Peak Inspiratory Mouth Pressure in Healthy Subjects and in Patients With COPD

The validity of peak inspiratory mouth pressure (P.PImax) as a measure of inspiratory muscle strength was investigated by comparing it with sniff Pes in patients with COPD with respect to (1) learning effect, (2) reproducibility, and (3) measures of agreement. To assess the discriminating capacity of P.PImax, we compared the values in patients with COPD with those of healthy elderly subjects. Thirty-four patients (mean age, 62.5 years) with severe airways obstruction (FEV(1), 44% predicted; FEV(1)/IVC, 37% predicted) and 149 healthy subjects (age greater than or equal to 55 years) were included. P.PImax was assessed during a maximal static inspiratory maneuver, while sniff Pes was assessed during a maximal sniff maneuver. Both maneuvers were performed from residual volume ten times on the same day. P.PImax showed no learning effect, while the sniff maneuver used seven attempts to obtain a maximal value. The intraindividual coefficients of variation of P.PImax and sniff Pes were 11.2% and 6.0%, respectively. Measures of agreement showed no significant discrepancies between the mean P.PImax and mean sniff Pes (0.29 kPa, p = 0.49). There was a significant correlation (r = 0.57, p