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Isoflurane Anaesthesia (isoflurane + anaesthesia)
Selected AbstractsInfluence of neurohumoral blockade on heart rate and blood pressure responses to haemorrhage in isoflurane anaesthetized ratsACTA PHYSIOLOGICA, Issue 3 2000UllmanArticle first published online: 24 DEC 200 Four groups of Sprague,Dawley rats were anaesthetized with isoflurane (ISO) (1.7% end-tidal concentration) in 40% oxygen, and mechanically ventilated. The animals were bled 15 mL kg,1 b.w. from the femoral vein over 10 min, followed by an observation period of 30 min. Ten minutes before haemorrhage each group of animals was pre-treated with intravenous injection/infusion of either: isotonic saline (Group B; CON; n=7), vasopressin V1 -receptor antagonist [d(CH2)5Tyr(Me)AVP; 10 ,g kg,1] (Group C; AVP-a; n=7), the non-selective angiotensin II receptor antagonist saralasin (10 ,g kg,1 min,1) (Group D; SAR; n=7) or hexamethonium (10 mg kg,1) (Group E; HEX; n=7). A separate group of conscious animals were pre-treated with isotonic NaCl and subjected to the same haemorrhage protocol (Group A; AW; n=7). Mean arterial pressure (MAP), heart rate (HR) and blood gases were observed during the experiments. Only pre-treatment with SAR and HEX reduced MAP significantly. The pre-haemorrhage HR was only affected by HEX, which caused a reduction by 17%. The HR was significantly lower at the end of haemorrhage compared with pre-haemorrhage levels in all groups except that group treated with HEX. In that group the HR changed in the opposite direction. The ability to maintain MAP during haemorrhage, and the post-haemorrhage period, was significantly impaired in the groups treated with AVP-a, SAR or HEX compared with the group receiving NaCl. It is concluded that autonomic nervous activity is of major importance for the maintenance of MAP during isoflurane anaesthesia, whereas circulating angiotensin II and vasopressin levels contribute to a much smaller degree in this regard. General anaesthesia in combination with different degrees of neurohumoral blockade impairs the haemodynamic responses to blood loss, seen in conscious individuals. The impairment involves both the early and late phases during haemorrhage, as well as the post-bleeding recovery period. All three neurohumoral systems (autonomic nervous activity, angiotensin II and vasopressin) are of importance for regulating MAP during and after haemorrhage, although the autonomic nervous outflow appears to contribute to a larger extent. [source] Effect of epidural dexmedetomidine on intraoperative awareness and post-operative pain after one-lung ventilationACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2010M. ELHAKIM Background: During combined general and regional anaesthesia, it is difficult to use autonomic signs to assess whether wakefulness is suppressed adequately. We compared the effects of a dexmedetomidine,bupivacaine mixture with plain bupivacaine for thoracic epidural anaesthesia on intraoperative awareness and analgesic benefits, when combined with superficial isoflurane anaesthesia (<0.05 maximum alveolar concentration) in patients undergoing thoracic surgery with one-lung ventilation (OLV). Methods: Fifty adult male patients were randomly assigned to receive either epidural dexmedetomidine 1 ,g/kg with bupivacaine 0.5% (group D) or bupivacaine 0.5% alone (group B) after induction of general anaesthesia. Gasometric, haemodynamic and bispectral index values were recorded. Post-operative verbal rating score for pain and observer's assessment of alertness/sedation scale were determined by a blinded observer. Results: Dexmedetomidine reduced the use of supplementary fentanyl during surgery. Patients in group B consumed more analgesics and had higher pain scores after operation than patients of group D. The level of sedation was similar between the two groups in the ICU. Two patients (8%) in group B reported possible intraoperative awareness. There was a limited decrease in PaO2 at OLV in group D compared with group B (P<0.05). Conclusion: In thoracic surgery with OLV, the use of epidural dexmedetomidine decreases the anaesthetic requirements significantly, prevents awareness during anaesthesia and improves intraoperative oxygenation and post-operative analgesia. [source] Sevoflurane versus isoflurane , anaesthesia for lower abdominal surgery.ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2003Effects on perioperative glucose metabolism Background: The aim of this study was to determine the impact of sevoflurane anaesthesia on metabolic and endocrine responses to lower abdominal surgery. Methods: A prospective randomized controlled study in 20 patients undergoing abdominal hysterectomy. Patients were randomly assigned to receive either sevoflurane (S) or isoflurane anaesthesia (I). Using a stable isotope dilution technique, endogenous glucose production (EGP) and plasma glucose clearance (GC) were determined pre- and postoperatively (6,6- 2H2 -glucose). Plasma concentrations of glucose, insulin, cortisol, epinephrine and norepinephrine were measured preoperatively, 5 min after induction of anaesthesia, during surgery and 2 h after the operation. Results: EGP increased in both groups with no intergroup differences (preop. S 12.2 ± 1.6, I 12.4 ± 1.6; postop. S 16.3 ± 1.9*, I 19.0 ± 3.1*µmol kg,1 min,1, all values are means ± SD, *P < 0.05 vs. preop.). Plasma glucose concentration increased and GC decreased in both groups. There were no differences between groups. (Glucose conc. mmol l,1 preop.: S 4.1 ± 0.3, I 3.9 ± 0.5; 5 AI S 5.1 ± 0.6*, I 5.1 ± 1.0*, postop. S 7.0 ± 1.0*, I 7.1 ± 1.4*; * = P < 0.05 vs. preop.; GC ml kg,1min,1 preop. S 3.0 ± 0.4, I 3.2 ± 0.4; postop. S 2.4 ± 0.3*, I 2.7 ± 0.3*; *=P < 0.05 vs. preop.) Insulin plasma concentrations were unchanged. Cortisol plasma concentrations increased intra- and postoperatively with no changes between the groups. Norepinephrine plasma concentration increased in the S group after induction of anaesthesia. I group norepinephrine was increased 2 h after operation and showed no intergroup differences. Conclusion: Sevoflurane, as well as isoflurane, does not prevent the metabolic endocrine responses to surgery. [source] Comparison of plasma , glutathione S-transferase concentrations during and after low-flow sevoflurane or isoflurane anaesthesiaACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2001H. Higuchi Background: We evaluated the effect of low-flow sevoflurane anaesthesia, in which compound A is generated, and isoflurane anaesthesia, in which compound A is not generated (n=13 in each group), on hepatocellular integrity using , glutathione S-transferase (GST). , GST is a more sensitive and specific marker of hepatocellular damage than is aminotransferase activity and correlates better with hepatic histology. Methods: Sevoflurane or isoflurane were delivered without nitrous oxide with a fresh gas flow of 1 l/min. Concentrations of compound A in the circuit were measured hourly, and plasma , GST concentrations were measured perioperatively. Results: Mean duration of anaesthesia was 338±92 min in the sevoflurane group and 320±63 min in the isoflurane group. Mean compound A concentration in the sevoflurane group was 28.6±9.0 ppm. There was no significant difference in , GST concentrations between the sevoflurane and isoflurane groups during or after anaesthesia. Conclusion: These results indicate that low-flow sevoflurane and isoflurane anaesthesia have the same effect on hepatic function, as assessed by plasma , GST concentrations. [source] Sublinear summation of afferent inputs to the nucleus accumbens in the awake ratTHE JOURNAL OF PHYSIOLOGY, Issue 8 2009John A. Wolf The mechanisms by which the nucleus accumbens integrates afferent input from limbic and cortical structures have been influential in the development of models of psychiatric disorders such as schizophrenia. Previous studies of the response of nucleus accumbens (Nacb) cells to the stimulation of afferent inputs from hippocampus (HC) and prefrontal cortex (PFC) have demonstrated that PFC throughput can be modulated by preceding HC input. Examination of the post-synaptic potential size has suggested, however, that summation of these inputs is sublinear. All studies to date examining Nacb integration of inputs via stimulation of afferents have been performed in the anaesthetized rat. The present experiments compare the response of Nacb cells to different combinations of PFC and HC stimulation in awake and isoflurane-anaesthetized rats that were chronically implanted with both stimulating and recording electrodes. The results of these experiments suggest that summation of afferent input in the Nacb of the awake rat is predominantly sublinear, with only a minority of neurons demonstrating modulation of PFC inputs by the HC in the awake or the anaesthetized animal. The response profile of many cells changed during anaesthesia when compared to the awake condition, and on average showed suppression to PFC input 50 and 150 ms following HC stimulation while under deep isoflurane anaesthesia. These results suggest that sublinear integration of afferent input from the PFC and HC is the dominant mode of integration of Nacb cells in the awake animal, which has implications for corticostriatal models of psychiatric dysfunction. [source] | ||||||||||