Comparison of PEFR and FEV1 in Patients with Varying Degrees of Airway Obstruction: Results
Ten subjects with airway obstruction demonstrated little or no reversible component and had diagnoses of COPD. The mean baseline FEVi for all patients with obstructive lung disease was 1.83 ±0.75 L (60.9 percent predicted) while the mean JPF was 314 ± 122 L/min (76.9 percent predicted). Airway symptoms had been present in this group from six months to 55 years, with a mean duration of 12.8 years. Seventy-two (71 percent) patients reported previous experience using either the JPF or the WPF. Thirty patients had no prior experience with either instrument. Here
In 31 subjects, no evidence of lower airway disease was found, although 13 had allergic rhinitis. The mean baseline FEVi for these patients was 3.01 ±1.14 L (91.4 percent predicted), and the mean JPF was 457 ± 144 L/min (104 percent predicted).
When the best of three efforts expressed as percent predicted was used for comparison, a strong correlation was observed among the three measurements of pulmonary function. The correlation of FEVj with JPF was highly significant (r=0.758, p<0.001; Fig 1). The majority of data points lie above the line of identity, indicating that peak flow values were in general higher than the corresponding value of FEV!. A similar pattern was observed when the best of three efforts for FEVj was compared with WPF (Fig 2). The correlation coefficient for these data is 0.744 (p<0.001). On the other hand, a better correlation was observed between values of peak flow obtained with the JPF and peak flow values obtained with the WPF, r=0.846 (p<0.001). When the mean of the three efforts was used rather than the best value, a poorer correlation was obtained in all comparisons. Other combinations of percent predicted and absolute values were compared and the data summarized (Table 1).
The mean SD for the three efforts were calculated for FEVj, JPF, and WPF in all 102 patients. The mean SD for FEV, was 3.01, for JPF, 7.2, and for WPF, 5.12.
Figure 1. Percent predicted FEV, plotted against percent predicted peak flow obtained with the Jones Pulmonor spirometer. Line, line of identity.
Figure 2. Percent predicted FEV, plotted against percent predicted peak flow obtained with mini-Wight peak flow meter. Line, line of identity.
Table 1—Correlation Between AH Values Obtained
|% Fred FEV, vs % pred JPF||.758*|
|% Pred FEV, vs % pred WPF||.744|
|% Pred JPF vs % pred WPF||.846|
|Mean % pred FEV, vs mean % pred JPF||.692|
|Mean % pred FEV, vs mean % pred WPF||.711|
|Mean % pred JPF vs mean % pred WPF||.820|
|% Pred FEV, vs JPF absolute||.726|
|% Pred FEV, vs WPF absolute||.776|
|% Pred JPF vs FEV, absolute||.ODD|
|% Pred JPF vs WPF absolute||.788|
|% Pred WPF vs FEVi absolute||.597|
|% Pred WPF vs JPF absolute||.654|
|FEV, absolute vs JPF absolute||.833|
|FEV, absolute vs WPF absolute||.868|
|JPF absolute vs WPF absolute||.931|