Analgesia for labour and delivery using incremental diamorphine and bupivacaine via a 32-gauge intrathecal catheter.

Twenty mothers who had requested regional analgesia during labour had a 32-gauge catheter inserted into the lumbar subarachnoid space. The mean time to place the catheters was 116 s (range 55-270 s) and there were no technical difficulties. Incremental diamorphine was given, up to a maximum initial dose of 0.5 mg. Analgesia was excellent in 11 mothers, good in seven and unsatisfactory in two. The duration of initial analgesia from diamorphine was 101 min (range 30-170 min). Eight mothers were able to move about during the first stage, with effective analgesia. Side effects were common: 15 mothers had pruritus, 15 had nausea or vomiting, and eight had mild sedation. No mother had a ventilatory frequency of less than 12 b.p.m. in the 12 h after the last dose of intrathecal diamorphine. Intrathecal 0.5% bupivacaine was given to 16 mothers in the first stage because the analgesia after a top-up with diamorphine became insufficient later in the labour. Fifteen mothers were pain free after bupivacaine; there was one failure. The initial effective dose of bupivacaine was between 0.25 ml and 2 ml. The maximum height of the block after bupivacaine was T9, and there was no hypotension. Nine mothers were given hyperbaric 0.5% bupivacaine 1-2 ml during the second stage; all were pain free for the procedure. The maximum force needed to withdraw the catheters was 700 g; and all catheters were removed intact. There were no post-spinal headaches.

Comparison of incremental spinal anesthesia using a 32-gauge catheter with extradural anaesthesia for elective caesarean section.

Forty-three mothers who had requested regional anaesthesia for elective Caesarean section were allocated randomly to receive either extradural anaesthesia with pH-adjusted 2% lignocaine with 1/200,000 adrenaline, or incremental spinal anaesthesia using a 32-gauge catheter with 0.5% plain bupivacaine. Increments of lignocaine or bupivacaine were given with the aim of achieving a block from T4 to S5. The spinal catheter was quicker to place (median 3 min, range 1-45 min, compared with median 10 min, range 1.5-50 min) and spinal anaesthesia was quicker to establish (median 20 min, range 10-46 min compared with median 48 min, range 15-59 min) compared with the extradural technique. The maximum height of the spinal block was significantly higher (median T3-4, range T5-T3) than the extradural group (median T5, range T6-T3). The total dose of intrathecal 0.5% bupivacaine was unpredictable, with a mean dose of 2.7 ml and a range between 1.5 ml and 7.4 ml. Haemodynamic stability and the quality of the block were similar between the groups. There were two mild spinal-headaches in the spinal group. All the spinal catheters were removed intact.

Comparison of recovery after neuromuscular blockade by atracurium or pancuronium.

Thirty patients were randomly allocated to receive either atracurium or pancuronium for neuromuscular blockade during surgery. At the end of the operation residual paralysis was antagonized with neostigmine. Voluntary strength was assessed at intervals after the antagonism, by observing grip strength, maximum inspiratory and expiratory force, 5-s head lift and the presence or absence of double vision. Grip strength and maximum expiratory force recovered significantly more quickly in the atracurium group over the 2-h measurement period. Double vision was significantly more frequent at up to 1 h when pancuronium had been used. At no time was there any significant difference between the two groups in respect of the 5-s head lift or, after 30 min, in the measurement of inspiratory force.

Assessment of tetanic fade following atracurium.

The records of the recovery pattern of 30 patients given atracurium 0.2-0.9 mg kg-1 were studied. Recovery of the sustained tetanic contraction did not follow an exponential curve as had previously been assumed. However, it did fit a logistic curve so that the plot of logit blockade against time was linear between 99% and 5% blockade. The results support the previous claim that the rate of recovery is independent of dose and that the effects of atracurium are not cumulative in the clinical dose range. The use of the logit transformation may also prove helpful in the analysis of the single twitch contraction during recovery from neuromuscular blockade by atracurium.