Assessment of Airway Obstruction Using a Novel Multiple Pulmonary Function Measurement System (FB-8010^®)

Abstract

Background. In severe airway obstruction, patients complain of dyspnea due to flow limitation, and respiratory failure can occur due to ventilation-perfusion mismatch. We previously reported the significance of estimating the regional pulmonary function during interventional bronchoscopy. The multiple pulmonary function measurement system (FB-8010^®) has been certified in Japan since January 2020. Purpose. To assess the flow limitation and ventilation-perfusion mismatch in patients with airway obstruction using the multiple pulmonary function measurement system during bronchoscopy. Methods. Lateral airway pressure was measured simultaneously at two points using a double-lumen catheter and the pressure difference between two points was calculated. Lateral airway pressure was plotted on the x/y axes, representing the pressure-pressure curve (P-P curve). We then calculated the angle of the P-P curve defined as the angle between the peak inspiratory and expiratory pressure points and baseline of the angle. In addition, partial pressure of oxygen (PO₂) and partial pressure of carbon dioxide (PCO₂) were measured at the target region using a single-lumen catheter. Results. Pressure differences were noted at the site of airway obstruction, and the angle of the P-P curve was small. When flow limitation was restored after stenting, the pressure differences disappeared, and the angle of the P-P curve was closer to 45°. The baseline PO₂ was lower for the severe bronchial obstruction side than the healthy side, and there was no marked difference in PCO₂. After the airway was restored, the difference between the right and left was reduced in the baseline PO₂. Conclusion. This novel multiple pulmonary function measurement system was able to assess the regional pulmonary function during bronchoscopy. The lateral airway pressure, PO₂ and PCO₂ help clarify the pathophysiology and estimate the outcome of interventional procedures in real-time.