British journal of anaesthesia
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Randomized Controlled Trial
Removal of the laryngeal tube in children: anaesthetized compared with awake.
Laryngeal tube (LT) is a useful airway device in children, but there is no objective evidence that removal of LT in awake state is better than in anaesthetized state. So, we compared the incidence of respiratory adverse events after the removal of LT, either under anaesthesia or on awakening. ⋯ LT removal in anaesthetized state reduced cough, hypersalivation, and prevented tube displacement and hypoxia. Upper airway obstruction in the anaesthetized state should be predicted and managed with chin or jaw lifting.
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Comparative Study
Multi-level approach to anaesthetic effects produced by sevoflurane or propofol in humans: 2. BIS and tetanic stimulus-induced withdrawal reflex.
General anaesthesia could be assessed at two sites: cortical structures and the spinal cord. However, the practicalities of measurement at these two sites differ substantially. ⋯ High concentrations of sevoflurane depress TIWR more than propofol. With propofol, we frequently observed a paradoxical behaviour of muscles of the lower leg. TIWR lags behind BIS, indicating different effect sites for two intended anaesthetic effects: unresponsiveness to noxious stimulation and unconsciousness.
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Several physiological scoring systems (PSS) have been proposed for identifying those at risk of deterioration. However, the chosen specific physiological values chosen and the scores allocated have not been prospectively validated. In this study, we investigate the relative contributions of the ventilatory frequency, heart rate, arterial pressure, temperature, oxygen saturation, and conscious level to mortality in order to devise a robust scoring system. All data were collected on admission to the emergency unit. Precise 'intervention-calling scores' could then be derived to trigger interventions. ⋯ A simple validated scoring system to predict mortality in medical patients with precise 'intervention-calling scores' has been developed.
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Comparative Study
Multi-level approach to anaesthetic effects produced by sevoflurane or propofol in humans: 1. BIS and blink reflex.
The relative roles of forebrain and brainstem in producing adequate anaesthesia are unclear. ⋯ The blink reflex (brainstem function) is more sensitive to sevoflurane or propofol than BIS (forebrain function). Sevoflurane suppresses the blink reflex more than propofol. Different k(e0)s for blink reflex vs BIS indicate different effect sites.
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Anatomical dead space is usually measured using the Fowler equal area method. Alternative methods include the Hatch, Cumming, and Bowes methods, in which first, second, and third order polynomials, respectively, fitted to an expired CO2 volume vs expired volume curve, intercept the x-axis at the anatomical dead space. This study assessed systematic errors and susceptibility to noise of the Fowler, Hatch, Cumming, and Bowes dead spaces calculated over 40-80% of the CO2 expirogram. ⋯ The Fowler method shows greatest susceptibility to measurement noise and the Hatch method exhibits the largest systematic error. The Cumming method, which exhibits both low bias and low noise susceptibility, is preferred for estimating anatomical dead space from CO2 expirograms.