We have studied the effects of phonation and posture on the Mallampati classification of view of the pharyngeal structures. Differences between observers were allowed for by the experimental design and log-linear modelling. Sixty-four patients were assessed on the ward, sitting upright, with and without phonation, by each of two observers. Another 64 patients were assessed without phonation, but both upright and supine, again by both observers. Phonation (the patient saying "Ah") produced a marked, systematic improvement of view; moving to the supine posture produced a small, systematic, non-significant worsening of the view. Differences between observers were non-systematic but substantial. About 25% of patients phonated spontaneously. It is recommended that anaesthetists make their own assessments of Mallampati classification, with the patient in either of the postures but always either with or without phonation, and thereby gradually "calibrate" their assessments against the degree of difficulty encountered in intubation.

We concluded that a significant proportion of epidural catheter tips may be "culture positive" after removal. It is suggested that this probably represents colonization of the skin at the catheter insertion site and subsequent contamination of the catheter tip on removal of the catheter. The large number of "culture positive" tips in the absence of clinically identifiable epidural space infection suggests that routine culture of epidural catheter tips is clinically irrelevant in the vast majority of cases, and that it is not a good predictor of the presence of an epidural space infection.

SummaryWe have investigated the local anaesthetic effects of 0.1% and 0.2% pethidine compared with 0.5% prilocaine using an intravenous regional anaesthetic technique, in a randomised, double-blind study in volunteers. Both pethidine and prilocaine produced a sensory and motor blockade, although the latter had a more profound effect, with a faster onset and slower recovery. Pethidine in low concentration clearly has a local anaesthetic action on peripheral nerves. Key wordsAnaesthetics, local; prilocaine, pethidine. Anaesthetic techniques, regional; intravenous.It is known that pethidine has local anaesthetic effects, both in vitro [l] and in vivo, where it has been used successfully as the sole anaesthetic agent for subarachnoid block for perineal [2] and urological surgery [3]. Intrathecally, pethidine was used as a 5% solution; however, in isolated rabbit vagus nerve preparations, pethidine resulted in complete blockade of A-and C-fibre conduction in much lower, more clinically relevant, concentrations [I]. Recent work has demonstrated that pethidine potentiates prilocaine when used in intravenous regional anaesthesia (IVRA) [4]; what is not known is whether pethidine alone has a clinically obvious anaesthetic effect in low concentrations. The purpose of this study is to investigate whether pethidine in low concentrations has local anaesthetic properties in vivo in comparison with prilocaine using the IVRA technique. An IVRA technique was used to separate the local from the systemic effects of the opioid. MethodsRegional ethics committee approval was given for the study. Five healthy, male volunteers, aged 30-40 years, were entered into the study after giving written informed consent. Each volunteer received IVRA in the nondominant arm on three occasions, separated by a minimum of at least 4 days. The study was performed in a clinical area with full monitoring and resuscitation equipment.A preliminary study was performed to determine the optimal effective concentration of pethidine to be used. In this, each volunteer had three doses of 1 ml of 0.05%, 0.1 % and 0.2% pethidine solution injected intradermally into the flexor surface of the forearm. Sensory testing to sharpness, touch and temperature were recorded at 1 min intervals. As a result of this preliminary study it was decided to use 0.1 YO and 0.2% pethidine solutions for the IVRA study.A standard technique was used for the IVRA procedure. A 22-gauge cannula was inserted into a vein in the dorsum of the nondominant hand and an 18-gauge cannula inserted into a vein in the dominant hand, the latter preceded by skin infiltration with 1 % lignocaine. The same cannulation sites were used for all three occasions in each volunteer. A padded pneumatic tourniquet was placed around the widest aspect of the upper, nondominant arm. The arm was exsanguinated using an Esmarch bandage and the tourniquet inflated to 250 mmHg. The Esmarch bandage was removed and 40ml of the test solution injected slowly over 40 s. The end of injection was taken as time zero and sensat...

We have evaluated prilocaine as a topical anaesthetic agent for fibreoptic bronchoscopy in comparison with lidocaine in terms of efficacy and safety. Forty patients were included in a randomised double-blind parallel-group study. Efficacy was assessed using visual analogue scales, a patient ranking scale and the number of doses of local anaesthetic and intravenous sedative required. Measures of toxicity included peak plasma concentration of local anaesthetic, whether supplementary oxygen was needed and change in methaemoglobin concentration. For most of the outcome variables, the medians and quartiles were similar for the two local anaesthetics. However, the median peak plasma concentration of prilocaine (0.5 micrograms.ml-1) was less than one-third that of lidocaine (1.76 micrograms.ml-1). The merits and hazards of using multiple-regression modelling to improve the precision of the analysis of the results are considered. We conclude that prilocaine can be used successfully as a topical anaesthetic agent for fibreoptic bronchoscopy and is associated with a lower risk of toxicity.