SummaryThe Portex percutaneous trachestomy kit incorporates guidewire dilating forceps which pass over a guidewire and perform rapid dilatation. These forceps have curved jaws which are designed to reduce possible damage to the lateral and posterior walls of the trachea. The guidewire dilating forceps arejrst opened in.front of the trachea to dilate the pretracheal tissues and then opened in the trachea to dilate the anterior tracheal wall. A tracheostomy tube is then passed over the guidewire and into the trachea. The procedure was rapid and successful in all 20 patients, with no serious complications. Mean time to perform tracheostomy was 4.9min (range 90s-ISmin). Oi~erall, the Portex percutaneous tracheostomj kit worked well and proved a rapid and acceptable method for performing percutaneous tracheostomy.

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...

In this study the subjective effects (sedation and mood) of subanaesthetic doses of propofol were examined in 28 healthy male volunteers. A computer model was used to predict the infusion projiles necessary to obtain steady state propofol plasma concentrations of 0.3 pg.ml-', 0.6 pg.rn1-I. 0.9 pg.ml-'. Objective measures of sedation from saccadic eye movement and choice reaction time gave significant dose responses at each level but a battery of psychometric tests failed to show dose-related subjective responses. Of particular note in the subjective data is the lack of a drerence between groups or even of a consistent trend within the data. This suggests that a low concentration of propofol in plasma does not induce euphoria or a sense of wellbeing. The anecdotal evidence available for mood changes with propofol therefore remains unsubstantiated.

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