A migrating epidural cannula

Epidural bupivacaine for aortic surgery. The effect of dilution on the quality of analgesia

Twenty patients undergoing elective abdominal aortic aneurysm repair were randomly allocated to two groups and studied for 24 h following surgery. Postoperative analgesia was provided by epidural bupivacaine infusion and intravenous patient-controlled 0.05 mg boluses of alfentanil. One treatment group received 7 ml.h-1 of a 0.25% solution of bupivacaine, the other 25 ml.h-1 of a 0.07% solution. The rate of infusion was thus 17.5 mg.h-1 in both groups. Patients receiving 7 ml.h-1 of epidural infusate required more doses of alfentanil (median 26.5, range 0-50) than the group receiving 25 ml.h-1 of the dilute infusion (median 3.0, range 0-16). It is concluded that 17.5 mg.h-1 of bupivacaine infused into the epidural space produces better analgesia when infused in a volume of 25 ml.h-1 (0.07%) than when given in a volume of 7 ml.h-1 of solution (0.25%).

Dural taps revisited. A 20-year survey from Birmingham Maternity Hospital

The records from 34,819 obstetric epidurals performed at Birmingham Maternity Hospital over the period 1969-1988 were examined. During that time there were 460 dural taps (overall incidence 1.3%). Of the methods used to detect the epidural space, loss of resistance to injection of saline was associated with the lowest incidence of dural tap (0.6%). The incidence of typical postdural puncture headache when managed conservatively was 86%. Provision of an epidural drip after delivery reduced the incidence of headache to 70%. Elective forceps delivery conferred no additional benefit, and tended to delay the onset of headache. Blood patches were performed on 135 patients and provided complete relief of headache in 93 (68%). A further 23 patients (16%) obtained partial relief.

Unexpectedly extensive conduction blocks in obstetric epidural analgesia

Life-threatening extensions of conduction block during obstetric epidural analgesia can be classified according to the risk to the mother. High blocks that occur in the presence of the anaesthetist should present a readily treatable problem. Reports of total spinal anaesthesia that occur with no anaesthetist in attendance call for a reappraisal of present practice. Changes in current anaesthetic practice, which might increase safety with epidural analgesia, are top-ups by midwives, but only when the anaesthetist is on the delivery suite; repeated assessment of the nature of the conduction block by an anaesthetist; and continuous infusions with anaesthetist-only top-ups.

Migration of thoracic epidural catheters. Three methods for evaluation of catheter position in the thoracic epidural space

Migration of thoracic epidural catheters was evaluated in 25 patients by three methods either after placement of the catheter or immediately after surgery. The first method was the determination of the depth of the catheter from the skin, the second the determination of the level of sensory blockade which resulted from a test dose of a local anesthetic agent, while the third consisted of radiological visualisation of the catheter tip in the epidural space with radiopaque dye. The evaluations were repeated on the third or fourth day after operation. We observed an inward movement of the catheter in 56% of the patients instead of the expected outward movement. This inward movement was accompanied by a higher level of sensory blockade. No relationship with radiological visualisation was found.

The effect of rotation of an epidural needle. An in vitro study

A study using postmortem dura mater demonstrated that rotation of the epidural needle significantly decreases the force required to puncture the dura. It is recommended that epidural needles should not be rotated after insertion of the tip into the epidural space.

Epidural catheter migration during labour

A study was undertaken to determine the incidence, magnitude and direction of catheter migration in 100 patients who had epidural analgesia for pain relief in labour. Over 50% of catheters migrated from the original position at siting. The relevance of this migration and the usefulness of its measurement are discussed.