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Re: Coffee cup Spacers versus Bottle spacers for MDIs

Dear Editor,

Zar et al(1) are to be congratulated for their important paper regarding the efficacy of "bottle spacers" for delivering beta 2 agonists in acute asthma in the under 5s. Clearly this bit of intermediate technology will facilitate delivery of treatment to large numbers of asthmatic children in resource-poor countries, and is equally relevant to practice in more fortunate countries, none of whom have infinite resources for health care.

However, the authors fail to recognise the prior contribution of Henry, Milner and Davies in their short report in the BMJ in 1983(2). In this paper they report the fact that delivery of a beta 2 agonist by a "Coffee cup" spacer achieved equivalent effects to twice the dose of the same drug delivered via a nebuliser. Compared with Zar et al's bottle spacer, the coffee cup method does not require a face mask and is therefore of infinitesimal cost. Otherwise the two approaches are extremely similar and effective.

References:

1)"RCT of the efficacy of an MDI with bottle spacer for bronchodilator treatment in acute lower airway obstruction" Zar HJ, Streun S, Levin M, Weinberg EG and Swingler GH Arch Dis Child 2007;92:142-146.

Send letter to journal:
Re: Re: Coffee cup Spacers versus Bottle spacers for MDIs

Dear Editor,

We thank Dr Speight for raising the possibility of using a coffee cup spacer to obviate the use of a face mask. In fact, we began the search for an effective homemade spacer by investigating the clinical efficacy of both a coffee cup spacer and a bottle spacer. Unfortunately, we found that the cup performed very poorly as a spacer. In aerosol deposition studies of children we found a polystyrene cup produced the least amount of lung deposition, delivering between a third and a fifth of the dose that either a conventional or bottle could deliver.(1) In addition, in a randomized clinical trial comparing the efficacy of home-made spacers (plastic bottle, cup) to a conventional spacer in 88 children with acute asthma, a bottle was confirmed to be an effective spacer for delivery of bronchodilators. However a cup was least effective, especially for children with moderate to severe airway obstruction in whom it produced only minimal bronchodilation.(2) The poor efficacy from a cup is most likely due to loss of aerosol around the edges of the cup where it fits onto the face.(1) We therefore believe that a cup spacer is ineffective and that use in a clinical trial for delivery of bronchodilators would therefore be unethical.

References:

1. Zar HJ, Liebenberg M, Weinberg E, Binns HJ, Mann MD. The efficacy of alternative spacer devices for delivery of aerosol therapy to children with asthma. Ann Trop Paediatr 1998:18;75-9.