Table 1 represents comparisons for the following indices of pulmonary function: total lung capacity (TLC), FRC, RV, FEVi, Raw, Vmax50 (uncorrected for lung volume), and V/V25-75. Comparisons were made in the following fashion. Consider the values of Raw for subject 1. On the first occasion listed, subject 1 was asymptomatic, the Raw being 76 percent of predicted. A change of 127 percent from that baseline level was seen when symptoms first became apparent.
On the second occasion listed, subject 1 again initially was asymptomatic, but her baseline value of Raw was somewhat impaired (166 percent of predicted). On this occasion, only a 93 percent increase from this baseline level was required for her to reach a threshold point. Subject 1 was thus considered to be relatively more sensitive to acute fluctuation on the occasion when she commenced with already impaired pulmonary function. Such a comparison was not possible in every subject, since baseline indices did not necessarily differ by 25 percent or more. Thus, only those tests when baseline fluctuation allowed such comparisons are tabulated.
Seven of the ten subjects demonstrated sufficient fluctuation in baseline values for static lung volumes (TLC, FRC, or RV) to allow comparisons. In each case, as the baseline value for static lung volume increased, the relative change (ie, further increase) needed to attain a threshold point became less.
A 25 percent fluctuation in baseline FEV1 was not seen in any subject. When Raw was considered, comparisons of sensitivity to internal loading were possible in six subjects. In four of these six subjects, as baseline Raw became impaired, the subject appeared relatively more sensitive to further acute deterioration. Similar trends were seen in four of the seven subjects in whom comparisons of Vmax50 were possible and in six of the seven subjects in whom comparisons of V/V25-75 were made. Thus, only a minority of subjects had a relative blunting in their perception of acute “bronchospasm” as their baseline pulmonary function deteriorated.
Table 1—Comparison of Baseline indices of Pulmonary Function and Change Required to Produce Threshold Symptoms
| Subject and Measurement | TLC | FRC | RV | FEVi | Raw | Vmax50 | V/V25-75** |
| Subject 1 (F, 21 yr) Determination 1 Initial value, percent of predicted | 66 | 99 | 76 | 121 | 3.4 | ||
| Percent change to threshold | 13 | 84 | 127 | 40 | 15 | ||
| Determination 2 Initial value, percent of predicted | 114f | 173t | 166t | 71 | 1.9t | ||
| Percent change to threshold | 8t | 4t | 93t | 43 | 8t | ||
| Subject 2 (M, 23 yr) Determination 1 Initial value, percent of predicted | 82 | 2.9 | |||||
| Percent change to threshold | 31 | 28 | |||||
| Determination 2 Initial value, percent of predicted | 63 | 2.01 | |||||
| Percent change to threshold | 53 | 13t | |||||
| Subject 3 (F, 22 yr) Determination 1 Initial value, percent of predicted | 71< | 65 | |||||
| Percent change to threshold | 56 | 158 | |||||
| Determination 2 Initial value, percent of predicted | 1211 | 152t | |||||
| Percent change to threshold | 30f | 511 | |||||
| Subject 4 (M, 24 yr) Determination 1 Initial value, percent of predicted | 93 | 46 | 4.1 | ||||
| Percent change to threshold | 79 | 43 | 37 | ||||
| Determination 2 Initial value, percent of predicted | 143t | 32t | 2.8t | ||||
| Percent change to threshold | 72t | 35t | Ht | ||||
| Subject 5 (M, 22 yr) Determination 1 Initial value, percent of predicted | 76 | 83 | 101 | 46 | 1.8 | ||
| Percent change to threshold | 53 | 151 | 79 | 43 | 38 | ||
| Determination 2 Initial value, percent of predicted | lilt | 1811 | 2631 | 32t | 1.4t | ||
| Percent change to threshold | 18t | 59t | 72t | 35t | 27t | ||
| Subject 6 (F, 25 yr) Determination 1 Initial value, percent of predicted | 87 | 121 | 81 | ||||
| Percent change to threshold | 20 | 21 | 21 | ||||
| Determination 2 Initial value, percent of predicted | 1231 | 179t | 39 | ||||
| Percent change to threshold | iot | 2t | 37 | ||||
| Subject 7 (M, 23 yr) Determination 1 Initial value, percent of predicted | 87 | 116 | 2.4 | ||||
| Percent change to threshold | 63 | 49 | 28 | ||||
| Determination 2 Initial value, percent of predicted | 155t | 68t | 1.4t | ||||
| Percent change to threshold | 19t | 24t | 12t | ||||
| Subject 8 (F, 31 yr) Determination 1 Initial value, percent of predicted | 130 | 74 | 2.5 | ||||
| Percent change to threshold | 141 | 194 | 25 | ||||
| Determination 2 Initial value, percent of predicted | 172t | 286 | 1.7 | ||||
| Percent change to threshold | 116t | 334 | 50 | ||||
| Subject 9 (M, 23 yr) Determination 1 Initial value, percent of predicted | 85 | 60 | 86 | 68 | 2.2 | ||
| Percent change to threshold | 27 | 152 | 49 | 2 | 27 | ||
| Determination 2 Initial value, percent of predicted | 114f | 172t | 156t | 441 | 1 6t | ||
| Percent change to threshold | 5t | 17t | 341 | ot | 6t | ||
| Subject 10 (M, 22 yr) Determination 1 Initial value, percent of predicted | 139 | ||||||
| Percent change to threshold | 151 | ||||||
| Determination 2 Initial value, percent of predicted | 238 | ||||||
| Percent change to threshold | 426 |