1031 Hypertonic saline/epinephrine nebulisation for bronchiolitis

In the USA bronchiolitis is said to be responsible for 120 000 hospital admissions per annum. Scaling this down to South Africa’s population one might be looking at around 150 admissions nationally per day during the peak season. Because the disease involves airway obstruction, similar treatments to those used in asthma have been tried, however results are generally disappointing and the prevailing mainstay of treatment has been hydration and supplemental oxygen, with the anti-RSV agent ribavirin also having a place. The failure of asthma treatments is not particularly surprising given that the pathophysiology of the conditions is different, with bronchiolitis characterised by necrosis and sloughing of epithelial cells, increased mucus secretion and peribronchiolar mononuclear infiltration. Since the late 1990’s there has been evidence that there might be a place for hypertonic saline which in vitro improves mucus rheology (viscosity and elasticity) and accelerates mucus transport rates, and in vivo increases the volume of airway surface liquid and increases rates of mucociliary clearance in normal and abnormal subjects. Viscosity has also been reduced in cystic fibrosis patients and mucus clarity increased (to a greater extent than with DNase treatment). Hypertonic saline has also been implicated in modulating the inflammatory response (decreased leucocyte response and increased prostacyclin production). The conclusion is that hypertonic saline is a legitimate agent in its own right. Several studies have now been published comparing different combinations of epinephrine/saline nebulisations, the earlier ones comparing normal saline against 3%. Consistently, and confirmed by a Cochrane review, the hypertonic saline concentration is effective in lowering bronchiolitis scores and length of stay. These results are not found with epinephrine nebulisations alone. A question remains as to whether 3% is the appropriate concentration or would higher concentrations be more effective? A recent study has addressed this question and come up with a positive result for a 5% solution; going higher there is some evidence that 7% could have adverse effects.

Read more:
J Pediatr July 2010 online
Emerg Med J 2009; 26: 518-9
IMAJ 2006; 8: 169-73