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SummaryWe have investigated the relationship between changes in the middle latency auditory evokedpotentials during alternating periods of consciousness and unconsciousness produced by propofol infusion combined with spinal anaesthesia for total knee replacement. Eleven patients completed the study, of whom two had recollection of events after the onset of the anaesthetic. There were no SigniJicant diyerences in heart rate or systolic arterial pressure between any conscious and unconscious period. With the first change from consciousness to unconsciousness, latencies of Na, Pa and Nb increased from mean (SD) starting values of 20.0 (1.4), 31.7 (1.0) and 42.8 (1.6) ms to 22.5 (2.0), 39.3 (2.1) and 57.8 (4.4)ms, respectively. During successive transitions from unconsciousness to consciousness, awake latencies were slightly higher than those of baseline awake, whereas anaesthetised latencies were similar to the ones obtained during the first period of unconsciousness. The consistent changes demonstrated, suggest that the auditory evoked potentials could represent a reliable indicator of potential awareness during anaesthesia. Key wordsMeasurement techniques; auditory evoked potentials. Anaesthetics, intravenous; propofol.The objective measurement of anaesthetic depth and its implications for the production of a reliable monitor of awareness, remains a desirable but elusive goal in anaesthesia [I]. Previous attempts to obtain an index of anaesthetic depth have included the use of the spontaneous electroencephalogram [2] and its processed derivatives, the cerebral function monitor [3], the cerebral function analysing monitor [4], fast Fourier transformation (FFT) and aperiodic waveform analysis [5]. More recently, the change in lower oesophageal contractility associated with anaesthesia has been investigated and shown to be related to the end-tidal concentration of volatile anaesthetics [6]. It was, however, insufficiently discriminating at the interface between consciousness and unconsciousness to be used as a monitor of awareness [7], and proved to be unrelated to blood concentration of intravenous anaesthetics [8].The most promising area of investigation has been the auditory evoked potential (AEP), which appears to show specific changes in its early cortical components related to depth of anaesthesia. These changes are independent of the anaesthetic agent used [8-131 and are partially reversed by surgical stimulation [ 141, properties thought to be necessary to qualify as an indicator of anaesthetic depth [IS]. In a recent study [16], the early cortical AEP was shown to be 'able to demonstrate potential awareness' under isoflurane anaesthesia. During some of those studies, a partial recovery of the AEP was observed after temporary discontinuation of the anaesthetic before the start of surgery [8-131. However, the patients were not allowed to recover completely and no quantitative data were published.Using a purpose-built, computer-based system, capable of processing the raw EEG and obtaining the AEP in real time,...

Background-Fenestrated endovascular repair of abdominal aortic aneurysms has been proposed as an alternative to open surgery for juxtarenal and pararenal abdominal aortic aneurysms. At present, the evidence base for this procedure is predominantly limited to single-center or single-operator series. The aim of this study was to present nationwide early results of fenestrated endovascular repair in the United Kingdom. Methods and Results-All patients who underwent fenestrated endovascular repair between January 2007 and December 2010 at experienced institutions in the United Kingdom(Ͼ10 procedures) were retrospectively studied by use of the GLOBALSTAR database. Site-reported data relating to patient demographics, aneurysm morphology, procedural details, and outcome were recorded. Data from 318 patients were obtained from 14 centers. Primary procedural success was achieved in 99% (316/318); perioperative mortality was 4.1%, and intraoperative target vessel loss was observed in 5 of 889 target vessels (0.6%). The early reintervention (Ͻ30 days) rate was 7% (22/318). There were 11 deaths during follow-up; none were aneurysm-related. Survival by Kaplan-Meier analysis was 94% (SE 0.01), 91% (0.02), and 89% (0.02) at 1, 2, and 3 years, respectively. Freedom from target vessel loss was 93% (0.02), 91% (0.02), and 85% (0.06), and freedom from late secondary intervention (Ͼ30 days) was 90% (0.02), 86% (0.03), and 70% (0.08) at 1, 2, and 3 years. Conclusions-In

This prototype laser Doppler flowscanner overcomes the previous limitations of laser Doppler flowmeters and may have many clinical and research applications.