Detection of wheezing during maximal forced exhalation in patients with obstructed airways.
OBJECTIVE
Wheezing is a common clinical finding in patients with asthma and COPD during episodes of severe airway obstruction, and can also be heard in normal subjects during forced expiratory maneuvers; however, the properties of wheezing are difficult to perceive and quantify during auscultation. We therefore developed and evaluated a new technique for recording and analyzing wheezing during forced expiratory maneuvers in a group of patients with obstructed airways (asthma, COPD) and a control group of healthy subjects.


METHODS
Sixteen patients with asthma (9 men and 7 women), 6 patients with COPD (6 men), and 15 healthy subjects (7 men and 8 women) were enrolled. The patients had moderate-to-severe obstruction (FEV(1) of 40 to 53% predicted). A contact sensor on the trachea was used to record sound during forced expiratory maneuvers. Wheeze detection was carried out by a modified algorithm in a frequency-time space after applying the fast Fourier transform.


RESULTS
More wheezes were recorded in patients with obstructed airways than in control subjects: asthma patients, 8.4 +/- 6.4 wheezes; COPD patients, 10.4 +/- 6.1 wheezes; and control subjects, 2.9 +/- 2.0 wheezes (mean +/- SD). The mean frequency of all detected wheezes was higher in control subjects than in patients with obstructed airways (asthma patients, 560.9 +/- 140.8 Hz; COPD patients, 669.4 +/- 250.1 Hz; and control subjects, 750.7 +/- 175.7 Hz). The total number of wheezes after terbutaline inhalation changed more in patients with obstructed airways than in control subjects.


CONCLUSIONS
The new method that we describe for studying airway behavior during forced expiratory maneuvers is able to identify and analyze wheeze segments generated in patients with obstructed airways, as evidenced by the greater number of wheezes detected in the patient group, the main finding of this study. This method clearly and objectively identifies the presence of obstructive disease.
Fiz
José A
JA
Department of Respiratory Medicine, Hospital Universitario Germans Trias i Pujol, Badalona, Spain. jafiz@ns.hugtip.scs.es
Jané
Raimon
R
Homs
Antonio
A
Izquierdo
José
J
García
Maria A
MA
Morera
José
J
D000704:Analysis of Variance; D000886:Anthropometry; D001249:Asthma / Q000188:drug therapy / Q000503:physiopathology*; D001993:Bronchodilator Agents / Q000627:therapeutic use; D016022:Case-Control Studies; D005260:Female; D005540:Forced Expiratory Flow Rates; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000188:drug therapy / Q000503:physiopathology*; D012135:Respiratory Sounds / Q000175:diagnosis* / Q000187:drug effects; D013147:Spirometry; D013726:Terbutaline / Q000627:therapeutic use
D001993:Bronchodilator Agents; D013726:Terbutaline