The use of a non-invasive method to measure intrapulmonary shunt during one-lung anaesthesia

The Non Invasive Virtual Shunt computer program has previously been described and validated. The system has subsequently been developed to give a real time, continuous trace of virtual shunt. A portable computer connected to routine monitoring equipment displays a plot of virtual shunt updated every 10 s. A practical use of this device in the clinical setting of one-lung anaesthesia is described. The equipment was used to monitor shunt before, during and after surgery in three patients. In one case, a displaced double lumen bronchial tube was detected before there was any other indication of the problem.