British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Clonidine decreases propofol requirements during anaesthesia: effect on bispectral index.
Assessment of the effect of clonidine on depth of anaesthesia is difficult because clonidine combines analgesic, sedative and direct haemodynamic effects. We thus evaluated the influence of clonidine on the bispectral index (BIS) and its potential dose-sparing effect on propofol. After induction of anaesthesia with target-controlled infusion of propofol and obtaining an unchanged bispectral index (pre-BIS), clonidine 4 microg kg(-1) or placebo was administered randomly to 50 patients in a double-blind manner. ⋯ Administration of clonidine resulted in a decrease in the BIS from 45 (SD 4) to 40 (6) (P<0.001), which allowed a reduction of propofol target concentration from 3.3 (0.6) to 2.7 (0.7) microg ml(-1) (P<0.001) and measured propofol concentration from 2.9 (0.6) to 2.5 (0.7) kg ml(-1) (P=0.009) in order to maintain the pre-BIS value. During subsequent surgery, propofol requirements were reduced by 20% (P=0.002) in the clonidine group and a similar amount of remifentanil was used in each group. The increase in anaesthetic depth given by clonidine can therefore be measured with bispectral EEG analysis and allows reduction of the propofol dose to achieve a specific depth of anaesthesia.
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Case Reports
Incremental spinal anaesthesia for elective Caesarean section in a patient with Eisenmenger's syndrome.
We describe a new approach to anaesthesia for elective Caesarean section in a woman with Eisenmenger's syndrome. Incremental regional anaesthesia was performed using a microspinal catheter and haemodynamic monitoring included transthoracic bioimpedance cardiography. This approach allowed the disadvantages of general anaesthesia and invasive cardiac output monitoring to be avoided.
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Randomized Controlled Trial Clinical Trial
Effects of dexmedetomidine on adrenocortical function, and the cardiovascular, endocrine and inflammatory responses in post-operative patients needing sedation in the intensive care unit.
We have compared the effects of dexmedetomidine and propofol on endocrine, metabolic, inflammatory and cardiovascular responses in patients in the intensive care unit (ICU) after major surgery. Twenty patients who were expected to require 8 h of post-operative sedation and ventilation were allocated randomly to receive either an infusion of dexmedetomidine 0.2-2.5 microg kg(-1) h(-1) or propofol 1-3 mg kg(-1) h(-1). Arterial pressure, heart rate and sequential concentrations of circulating cortisol, adrenocorticotrophic hormone (ACTH), growth hormone, prolactin, insulin, glucose and interleukin 6 were measured. ⋯ Growth hormone concentrations were significantly higher in dexmedetomidine-treated patients overall (P=0.036), but circulating concentrations remained in the physiological range. Interleukin 6 decreased in the dexmedetomidine group. We conclude that dexmedetomidine infusion does not inhibit adrenal steroidogenesis when used for short-term sedation after surgery.
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Randomized Controlled Trial Comparative Study Clinical Trial
Double-blind comparison of ropivacaine 7.5 mg ml(-1) with bupivacaine 5 mg ml(-1) for sciatic nerve block.
Two groups of 12 patients had a sciatic nerve block performed with 20 ml of either ropivacaine 7.5 mg ml(-1) or bupivacaine 5 mg ml(-1). There was no statistically significant difference in the mean time to onset of complete anaesthesia of the foot or to first request for post-operative analgesia. ⋯ Although there was no statistically significant difference in the mean time to peak plasma concentrations the mean peak concentration of ropivacaine was significantly higher than that of bupivacaine. There were no signs of systemic local anaesthetic toxicity in any patient in either group.
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Randomized Controlled Trial Clinical Trial
Amrinone can accelerate the cooling rate of core temperature during deliberate mild hypothermia for neurosurgical procedures.
We investigated the effects of i.v. amrinone on intraoperative changes of core temperature during deliberate mild hypothermia for neurosurgery. The patients in a control group (n=10) did not receive amrinone and patients in the amrinone group (n=10) received amrinone 5 microg kg(-1) min(-1) after a loading dose of 1.0 mg kg(-1). Anaesthesia was maintained with nitrous oxide in oxygen, propofol and fentanyl. ⋯ Tympanic membrane temperatures between 30 and 90 min after cooling were significantly lower in the amrinone group than in the control group. During cooling, the times taken to cool to 35 degrees C and to the lowest temperature were significantly shorter in the amrinone group than in the control group. These results suggest that i.v. amrinone can accelerate the cooling rate of core temperature during deliberate mild hypothermia for neurosurgical procedures.