British journal of anaesthesia
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Comparison of ropivacaine with bupivacaine for paediatric caudal block.
In a double-blind, multicentre study 245 children aged 1-10 yr undergoing elective minor surgery as inpatients were randomly allocated to receive a single caudal extradural injection of 1 ml kg-1 of either 0.25% bupivacaine or 0.2% ropivacaine after induction of light general anaesthesia. The groups were comparable for age, weight, vital signs and duration of surgery. The onset time was similar for ropivacaine and bupivacaine (9.7 vs 10.4 min). ⋯ The mean time to first analgesia in the remainder was 233 min in the bupivacaine group and 271 min in the ropivacaine group. No motor block was measurable in either group. Ropivacaine 2 mg kg-1 was as effective as bupivacaine 2.5 mg kg-1 for caudal analgesia in children.
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A general (multiple-gas) three-compartment mass-balance model of the circle-absorber breathing circuit with intermittent positive-pressure ventilation has been developed. We propose it as a tool to determine flowmeter and vapourizer settings for inhalation anaesthesia by low-flow methods (less than 1 litre min-1 total fresh gas flow). ⋯ The mean inspired oxygen concentration over all trials was 32.8% (SD = 1.9%), while the mean inspired halothane concentration was 1.2% (SD = 0.3%). The flow meter and vapourizer settings calculated from the model appear to have sufficient accuracy to be useful in the clinical setting in conjunction with active oxygen and anaesthetic agent monitoring.
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Alpha2-adrenergic agonists given intrathecally result in antinociception and intracerebroventricularly (ICV) in sedation. To examine whether different alpha2-adrenergic receptor subtypes differentially mediate antinociception and sedation, we measured the relative potency of three alpha2-adrenergic agonists, dexmedetomidine (DMET), clonidine (CLON) and UK-14.304 (UK), after spinal and ICV administration. Each agonist was given either alone or in the presence of systemically administered yohimbine, which acts as a competitive alpha2-antagonist in unanaesthetized rats. ⋯ Again, yohimbine pretreatment produced a right shift of the ICV sedation dose-response curves (UK > DMET > CLON). Thus, we conclude that the spinal analgesic effects of DMET, CLON and UK appear to be mediated by two sites. After ICV delivery, DMET, CLON and UK appear to act at a common supra-spinal site to produce sedation and this site resembles that acted upon by UK in the spinal cord.
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Randomized Controlled Trial Comparative Study Clinical Trial
Effects of lightwand (Trachlight) compared with direct laryngoscopy on circulatory responses to tracheal intubation.
We compared the effects of the lightwand technique on circulatory responses to tracheal intubation with those of direct-vision laryngoscopy. Forty adult patients received propofol and vecuronium, and their lungs were ventilated for 2 min via a mask with 5% sevoflurane in oxygen, after which the trachea was intubated orally using either the lightwand (Trachlight, n = 20) or the Macintosh laryngoscope (n = 20). ⋯ There were no differences between the lightwand technique and direct-vision laryngoscopy in changes in mean arterial pressure and heart rate during and after tracheal intubation. We conclude that the effects of the lightwand technique on circulatory responses to tracheal intubation were similar to those of direct-vision laryngoscopy.