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A computer controlled infusion pump was used to deliver propofol to two groups of eight patients undergoing body surface surgery. The patients were premedicated with morphine sulphate i.m. and anaesthesia was supplemented with 66% nitrous oxide in oxygen. Patients in group 1 breathed spontaneously, whereas patients in group 2 underwent artificial(More)
The theory and construction of a prototype computer-controlled gas mixer and flow regulator are described. The device is capable of controlling and mixing flows of oxygen, nitrous oxide and air. The accuracy and repeatability of the device is very high under given conditions, and its performance is quantified. The flow rate and oxygen concentration are(More)
We describe the successful use of a guide wire and ureteral dilator to pass a tracheal tube into the trachea through the mouth in an awake, sedated patient when attempts to pass a larger tube over an Olympus LF1 fibreoptic bronchoscope were unsuccessful. Since the ureteral and renal dilators are available in a variety of sizes, if too large a tube is(More)
The theory and construction of a prototype digital gas flow controller are described. Using eight preset needle valves, it has the ability to deliver any flow from 50 to 12750 ml/minute in steps of 50 ml/minute. Under given conditions, the accuracy of this device is very high and its variation in performance with pipeline supply pressures is quantified. The(More)
The pressure-flow characteristics of needle valves used on anaesthetic equipment were investigated. It was found that, under normal conditions of use, the valves behaved in a manner similar to convergent nozzles with sonic velocity at the throat. This means that, once the valve has been set, the mass flow rate of gas is effectively independent of the(More)
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