Method for manipulating peak flow measurements producing falsely raised readings.

Methods by which patients can artificially produce raised peak flow measurements have been described. We recently observed a patient manipulating the peak flow meter in a way that had not been described before. A study was therefore undertaken to determine if this technique could repeatedly produce clinically significant changes in peak flow readings. Fifteen adults, using a mini-Wright peak flow meter, made five measurements using the correct technique followed by five manipulated measurements under observation. Significant increases in peak flow measurements were observed in 14 of the 15 subjects. The mean increase in peak flow rate using the incorrect technique was 56% (range -4% to 86%). Clinicians should be aware that patients might employ this technique to manipulate measurements which could have consequences for management.