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Background: This study aimed to evaluate whether exposure to sevoflurane at the onset of reperfusion provides protection similar to sevoflurane preconditioning and whether the effect depends on mitochondrial potassium ATP-dependent channel (mitoK(ATP)) in a rat model of focal cerebral ischaemia., Methods: Adult Wistar male rats were subjected to focal cerebral ischaemia for 1 h followed by 24 h or 7 days of reperfusion. Preconditioning consisted of 15 min exposure to sevoflurane at 1 minimum alveolar concentration (2.6%) 72 h before ischaemia. Post-conditioning was performed by exposure to sevoflurane immediately at the onset of reperfusion or by a delayed exposure 5 min after the onset of reperfusion. The role of the mitoK(ATP) channel was assessed by i.p. injection of the selective blocker 5-hydroxydecanoate before each sevoflurane administration or by the mitoK(ATP) channel opener, diazoxide (DZX), given in place of sevoflurane. Cerebral infarct size, neurological deficit score, and motor coordination were evaluated 24 h and 7 days after reperfusion., Results: Sevoflurane preconditioning and early post-conditioning reduced both cerebral infarct size and neurological defect score at 24 h of reperfusion whereas the sole sevoflurane post-conditioning improved motor coordination. At 7 days, only infarct volume remained lower in pre- and post-conditioned animals. Neuroprotection mediated by sevoflurane was lost when it was given 5 min after the onset of reperfusion and was abolished by inhibition of mitoK(ATP). DZX alone mimicked sevoflurane-induced pre- and post-conditioning., Conclusions: The pretreatment with sevoflurane or its early administration at reperfusion provides neuroprotection via mitoK(ATP) in a rat model of focal cerebral ischaemia.

Background: Off-line calculation of the pulse pressure variation (PPV(ref)) has repeatedly been shown to be a reliable predictor of fluid responsiveness in mechanically ventilated patients. This study was designed to assess the ability of two algorithms for automated calculation of PPV (PPV(auto)) (Intellivue MP 70) and stroke volume variation (SVV(auto)) (FloTrac/Vigileo) to predict fluid responsiveness during abdominal surgery., Methods: We conducted a prospective study of 56 fluid challenges given for haemodynamic instability in 11 patients undergoing major abdominal surgery. Fluid responsiveness was defined as an increase in stroke volume index (SVI) >10%. PPV(ref), PPV(auto), SVV(auto), and SVI (oesophageal Doppler) were recorded simultaneously before and after each fluid challenge., Results: PPV(auto) and SVV(auto) both correlated with PPV(ref) [r(corr)=0.87 (P<0.0001) and 0.84 (P<0.0001), respectively; n=77]. All three indices measured before fluid challenges were higher in responder (n=32) than in non-responder (n=24) fluid challenges (P < or = 0.02). The mean areas under the receiver operating characteristic curves were 0.96 (PPV(ref)), 0.96 (PPV(auto)), and 0.95 (SVV(auto)), and the optimal threshold value for each variable was 13%, 13%, and 12%, respectively. All indices correlated with the fluid challenge-induced changes in SVI (PPV(ref): r(corr)=0.65; PPV(auto): r(corr)=0.58; SVV(auto): r(corr)=0.58, P<0.001 for all)., Conclusions: PPV(auto) and SVV(auto) predict fluid responsiveness as accurately as off-line PPV(ref) in patients with haemodynamic instability during major abdominal surgery.

Background: The use of regional anaesthesia in thyroid surgery remains controversial. This double-blind, randomized controlled study was conducted to evaluate the analgesic efficacy of bilateral superficial cervical plexus block (BSCPB) performed under general anaesthesia in patients undergoing total thyroidectomy., Methods: Eighty-seven consecutive consenting patients were randomized to receive a BSCPB with saline (Group P, n = 29), ropivacaine 0.487% (Group R, n = 29), or ropivacaine 0.487% plus clonidine 5 microg ml(-1) (Group RC, n = 29). Sufentanil was given during the intraoperative period for a 20% increase in arterial mean pressure or heart rate in a patient with a bispectral index between 40 and 60. All patients received 4 g of acetaminophen during the first 24 h after operation. The pain score was checked every 4 h and nefopam was given for pain score >4 on a numeric pain scale., Results: During surgery, the median sufentanil requirements were significantly reduced in Group RC compared with Groups R and P (0.32 vs 0.47 and 0.62 microg kg(-1); P < 0.0001). After surgery, the number of patients requiring nefopam within 24 h of surgery was significantly lower in Groups R and RC than in Group P (16 and 19 vs 25; P = 0.03). At post-anaesthetic care unit admission, median (range) pain scores were significantly lower in Groups R [3 (0-10)] and RC [3 (0-8)] than in Group P [5 (0-8), P = 0.03]. No major complications of BSCPB occurred during study., Conclusions: BSCPB with ropivacaine and clonidine improved intraoperative analgesia. BSCPB with ropivacaine or ropivaciane and clonidine was effective in reducing analgesic requirements after thyroid surgery.

Background: The aim of this study was to evaluate potential predictors of fluid responsiveness obtained during major hepatic surgery. The predictors studied were invasive monitoring of intravascular pressures (radial and pulmonary artery catheter), including direct measurement of respiratory variation in arterial pulse pressure (PPVart), transoesophageal echocardiography (TOE), and non-invasive estimates of PPVart from the infrared photoplethysmography waveform from the Finapres (PPVfina) and the pulse oximetry waveform (PPVsat)., Methods: We conducted a prospective study of 54 fluid challenges (250 ml colloid) given for haemodynamic instability in eight patients undergoing hepatic resection. Fluid responsiveness was defined as an increase in stroke volume index (SVI) >or=10%. The following variables were recorded before each fluid challenge: right atrial pressure (RAP), pulmonary artery occlusion pressure (PAOP), PPVart, PPVfina, PPVsat, and the TOE-derived variables left ventricular end-diastolic area index (LVEDAI), early/late (E/A) diastolic filling wave ratio, deceleration time of the E wave (MDT) of mitral flow and the systolic fraction of the pulmonary venous flow (SF)., Results: Only PPVfina, PPVart (both P<0.001), PPVsat (P=0.02), LVEDAI and MDT (both P=0.04) were different in responder vs non-responder fluid challenges. The areas under the receiver operating characteristic (ROC) curves were 0.81 (PPVfina), 0.79 (PPVart), 0.70 (LVEDAI), 0.68 (PPVsat and MDT), 0.63 (RAP), 0.62 (E/A), 0.55 (PAOP) and 0.42 (SF). The areas under the ROC curves for RAP, E/A, PAOP and SF were significantly less than that for PPVfina (P<0.05 in each case). Only PPVart (r=0.59, P=0.0001) and PPVfina (r=0.56, P=0.0001) correlated with the fluid challenge-induced changes in SVI., Conclusions: PPVart and PPVfina predict fluid responsiveness during major hepatic surgery. This suggests that intraoperative monitoring of fluid responsiveness may be implemented simply and non-invasively.

Background: Remifentanil and alfentanil are opioids often used during direct laryngoscopy (DL). This prospective, randomized study compared these agents with respect to haemodynamic and Bispectral Index (BIS) responses, glottic visualization, and rapidity of recovery (spontaneous ventilation, eye opening) in DL without intubation., Methods: A total of 60 patients undergoing DL were randomized into two groups: remifentanil (R) and alfentanil (A). Anaesthesia was induced with propofol 2.5 mg kg(-1) and the opioid was administered 1 min later (R=2 microg kg(-1) or A=30 microg kg(-1) over 30 s). DL was commenced 1 min after (corresponding to 3 min after the beginning of induction). Glottic visualization, opioid and/or propofol re-injection, spontaneous ventilation recovery, and eye opening were recorded., Results: During DL, mean arterial pressure (MAP) increased by 6% in the R group vs 20% in the A group (P<0.05) when compared with post-induction values without affecting heart rate or BIS. No significant difference was observed between groups with respect to glottic exposure, opioid and/or propofol re-injection, and spontaneous ventilation recovery (mean (SEM) 3.8 (0.6) min, R group vs 3.2 (0.7) min, A group, NS) or eye opening (7.1 (1.1) min, R group vs 7.4 (0.9) min, A group, NS). Thirty minutes after postanaesthesia care unit (PACU) admission, MAP returned to its pre-induction value in the R group (104 (3) vs 109 (3) at baseline, NS), whereas in the A group MAP remained significantly lower at this time point (96 (4) vs 106 (3) at baseline, P<0.05)., Conclusion: This study showed that only remifentanil prevented MAP increase without adverse effects such as bradycardia during DL, and prevented MAP decrease 30 min after PACU admission.

Volatile anaesthetics induce hypotension by both indirect and direct effects; they have been reported to inhibit vasoconstriction produced by a variety of agonists. These studies were performed to see if halothane, enflurane and isoflurane attenuate endothelin-1-evoked contraction and if they interact with endothelium-dependent or -independent vasoactive substances. Rat aortic rings were suspended in aerated Krebs' solution (37 degrees C) and contracted by incremental doses of endothelin-1 5 x 10(-10) to 5 x 10(-8) mol litre-1. Volatile anaesthetics at 1 and 2 MAC were tested on endothelium intact and denuded rings. They were tested also on L-NAME incubated endothelium intact and indomethacin-incubated endothelium intact and denuded rings. Responses to endothelin-1 were compared in the presence and absence of volatile anaesthetics. Isoflurane at 1 and 2 MAC concentration, and enflurane at 2 MAC, induced a rightward shift of the dose-response curve obtained with endothelin-1 in both endothelium denuded and intact rings, associated with a decrease in maximal tension generated in the latter rings. In L-NAME-incubated endothelium intact rings and in indomethacin endothelium denuded rings, the anaesthetics induced a rightward shift of the dose-response curve without modification of maximal tension. In indomethacin-incubated endothelium intact rings there was significant attenuation of endothelin-1 contraction in control rings which was not enhanced by volatile anaesthetics in treated rings. The present study indicates that isoflurane at 1 and 2 MAC, and enflurane at 2 MAC, significantly decreased endothelin-1-induced contraction of isolated rat aorta. This inhibition was observed in both intact and denuded rings and probably involves mechanisms within the smooth muscle. Nevertheless, our results suggest that part of the anaesthetic-induced inhibition of endothelin-1-evoked vasocontraction involves an "indomethacin-like" effect on an endothelial-derived vasoconstricting cyclo-oxygenase product.