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The Guidelines for the Management of Cough and Sputum (2019) of the Japanese Respiratory Society (JRS) were the first internationally published guidelines for the management of sputum. However, the data used to determine the causative diseases of bloody sputum and hemoptysis in these guidelines were not obtained in Japan.

Dexamethasone, remdesivir, and baricitinib reduce mortality in patients with coronavirus disease 2019 (COVID-19). A single-arm study using combination therapy with all three drugs reported low mortality in patients with severe COVID-19. In this clinical setting, whether dexamethasone administered as a fixed dose of 6 mg has sufficient inflammatory modulation effects of reducing lung injury has been debated.

Although high-flow nasal cannula (HFNC) oxygen treatment has been frequently used in coronavirus disease 2019 (COVID-19) patients with acute respiratory failure after the 3rd wave of the pandemic in Japan, the usefulness of the indicators of ventilator avoidance, including respiratory rate-oxygenation (ROX) index and other parameters, namely oxygen saturation/fraction of inspired oxygen ratio and respiratory rate (RR), remain unclear.

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), is an enveloped, single-stranded RNA virus. Favipiravir is an orally administrable antiviral drug whose mechanism of action is to selectively inhibit RNA-dependent RNA polymerase. A preliminary trial in COVID-19 patients reported significant improvements across a multitude of clinical parameters, but these findings have not been confirmed in an adequate well-controlled trial. We conducted a randomized, single-blind, placebo-controlled Phase III trial assessing the efficacy and safety of favipiravir in patients with moderate pneumonia not requiring oxygen therapy. Methods: COVID-19 patients with moderate pneumonia (SpO2≥ 94%) within 10 days of onset of fever (temperature ≥ 37.5 °C) were assigned to receive either placebo or favipiravir (1800 mg twice a day on Day 1, followed by 800 mg twice a day for up to 13 days) in a ratio of 1:2. An adaptive design was used to re-estimate the sample size. The primary endpoint was a composite outcome defined as the time to improvement in temperature, oxygen saturation levels (SpO2), and findings on chest imaging, and recovery to SARS-CoV-2-negative. This endpoint was re-examined by the Central Committee under blinded conditions. Results: A total of 156 patients were randomized. The median time of the primary endpoint was 11.9 days in the favipiravir group and 14.7 days in the placebo group, with a significant difference (p= 0.0136). Favipiravir-treated patients with known risk factors such as obesity or coexisting conditions provided better effects. Furthermore, patients with early-onset in the favipiravir group showed higher odds ratio. No deaths were documented. Although adverse events in the favipiravir group were predominantly transient, the incidence was significantly higher. Conclusions: The results suggested favipiravir may be one of options for moderate COVID-19 pneumonia treatment. However, the risk of adverse events, including hyperuricemia, should be carefully considered. Trial registration: Clinicaltrials.jp number: JapicCTI-205238.

Bronchiolitis obliterans syndrome (BOS) occurring after hematopoietic stem cell transplantation (HSCT) for hematologic malignancies is a progressive and refractory disease, and lung transplantation (LTx) seems to be the only promising treatment. We report two cases of BOS after HSCT, which showed distinct clinical courses and were successfully treated with LTx. The respiratory symptoms and function of the two patients progressively deteriorated to a critical level during the waiting period. In one patient, recurrent and intractable pneumothoraxes consistent with thoracic air-leak syndrome (TALS) occurred, which were associated with pleuroparenchymal fibroelastosis. TALS could accelerate clinical deterioration, thus permitting a shorter waiting period for LTx.

The presence of pulmonary hypertension (PH) and treatment with anticoagulant agents could potentially increase the risk for bleeding/hemodynamic complications associated with bronchoscopic procedures. The aim of this study was to assess the safety of diagnostic flexible bronchoscopy (FB) in patients with PH.

Cases of extracorporeal membrane oxygenation (ECMO) bridged lung transplantation (LTx) are rare in Japan because an allocation system to prioritize patients based on urgency remains to be established. For critically ill patients who cannot wait for a brain-dead donor LTx, ECMO bridge to living-donor LTx may be the only practical option. A 21-year-old woman with pleuroparenchymal fibroelastosis after hematopoietic stem cell transplantation was admitted to our hospital with rapidly progressive respiratory failure. She was waitlisted for 6 months before admission, but veno-venous ECMO was initiated. She was transported under ECMO support via a jet plane and underwent successful living-donor LTx.

Management of chronic thromboembolic pulmonary hypertension (CTEPH) has recently improved because of advances in pulmonary endarterectomy (PEA), balloon pulmonary angioplasty (BPA), and disease-targeted medications. However, patients with inoperable CTEPH or persistent pulmonary hypertension (PH) after these interventions continue to exhibit impaired exercise capacity and limited quality of life (QOL).

Cigarette smoking is the primary causative factor for lung carcinoma and respiratory bronchiolitis (RB), particularly RB-associated interstitial lung disease (RB-ILD). However, the link between lung cancer and RB/RB-ILD remains undefined. We examined whether pathological fibrosis lesions exist simultaneously in patients with lung carcinoma because the fibrous lesions could be precancerous.

We describe an acceleration sensor composed of four vibration bars, with a detection mechanism in which the resonant frequencies of the four bars are brought close together. The bars are connected mechanically at the center, and a cross-shaped layout is used such that for any load direction, the sizes of the loads on the vibration bars mutually oppose each other. Using this structure, acceleration can be easily calculated by differential detection of the oscillation amplitude signals of each of the four vibration bars. The body of the sensor is made of stainless steel (SUS304). The volume of the experimental sample is about $76 \times 76 \times 8$ mm3, and the resonance frequency and quality factor are about 1041 Hz and 87, respectively. The sensor characteristics are measured using the gravitational field, and the acceleration is changed by rotating the sensor around the axis along the length of the vibrator.

The pathogenesis of daytime hypercapnia (Paco2≥ 45 mm Hg) may be directly linked to the existence of obstructive sleep apnea syndrome (OSAS) per se, although only some patients with OSAS exhibit daytime hypercapnia.

An online questionnaire survey was used to assess the application of noninvasive strategies in the management of COVID-19 patients. We found a marked increase in the proportion of facilities using high flow nasal cannula (HFNC) oxygen therapy successfully in the 3rdepidemic wave as compared to the 1stwave (49% vs. 12%) and rare reports of associated nosocomial infection in the medical personnel. Furthermore, the proportion of facilities using HFNC as first-line therapy for half or more than half of their patients who did not respond to conventional oxygen therapy increased from 9% in the first to 33% in the second survey. Conversely, the rate of mechanical ventilation with intubation usage following conventional oxygen therapy failure decreased from 62% to 54%. These changes could be due to the limited medical resources available during the larger 3rdwave coupled with increased internal reports on the success of HFNC.

Cough and sputum are common complaints at outpatient visits. In this digest version, we provide a general overview of these two symptoms and discuss the management of acute (up to three weeks) and prolonged/chronic cough (longer than three weeks). Flowcharts are provided, along with a step-by-step explanation of their diagnosis and management. Most cases of acute cough are due to an infection. In chronic respiratory illness, a cough could be a symptom of a respiratory infection such as pulmonary tuberculosis, malignancy such as a pulmonary tumor, asthma, chronic obstructive pulmonary disease, chronic bronchitis, bronchiectasis, drug-induced lung injury, heart failure, nasal sinus disease, sinobronchial syndrome, eosinophilic sinusitis, cough variant asthma (CVA), atopic cough, chronic laryngeal allergy, gastroesophageal reflux (GER), and post-infectious cough. Antibiotics should not be prescribed for over-peak cough but can be considered for atypical infections. The exploration of a single/major cause is recommended for persistent/chronic cough. When sputum is present, a sputum smear/culture (general bacteria, mycobacteria), cytology, cell differentiation, chest computed tomography (CT), and sinus X-ray or CT should be performed. There are two types of rhinosinusitis. Conventional sinusitis and eosinophilic rhinosinusitis present primarily with neutrophilic inflammation and eosinophilic inflammation, respectively. The most common causes of dry cough include CVA, atopic cough/laryngeal allergy (chronic), GER, and post-infectious cough. In the last chapter, future challenges and perspectives are discussed. We hope that the clarification of the pathology of cough hypersensitivity syndrome will lead to further development of “pathology-specific non-specific therapeutic drugs” and provide benefits to patients with chronic refractory cough.

While the prognosis of idiopathic pulmonary arterial hypertension has improved significantly due to newer medications, lung transplantation remains a critical therapeutic option for severe pulmonary arterial hypertension. Hence, it is essential for patients awaiting lung transplantation to avoid complications, including thrombocytopenia, which may affect their surgical outcomes. Herein we present the case of a 21-year-old woman diagnosed with idiopathic pulmonary arterial hypertension at the age of 15. She developed thrombocytopenia while awaiting lung transplantation. Her medication was switched from epoprostenol to treprostinil, suspecting possible drug-induced thrombocytopenia. Furthermore, she was administered thrombopoietin receptor agonists in view of the possibility of idiopathic thrombocytopenic purpura, along with maximum support for right heart failure. Subsequently, her platelet count increased to >70,000/µL, enabling her to successfully undergo bilateral lung transplantation. Post-bilateral lung transplantation, pulmonary arterial hypertension as well as thrombocytopenia appeared to have resolved. In this case, we suspected that thrombocytopenia could have resulted owing to a combination of pulmonary arterial hypertension, right heart failure, drug interactions, and idiopathic thrombocytopenic purpura. Thrombocytopenia is a very critical condition in patients with pulmonary arterial hypertension, especially those awaiting lung transplantation. Several approaches are known to improve intractable thrombocytopenia in patients with pulmonary arterial hypertension.

Pulmonary capillary hemangiomatosis (PCH) is a very rare and refractory disease characterized by capillary angioproliferation. The updated classification of pulmonary hypertension categorizes PCH into a subgroup of pulmonary arterial hypertension (PAH) alongside pulmonary veno-occlusive disease (PVOD). However, the definitive diagnosis of PCH only with noninvasive tools remains difficult. The aim of this study was to elucidate the radiological and physiological characteristics of PCH. We searched for cases of pathologically confirmed PCH in the English literature published between 2000 and 2018. We identified 26 cases among 39 studies. Then, we extracted and evaluated the relevant clinical information in all cases with available data. On chest computed tomography (CT), ground-glass opacities (GGOs) were observed in 92% of the cases, in which poorly defined nodular pattern was the most common (88%). GGOs in a bat-wing distribution were observed in one case. Septal lines and lymph node enlargement were observed less frequently (each 19%, 12%). Seven cases (27%) had overlapping abnormalities. Diffusing capacity of the lung for carbon monoxide (DLCO) was remarkably decreased. Alveolar hemorrhage by histological findings or bronchoalveolar lavage (BAL) was observed in seven cases. The present study showed that the most characteristic findings of CT in PCH was centrilobular GGOs with a poorly defined nodular pattern, and septal lines and lymph node enlargement were seen less frequently. Alveolar hemorrhage detected by BAL and decreased DLCOmay also be helpful to recognize the possibility of PCH like PVOD.

We describe an acceleration sensor composed of four vibration bars, with a detection mechanism in which the resonant frequencies of the four bars are brought close together. The bars are connected mechanically at the center, and a cross-shaped layout is used such that for any load direction, the sizes of the loads on the vibration bars mutually oppose each other. Using this structure, acceleration can be easily calculated by the differential detection of the oscillation amplitude signals of each of the four vibration bars. The acceleration sensor in these three axes realized high stability and highly sensitive detection by driving four coupled vibrators. The sensor characteristics are measured using the gravitational field, and the acceleration is changed by rotating the sensor around the axis along the length of the vibrator.

The characteristics of the coupled bending vibrator that linearly connects the two bending vibrators are analyzed by the finite-element method, and then the characteristics of the coupled bending vibrator used as a force sensor are investigated. The coupled bending vibrator is applied to an acceleration sensor as a force sensor. The vibration mode in which the two vibrators of the coupled vibrator are out of phase is used here and is very stable because it does not couple with other vibration modes. When the axial force is applied, the amplitude of one vibrator of the coupled vibrator decreases with increase in compressive force. The amplitude of the other vibrator also decreases when the force is applied in the opposite direction. Therefore, the coupled vibrator is used as a force sensor that can estimate the axial force as a change in the amplitude of the vibrator.

We describe an acceleration sensor comprised of a detection structure constructed from a pair of adjacent vibration bars with resonance frequencies closely aligned to the drive resonance and which are connected to, and placed in opposite directions from each other, in the load direction. Using this structure, acceleration can be easily calculated by differential detection of the oscillation amplitude signals of each of the two vibration bars. The volume of the sensor is made of stainless steel (SUS304). The volume of the experimental sample is about $80\times 90\times 8$ mm3, and the resonance frequency and quality factor are about 770 Hz and 145, respectively. The sensor characteristics are measured using the gravitational field, and the acceleration is changed by rotating the sensor around the axis along the length of the vibrator.