• Paediatric Practice
• Therapeutics
• Respiratory

Acute bronchiolitis is the most common cause for hospitalisation in infancy with 2–3% of all UK infants admitted in their first winter.1 ,2 It has a substantial health economic burden with annual costs in the USA of over $0.5 billion for hospital care alone.3 In addition to short-term morbidity, there are also associated long-term consequences with 40–50% of those admitted subsequently enduring recurrent wheeze.4 ,5 The significant impact of bronchiolitis has led to an extensive search for effective therapies over the last half century since Reynolds’ oft-quoted aphorism that “oxygen is vitally important in bronchiolitis and there is little convincing evidence that any other therapy is consistently, or even occasionally, useful”.6

Nebulised hypertonic saline represents an attractive potential treatment for bronchiolitis. Hypertonic saline improves both mucous rheology (elasticity and viscosity) and mucociliary clearance in vitro7 ,8 with clinical studies in cystic fibrosis demonstrating beneficial effects on pulmonary exacerbation rates.9 Bronchiolitis has a number of pathophysiological features, including increased mucous production, airway oedema and mucous plugging, which could potentially be amenable to treatment with hypertonic saline.10

Since the first published trial of hypertonic saline from Israel in 2002,11 there have been almost 20 randomised controlled studies published of its use in bronchiolitis. Unfortunately, overall interpretation of these studies is hampered by factors that have repeatedly beleaguered bronchiolitis research. One of the principal difficulties is the lack of an internationally recognised bronchiolitis definition. In the UK, Australasia and some parts of Europe, the diagnosis is based on the presence of cough, tachypnoea and widespread inspiratory crackles.12 In North America and many other parts of the world, bronchiolitis is diagnosed when a young child has a first episode of wheeze with increased work of breathing in the presence of an …