2. Ausgabe 1995

Continuous spinal anaesthesia with plain bupivacaine 0.5%: a dose findingstudy

A. A. Broekema, H. J. Krijnen, M. G. M. Gielen, P. J. Hennis

Introduction

Continuous spinal anaesthesia (CSA) may have the following advantages over a single shot technique: the initial bolus dose can be titrated to achieve the desired level of sensory blockade, hypotension can be avoided, and the duration of the blockade can be prolonged. In this study the optimal dose regumen of plain bupivacaine 0.5% was investigated in patients, scheduled for surgery of the lower extremities.

Methods

Patients, older than 60 years, ASA II and III, were studied. They were premedicated with midazolam, 0.1 mg/kg orally, 1 h before anaesthesia. In patients younger than 60 yrs a 27-G catheter was inset and in patients older than 60 yrs a 19-G spinal catheter at the level L3-4, L4-5 or L2-3. After a bolus dose of 2 ml plain bupivacaine 0.5%, the onset time and the sensory level and degree of motor blockade were recorded. A second dose of 1 ml was injected after 15 min, if the level of the sensory blockade was insufficient. Thirty minutes later a continuous infusion was started with plain bupivacaine 0.5% at a rate of 2-4 ml/h. Postoperatively the infusion was changed to bupivacaine 0.25%, 2-4 ml/h, and continued for 4 h. Postoperative pain relief was evaluated by a visual analogue scale (VAS) every hour. The level of sensory blockade and the degree of motor blockade according to the scale of Bromage, and cardiovascular parameters were recorded regularly. The time until total recovery of sensory and motor blockarde was assessed. The patients were discharged to the ward after complete recovery of the block; the spinal catheter was removed. During 7 days the patients were investigated with respect to postdural puncture headache (PDPH), infection, or neurologic sequelae.

Results

The patients were 68 +/-10 years old (mean +/- SD). Minor or major technical difficulties occured in 4 and 5 patients respectively. The initial bolus dose was sufficient in 5 out of 12 patients; 6 patients needed an additional 1 ml. One patient had no blockade at all and received 1 ml of hyperbaric lidocaine 5% with good result. The mean level of anaesthesia was T9. The degree of motor blockade was 3 in all patients. The preoperative infusion was sufficient in 7 patients; 5 patients needed a top-up dose. The rate of infusion was 1.9 +/- 0.4 ml/h. The postoperative infusion provided excellent pain relief in 9 patients; 2 patients needed a top-up dose. Pain relief was insufficient in one patient. Nine (9) patients experienced an unwanted motor blockade degree 3. The rate of infusion was 2.1 +/- 0.5. The recovery time was 194 +/- 83 min. PDPH occured in 2 patients; one recovered spontaneously and one required an epidural blood patch. No signs of infection and no neurologic sequelae were recorded.

In conclusion

A continuous infusion with plain bupivcaine 0.5% at a rate of 2-4 ml/h resulted in a "steady state" spinal anaesthesia preoperatively in about 50% of the patients. In the other 50% the level of anaesthesia was unpredictable. Postoperatively a continuous infusion with bupivacaine 0.25% provided sufficient pain relief in most patients. Reducing the dose to 0.125% or applying an opioid may resolve the problem of unwanted motor blockade. CSA is technically complicated and time-consuming. Widespread use of CSA for peri-operative analgesia will therefore probably be limited.

Keywords
Anaesthesie, Spinalanaesthesie, Medikation

Anschrift

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