Test/Retest Reliability of Maximum Mouth Pressure Measurements With the MicroRPM in Healthy Volunteers

the respiratory muscles ’ ability to generate force is important for recognizing respiratory muscle weakness in both sick and healthy people. OBJECTIVE: To assess the test/retest reliability of the MicroRPM portable manometer’s measurements of maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) in the sitting and standing positions; the number of expira-tory maneuvers needed with the MicroRPM for reliability in MIP and MEP measurement; and the MicroRPM’s test/retest reliability in other respiratory function indices, such as the maximum rate of pressure development (MRPD), the time constant of relaxation (tau), and the maximum relax-ation rate (MRR). METHODS: We recruited 15 healthy volunteers (mean age 21.6 1.1 years). We assessed respiratory muscle strength on 3 separate occasions, each a week apart. We calculated reliability with the intraclass correlation coefficient (ICC), the standard error of measurement (SEM) and the smallest detectable difference (SDD). RESULTS: MicroRPM reliably measured MIP and MEP in both the sitting position (ICC 0.86–0.90, SEM 9–10, SDD 18–22) and standing position (ICC 0.78–0.83, SEM 12–14, SDD 23–26). After a 5-breath practice, 2 expiratory/inspira-tory maneuvers on each testing occasion gave adequate MIP and MEP reliability (ICC> 0.90). MRR reliability was moderate to excellent (ICC 0.58–0.87), MRPD reliability was moderate (ICC 0.59–0.64), and tau reliability was insufficient (ICC 0.27–0.67). CONCLUSIONS: The Mi-croRPM reliably measures MIP and MEP, but its MRPD, MRR, and tau measurements should be considered with caution. Key words: respiratory muscle; lung function; maximum expiratory pressure; maximum inspiratory pressure; manometer; reliability. [Respir Care 2011;56(6):776–782. © 2011 Daeda-lus Enterprises