[Evaluation of the tracheobronchial clearance in patients with chronic bronchial infections by an integrated system using radioactive aerosol inhalation scintigraphy].

Abstract

It is widely accepted that the impairment of tracheobronchial clearance (TBC) are closely related to the development and the progression of chronic bronchial infections. We investigated TBC in patients with chronic bronchial infections (bronchiectasis; 11 cases, diffuse panbronchiolitis; 9 cases and primary ciliary dyskinesia; 3 cases) and also in 6 healthy subjects by a radioactive aerosol (99mTc-human serum albumin, 4.4 +/- 1.4 microns in diameter) inhalation scintigraphy with cough control in order to elucidate the relationships between impaired TBC and chronic bronchial infections. All subjects were not current smokers. After 4-minutes inhalation of radioactive aerosols (tidal volume: 500 ml x 20/min.), radioactivities in whole right lung were measured every 20 seconds for 2 hours serially and then measured at the time of 6 and 24 hours after inhalation. Immediately after the serial recording for 2 hours, single photon emission computed tomography (SPECT) was performed to assess the deposition pattern of radioactive aerosols. During the first 2 hours, all the subjects were instructed to avoid coughing as much as possible to evaluate the mucociliary clearance without cough effect. And then the subjects were allowed to cough between 2 and 24 hours after inhalation. All radiation counts were corrected for background radiation and physical decay of 99mTc. Because it is considered that the deposited aerosols are eliminated much more slowly in alveoli (biological half life: several months) than in airways (biological half life: several hours), the radioactivity remaining at the time of 24 hours was defined as alveolar deposition (ALV). Initial bronchial deposition (Br0) was defined as initial whole lung deposition (L0) minus ALV. We evaluated the TBC with following parameters; 1) Br0/L0 (%):ratio of initial bronchial deposition to initial lung (bronchial and alveolar) deposition. 2) Br2/Br0 (%), Br6/Br0 (%):bronchial retention ratio; the ratio of bronchial deposition at the time of 2 and 6 hours after inhalation to initial bronchial deposition, respectively. 3) TMV (mm/min.):tracheal mucus velocity (rate of shift of radioactive bolus on tracheal mucosa), which was measured during the period of first 2 hours under prohibition of cough. The patients (23 cases) were divided into two groups with regards to cough control for the first two hours of the scintigraphy:cough-controlled group (19 cases) and cough-uncontrolled group (4 cases). The cough-controlled group was subdivided into two subgroups (group A and group B) according to Br0/L0:group A less than 47.9% (mean + SD of Br0/L0 in healthy control) less than or equal to group B.(ABSTRACT TRUNCATED AT 400 WORDS)