一、立项依据：与选题直接相关的国内外现状、水平和发展趋势；选题的 .doc

一、立项依据：与选题直接相关的国内外现状、水平和发展趋势；选题的理论和实践依据；研究目的、意义；本研究达到的科学技术水平，预期社会经济效益和应用推广前景。 容量监测是围手术期治疗的一项重要内容，麻醉医师正确评估患者的血流动力学状态及其对液体治疗的反应性有助于改善患者的治疗质量。在临床麻醉中术前禁食可能产生血肿感染血栓等并发症, 12]。 因此，对于全身麻醉下行机械通气的患者，我们可能需要寻找另一种简便、快速，微创（其完全位于胸腔内收集头颈、上肢、胸壁及部分胸腔脏器回流膈以上上半身的静脉血，经上腔静脉回流入右心房呼吸影响较小监测研究和容易通过，但是并不能反应手术麻醉患者的及塌陷指数拟行胃肠道手术的患者其禁食时间一般，同时术前准备包括灌肠，灌肠造成体液大量丢失，更进一步加剧了患者的低血容量状态。塌陷指数Vincent JL. Understanding cardiac output. Crit Care, 2008, 12: 174. [2] Vincent JL. “Lets give some fluid and see what happens”versus the “mini-fluid challenge”. Anesthesiology, 2011, 115: 455-456. [3] Osman D, Ridel C, Ray P, et al. Cardiac filling pressures are not appropriate to predict hemodynamic response to volume challenge. Crit Care Med, 2007, 35: 64-68. [4] Marik PE, Baram M, Vahid B. Does central venous pressure predict fluid responsiveness? A systematic review of the literature and the tale of seven mares. Chest, 2008,134: 172-178. [5] Renner J, Cavus E,Meybohm P, et al. Stroke volume variation during hemorrhage and after fluid loading: impact of different tidal voumes. Acta Anaesthesiol Scand, 2007, 51: 538-544. [6] Prekker ME, Scott NL, Hart D, et al. Point-of-care ultrasound to estimate central venous pressure: a comparison of three techniques. Critical care medicine 2013:41:833-841. [7] Stawicki SP, Braslow BM, Panebianco NL, et al.. Intensivist use of hand-carried ultrasonography to measure IVC collapsibility in estimating intravascular volume status: correlations with CVP. Journal of the American College of Surgeons 2009:209:55-61. [8] Ferrada P, Anand RJ, Whelan J, et al. Qualitative assessment of the inferior vena cava: useful tool for the evaluation of fluid status in critically ill patients. The American surgeon 2012:78:468-470. [9] Zengin S, Genc S, Yildirim C, et al. Role of inferior vena cava and right ventricular diameter in assessment of volume status: a comparative study: ultrasound and hypovolemia. The American journal of emergency medicine 2013:31:763-767. [10] Zhang X, Luan H, Zhu P, et