Yoshihiro Nishi

Background/Objectives: Relapsing polychondritis (RP) is a rare autoimmune disorder marked by recurrent inflammation of cartilaginous tissues, including the airways. Airway involvement, such as subglottic stenosis and airway malacia, significantly impacts prognosis. Although spirometry is the standard for evaluating respiratory function, it may be unfeasible in patients with severe airway narrowing or tracheostomy. This study evaluated the potential of a smartphone-based application, DepthRecorder, which uses the iPhone’s TrueDepth camera to analyze thoracic motion in real time. Methods: Twelve patients with RP were enrolled. All underwent simultaneous respiratory assessment using spirometry and the DepthRecorder application. Thoracic motion data were corrected for height using previously validated regression formulas. Correlation between DepthRecorder and spirometry values was analyzed using Spearman’s rank correlation for forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), and the FEV₁/FVC ratio. Results: Mean age was 53.8 ± 13.3 years, with equal numbers of males and females. Before correction, DepthRecorder showed moderate correlations for FEV₁ (ρ = 0.48, p = 0.003) and FEV₁/FVC (%) (ρ = 0.57, p < 0.001). After correction, stronger correlations were observed for FVC (ρ = 0.76, p < 0.001), FEV₁ (ρ = 0.72, p < 0.001), and FEV₁/FVC (%) (ρ = 0.60, p < 0.001). Conclusions: The DepthRecorder application demonstrated strong correlations with spirometry following height-based correction. This method may offer a practical, non-invasive tool for respiratory assessment in RP patients who cannot undergo conventional lung function testing. Further studies are needed to validate these findings and establish clinical reference standards.

Bronchial hyperresponsiveness testing is useful for diagnosing and predicting the risk of bronchial asthma attacks. The Astograph is a tidal breathing method often used in as bronchial provocation testing in Japan. The minimum methachorine dose (Dmin) indicates bronchial sensitivity and is used mainly as an index of bronchial hyperresponsiveness. However, Dmin does not measured hyperresponsiveness, it cannot be compared directly with PC₂₀ in standard methods using FEV₁. We investigated the relationship among sensitivity, reactivity, and hyperresponsiveness with the Astograph. We recruited 142 patients with confirmed or suspected bronchial asthma from outpatient clinic at St. Marianna University School of Medicine, Yokohama City Seibu Hospital. We calculated Dmin, SGrs/Grscont, PD_35Grs, and PD_15Grs compared them as bronchial hyperresponsiveness indices. Subjects had suspected asthma (n=103), or required assessment of asthma remission (n=39). There were significant relationships between logDmin and logPD_35Grs (r=0.838, p35Grs r=-0.504, p15Grs was a strongly and significantly correlated with Dmin and PD_35Grs. The ROC curve to detect PD_35Grs15Grs was 10.7 (AUC 0.983, sensitivity 0.984, specificity 0.905). In Astograph, evaluation of bronchial hyperresponsiveness, we focused on relationship differences between sensitivity and reactivity, and hyperresponsiveness. We revealed the usefulness of the PD_15Grs evaluation method.

Bronchial schwannoma is extremely rare, accounting for a small percentage of benign bronchial tumors, with no determined standardized treatment. An 89-year-old woman with a persistent cough underwent CT scan which revealed a tracheal tumor. A diagnosis of endobronchial schwannoma was confirmed based on tissue obtained by high-frequency snare polypectomy. A hybrid stent was implanted in the trachea due to tumor regrowth; however, stent migration occurred, and it was removed after 1 month. Subsequently, radiation therapy was performed, and airway patency was well maintained for over 3 years. In general, surgical resection is recommended for endobronchial schwannoma; however, due to the age of this patient, resection was deemed invasive. Therefore, radiation therapy was administered as an alternative treatment.