We have previously shown that patients with nocturnal worsening of asthma (nocturnal asthma) exhibit increased parenchymal inflammation at night. To evaluate the functional significance of this parenchymal inflammation, 10 subjects with nocturnal asthma (NA), four subjects with non-nocturnal asthma (NNA), and four normal control subjects underwent bronchoscopy with measurement of peripheral airways resistance (Rp) at 4:00 P.M. and at 4:00 A.M. Employing a wedged bronchoscope technique, Rp was measured. Flow was stopped, and the pressure reached after 10 s of decay was termed the plateau pressure. The time constant of this decay (τ) was measured, and the peripheral compliance (Cp) was calculated as τ/Rp. The NA group exhibited the highest Rp values at 4:00 P.M. and at 4:00 A.M. as compared with the NNA and control groups, but all groups were significantly different from each other at 4:00 P.M.: NA, 0.113 ± 0.02 cm H2O/ml/min; NNA, 0.033 ± 0.005 cm H2O/ml/min; Control subjects, 0.010 ± 0.001 cm H2O/ml/min; p = 0.0001; and at 4:00 A.M.: NA, 0.129 ± 0.023 cm H2O/ml/min; NNA, 0.035 ± 0.007 cm H2O/ml/min; Control subjects, 0.009 ± 0.002 cm H2O/ml/min; p = 0.0003. None of the groups exhibited statistically significant differences in Rp between 4:00 P.M. and 4:00 A.M.. The plateau pressure increased significantly from 4:00 P.M. to 4:00 A.M., but only in the NA group (7.7 ± 0.9 cm H2O at 4:00 P.M. versus 16.9 ± 4.6 cm H2O at 4:00 A.M.; p = 0.0004). Cp was decreased in the NA group as compared with the NNA and control groups at both 4:00 P.M. (p = 0.0003) and 4:00 A.M. (p = 0.003). The Rp positively correlated with the residual volume at both 4:00 P.M. (r = 0.71, p = 0.004) and 4:00 A.M. (r = 0.59, p = 0.03). We conclude that the distal lung units, specifically the collateral channels, and may be functionally altered at night in NA.
|Original language||English (US)|
|Number of pages||6|
|Journal||American journal of respiratory and critical care medicine|
|State||Published - 2001|
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine
- Critical Care and Intensive Care Medicine