Peak expiratory flow (PEF) depends on the type of maneuver used and especially the duration of postinspiratory pause prior to expiration. Forceful expiratory maneuvers with a 4–5 s pause at total lung capacity prior to expiration may produce lower PEF values compared with maneuvers without a pause. In the absence of guidelines about the appropriate duration of pause, a 1.5 to 2 s postinspiratory pause is invariably allowed prior to forced expiration in most laboratories. The purpose of this study was to compare PEF and PEF reproducibility obtained with maneuvers including a brief (<2 s) pause (P) with those obtained with maneuvers without pause (NP).
Nineteen healthy volunteers (38±8 yrs) performed maximal forceful expirations, using P and NP maneuvers. PEF was measured spirometrically four times with each maneuver. All measurements were repeated in a second session, approximately 20 days apart. Individual PEF variability was expressed as coefficient of variation (CV) and amplitude percent mean (A%M).
For the P maneuver, the average pause was about 1.7 s. Within- or between-session analysis showed no intermaneuver differences in best PEF, CV, or A%M. (p>0.05, TableSESSION 1SESSION 2PNPPNPPEF (L/s)7.94±1.77.98±1.67.76±1.67.87±1.7CV (%)5.35±2.94.69±3.65.56±2.95.02±3.8A%M (%)11.9±7.210.6±7.713.6±6.911.8±9.2). Bland and Altman analysis of intermaneuver differences in best PEF showed no significant systematic bias in session 1 (−0.04 ±1.5 L/s, mean±2SD, bias±precision) or session 2 (−0.11±0.9 L/s, mean±2SD, bias±precision); intersession repeatability was also comparable for the two maneuvers.
Postinspiratory pauses up to 2 sec prior to forced expiration do not significantly affect PEF and its repeatability.
Maneuvers with a brief (<2 s) postinspiratoty pause prior to forceful expiration are as effective as maneuvers without a pause and can be used interchangeably for measuring PEF.
T. Omar, None.