PURPOSE: Capnography is widely used to monitor the ventilatory status of patients. Wave analysis of capnograms also yields important information concerning lung function. In patients with central airway stenosis, interventional bronchoscopy is considered as a method of maintaining airway patency. In patients with long-term atelectasis, it is important to assess the presence of dead space ventilation. The purpose of this study is to estimate the regional gas exchange by measuring carbon dioxide (CO2) concentration during interventional bronchoscopy.
METHODS: We measured CO2 concentration before and after interventional bronchoscopy in 5 patients with bronchial stenosis. Computed tomography and/or perfusion scintigraphy were performed before intervention. After intubation with a rigid bronchoscope, a CO2 sampling tube was advanced through the working channel of the bronchoscope into each main stem bronchus collecting inspired and expired gas continuously through the tube. The CO2 concentration curve was recorded using a CO2 monitor. Patients breathed room air during measurements.
RESULTS: In patients with lung cancer, two different findings were obtained depending on the presence of dead space ventilation. In patients without dead space ventilation, there were no differences in terms of CO2 concentration curve between each side of the lung. In patients with dead space ventilation for one month, reduced perfusion was not seen at the obstructed area and end-tidal CO2 (Et CO2) gradually increased at the obstructed side after balloon dilation. In a patient with long-term lung collapse due to tracheobronchial tuberculosis, perfusion and ventilation were severely reduced at the obstructed area. Et CO2 was lower at the obstructed side than at the normal side. This case did not warrant additional therapy.
CONCLUSIONS: This method was useful for the assessment of regional gas exchange and response to the treatment in real-time.
CLINICAL IMPLICATIONS: This approach is intended to provide with physiologic information to guide basis for additional procedures.
DISCLOSURE: The following authors have nothing to disclose: Hiroki Nishine, Takehiko Hiramoto, Hirotaka Kida, Tepei Inoue, Naoki Furuya, Hiroshi Handa, Miho Nakamura, Seiichi Nobuyama, Takeo Inoue, Taeko Shirakawa, Masamichi Mineshita, Noriaki Kurimoto, Teruomi Miyazawa
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