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[Single-shot spinal anesthesia versus continuous spinal anesthesia using the CoSPAN catheter].

OBJECTIVE
We compared conventional single-shot spinal anaesthesia (SS) with continuous spinal anaesthesia (CS) in a randomised prospective study.


PATIENTS AND METHODS
Sixty patients undergoing urological surgery received either SS (n = 30) using an atraumatic needle or CS (n = 30) using a CoSPAN catheter. Prior to performing the spinal anesthesia, patients were prehydrated with 250 ml of hydroxyethyl starch 10%. Spinal anaesthesia was performed with the patients in the sitting position at L3-4 interspace. In the CS group CSF was aspirated via the catheter to check its correct position, and initially 0.5 ml of hyperbaric 5% lidocaine were injected. 0.25 ml boli at 5 min intervals were repeated as often as necessary to reach the desired sensory blockade up to the T10 segment. In patients undergoing the single-shot technique 1.5 to 3.5 ml of hyperbaric 0.5% bupivacaine was injected. After performing the block, haemodynamic parameters were assessed for 20 minutes at 2 min intervals, before and thereafter at 5 min intervals. The required time for recovery of motor activity of the legs was assessed postoperatively. The patients were visited on the 1st, 3rd and 5th postoperative day and asked about possible headache.


RESULTS
The CoSPAN spinal catheter was easy to handle. CSF could be aspirated via this catheter within 33.1 +/- 7.6 seconds. The desired maximum cephalad spread (T10) was exceeded by a mean of 0.63 +/- 1.3 segments in the CS group and by a mean of 1.4 +/- 2.6 segments in the SS group. In the SS group a mean volume of hyperbaric 0.5% bupivacaine of 2.59 +/- 0.4 ml was used. In the CS group a mean volume of 1.08 +/- 0.4 ml of hyperbaric 5% lidocaine was necessary. In the SS group, mean arterial blood pressure was found to have significantly decreased to lower than the initial value within the first 20 min after injection at each of the 10 determinations. Maximal decrease of mean arterial pressure to 89.3 +/- 7.7% was registered 14 min after injection. In the CS group, only the measurement 14 min after injection of the initial bolus revealed a significant decrease of the mean arterial blood pressure to 94.2% of the initial value. The mean interval elapsed before motor function of the legs returned after the end of surgery was 67.7 +/- 50 min in the SS group and 26.7 +/- 15.4 min in the CS group. None of the 60 patients complained about postspinal headache.


DISCUSSION
Fractionated injection of the local anesthetic via a spinal catheter was more precise in achieving the desired maximum cephalad spread than SS. The CS group revealed a significantly more stable blood pressure than the SS group. The use of a short-acting local anesthetic for CS provided an earlier postoperative return of motor function of the legs. Postspinal headache appears not to be a clinically relevant problem when 28-gauge spinal catheters are used.