Development of novel methods for non-invasive measurement of cardiac output and lung volume during anaesthesia

在澳大利亚，每年大约有200万例麻醉手术。大约每20000名患者中就有1人在麻醉过程中或麻醉后不久死于与麻醉本身有关的并发症，每170名患者中就有1人患有严重并发症。死亡和严重的发病率往往最终与组织缺氧有关。氧气通过血液从肺部输送到组织。在每次麻醉过程中，动脉血液中的氧含量由脉搏血氧仪监测，但血流不是。只有很小比例的麻醉患者使用通过心脏到肺部的静脉导管测量心输出量。该手术是侵入性的，具有显著的发病率和死亡率。目前还没有一种简便的方法可以在麻醉期间无创地监测心输出量。我们提议的研究项目，目前正在与一个工业合作伙伴一起进行，旨在开发一种可靠的、快速重复的、无创的方法来监测每个麻醉患者的总心输出量和肺容量。新监测器的目的是确保组织供氧的潜在问题被发现并及时纠正。我们的新监测技术是电脑控制的，可以在没有麻醉师干预的情况下工作，而且副作用很小。它可以添加到任何麻醉机上。这种测量技术很可能对麻醉产生类似于20世纪80年代脉搏血氧仪的影响，如果经过适当调整，很可能在其他领域得到应用，例如重症监护、运动医学、呼吸功能实验室和兽医医学。

In Australia approximately 2 million anaesthetic procedures are performed annually. Approximately one patient in 20,000 dies during or shortly after an anaesthetic from complications related to the anaesthetic itself, and as many as one in 170 suffers severe complications. Mortality and severe morbidity are often ultimately associated with lack of oxygen in the tissues. Oxygen is transported from the lungs to the tissues by the blood. The oxygen content of arterial blood is monitored by pulse oximetry during every anaesthetic, but blood flow is not. Cardiac output is measured in only a very small proportion of anaesthetised patients using intravenous catheters that pass through the heart to the lungs. This procedure is invasive and is associated with significant morbidity and mortality. At present there is no easy way to monitor cardiac output non-invasively during anaesthesia. Our proposed research project, currently underway in conjunction with an industrial partner, is aimed at the development of a reliable, rapidly repeating, non-invasive method for monitoring total cardiac output and lung volume in every patient who has an anaesthetic. The purpose of the new monitor is to ensure that potential problems with oxygen supply to the tissues are detected and corrected promptly. Our new monitoring technique is computer-controlled, can function without intervention by the anaesthetist and has very few side-effects. It can be added to any anaesthetic machine. Such a measurement technique is likely to have an impact on anaesthesia similar to that of pulse oximetry in the 1980's, and, if suitably adapted, is likely to find applications in other fields, such as intensive care, sports medicine, the respiratory function laboratory and in veterinary medicine.