Anaesthesia and intensive care
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Anaesth Intensive Care · Nov 2008
Performance of BIS in children using the paediatric BIS Quattro sensor.
The Bispectral Index (BIS) is one of the most frequently used electroencephalogram-derived depth of anaesthesia monitors. Previous studies in children have suggested BIS performs well in older children, however these studies have used earlier versions of the BIS device. The aim of this study was to compare the performance of BIS over different age groups using the BIS paediatric Quattro sensor (Aspect Medical Systems, Norwood, MA, U. ⋯ When combining all age groups taking a BIS value of 50 or greater provided 100% sensitivity to detect wakefulness. This study found no evidence for any substantial difference in performance between ages one and 13 years. If BIS is used in children to detect wakefulness occurring with lightening of anaesthesia, then this study suggests that if the BIS is maintained below 50 then wakefulness is unlikely to have occurred.
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Anaesth Intensive Care · Nov 2008
Effect of open-chest surgery in the lateral position on blood propofol concentration during target-controlled infusion of propofol.
Our research hypothesis was that single lung ventilation during thoracic surgery in the lateral position increases the blood concentration of propofol during target-controlled infusion. Thirty adult patients in two tertiary referral hospitals undergoing open-chest surgery were studied. Anaesthesia was induced and maintained with propofol using a Diprifusor (Graseby 3500) computer-controlled pump set to deliver a blood concentration of 4 tg.ml(-1). ⋯ Repeated measures ANOVA showed an F value 1.9, lambda 5.5 and P value 0.15. Post hoc analysis did not identify a significant difference between the sample times. During target-controlled infusion of propofol, mean blood propofol concentrations did not change significantly from those obtained with the patient supine after up to 50 minutes in the lateral position during thoracic surgery, or 20 minutes after commencing one-lung ventilation.
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Anaesth Intensive Care · Nov 2008
Effect of recruitment and body positioning on lung volume and oxygenation in acute lung injury model.
The mechanism of oxygenation improvement after recruitment manoeuvres or prone positioning in acute lung injury or acute respiratory distress syndrome is still unclear. We tried to determine the mechanism responsible for the effects of recruitment manoeuvres or prone positioning on lung aeration using a whole lung computed tomography scan in an oleic acid induced acute lung injury canine model. Twelve adult mongrel dogs were allocated into either the supine group (n=6) or the prone group (n=6). ⋯ Prone positioning increased oxygenation (P=0.004) that also correlated with increase of the poorly- and well-aerated dorsal (nondependent) lung volume (r=0.787, P<0.001). However, the recruitment manoeuvre in the prone position had no effect on oxygenation despite an increase in ventral (dependent) lung volume. The increase in PaO2 after recruitment manoeuvres in the supine position or after prone positioning is related to the increase of the poorly- and well-aerated dorsal lung.