Clinical Study Intravenous Infusion of Dexmedetomidine Combined Isoflurane Inhalation Reduces Oxidative Stress and Potentiates Hypoxia Pulmonary Vasoconstriction during One-Lung Ventilation in Patients Rui Xia, 1 Jinjin Xu, 2 Hong Yin, 1 Huozhi Wu, 3 Zhengyuan Xia, 4,5,6 Daiwei Zhou, 7 Zhong-yuan Xia, 2 Liangqing Zhang, 5,6 Haobo Li, 5,6 and Xiaoshan Xiao 7 1 Department of Anesthesiology, First Afliated Hospital, Yangtze University, Jingzhou 434000, China 2 Department of Anesthesiology, Wuhan University Renmin Hospital, Wuhan 430060, China 3 Department of Cardiothoracic Surgery, Fifh Afliated Hospital of Zunyi Medical College, Zhuhai 519100, China 4 Department of Anesthesiology, Te Second Afliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325000, China 5 Department of Anesthesiology, Afliated Hospital of Guangdong Medical College, Zhanjiang, Guangdong 524001, China 6 Department of Anesthesiology, Te University of Hong Kong, Hong Kong 7 Department of Anesthesiology, Guangdong No. 2 Provincial People’s Hospital, Guangdong Provincial Emergency Hospital, Guangzhou, Guangdong 510317, China Correspondence should be addressed to Zhengyuan Xia; zhengyuan xia@yahoo.com and Xiaoshan Xiao; gd177mzk@163.com Received 7 January 2015; Accepted 13 February 2015 Academic Editor: Huang-Ping Yu Copyright © 2015 Rui Xia et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Inhalation anesthetic isofurane inhibits hypoxia pulmonary vasoconstriction (HPV), while dexmedetomidine (Dex) could reduce the dose of isofurane inhalation and potentiate HPV, but the mechanism is unclear. Inhibition of reactive oxygen species (ROS) production can favor HPV during one-lung ventilation (OLV). Similarly, nitric oxide (NO), an important endothelium- derived vasodilator in lung circulation, can decrease the regional pulmonary vascular resistance of ventilated lung and reduce intrapulmonary shunting. We hypothesized that Dex may augment HPV and improve oxygenation during OLV through inhibiting oxidative stress and increasing NO release. Patients undergoing OLV during elective thoracic surgery were randomly allocated to either isofurane + saline (NISO,  = 24) or isofurane + dexmedetomidine (DISO,  = 25) group. Anesthesia was maintained with intravenous remifentanil and inhalational isofurane (1.0–2.0%), with concomitant infusion of dexmedetomidine 0.7 gkg −1 h −1 in DISO and saline 0.25 mL kg −1 h −1 in NISO group. Hemodynamic variables or depth of anesthesia did not signifcantly difer between groups. Administration of Dex signifcantly reduced Qs/Qt and increased PaO 2 afer OLV, accompanied with reduced lipid peroxidation product malondialdehyde and higher levels of SOD activity as well as serum NO (all  < 0.05 DISO versus NISO). In conclusion, reducing oxidative stress and increasing NO release during OLV may represent a mechanism whereby Dex potentiates HPV. 1. Introduction With the popularity of video-assisted thoracic surgery, the requirement for one-lung ventilation (OLV) has been increas- ing. OLV is used to provide a good surgical feld and protect normal lungs from hemorrhage or abscess caused by afected lung [1]. However, OLV can induce ventilation- perfusion mismatch and pulmonary arteriovenous shunt in the nonventilated lung that can cause hypoxemia [2]. Hypoxic pulmonary vasoconstriction (HPV) is an important protec- tive mechanism by which blood fow is diverted from the nonventilated lung toward a better ventilated region, thereby Hindawi Publishing Corporation Mediators of Inflammation Volume 2015, Article ID 238041, 7 pages http://dx.doi.org/10.1155/2015/238041