Abstract: 〓Objective To investigate the effects of alveolar recruitment strategy (ARS) combined with intrabronchial administration of dexmedetomidine on pulmonary oxygenation and inflammatory factors in elderly patients undergoing thoracoscopic radical resection for esophageal cancer. 
Methods A total of 60 patients, aged 55-75 years and classified as American Society of Anesthesiologists （ASA） grade Ⅰ-Ⅱ, were selected for elective thoracoscopic radical surgery for esophageal cancer under general anesthesia in Xingtai People′s Hospital. They were randomly divided into three groups: intrabronchial administration group (group A), intravenous administration group (group B), and ARS+ intrabronchial dexmedetomidine group (group C). In group C, ARS was performed before, during and after surgery, that is, 10 consecutive manual breaths, with the duration of ＞15 s each time, enabling the inspiratory platform pressure to reach 40 cmH2O, followed by implementation of the volume-controlled ventilation mode, 1〖DK〗∶E=1〖DK〗∶2, VT 6 mL/kg, fraction of inspiration O2 (FiO2) 80%, RR 14 times/min. The first ARS was performed before single lung ventilation after surgery, the second ARS was performed at 90 min after the initiation of operation, and the third ARS was performed after operation. The ARS was performed for three times simultaneously with intravenous administration of dexmedetomidine at a concentration of 10 μg/mL and a dose of 1.0 μg/kg. Group B received a dose of 1.0 μg/kg dexmedetomidine within 10 min before initiation of anesthesia, and then the dose was adjusted to 0.5 μg·kg-1·h-1 until the end of the operation. Group A and group C were given the same concentration and dose of dexmedetomidine in the bronchus at the same period of time (that is, before single lung ventilation, at 90 min after surgery, and after surgery). Routine single lung ventilation (the same as group C) was performed in both groups after operation, and no ARS was performed before, during and after operation. Before anesthesia induction (T0), immediately after single lung ventilation (T1), at 60 min after single lung ventilation (T2), at 90 min after single lung ventilation (T3), and at 24 h after operation (T4), interleukin 6 (IL-6) concentration, partial pressure of oxygen (PaO2), and end-expiratory CO2 were recorded, intrapulmonary shunt rate Qs/Qt was calculated, and perioperative adverse reaction rate ［hypotension, i.e., intraoperative mean artery pressure (MAP) decrease of more than 30%］, incidence of bradycardia, i.e. HR less than 50 times/min and duration greater than 10 min, pulmonary infection, i.e., increased respiratory secretions, pulmonary bronchial rales or increased sputum aspiration, progressive and persistent pulmonary infiltration by chest radiography, hypoxemia, i.e. PaO2＜80 mmHg (1 mmHg=0.133 kPa), atelectasis, namely, increased lung density on chest X-ray examination was recorded. 

Results IL-6 and IL-8 indexes showed an increasing trend at T3 and a decreasing trend at T4 in all groups, and there were significant differences in interaction betwen groups, time points, and time points between groups (P＜0.05). PaO2 index showed an increasing trend at T1 in all groups, groups A and B showed a decreasing trend at T2, and all groups showed a decreasing trend at T3 and T4. There were significant differences in interaction betwen groups, time points, and time points between groups (P＜0.05). CO2 index showed a downward trend at T1 in both groups A and C, but an upward trend in group B. At T2, group B showed a downward trend while group C showed an upward trend. At T3, both groups A and C showed a decreasing trend, while group B showed an increasing trend. At T4 point, A group showed an increasing trend, while B group and C showed a decreasing trend, and there were significant differences in interaction between groups, time points, and time points between groups (P＜0.05). For the intrapulmonary shunt rate Qs/Qt, groups A, B and C showed a downward trend at T1, while groups A, B and C showed an upward trend at T2; groups A, B and C showed an upward trend at T3, and groups A, B and C showed a downward trend at T4, with significant differences in interaction between groups, time points and time points between groups (P＜0.05). For the comparison among the three groups, the incidence of hypotension and bradycardia in group B was higher than that in group A and group C, and the difference was statistically significant (P＜0.05). The postoperative pulmonary complications in groups A and B were higher than those in group C, and the difference was statistically significant (P＜0.05). There was no significant difference in the incidence of hypotension and bradycardia between group A and group C (P＞0.05). 
Conclusion ARS combined with intrabronchial administration of dexmedetomidine can improve perioperative pulmonary oxygenation function, reduce intrapulmonary shunt, alleviate inflammatory response, and reduce complications in patients undergoing thoracoscopic radical resection of esophageal cancer. 

Key words: esophageal neoplasms, thoracoscopy, dexmedetomidine