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monitoring improved asthma outcomes (Toelle and Ram 2004). A further Cochrane review
(Bhogal, Tnmek et al. 2006) in 2006 assessed four trials with 355 children comparing
symptom based written action asthma plans to PEF monitoring and found no differences in
the rate of exacerbation, oral steroid courses, admissions, symptoms, lung function, school
absenteeism or quality of life (Charlton, Charlton et al. 1990; Yoos, Kitzman et a:.2002;I*ta,
Schlie et al. 2004; Wensley and Silverman 2004). Symptom monitoring was actually
preferred over peak flow monitoring by the children. The final conclusion from this analysis
was "symptom based written action plans are superior to peak flow written action plans for
preventing acute care visits." (Bhogal, Tnmek et aL.2006). The daily use of pEF in a large
prospective study was not perceived to be useful by most families and therefore unlikely to be
adhered to by many (McMullen, yoos et aI.2002).
Electronic recording spirometers were compared to hand written diaries in 6l subjects aware
of the recording. Adherence to PEF monitoring over 72 weeks gradually declined fromg67o
to 89Vo with l3vo of participants ultimately withdrawn because of poor adherence (Reddel,
Toelle et al.2002). When participants were unaware of electronic recording and completed a
pen and paper diary over 3 month periods, 64Vo and,44vo adherence to monitoring was noted
(Chowienczyk, Parkin et al. 1994; Verschelden, Cartier et al. 1996). Two groups of children
reported 96.6Vo and 94.8Vo PEF monitoring compliance while the simultaneously monitoring
electronic device recorded compliance at 73.4Vo and 80.9Vo. Compliance decreased
significantly from week one to week four such that overall the compliance was less than 50Vo
in l2.5%o of the children and 50-75Vo in 20Vo of the children. Invention of some pEF
measurements occurred and increased threefold during the study time (Kamps, Roorda et al.
2001). This adds to the difficulty of giving action points, especially if figures are made up
and./or it is not perceived as useful.
In addition to these difficulties, differences have also been demonstrated when using different
PEF techniques. These include fast or slow exhalation (Richards 1993; Tzelepis, Zakynthinos
et al. 1997), a breath-hold at total lung capacity (Matsumoto, Walker et al. 1996), if the
position of the instrument is changed in relation to the mouth (Nolan, Tolley et al. 1999) or
with posture differences (Bongers and O'Driscoll 2006; Lin, parthasarathy et al. 2006).
Increased air trapping also reduced the ability of a normal PEF to predict a normal FEVI or
FEF25-75E" from 83 to 53Vo potentially falsely reassuring an individual of having better
pulmonary function than is correct @id, yandell et al. 2000).
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