SummaryThe pressure within latex balloons remains constant despite the balloons being in¯ated to more than 40 times their initial volume. We used this property to enable improved tracheal cuff pressure control. A latex balloon with an initial volume of 5 ml was connected via a vinyl duct attached with a roller clamp and three-way stopcock to a standard tracheal tube cuff. The 5 ml latex balloon was then in¯ated with 250 ml of air. The pressure within the tracheal tube cuff was monitored throughout anaesthesia with the in¯ated latex balloon acting as a pressure controller. Throat symptoms were recorded on the ®rst four postoperative days. The controller kept the tracheal tube cuff pressures constant, and reduced the incidence of postoperative throat symptoms. Variations in cuff pressures with and without the controller were investigated in an altitude chamber to simulatē ight. In the altitude chamber, cuff pressure reached over 200 cmH 2 O at 10 000 feet without the controller, whereas such variations were practically eliminated when the controller was used.
A female patient exhibiting functional hearing loss in her left ear demonstrated reduced amplitude of P3 component in event-related potentials (ERP) to left monaural stimulation, with preserved N1 and N2 components to stimulation of either ear. This result suggested that stimuli in the affected ear were conducted successfully up to the auditory cortex but that further processing in higher brain regions was 'repressed'. Event-related potential examination for such hysterical disorders could be useful in clarifying their brain mechanism and offer a useful diagnostic clue to its nature.
Clinical experiences indicate that schizophrenic cognitive disturbances may be partly due to the unsuccessful construction of their cognitive context. In this article, two experiments are introduced in which schizophrenic deficits in utilization of information for construction of effective cognitive context were examined through measurements of event-related potentials, particularly P300s. In a 3-tone discrimination task, schizophrenic subjects failed to elicit P300s to frequent nontarget tones that were as important as standard tones for performing the required task. In the second task, consisting of detecting two consecutive identical tones, unlike healthy controls, schizophrenic subjects failed to display P300s to nontarget tones at target position. These results are discussed in relation to ineffective context construction of schizophrenic subjects. Moreover, a single-trial analysis of relationships between P300s and reaction times in the 3-tone discrimination task disclosed a loose coupling between the stimulus set and response set in patients.
The effects of zolpidem and zopiclone, non-benzodiazepine ultra-short-acting hypnotics, on cognitive function and vigilance level were investigated in the morning following nocturnal administration using event-related potentials (ERP) and a sleep latency test (SLT). Zopiclone significantly shortened the sleep latency the following morning, whereas zolpidem did not, perhaps due to the difference in the elimination half-lives between the compounds. No significant effect was observed for either drug on the ERP indices, including the P3, mismatch negativity and negative difference components. At a clinically prescribed dosage these sleep inducers have no remarkable effect on cognitive or attentional functions but increase sleepiness of the subjects.
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