Sputum induction in corticosteroid-dependant asthmatics: risks and airway cellular profile.
Sputum induction with nebulized hypertonic saline is increasingly being used to evaluate airway inflammation. We investigated the procedure-associated risk in 16 asthmatics that were still symptomatic despite on high doses of regular corticosteroid (CS) therapy (7 on daily inhaled CS > or = 800 microg budesonide or equivalent; 9 on additional daily oral CS) and their sputum cellular profile. For comparison, 12 mild stable asthmatics and 10 normal healthy subjects were included. All subjects inhaled 3%, 4% and 5% hypertonic saline sequentially via ultrasonic nebulizer as a means to induce sputum. Maximal percentage fall of Forced Expiratory Volume on One Second (FEV1) during sputum induction was significantly greater in CS-dependent asthmatics (median % [IQR]: 16.0 [11.0-32.3]) than in mild asthmatics (5.3 [4.2-10.8], p = 0.002] and in normal subjects (4.6 [3.4-6.4]), p = 0.0001). The maximal percentage FEV1 fall was inversely correlated with baseline FEV1 (Rs= -0.69; p < 0.0001). Compared to mild asthmatics, induced sputum from CS-dependant asthmatics had proportionately fewer eosinophils (2.2 [0.8-7.0] versus 23.3% [10.7-46.3], p = 0.003) and greater neutrophils (64.2 [43.9-81.2] versus 28.7 [19.0-42.6], p = 0.009). Sputum neutrophils showed a significant inverse correlation to FEV1 (Rs = -0.51, p = 0.01). We concluded that sputum induction using nebulized hypertonic saline should be performed with caution in CS-dependant asthmatics. The airway cellular profile observed suggests that the immunopathology underlying CS-dependant asthmatics may be different or a consequence of CS therapy.
Loh
L C
LC
Department of Medicine, International Medical University, Malaysia. loh@imu.edu.my
Kanabar
V
V
D'Amato
M
M
Barnes
N C
NC
O'Connor
B J
BJ
D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000276:immunology* / Q000503:physiopathology; D001993:Bronchodilator Agents / Q000627:therapeutic use*; D019819:Budesonide / Q000627:therapeutic use*; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D009330:Nebulizers and Vaporizers; D012462:Saline Solution, Hypertonic / Q000008:administration & dosage*; D013183:Sputum / Q000166:cytology*
D000305:Adrenal Cortex Hormones; D000893:Anti-Inflammatory Agents; D001993:Bronchodilator Agents; D012462:Saline Solution, Hypertonic; D019819:Budesonide