Peak expiratory flow in bed? A comparison of 3 positions.

BACKGROUND Current guidelines for the correct peak expiratory flow (PEF) maneuver include standing. In the hospital setting, PEF values are often ordered to assess response to asthma therapy for exacerbations. We have observed that the PEF is sometimes performed with the patient in bed. METHODS Healthy adults performed the PEF maneuver in random order, standing, lying back at an ~45° angle on pillows, and sitting, slumped forward ~10° with legs extended. PEF was recorded for 3 attempts in each of the 3 positions. RESULTS We enrolled 94 subjects (39 male, 55 female, mean age 24 y) in 2011. Mean PEF in the standing position (669 ± 42 L/min) was significantly higher than in the lying back (621 ± 42 L/min) (P < .001) and sitting (615 ± 42 L/min) positions in males (P < .001), and, similarly, in females, standing produced a significantly higher mean PEF (462 ± 42 L/min) than the lying back (422 ± 42 L/min) (P < .001) and sitting (447 ± 42 L/min) positions (P < .05). CONCLUSIONS Clinicians should ensure that PEF is obtained with patients out of bed and in the standing position.