In order to assess the effects of different concentrations of glucose on the spread of spinal anesthesia with 0.5% bupivacaine, the authors randomly divided 30 healthy patients scheduled for elective varicose vein surgery into 3 groups. All patients had vital signs monitored but no IV solutions were administered via an existing venous cannula. With the patients in the right lateral position, 3 ml of solution containing 0.5% bupivacaine with 0.33%, 0.83% or 8% glucose (with specific gravities at 23°C of 1.0018,1.0045 and 1.0203 respectively) were injected over 10 seconds. Patients were then immediately placed supine, and assessment made of onset and spread of analgesia to pinprick, motor power and changes in vital signs.