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Distal lung dysfunction at night in nocturnal asthma.
1Division of Pulmonary Sciences and Critical Care Medicine, University of Colorado Health Sciences Center, National Jewish Medical and Research Center, Denver, Colorado 80206, USA. kraftm@njc.org
Summary
Patients with nocturnal asthma experience increased airway resistance and decreased lung compliance at night, suggesting functional changes in distal lung units. These findings highlight potential targets for managing nighttime asthma symptoms.
Area of Science:
- Pulmonary Medicine
- Respiratory Physiology
Background:
- Nocturnal asthma is associated with increased nighttime parenchymal inflammation.
- The functional implications of this inflammation require further investigation.
Purpose of the Study:
- To evaluate the functional significance of nighttime parenchymal inflammation in nocturnal asthma.
- To assess peripheral airways resistance and compliance in patients with nocturnal asthma compared to non-nocturnal asthma and control subjects.
Main Methods:
- Bronchoscopy with measurement of peripheral airways resistance (Rp) and calculation of peripheral compliance (Cp) at 4:00 P.M. and 4:00 A.M.
- Involved 10 subjects with nocturnal asthma (NA), 4 with non-nocturnal asthma (NNA), and 4 controls.
- Used a wedged bronchoscope technique to measure Rp, plateau pressure, and time constant (tau).
Main Results:
- The NA group exhibited significantly higher Rp at both 4:00 P.M. and 4:00 A.M. compared to NNA and control groups (p < 0.0001).
- Plateau pressure significantly increased from 4:00 P.M. to 4:00 A.M. only in the NA group (p = 0.0004).
- Peripheral compliance (Cp) was decreased in the NA group at both time points (p < 0.003) and Rp positively correlated with residual volume.
Conclusions:
- Distal lung units, specifically collateral channels, may be functionally altered at night in patients with nocturnal asthma.
- Increased peripheral airways resistance and decreased compliance contribute to nighttime asthma exacerbations.
- Findings suggest a potential mechanism for nocturnal asthma symptoms related to altered distal airway function.