Restricted Pulmonary Function in Cystic Fibrosis: Results
Pulmonary Function Tests
General characteristics and results of selected pulmonary function tests of the restricted and matched nonrestricted patients are summarized in Table 1. There were no significant differences between groups for age, height, and weight, the variables used for matching. A significant difference was observed only for plethysmographic TLC (TLC[P]), which was used in the selection of restricted patients. Plethysmographic RV and FRC were lower in the restricted group but not significantly different from the nonrestricted patients. The TLC by nitrogen washout (TLC [N]) was measured in only six restricted and eight nonrestricted patients. In five pairs of matched subjects, TLC(N) was not significantly lower in the restricted group. Radiographic TLC (TLC[R]) was also not significantly different between the groups. In addition, there were no differences in VC or expiratory flow rates (reduced in both groups), Raw (elevated in both groups), maximal inspiratory pressure (normal), or change in FEVX after bronchodilator. generic paxil
Chest Radiographic Grades
There were no significant differences between restricted and nonrestricted patients for any of the radiographic criteria scored (Table 1). Reproducibility of the radiographic grading was assessed by correlating the radiologists two readings for the three criteria graded on the second reading. Correlations between the first and second radiographic grades were 0.90 for bronchial markings, 0.84 for nodular cystic lesions, and 0.91 for general severity.
Clinical Scores
Mean clinical scores were higher in all categories for the restricted patients (representing less severe disease), but the differences were statistically significant only for the activity scores (Table 1). Correlation for all patients between total clinical score and total radiographic grade was 0.46 (p<0.05).
Radiographic-Gas Volume Differences
Even though the restricted patients were selected on the basis of decreased TLC(P), TLC(R) in these same patients was not significantly different between groups. We postulated that measurements of TLC(R) would overestimate the TLC(P) or TLC(N) in patients with a significant amount of abnormal air-space filling. Therefore, we subtracted TLC(P) or TLC(N) from TLC(R) to estimate the amount that air-space filling might be contributing to the restrictive process. The differences between radiographic and gas volumes (TLC[R-P] and TLC[R-N]) were higher in the restricted patients, as expected, but the difference did not reach statistical significance because of the high variance within groups (Table 2).
The differences between radiographic and gas volumes were also correlated with specific radiographic findings. These results, summarized in Table 3, demonstrated highly significant correlations between TLC(R-P) and TLC(R-N) with the scores for air trapping and bronchial markings in the restricted patients only, but not with radiographic evidence of parenchymal lesions (nodular or air-space lesions).
Table 1—Comparison of Restricted and Matched Nonrestricted Patients with Cystic Fibrosis
| Data | No.ofPairs | RestrictedPulmonaryFunction | NonrestrictedPulmonaryFunction | p Valuef |
| Matched variables# | ||||
| Sex | 5M/5F | 5M/5F | ||
| Age, yr | 10 | 22 ±5 | 21 ±5 | NS |
| Weight, kg | 10 | 54.0 ±10.9 | 53.9±7.9 | NS |
| Height, cm | 10 | 166.6 ±10.6 | 164.1 ±10.7 | NS |
| Pulmonary function# | ||||
| SVC, percent of predicted | 10 | 55 ±17 | 67 ±24 | NS |
| TLC, percent of predicted | ||||
| Plethysmography (P) | 10 | 78 ±4 | 100 ±8 | <0.001 |
| Nitrogen washout (N) | 5 | 78 ±7 | 98 ±17 | NS |
| Radiographic (R) | 10 | 92 ±21 | 99 ±8 | NS |
| FRC(P), percent of predicted | 10 | 99 ±21 | 125 ±22 | NS (0.06) |
| RV(P), percent of predicted | 10 | 152 ±63 | 205 ±63 | NS |
| RV/TLC(P), percent | 10 | 47 ±16 | 49 ±16 | NS |
| FEV10/FVC, percent | 10 | 64 ±14 | 63 ±21 | NS |
| FEF25–75%, percent of predicted | 10 | 24 ±24 | 37 ±42 | NS |
| Post BD FEVi/preBD FEVX§ | 10 | 1.03 ±0.13 | 1.04 ±0.07 | NS |
| PEFR, percent of predicted|| | 10 | 72 ±50 | 68 ±39 | NS |
| Raw, cm H20/L/s | 9 | 3.8±2.2 | 3.2± 1.1 | NS |
| UIF, cm H2Q1I | 10 | 108 ±31 | 91 ±39 | MS |
| Radiographic grades# | ||||
| Air trapping | 10 | 1.5± 1.3 | 1.7± 1.0 | NS |
| Bronchial markings | 10 | 2.4± 1.0 | 2.3±0.8 | NS |
| Nodular cystic lesions | 10 | 1.4±0.8 | 1.3±0.8 | NS |
| Air-space lesions | 10 | 1.1± 1.2 | 1.0±0.7 | NS |
| Overall severity | 10 | 2.6± 1.2 | 2.7± 1.1 | NS |
| Total score | 10 | 16.0±3.6 | 16.1 ±3.2 | NS |
| Clinical scores# | ||||
| Physical examination | 9 | 19.6±3.3 | 17.7±3.8 | NS |
| Activity | 9 | 20.9± 1.4 | 17.3±4.4 | <0.05 |
| Nutrition | 9 | 20.2 ±2.4 | 19.3±4.5 | NS |
| Total score | 9 | 60.7 ±5.3 | 54.0± 11.7 | NS |
Table 2—Radio graphic-Gas Volume Differences in Restricted and Matched Nonrestricted Patients with Cystic Fibrosis
| Data | Restricted | Nonrestricted | p Valuef |
| TLC(R-P), L | 0.62 ±0.98 | — 0.07±0.49 | 0.11 |
| TLC(R-N), L | 0.82 ±1.05 | 0.15 ±0.96 | 0.46 |
Table 3—Correlations between Initial Radiographic Grades and Radiographic-Gas Volume Differences
| Data | TLC (R-P) | TLC (R-N) | ||
| Restricted (n = 10) | Nonrestricted (n = 10) | Restricted(n = 6) | Nonrestricted (n = 8) | |
| Air trapping | 0.78f | 0.47 | 0.93f | 0.36 |
| Bronchial markings | 0.72$ | 0.20 | 0.92f | 0.44 |
| Nodular cystic lesions | -0.28 | -0.19 | 0.13 | 0.23 |
| Air-space lesions | -0.27 | -0.19 | -0.61 | -0.22 |
| Overall severity | 0.43 | 0.20 | 0.49 | 0.25 |
| Total score | -0.45 | -0.25 | -0.62 | -0.32 |
Category: Pulmonary Function
Tags: airway, cystic fibrosis, Pulmonary Function