CONTINUOUS SPINAL-ANESTHESIA VERSUS SINGLE DOSING - A COMPARATIVE-STUDY

Continuous and single dose spinal anaesthesia were compared in a prosp ective randomized fashion in 108 patients undergoing orthopaedic surge ry. Continuous spinal anaesthesia was via a 20 gauge polyamide multipe rforated catheter introduced through an 18 gauge Tuohy needle. Single- dose spinal anaesthesia was performed with a 24 gauge x 103 mm Sprotte spinal needle. The mean local anaesthetic dose for the continuous tec hnique was 38.4 (SD 16.5) mg as hyperbaric lignocaine 5%, and for the single-dose spinal anaesthesia 10.8 (SD 2.2) mg as hyperbaric bupivaca ine 0.5%. Segmental levels reached with the initial dose did not diffe r significantly between the two groups. Mean time required to perform continuous spinal anaesthesia was 6.7 (SD 3.9) min, which was longer t han for single dose 4.9 (SD 2.8) min (P<0.05). The onset time and effi cacy of anaesthesia, and the duration of the operation were similar in the two groups. Analgesia was inadequate in six patients who received continuous spinal anaesthesia (11%) and one patient who received sing le dose (2%) (P=0.18). Hypotension was more frequent in those receivin g single doses (P<0.05). Caudal rotation of the outlet needle orifice to advance the catheter correlated with inadequate analgesia (P<0.01, r=0.38). There were no significant differences in the incidence of pos toperative complications.