SINGLE-BREATH COUNTING IN THE ASSESSMENT OF PULMONARY-FUNCTION

Study objectives: To assess the correlation of single breath counting (SBC) and peak expiratory flow rate (PEFR) to forced expiratory volume in the first second (FEV1). Design: Prospective comparison of pulmona ry function measurements. Setting: University hospital pulmonary funct ion test (PFT) laboratory. Type of participants: Consenting patients s cheduled to have PFTs May 1, 1992, through November 1, 1992. Intervent ions: SBC was measured by asking patients to take a deep breath and co unt as far as possible in their normal speaking voice without taking a nother breath. Counting was timed to a metronome set at 2 counts per s econd. A hand-held peak flowmeter was then used to measure PEFR. Stand ard PFTs then were performed. Measurements and main results: Twenty-tw o patients were enrolled. The correlation of SBC to FEV1 (r=.68) was s lightly better than of PEFR to FEV1 (r=.63). SBC was also found to cor relate well with PEFR (r=.68). Conclusion: SBC is a reasonable alterna tive to PEFR. Further investigation in an emergency department setting is warranted.