Barbotage and spinal anaesthesia. The effect of barbotage on the spread of analgesia during isobaric spinal anaesthesia.

Subarachnoid block was performed with 0.5% plain bupivacaine in 67 patients with patients in the lateral position and the table horizontal. Thirty-six patients had a single injection while in the remaining 31 patients barbotage was used. Injection rates and aspiration rates were constant in both groups at 0.33 ml/second. Mean volumes of bupivacaine used in the two groups were 3.30 and 3.35 ml, respectively. The mean spread of analgesia after 30 minutes was 0.9 dermatomes higher in the group which received a single injection, and this was not statistically significant. The range of spread of analgesia was large in both groups, there was no correlation between spread of analgesia and volume of local anaesthetic used, and there was no correlation between age of patient and spread of analgesia in either group. Control of the level of analgesia during isobaric spinal block is difficult, and is not facilitated by barbotage.