Copyright by the American Society of Anesthesiologists. Unauthorized reproduction of this article is prohibited.Anesthesiology, V 118 No 2 1 February 2013ABSTRACTBackground: Use of ultrasound-guided techniques to facili- tate central venous cannulation (CVC) may reduce the risk of misplacement and complications. A meta-analysis was conducted to compare real-time two-dimensional ultra- sound (RTUS) guidance technique with anatomical land- mark technique for CVC to determine whether RTUS has any advantages. Methods: Randomized studies comparing outcomes in patients undergoing CVC with either RTUS or landmark technique were retrieved from PubMed, ISI Web of Knowl- edge, EMBASE, and OVID EBM Reviews from their incep- tion to March 2012. Results: Twenty-six studies involving 4,185 CVC proce- dures met the inclusion criteria. Compared with landmark technique, patients with RTUS had a pooled relative risk (RR) of 0.18 (95% CI: 0.100.32) for cannulation failure, 0.25 (95% CI: 0.150.42) for arterial puncture, 0.30 (95% CI: 0.190.46) for hematoma, 0.21 (95% CI: 0.060.73) for pneumothorax, and 0.10 (95% CI: 0.020.54) for hemothorax from random-effects models. However, RTUS did not show a reduction in the risk of cannulation failure (RR = 0.26, 95% CI: 0.032.55), arterial puncture (RR = 0.34, 95% CI: 0.052.60), hematoma (RR = 0.13, 95% CI: 0.012.42), pneumothorax (RR = 0.40, 95% CI: 0.02 9.61), and hemothorax (RR = 0.40, 95% CI: 0.029.61) in children or infants when the limited data were analyzed. Conclusions: Among adults receiving CVC, RTUS was associated with decreased risks of cannulation failure, arterial puncture, hematoma, and hemothorax. Additional data of randomized studies are necessary to evaluate these outcomes in pediatric patients. CENTRAL venous cannulation (CVC) is a commonly followed procedure for hemodynamic monitoring (such as central venous pressure), long-term administration of fluids, antibiotics, total parenteral nutrition, hemodialy- sis, and so on.13 The internal jugular, subclavian, and femo- ral veins (FV) are commonly used sites.4 However, it may be technically difficult due to anatomical and morphological variations among patients or because of previous catheteriza- tion.5 Attempting CVC may be unsafe or even fatal in some rare cases because of various complications, including car- diac tamponade,6 massive cervical hematoma,7 and puncture of endotracheal tube cuff.8 Ultrasound guidance for CVC has gained popular- ity among practitioners. Ultrasound modalities usually include color flow Doppler sonography, auditory Doppler guidance, two-dimensional ultrasound guidance (2-DUS), and the state-of-the-art technique three-dimensional ultra- sound guidance.9 Color flow Doppler sonography is a reli- able method for detecting thrombosis but it is not necessary for cannulation.10 With advances in ultrasound technology, auditory Doppler guidance, which includes SMART nee- dle11 and fingertip pulsed Doppler,12,13 is not recommended Real-time Two-dimensional Ultrasound Guidance for Central Venous CannulationA Meta-analysisShao-yong Wu, M.D.,* Quan Ling, M.D., Long-hui Cao, M.D., Ph.D., Jian Wang, M.D., Mei-xi Xu, M.D., Wei-an Zeng, M.D., Ph.D.* Resident Doctor, Associate Professor, Attending Doctor, Professor, Department of Anesthesiology, State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China. Resident Doctor, Department of Anesthesiol- ogy, Zhongshan Peoples Hospital, Zhongshan, Guangdong, China. Received from the Department of Anesthesiology, State Key Lab- oratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, China. Submitted for publication February 10, 2012. Accepted for publication September 10, 2012. Supported by the National Science Foundation for Distinguished Young Scholars (Beijing, China), grant no. 81101668/H1609 (to Dr. Cao) and the National Science Foundation (Beijing, China), grant no. 30972849 (to Dr. Zeng). Address correspondence to Dr. Zeng: Department of Anesthesi- ology, State Key Laboratory of Oncology in South China, Sun Yat- Sen University Cancer Center, 651 Dongfeng East Road, Guangzhou 510060, P.R. China. zengwamail.sysu.edu.cn. Information on pur- chasing reprints may be found at www.anesthesiology.org or on the masthead page at the beginning of this issue. Anesthesiologys articles are made freely accessible to all readers, for personal use only, 6 months from the cover date of the issue.Copyright 2013, the American Society of Anesthesiologists, Inc. Lippincott Williams 118:00-00What We Already Know about This Topic Use of ultrasound-guided techniques to facilitate central ve- nous cannulation may reduce the risk of misplacement and complicationsWhat This Article Tells Us That Is New The current meta-analysis showed that compared to the use of an anatomical landmark technique for central venous can- nulation