Home nebulisers.

3 downloads 0 Views 318KB Size Report
meters bear the name Wright; they assume that both were designed by Dr Martin Wright, the inventor of the original peak flow meter,2 which also bears his nameĀ ...
I Bendefv IM. Home nebulisers in childhood asthma: survey of hospital supenrised use. BMI7 1991;302:1180-1. (18 MNay.) 2 Rees J. 1i, Agonists and asthma. BA!_ 1991;302:1116-7. 18 Mav.) 3 Warner JO, Gotz M, Landau L, et al. Management of asthma: a consensus statement. Arch Dis Child 1989;64:1065-79. 4 British Thoracic Society. Guidelines for management of asthma in adults. B.P_ 1990;301:651-3.

SIR, - Dr Ilona Bendefy's descriptive study draws attention to how common the use of home nebulisers has become, with little previous scientific appraisal.' The study's design, however, does not support her conclusion that home nebulisers are valuable in childhood asthma-for example, there are no comparison groups for frequency of admission to hospital and severity of disease. There is, moreover, abundant evidence from the parents' responses that this is a potentially dangerous treatment. An analytical study, such as an intervention trial, is required to establish its value.2

Important questions are raised by the results. Dr Bendefy states that 59 of 107 children used their nebulisers for prophylactic drugs; why did 48 children require nebulisers if not for prophylactic drugs? Table I shows that 42 children from a total of 84 using nebulised salbutamol were aged 5 or over; why do school age children need as many nebulisers as preschool children when other effective methods are available to them?3 Protocols of when to use home nebulisers have not been published.4 Essentially, a home nebuliser is indicated when inhalation treatment is necessary and cannot adequately be achieved with the alternative methods of aerosols and dry powders. This is the case for a small group of subjects. Specific disadvantages are associated with home nebulisers: (a) their contribution to avoidable mortality; (b) delay in seeking medical help; (c) the tendency for child and family to use high doses of bronchodilators and reduce or stop prophylactic drugs; and (d) greater interference in the subject's lifestyle than occurs with other methods. Most deaths from asthma in childhood occur in adolescence, and particular problems may develop in the future if treatment with home nebulisers is not changed to an alternative inhalation treatment at the earliest opportunity. This will be increasingly difficult to control as increased numbers of nebulisers are obtained by parents buying their own nebulisers from general practitioners or by them being passed on from siblings and friends. Home nebulisers probably have a valuable place in managing some asthma. They should probably be limited to younger children and used mainly for prophylactic drugs.56 Dr Bendefy's study does not support the conclusion that home nebulisers are valuable in childhood asthma. Further investigation is required, and caution must be exercised in using home nebulisers. P A G GIBSON

Department of Public Health, Preston Health Authority, Preston PR2 4DX

1 Bendefy IM. Home nebulisers in childhood asthma: survey of hospital superised use. BMJ7 1991;302:1180-1. (18 May.) 2 Cochrane AL. Effectiveness and efficiency: random reflections on health services. London: Nuffield Provincial Hospitals Trust, 1972. 3 Warner JO. Treating asthma in pre-school children: children over 2 may use a nebuliser. BMJ 1988;297:154-5. 4 Warner JO, GCitz M, Landau LI, Levison H, Milner AD, Pedersen S, et al. Management of asthma: a consensus statement. Arch Dis Child 1989;64:1065-7 1. 5 Cogswell JJ, Simnpkiss MJ. Nebulised sodium cromoglycate in recurrently wheezy pre-school children. Arch Dis Child

1985;60:736-8. 6 Godfrey S, Avital A, Rosler A, Mandelberg A, Unwyved K. Nebulised budesonide in severe infantile asthma. Lancet

1987;ii:851-2.

SIR,-We run an extensive service that lends home nebulisers to patients, and we do not agree with Dr Ilona M Bendefy that nebulised bronchodilators should be regarded as the main method of treatment

1600

for children of preschool age with moderate and severe asthma.' After instruction many of these children can use a spacing device to deliver preventive medication from a metered dose inhaler. A mask can be attached to the end of the inhaler if the child is too young to use the mouthpiece.2 We prefer to use this delivery system to prevent symptoms of asthma in this age group, reserving a nebulised bronchodilator for those children troubled by frequent symptoms despite attempts at prophylaxis. Though nebulised bronchodilators are of undoubted benefit in acute asthma, it is important that their use at home does not delay appropriate assessment by a doctor and the opportunity to prescribe short courses of oral prednisolone. The improvements resulting from such treatment should decrease the subsequent need for nebulisers.3 Bronchodilator solutions for nebulisers are conveniently available in single dose ampoules. Overdosage should not be a problem if written guidelines clearly state a minimum of four hours between doses. The use of weight related doses has major drawbacks. It is asking a lot to expect parents to draw up accurate doses ofbronchodilator and saline in the middle of the night when confronted with their acutely wheezy child. Furthermore, the shelf life of an opened bottle of nebuliser solution is one third that of an opened packet of ampoules. We have had feedback from a small number of parents who have used bottles of nebuliser solution at home; they found them fiddly and time consuming to use. The nebuliser epidemic of the 1980s is endemic in the '90s. Future management of asthma should address the extent to which nebulised bronchodilators are used. G CONNETT C WARDE E WOOLER W LENNEY Royal Alexandra Hospital for Sick Children, Brighton BN I 3JN 1 Bendefy IM. Home nebulisers in childhood asthma: survey of hospital supervised use. BMJ 1991;302:1180-1. (18 May.) 2 O'Callaghan C, Milner AD, Swarbrick A. Spacer device with face mask attachment for giving bronchodilators to infants with asthma. BMJ 1989;298:160-1. 3 Storr J, Barry W, Barrell E, Hatcher G, Lenney W. Effect of a single dose of prednisolone in acute childhood asthma. Lancet

1987;i:879-81.

AUTHOR'S REPLY, -Dr Gibson's concerns are well founded. My own, similar concerns prompted my study. He correctly highlights two potential inappropriate uses of home nebulisers shown by the study: firstly, in giving bronchodilators but not regular prophylaxis; and, secondly, their use by school age children, who, theoretically, could use other methods. Parents were asked about other treatment used. In 32 cases children received no treatment except nebulised bronchodilators. In mostcases school age children possessed alternative inhalational devices but their parents stated that the nebuliser was a more effective route for giving drugs during attacks. In response to Dr Connett and colleagues' letter I would draw attention to my conclusion, which was that home nebulisers were valuable in childhood asthma. I did not conclude, as they have stated, that nebulised bronchodilators should be regarded as the main method of treatment for children of preschool age with moderate and severe asthma, although I referred to the work of others who have recommended this line of management.' 2 This was a descriptive study based on parents' responses. My conclusion would more accurately be that parents found home nebulisers useful in childhood asthma. I agree that an analytical study is required to establish correct guidelines for the

safe and effective use of nebulisers in childhood asthma. ILONA BENDEFY

Multiple Births Foundation, Queen Charlotte's and Chelsea Hospital, London W6 OXG 1 Milner AD. Recent advances in childhood asthma. Update 1987 Feb 15:398-403. 2 Reiser J, Warner JO. Inhalational treatment for asthma. Arch Dis Child 1986;63:774-9.

Differences between peak flow meters on prescription SIR,-In the editorial on home peak flow meters by Drs A S Vathenen and N J Cooke' and in subsequent correspondence no reference has been made to differences between the three types of meter that can be dispensed on NHS prescriptions. Inquiries that I have received suggest that many doctors and pharmacists are confused that two meters bear the name Wright; they assume that both were designed by Dr Martin Wright, the inventor of the original peak flow meter,2 which also bears his name. In fact, only the mini-Wright meter3 was designed by Dr Wright. Presumably, the Wright pocket meter was so named by virtue of its using a mechanical principle similar to that of Wright's original peak flow meter.2 The extreme simplicity of its design, however, raises serious doubts about its accuracy and also makes it impossible to calibrate individual instruments. As the pocket meter was introduced less than a year ago experience of its use in clinical practice is limited and no trials to assess its accuracy have been reported, nor is it known for how long its performance remains consistent. In contrast, extensive experience of the mini-Wright meter over some 15 years confirms that its readings agree closely with those given by the Wright peak flow meter4' and that it maintains its accuracy satisfactorily during prolonged use.67 So long as there is doubt over the accuracy of the pocket meter its readings should not be assessed by comparison with reference values of peak expiratory flow that have been derived from studies in which the Wright peak flow meter was used.89 Appreciation of this may have been the reason why the manufacturers of the pocket meter supply a nomogram (but without any reference to its source) for predicting peak expiratory flow in adults. This is likely to cause great confusion as it gives predicted values that, at certain ages and in both sexes, differ by between -30 and 50 1/min from those obtained from the nomogram of Nunn and Gregg provided by the manufacturers of the mini-Wright and Vitalograph meters.9 In view of such lack of evidence of the pocket meter's performance I am astonished that the Department of Health approved it for prescription on the NHS. Doubtless, the decision was influenced by cost: the pocket meter is 14p cheaper than the Vitalograph meter and 54p cheaper than the mini-Wright meter. IAN GREGG

Bassett, Southampton S02 3TT 1 Vathenen AS, Cooke NJ. Home peak flow meters. BMJ7

1991;302:738. (30 March.) 2 Wright BM, McKerrow CB. Maximal forced expiratory flow rate as a measure of ventilatory capacity with a description of a new portable instrument for measuring it. BMJ 1959;ii: 1041-7. 3 Wright BM. A miniature Wright peak flow meter. BM3' 1978;ii: 1627-8. 4 Schapira A. A controlled study of lung function in cashew nut factory workers. J7 Trop Med Hyg 1983;86:123-5. 5 Morrill CG, Dickey DW, Weiser PC, Kinsman RA, Chai H, Spector SL. Calibration and stability of standard and miniWright peak flow meters. Ann Allergy 1981;46:70-3. 6 Josephs LK, Gregg I, Mullee MA, Holgate ST. Nonspecific bronchial reactivity and its relationship to the clinical expression of asthma: a longitudinal study. Am Rev Respir Dis

1989;140:350-7.

BMJ VOLUME 302

29 JUNE 1991