Inaccuracies in measuring tourniquet pressures.

Since Roman times the surgical tourniquet has been used to arrest blood flow in a limb.' Initially they were applied to stop severe haemorrhage either due to injury or as a result of emergency amputation.Since the middle of the nineteenth century they have been used during elective surgery.Any fault in the gauge measuring the pressure of the inflatable cuff may cause problems.Firstly, too low a reading may result in excessive pressure on the limb and cause local tissue damage or nerve palsies.Secondly, too high a reading may allow blood to flow into the wound-so increasing the difficulties of the surgical procedure-and, in the case of intravenous regional analgesia, allow a large bolus of local anaesthetic to enter the circulation.2The commonest gauge in use in operating theatres is of the Bourdon type (figure).They are accurate and robust, but unlike a mercury manometer it is not immediately obvious if they are damaged or have become inaccurate.For this reason they must be tested regularly,4 8 as recommended by the manufacturers.Realising that I had never seen a tourniquet gauge checked or Flattened tube in 250 degree arc Pressure to be measu red I'ype ot gauge commonly used with surgical measure the pressure of the inflatable cuff.tourniquet equipment to