Objective To observe the effect of jet ventilation (JV) at different frequencies on ventilation in patients undergoing rigid bronchoscopy by electrical impedance tomography (EIT). Methods Ninety patients, 42 males and 48 females, aged 18-60 years, BMI 18.5-27.9 kg/m2, ASA physical status Ⅰ or Ⅱ, undergoing elective rigid bronchoscopy were selected. The patients were divided into three groups by random number table: low frequency jet ventilation group was treated with jet ventilation at a rate of 20 beats/minutes (group J20), normal frequency ventilation group was treated with jet ventilation at a rate of 60 beats/minutes (group J60), high frequency ventilation was treated with jet ventilation at a rate of 150 beats/minutes (group J150), 30 patients in each groups. Peak inspiratory pressure (PIP), mean inspiratory pressure (MIP), oxygenation index (PaO2/FiO2), and PaCO2 under jet ventilation were recorded at 5 minutes after induction of anesthesia (T1), 5 minutes after the start of surgery (T2), and the end of surgery (T3). Ventilation ratio in different regions of the lung during jet ventilation (ROI1, ROI2, ROI3, ROI4) and impedance value (IR) were obtained and recorded by EIT. Results Compared with group J20, PIP, MIP and PaO2/FiO2 were significantly decreased and PaCO2 was increased during ventilation in group J60 and group J150 (P < 0.05), the proportion of ventilation in ROI1, ROI2, ROI3 and ROI4 regions was significantly decreased in group J60 and group J150 (P < 0.05), and IR values were significantly decreased in group J60 and group J150 (P < 0.05). Compared with group J60, PIP, MIP and PaO2/FiO2 were significantly decreased and PaCO2 was increased during ventilation in group J150 (P < 0.05), the proportion of ventilation in ROI1, ROI2, ROI3 and ROI4 regions was significantly decreased in group J150(P < 0.05), and IR values were significantly decreased in group J150 (P < 0.05). There were no significant differences in lung ROI1, ROI2, ROI3, and ROI4 regions at T1-T3. Conclusion The pulmonary gas distribution changes significantly in patients undergoing rigid bronchoscopy at different jet ventilation frequencies, and jet ventilation at 150 beats/minutes can significantly improve the homogeneity of pulmonary gas distribution under the premise of sufficient oxygenation. |