Pleuritis associated with immunoglobulin G4-related disease under normal thoracoscopic findings: a case report.

BACKGROUND: Immunoglobulin G4 (IgG4)-related disease is a chronic inflammatory disease that was recognized in 2011. Pleuritis associated with IgG4-related disease is rare and can be difficult to diagnose. Although there have been previous reports on pleuritis associated with IgG4-related disease by thoracoscopic findings, this is the first to observe pleuritis with IgG4-related disease from normal pleural thoracoscopic findings. CASE PRESENTATION: A 70-year-old Japanese female treated for breast cancer 33 years ago was referred to our hospital complaining of dyspnea on exertion. Chest computed tomography (CT) revealed left pleural effusion that was exudative and predominant with lymphocytes, elevated adenosine deaminase (ADA) and Class III cytology (malignancy suspected). Subsequently, thoracoscopic pleural biopsy was performed for definitive diagnosis. Although pleural macroscopic findings appeared normal, we performed pleural biopsy at random sites. This patient was negative for mycobacterium tuberculosis, and neither granulomas nor malignant cells were found in the collected specimens. An infiltration of inflammatory cells, mainly plasma cells and lymphocytes, was observed. Immunostaining revealed the number of IgG4-positive plasma cells was 102/high power field (HPF), and the percentage of IgG4 positive/immunoglobulin G (IgG)-positive cells was 41.4%. Since IgG4 serum levels were high and IgG4-related submandibular sialadenitis was also observed, a definitive diagnose of pleuritis associated with IgG4-related disease was confirmed. CONCLUSIONS: We diagnosed pleuritis associated with IgG4-related disease by thoracoscopic pleural biopsy samples taken from a visually normal pleura. Although exudative pleural effusion with high ADA and lymphocyte predominance is a characteristic of tuberculous pleuritis, other diseases might be present. Since thoracoscopy can increase the diagnostic yield, pleural biopsy should be considered even if thoracoscopic pleural findings are deemed normal.

Evaluation by various methods of the physiological mechanism of a high-flow nasal cannula (HFNC) in healthy volunteers.

INTRODUCTION: Several reports have described the usefulness of a high-flow nasal cannula (HFNC). However, the physiological mechanisms of this system are unclear. In the current study, various methods were used to investigate the physiological mechanisms of an HFNC in healthy volunteers. METHODS: The physiological mechanisms of the constant-flow and constant-pressure models of HFNC were studied in 10 healthy volunteers by the oesophageal balloon method, the electrical impedance method and the forced oscillation technique (FOT). RESULTS: The tidal volume (TV) increased markedly during HFNC (off, 30 L/min, 50 L/min: 685.6±236.5 mL, 929.8±434.7 mL, 968.8±451.1 mL). The end-inspiratory oesophageal pressure (EIOP) was not significantly different, but there was a tendency for it to decrease. HFNC 30 L/min and 50 L/min, the increment in TV and the difference in EIOP showed strong negative correlations (p=0.0025, 0.003). The end-expiratory oesophageal pressure (EEOP) increased. The respiratory system reactance at 5 Hz (X5) by FOT decreased significantly. There was a flow rate-dependent EEOP increase, and the positive end-expiratory pressure (PEEP) effect of HFNC was confirmed. There was a correlation between the difference in X5 and the difference in EEOP during HFNC 30 L/min and 50 L/min, with correlation coefficients of 0.534 and 0.404 (p=0.112, 0.281). The amount of change in EEOP and the fluctuation in X5 were positively correlated. CONCLUSIONS: The PEEP effect of HFNC was confirmed by the electrical impedance method and FOT. The increment in TV and the difference in EIOP of HFNC showed strong negative correlations.