A three-microphone acoustic reflection technique using transmitted acoustic waves in the airway.

The acoustic reflection technique noninvasively measures airway cross-sectional area vs. distance functions and uses a wave tube with a constant cross-sectional area to separate incidental and reflected waves introduced into the mouth or nostril. The accuracy of estimated cross-sectional areas gets worse in the deeper distances due to the nature of marching algorithms, i.e., errors of the estimated areas in the closer distances accumulate to those in the further distances. Here we present a new technique of acoustic reflection from measuring transmitted acoustic waves in the airway with three microphones and without employing a wave tube. Using miniaturized microphones mounted on a catheter, we estimated reflection coefficients among the microphones and separated incidental and reflected waves. A model study showed that the estimated cross-sectional area vs. distance function was coincident with the conventional two-microphone method, and it did not change with altered cross-sectional areas at the microphone position, although the estimated cross-sectional areas are relative values to that at the microphone position. The pharyngeal cross-sectional areas including retropalatal and retroglossal regions and the closing site during sleep was visualized in patients with obstructive sleep apnea. The method can be applicable to larger or smaller bronchi to evaluate the airspace and function in these localized airways.

[Cytokines and proteases involved in pathogenesis of COPD].

COPD is characterized by persistence of chronic inflammation in small airways and alveoli. Macrophages, neutrophils, and a specialized subset of T lymphocytes orchestrate the mild inflammation. This article focuses on humoral factors such as cytokines and chemokines that recruit these inflammatory and immune cells to the lungs, and proteases/antiproteases that ultimately cause structural derangement in the terminal respiratory zones. In addition to the classical protease and antiprotease imbalance hypothesis, alveolar homeostasis abnormality that comes from imbalance of lung constitutional cell apoptosis and regeneration may play a role in emphysema development. Also, autoimmunity to elastin degradation products may take part in the disease.

[Case of broncholithiasis lithoptysis occurring spontaneously after repeated pneumonia].

An abnormal chest shadow was pointed out in a 56-year-old woman in a health check in 2001. She had pulmonary tuberculosis at age 11. Because of repeated fever for the previous 2 years, she visited our hospital in 2003 and right upper lobe pneumonia was detected with a calcified nodule that completely obstructed the right upper lobe bronchus on CT. After admission, she spontaneously expectorated a stone. The composition of the stone was 57% calcium phosphate and 43% calcium carbonate. Radiological findings and the composition of the stone suggested that this broncholith was calcified bronchial mucus rather than a calcified lymph node that might have perforated into the airway. Bronchiectasis of the right B3 broncus was observed on CT scan after lithoptysis. Although the bronchiectasis was unchanged 2 years later, she had no symptoms, such as fever or cough.