British journal of anaesthesia
-
Randomized Controlled Trial Comparative Study Clinical Trial
Motor block during patient-controlled epidural analgesia with ropivacaine or ropivacaine/fentanyl after intrathecal bupivacaine for caesarean section.
We compared patient-controlled epidural analgesia (PCEA) with ropivacaine alone or combined with fentanyl in terms of analgesic efficacy, motor weakness and side-effects in patients who had received spinal anaesthesia for elective Caesarean section. ASA I patients received combined spinal-epidural anaesthesia and were randomly assigned, in a double-blind study, into two groups after operation: group R (n = 23) received PCEA ropivacaine 0.1%, bolus 5 mg, lock-out 15 min, 3 mg h-1 background infusion, and group RF (n = 24) received PCEA 0.1% ropivacaine/fentanyl 2 micrograms ml-1 at identical settings. Pain and satisfaction on a 100 mm visual analogue scale (VAS) and side-effects were noted. ⋯ Analgesic consumption was less in RF (P = 0.041), but there was no difference in time to first request for supplementary analgesia. Patient satisfaction with postoperative analgesia (mean (SD)) was higher in RF (79 (23) vs 57 (29) mm, P = 0.045). Caution should be exercised using ropivacaine PCEA after spinal bupivacaine for Caesarean section, because its reputed motor-sparing property may be unreliable.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Bispectral analysis of the electroencephalogram does not predict responsiveness to verbal command in patients emerging from xenon anaesthesia.
The bispectral index (BIS) is derived empirically from the electroencephalogram database of patients receiving common anaesthetics, but it may not be valid for uncommon agents. Therefore, we investigated how xenon affects the BIS. Nine and 11 patients were anaesthetized with 0.8 of the minimal alveolar concentration (MAC) of isoflurane (0.92%) and xenon (56%), respectively. ⋯ In contrast, four patients receiving xenon responded to verbal command while the BIS was below 50 [median 45 (range 41-49)]. The remaining seven patients in the xenon group awoke when their BIS was greater than 80 [median 96 (range 82-98)], but in four of them the BIS was no greater than 50 when the xenon concentration was only 0.1 MAC (7%) higher than that associated with awakening. We conclude that low BIS values (< 50) do not guarantee adequate hypnosis during xenon anaesthesia.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Transcranial magnetic-evoked potentials under total intravenous anaesthesia and nitrous oxide.
Magnetic stimulation of the cortex and recording of the motor-evoked potentials (MEPs) by electromyography (EMG) is a well proven method to assess the descending pathways of the spinal cord and detect neurological impairment. We have assessed, in 33 adult patients undergoing spinal surgery, the influence of four total i.v. anaesthesia regimens (TIVA) on this recording technique. In 20 patients, the effect of 50% nitrous oxide was also studied. ⋯ Propofol (in combination with alfentanil or ketamine) showed marked depression of the MEP amplitude and the lowest success rates of stimulation. The latencies did not change at all. The addition of nitrous oxide significantly depressed the registered MEPs and lowered the success rates.
-
Randomized Controlled Trial Comparative Study Clinical Trial
Nodal rhythm and bradycardia during inhalation induction with sevoflurane in infants: a comparison of incremental and high-concentration techniques.
We studied heart rate and rhythm changes during sevoflurane inhalation induction in 60 healthy, unpremedicated infants. Patients were allocated randomly to receive an incremental (2% sevoflurane, increased every four to six breaths by 2% increments, to 8%) or high-concentration induction technique (8% sevoflurane from the outset). The ECG was recorded for 330 s (30 s pre- and 300 s postinduction) using a mini-Holter device (Recollect Dual Channel, Hertford Medical) and later analysed by an independent observer. ⋯ The onset of nodal rhythm was associated with bradycardia (< 80 bpm) in seven out of 12 cases, and occurred significantly earlier in the high-concentration group (median 123 (range 99-139) s versus 164 (127-138) s). Its duration was similar in both groups (62 (2-84) s versus 90 (20-167) s). These findings highlight the importance of using continuous ECG analysis when studying volatile anaesthetic agents in young children.
-
Clinical Trial
Pharmacokinetics and clinical efficacy of long-term epidural ropivacaine infusion in children.
The clinical efficacy and pharmacokinetics of long-term epidural ropivacaine infusion were investigated in 18 postoperative children aged between 0.3 and 7.3 yr. A lumbar or thoracic epidural catheter was inserted after the anaesthetic induction. Sixty minutes following a bolus dose of ropivacaine 1 mg kg-1, 0.2% ropivacaine was infused at a fixed rate of 0.4 mg kg-1 h-1 for a mean of 61.3 h (range 36-96 h). ⋯ No clinical signs of local anaesthetic toxicity were seen. Total (100-3189 micrograms litre-1) and free (10-56 micrograms litre-1) ropivacaine concentrations were within the range reported to be 'safe' in previous studies in adults. Mean (95% CI) volume of distribution was 3.1 litre kg-1 (2.1-4.2 litre kg-1), total clearance was 8.5 ml kg-1 min-1 (5.8-11.1 ml kg-1 min-1), free clearance was 220 ml kg-1 min-1 (170-270 ml kg-1 min-1) and elimination half-life was 4.9 h (3.0-6.7 h).