◊ BACKGROUND:
The aim of this study was to compare the clinical effects of 'hyperbaric' bupivacaine for spinal anaesthesia with those of similar preparations of levobupivacaine and ropivacaine.

◊ METHODS:
Sixty ASA grade I-II patients undergoing elective surgery under spinal anaesthesia were randomized to receive 3 ml of bupivacaine, levobupivacaine, or ropivacaine, each at 5 mg ml(-1) and made hyperbaric by the addition of glucose 30 mg ml(-1). A standard protocol was followed after which a blinded observer assessed the sensory and motor blocks. The level and duration of sensory (pinprick) block, intensity and duration of motor block, and time to mobilize and to micturate were also recorded.

◊ RESULTS:
One patient (ropivacaine group) required general anaesthesia because of technical failure, but all the other blocks were adequate. There were no significant differences between the groups with regard to the mean time to onset of sensory block at T10, the extent of spread, or mean time to maximum spread. Regression of sensory block in the ropivacaine group was more rapid as demonstrated by duration at T10 (P<0.0167) and total duration of sensory block (P<0.0167). Patients in the ropivacaine group had more rapid recovery from motor block (P<0.0167) and shorter times to independent mobilization (P<0.0167). There were no significant differences between the bupivacaine and the levobupivacaine groups.

◊ CONCLUSIONS:
'Hyperbaric' ropivacaine provides reliable spinal anaesthesia of shorter duration than bupivacaine or levobupivacaine, both of which are clinically indistinguishable. The recovery profile of ropivacaine may be useful where prompt mobilization is required.

◊ Reviewed by R. Stienstra, MD, PhD
Nijmegen, Netherlands

Although there are reports about the profiles of the new long-acting local anesthetics ropivacaine and levobupivacaine in spinal anesthesia, this is the first study comparing both new drugs with (racemic) bupivacaine. Even though the results of this investigation are not totally unexpected and confirm the notion that ropivacaine is a suitable drug for ambulatory spinal anesthesia, the study is important for two reasons:

Firstly, it is the first direct comparison of the three drugs in one study protocol, and secondly, the authors chose to compare equal doses (although due to differences in molecular weight and drug labeling, the same concentrations of ropivacaine and levobupivacaine contain more active drug than bupivacaine: 4.5 % and 12.6 % respectively).

There has been much debate about the relative potency of ropivacaine compared to bupivacaine (and levobupivacaine). Some claim that differences in profiles are the result of a greater separation between sensory and motor block by ropivacaine, others attribute these differences to a difference in potency. In the present paper, the authors provide a balanced discussion on this complex issue, which I would gladly recommend to everyone interested in this matter.