paediatric asthma.

Infection and inflammation of the lung parenchyma, causing fever, cough, tachypnoea and focal signs such as crackles or reduced air entry. Children may also show abdominal pain or neck stiffness, and severity is judged by respiratory distress and hypoxaemia.

Pneumonia acquired outside hospital, commonly from Streptococcus pneumoniae or viruses in children. Management depends on age, severity and likely organism, with amoxicillin the usual first-line oral antibiotic for typical bacterial disease.

A collection of pus in the pleural space, usually complicating bacterial pneumonia. It causes persistent fever and pleural effusion, and may need chest drainage, fibrinolytics or surgery in addition to antibiotics.

An abnormal accumulation of fluid between the visceral and parietal pleura. In children it causes reduced breath sounds and dullness to percussion, and may be transudative, exudative or infective, requiring imaging and sometimes drainage.

An autosomal recessive disorder of the CFTR chloride channel causing thick secretions, bronchiectasis, pancreatic insufficiency and sweat gland dysfunction. Diagnosis uses sweat chloride testing and genetic analysis, and care is multidisciplinary and lifelong.

The diagnostic test for cystic fibrosis, measuring chloride concentration in sweat collected after pilocarpine iontophoresis. A chloride level above the diagnostic threshold on two samples confirms the diagnosis; borderline results need genetic testing.

Irreversible dilatation of bronchi with damaged walls, causing chronic productive cough and recurrent infection. In children it may follow severe infection or be associated with cystic fibrosis, immunodeficiency or primary ciliary dyskinesia.

Airway clearance techniques such as percussion, postural drainage, oscillating devices and active cycle of breathing. In paediatric respiratory disease they help clear retained secretions in conditions such as cystic fibrosis and bronchiectasis.

Inhalation of an object into the airway, typically in a toddler with sudden coughing or choking followed by unilateral wheeze or reduced air entry. It is a clinical diagnosis; suspected cases need urgent bronchoscopy rather than delayed imaging.

Repetitive upper airway collapse during sleep causing snoring, pauses in breathing and oxygen desaturation. In children it is commonly associated with adenotonsillar hypertrophy and may cause daytime behavioural problems or poor growth.

Enlargement of the adenoids and tonsils, which narrows the upper airway and is the commonest cause of obstructive sleep apnoea in children. It can also cause mouth breathing, nasal obstruction and recurrent ear problems.

A maintained airway pressure at the end of expiration that keeps alveoli and small airways open and improves oxygenation. It is applied in ventilation and, physiologically, by grunting or pursed-lip breathing in a child in distress.

The maximum speed of forced expiration, measured with a portable flow meter. In children it can support asthma monitoring and action plans, but effort dependence and wide normal ranges limit its value for diagnosis.