Hyaluronidase and peribulbar block.

We have assessed the effect of two concentrations of hyaluronidase on the quality of peribulbar block, using a low volume, single injection technique. We studied 200 patients undergoing elective intraocular surgery, allocated randomly to one of three groups. Group 1 (n = 50) received peribulbar block with 5 ml of a 1:1 mixture of 0.5% plain bupivacaine and 2% plain lignocaine. Group 2 (n = 75) received this solution supplemented with hyaluronidase 50 iu ml-1. Group 3 (n = 75) received the same solution supplemented with hyaluronidase 300 iu ml-1. Lack of ocular motility was considered to be the only objective sign of successful block and movement of each rectus muscle was scored at 1-, 5- and 10-min intervals. If the block was successful at 5 min, the 10-min score was omitted. If the block was unsuccessful at 5 min, a second injection of 2% lignocaine 3 ml was given and additional assessments performed at 5-min intervals. At 1 min, ocular motility scores were significantly lower in group 3 compared with the control group (P < 0.05). The incidence of satisfactory block at 5 min was increased in both groups given hyaluronidase (group 2, P < 0.05; group 3, P < 0.001). There were no significant differences between groups 2 and 3 with respect to quality of block at 5 min. Hyaluronidase in both concentrations improved the quality of peribulbar block at 5 min, and when used in a concentration of 300 iu ml-1, also improved the speed of onset of block.

Modification by alfentanil of the haemodynamic response to tracheal intubation in elderly patients. A dose-response study.

Fifty-five elderly patients undergoing elective ophthalmological surgery were randomly allocated to four groups. Following the induction of anaesthesia with thiopentone (given over 2 min) and the administration of atracurium 0.6 mg kg-1, patients received alfentanil 400, 600, 800 or 1000 micrograms. Intubation of the trachea was performed 90 s later. Heart rate was monitored continuously and systolic arterial pressure was measured at 1-min intervals for 3 min before induction, and both variables were monitored until 10 min had elapsed after tracheal intubation. In each of the groups there was a significant decrease in systolic arterial pressure and a significant increase in heart rate on induction of anaesthesia. In those patients who received either 400 or 600 micrograms of alfentanil, arterial pressure increased immediately after tracheal intubation, whereas in those receiving alfentanil 800 or 1000 micrograms, arterial pressure decreased immediately after tracheal intubation, and when measured 10 min after intubation. It is suggested that alfentanil 600 micrograms (10 micrograms kg-1) constitutes the optimal dose with which to obtund the haemodynamic response to tracheal intubation in elderly patients, and to minimize cardiovascular depression after tracheal intubation.