Peak expiratory flow with or without a brief postinspiratory pause.

BACKGROUND The duration of postinspiratory pause prior to forced expiration may significantly influence the peak expiratory flow (PEF) measured during maximal forceful expirations. In comparison with maneuvers without a postinspiratory pause, maneuvers with 4 to 6-s pause at total lung capacity (TLC) result in decreased PEF values. The extent to which brief pauses (< 2 s) similarly affect PEF values is unknown. METHODS Thirty-six healthy volunteers (mean [+/-SD] age, 35 +/- 8 years; 18 men) performed a series of maximal forceful expirations with two different types of maneuvers. One maneuver (NP) included no inspiratory pause at TLC prior to forceful expiration, whereas the second (P) included a brief pause (< or = 2 s). The speed of inhalation to TLC was rapid and similar for both maneuvers. The highest PEF for each maneuver was used for analysis. RESULTS The maximal PEF did not differ (p > 0.05) between the P and NP maneuvers (7.78 +/- 1.45 vs 7.83 +/- 1.45 L/s, respectively). Comparison of the intermaneuver differences showed a bias of 0.05 L/s and 95% confidence interval in the range of -0.9 to 1.0 L/s. CONCLUSIONS Forceful expiratory maneuvers with or without postinspiratory pauses of < or = 2 s produce identical maximal PEF values and, therefore, can be used interchangeably for the spirometric measurement of PEF in healthy subjects.