We have compared the delay in onset of 1% mepivacaine and 0.33% bupivacaine in different nerve fibre types in 10 volunteers undergoing median nerve blocks, in a randomized, double-blind, crossover study. Hot, cold, pinprick and light touch sensations, compound motor action potentials (CMAP), sensory nerve action potentials (SNAP) and skin temperature were recorded at 2-min intervals. Hot, cold, pinprick, light touch sensations, SNAP and CMAP were significantly inhibited, and skin temperature was significantly increased after administration of both agents. The first noticeable reduction in cold sensation was detected later after bupivacaine compared with mepivacaine, but after a delay similar to that of other nerve functions. Bupivacaine and mepivacaine inhibited SNAP and CMAP with a similar time delay to steady-state. Bupivacaine produced steady-state inhibition of hot and cold sensations significantly later than mepivacaine; nevertheless, the sequence that sensory modalities failed, with few exceptions, and the extent of anaesthesia at 40 min were similar for both agents. Our technique provides a novel, multi-modal method of comparing local anaesthetics and related agents over time.

A Mo-Si-B based coating was applied to niobium that produced a coating structure composed of molybdenum and niobium silicides. Oxidation tests at 1000°C and 1200°C showed that the Mo-Si-B coating provided enhanced oxidation protection of niobium due to the formation of a protective aluminosilica layer. The coating performance was identified to be limited by the formation of NbB 2 during the pack cementation process. A revised coating treatment was implemented using TiB 2 as the boron source to reduce the NbB 2 formation. The Mo-Si-B coating utilizing plasma spray deposition of Mo and a revised pack cementation exhibited a mass change of 0.44 mg cm À2 after TGA testing at 1300°C for 24 h.

SummaryThirty patients wheduled for routine eye surgery were randomly allocated to receive either diazepam 0.2 mglkg or ascorbic acid 100 mg orully 90 minuies pre-operutively in CI double-blind fashion. Diaiepam caused no signiJcant change in intra-ocular pressure. Key wordsPremedicution; diazepam. Measurement; intra-ocular pressure.The effect of anaesthetic drugs on the eye has recently been reviewed.l Diazepam is a useful premedicant for eye surgery as it reduces anxiety without causing nausea.2 Given parenterally diazepam may cause a decrease in intra-ocular p r e s s~~,~ but the effect of oral diazepam on intra-ocular pressure has not previously been reported. This paper presents the results of such a study. MethodsStudies were carried out on 30 patients over 20 years of age scheduled for eye surgery all of whom gave informed consent. The patients were randomly allocated to receive either ascorbic acid 100 mg or diazepam 0.2 mg/kg orally 90 minutes pre-operatively, Before premedication intra-ocular pressure was measured in the normal eye in the supine position using the hand held Perkins Applanation Tonometer4 after instillation of oxybuprocaine drops. Arterial blood pressure was also recorded in the supine position from the right arm by the auscultatory method. These observations were repeated prior to induction. ResultsThe results obtained in the patients who received diazepam are shown in Table 1 and the placebo in Table 2. The mean change in intra-ocular pressure in the diazepam group was -0.35 mmHg (SD 2.7), and in the ascorbic acid group was 0.46 mmHg (SD 4.8). The difference between the two groups was not statistically different (unpaired 'I' test). Furthermore there was no correlation between intra-ocular pressure and either the systolic or diastolic arterial pressures (r = 0.15 and 0.27, respectively). DiscussionThese results indicate that diazepam 0.2 mgjkg orally can be given safely to patients for eye surgery in whom changes in intra-ocular pressure may be undesirable. It was not expected that the arterial pressure would alter the intra-ocular pressure since gradual changes within the physiological range are known to have little effect.'

SummaryThe effect of atracurium 0.6 mg/kg (group A; n= 11) and fazadinium 1 mg/kg (group F; n= 11) on intraocular pressure (IOP) was investigated in 22 patienis during induction of anaesthesia with thiopentone 4 mg/kg and fentanyl 0.015 mg/kg. IOP was significantly reduced (p <0.01) in all patients following induction of anaesthesia. Intubation produced a rise in IOP in all patients hut this was not statistically significant and remained below pre‐induction values. The changes were similar in each group. Both of these neuromuscular blockers appear suitable relaxants to use for intraoculur surgery.

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