A prospective study on reproducibility of the spread of spinal anesthesia using plain 0.5% bupivacaine

This prospective study was carried out to determine whether a spinal block with plain 0.5% bupivacaine spreads similarly when repeated in the same patient. During a 14-month period, 50 patients underwent from two to five spinal anesthesias using identical anesthetic technique, including the same premedication, the same volume of injected plain 0.5% bupivacaine, the same site of injection and the same position of the patient. Plain 0.5% bupivacaine was injected with the patient lying in the lateral horizontal position. Thereafter, the patients were turned to the supine horizontal position. Pinprick analgesia was recorded 60 minutes after the injection. Regression analysis showed that the reproducibility of the maximal analgesic segmental spread of the second anesthesia on the basis of the initial anesthesia was highly significant (p less than 0.0001). The blocking results of the patients who underwent from three to five anesthesias within the study period were in accordance with the spread of the first anesthesia. If a higher or lower spread of anesthesia is desirable, a modification or another local anesthetic for the spinal anesthesia may be preferred.