Spinal anesthesia in the sitting position with low-dose local anesthetics usually provides satisfactory anesthesia for diabetic foot surgery because most operations do not require tourniquet application. This study was designed to investigate the influence of different sitting periods after subarachnoid injection of low dose bupivacaine on the spread of analgesia.

In this randomized, controlled clinical trial, 60 patients undergoing diabetic foot surgery under spinal anesthesia without a tourniquet were randomized to three groups. Patients remained sitting for 2 (Group D2, n = 20), 5 (Group D5, n = 20), or 10 (Group D10, n = 20) min after the completion of subarachnoid administration of 3.75 mg of 0.25% hyperbaric bupivacaine solution. They were then placed in the supine position. Analgesia levels were assessed bilaterally using pinpricks. Blood pressure and heart rate were also recorded.

The maximal sensory block level [median (range)] was higher in Group D2 [L3 (L2-L3)] compared with Group D10 [L4 (L3-L4)] (P = 0.002). The highest sensory block levels were T12, T11, and L2 in Group D2, 5 and 10, respectively. There were no hemodynamic differences among the three groups and none of the patients showed hemodynamic instability except for one patient in Group D10.

Although spinal anesthesia using a minimal dose of 0.25% hyperbaric bupivacaine provides adequate anesthesia for diabetic foot surgery without profound hypotension, regardless of the time spent in the sitting position, maintaining the position for 10 min required to confine the sensory blockade on the lower level.