British journal of anaesthesia
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Randomized Controlled Trial Clinical Trial
Sevoflurane anaesthesia causes a transient decrease in aquaporin-2 and impairment of urine concentration.
Sevoflurane anaesthesia is occasionally associated with polyuria, but the exact mechanism of this phenomenon has not been clarified. Aquaporin-2 (AQP2) is an arginine vasopressin (AVP)-regulated water channel protein localized to the apical region of renal collecting duct cells and is involved in the regulation of water permeability. To elucidate the effect of sevoflurane anaesthesia on urine concentration and AQP2, we have compared serum and urinary concentrations of AVP, AQP2 and osmolar changes during sevoflurane and propofol anaesthesia. ⋯ Although urinary AQP2 excretion in the propofol group increased together with changes in plasma and urinary AVP, urinary AQP2 was significantly lower at 90 min in the sevoflurane group. Urine osmolality in the sevoflurane group also showed a transient but significant decrease in parallel with suppression of AQP2. Our data suggest that sevoflurane anaesthesia transiently produced an impaired AQP2 response to an increase in intrinsic AVP.
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Randomized Controlled Trial Clinical Trial
Effect of omitting regular ACE inhibitor medication before cardiac surgery on haemodynamic variables and vasoactive drug requirements.
Adverse events during coronary artery bypass graft (CABG) surgery have been described in patients receiving angiotensin converting enzyme (ACE) inhibitors, including hypotension on induction of anaesthesia and an increase in vasoconstrictor requirements after cardiopulmonary bypass (CPB). Omitting regular ACE inhibitor medication before surgery may improve cardiovascular stability during anaesthesia. We evaluated prospectively the effect of omitting regular ACE inhibitor medication before CABG surgery on haemodynamic variables and use of vasoactive drugs. ⋯ However, these patients required more vasodilators to control hypertension after CPB and in the early postoperative period. There was no difference in hypotension on induction of anaesthesia or in the use of vasoconstrictors after CPB. We conclude that omitting ACE inhibitors before surgery did not have sufficient advantage to be recommended routinely.
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Randomized Controlled Trial Multicenter Study Comparative Study Clinical Trial
Comparison of 0.25% S(-)-bupivacaine with 0.25% RS-bupivacaine for epidural analgesia in labour.
We have compared the efficacy of 0.25% S(-)-bupivacaine with 0.25% RS-bupivacaine in providing epidural analgesia for labour in a randomized, multicentre, double-blind study. Analgesia was initiated with 10 ml of the study solution and maintained with 10-ml top-ups. We studied 137 women and treatments were found to be equivalent for onset, duration and quality of block. ⋯ However, median duration of pain relief from the first top-up was 82 (range 3-164) min for S(-)-bupivacaine and 76 (22-221) min for RS-bupivacaine. There were no significant differences in the quality of analgesia, as assessed by the investigators. There were no significant differences in the extent of sensory block, percentage of patients with motor block or incidence of adverse events.
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Randomized Controlled Trial Comparative Study Clinical Trial
Evaluation of pressure changes in a new design tracheal tube cuff, the Portex Soft Seal, during nitrous oxide anaesthesia.
We have measured pressure changes in a newly designed tracheal tube cuff, the Portex Soft Seal, during nitrous oxide anaesthesia compared with a Mallinckrodt Lo-Contour tube and a Portex Profile tube. The pressure increases in both control groups were significantly greater than those with the new design (P < 0.0001 in each case). The mean increase in pressure in the Mallinckrodt Lo-Contour tube cuff was 9.9 (SD 3.4) mm Hg compared with 10.3 (1.8) mm Hg in the Portex Profile tube cuff and 2.1 (1.5) mm Hg in the Portex Soft Seal tube cuff. We conclude that the Portex Soft Seal cuff prevented a significant increase in intracuff pressure during nitrous oxide anaesthesia.
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Randomized Controlled Trial Clinical Trial
Posterior epidural space depth: safety of the loss of resistance and hanging drop techniques.
We have compared skin to epidural space distance (SED) and tip to tip distance (TTD), a measure of posterior epidural space depth (PESD), in 40 patients with a 27-gauge Whitacre needle after identification of the epidural space using the hanging drop (HD) or loss of resistance (LOR) to air technique. After the LOR technique, TTD was found to be 2 mm greater than that after the HD technique, whereas SED was the same. We conclude that identification of the epidural space can be performed successfully with both techniques, but with a diminished risk of dural damage after LOR compared with the HD technique.