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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Randomized Controlled Trial Comparative Study Clinical Trial
Intrathecal diamorphine compared with morphine for postoperative analgesia after caesarean section under spinal anaesthesia.
A randomized, double-blind study of 40 women was performed to compare patient controlled anaesthesia (PCA) morphine requirements after spinal anaesthesia for elective Caesarean section. The women received 0.2 mg of either morphine or diamorphine mixed with 0.5% bupivacaine in 8% dextrose. ⋯ Similarly, the VAS for drowsiness were significantly higher in the morphine group at 6 and 8 h. Overall there was no difference in the 24-h PCA morphine demands between the two groups (diamorphine patients 5.5 mg, morphine patients 5.0 mg.
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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.
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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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The ratio of effective arterial elastance (Ea) to left ventricular elastance (Ees) is an indicator of the coupling between ventricular properties and arterial load properties. Another criterion for the coupling between an energy source and its load is the principle of economical fuel consumption, or mechanical efficiency, which is defined as the ratio of stroke work (SW) to myocardial oxygen consumption per beat (MVO2). It has been revealed that SW of ventricular contraction is maximized when Ea/Ees = 1, while mechanical efficiency is maximized when Ea/Ees = 0.5. ⋯ Before nicardipine (during hypertension), Ea was almost equal to Ees, whereas Ea/Ees was significantly reduced to about 0.5-0.6 at 3, 10, and 20 min after nicardipine. SWI/PVAI was maximized and significantly greater than the baseline value at 3 min after nicardipine. These results suggest that, during hypertension, ventricular and arterial properties were so matched as to maximize SW at the expense of the work efficiency, whereas mechanical efficiency of ventricular contraction was maximized after nicardipine.