Continuous spinal microcatheter (28 gauge) technique for arterial bypass surgery of the lower extremities and comparison of ropivacaine with or without morphine for postoperative analgesia

Abstract

The aim of this study was to evaluate a microcatheter technique for continuous spinal anaesthesia (CSA) and continuous spinal postoperative analgesia (CSPA) in vascular surgery. A total of 47 patients (range 51-95 yr, ASA II-IV) undergoing peripheral bypass surgery of the lower extremities received a spinal microcatheter (28 gauge) at L3-L4 or L2-L3. For CSA, ropivacaine 7.5 mg ml(-1) was given in small increments. Central venous pressure was maintained >or=3 mm Hg. Of 47 patients, 44 received CSPA, either using ropivacaine alone 2 mg h(-1) (group R, n=22) or ropivacaine 1 mg h(-1) with morphine 8 microg h(-1) (group RM, n=22) for 24 h after surgery (randomized, double-blinded). Intraoperative haemodynamic control was good; during the initial 60 min only four patients received phenylephrine i.v. for hypotension. Up to 30% of the patients felt mild pain at incision but surgery [mean duration 173 min (range 66-327)] was successfully completed under CSA in 45 patients. In four instances of acute revision surgery, a new block was administered utilizing the spinal catheter in place. Postoperative pain relief was comparably adequate in both groups with no difference in rescue pain medication. Four patients (three in R, one in RM) had weak motor blockade in the first postoperative morning. The described CSA technique offered good haemodynamic control, ease of maintaining spinal anaesthesia, and ease of providing a new spinal block for revision. The combination of low-dose ropivacaine and morphine for CSPA did not offer any benefit compared with the higher ropivacaine dose alone.