Anaesthesia and intensive care
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A mathematical model correlating the spread of analgesia to the dose of local anaesthetic and to age or body weight was found analysing the data of 763 caudal blocks in children from age one day to twelve years. Two graphs have been plotted: (1) spread of analgesia, dose, age and (2) spread of analgesia, dose, weight. Both age and weight can be used as predictors to determine the desired level of analgesia, but weight is more useful in very young patients while age is a better guide in older children.
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Thirteen commercially available ventilator monitoring alarms supplied by the distributors were evaluated. It was decided that devices with no power failure precautions or unprotected variable controls could not be recommended for general use. By these criteria only two devices could be recommended for general use as ventilator alarms and a further three as disconnect alarms; in each instance these recommendations are subject to certain reservations and suggested modifications. A ventilator alarm should be regularly serviced and checked before use and should be not used by anyone unfamiliar with the applications or limitations of that particular device.
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A new approach to the lateral cutaneous nerve of thigh is described. It depends on locating the depth of the canal through which the nerve passes immediately medial to the anterior superior iliac spine. ⋯ Two district 'pops' or loss of resistance can be identified during insertion of a short-bevelled needle. Location of the canal by the technique described has been confirmed radiographically.