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ADC Fetal and Neonatal Edition Letters and ADC Education and Practice Letters
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Spacers. the last word? I doubt it.
- Peter Barry (6 June 2000)
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Peter Barry, Doctor University of Leicester
Send letter to journal:
pwb1{at}le.ac.uk Peter Barry
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Dr Marcovitch's comments about Heather Zar's article (Arch Dis Child 2000;82:495-8), championing the use of home made spacers and in particular the coffee cup, do not stand up to a closer examination. In a recent randomised study of the bronchodilator effects of different spacers from the same authors as the ADC article, in 44 children with moderate to severe airways obstruction, a coffee cup gave significantly less bronchodilation (median increase in FEV1 0%; PEF 12%) compared with a 'conventional' spacer (FEV1 37%; PEF 59%)(Lancet 1999;89:979-82). So a coffee cup, which I used as well, 10 to 15 years ago, really cannot be recommended except for drinking coffee. What of other home made devices? Anaesthetic bags (Woodcock, Postgrad Med J 1984;60:37-39), Paper bags (El Kassimi, Eur J Resp Dis 1987;70:234-8), freezer bags (Lee, Pediatrics 1984;73:230-2) and even a chocolate Easter egg (Hayden, Med J Aus 1995;163:587-8) have all been evaluated and found to perform as well as 'conventional' spacers, at least at points high on the dose response curve or in relatively healthy subjects. They may be satisfactory, especially in the absence of evidence that more expensive devices are more efficacious in every day use. Zar's conclusions that choice of spacer should be based on factors such as patient preference echo previous advice on choice of delivery device. There are however methodological and ethical problems with Zar's study. The aerosol used (a nebulised solution) is completely different from the aerosol emitted from a pressurised metered dose inhaler, and is likely to have a very different interaction with the spacer. Zar asserts that a valid comparison may be made between spacers as the delivery system is kept constant. This is hardly credible given other studies which have demonstrated that different formulations of aerosols behave differently with spacers. Furthermore, subjects with clinical signs or recent symptoms of bronchoconstriction were excluded from Zar's study, the very children that you would want to treat! I'm not disdainful of attempts to provide a cheap, effective alternative, and have even presented data on the use of a 1 litre milk carton (great in an emergency, but avoid milk protein sensitive patients!) but Zar's study uses the wrong aerosol in the wrong patients and compares the coke bottle with the wrong 'conventional' spacers. It hardly justifies raising the hopes of those searching for the final word. |
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