Sevoflurane-nitrous Oxide Anaesthesia Research Articles

Comparison of recovery times by using bispectral index monitoring versus end-tidal agent concentration monitoring in patients undergoing inhalational general anaesthesia.

Background and Aims:End-tidal anaesthetic gas concentration (ETAG) and bispectral index (BIS) are both used to monitor depth of anaesthesia. Maintaining an accurate depth of anaesthesia helps in early post-operative recovery. This study compared the recovery times from sevoflurane–nitrous oxide anaesthesia using ETAG monitoring with BIS monitoring.Methods:Four hundred and two patients undergoing elective surgeries under sevoflurane- nitrous oxide anaesthesia were enroled in this double blinded parallel group prospective randomised trial and allocated into two groups. The depth of anaesthesia was monitored using BIS in BIS group (n = 202) and end-tidal sevoflurane concentration (EtSevo) in ETAG group (n = 200). The time to extubation and recovery were compared between the groups. Parametric, non-parametric and categorical variables were compared using Student’s ‘t’ test, Wilcoxon’s rank sum test and Chi-square test, respectively.Results:Time to extubation (min) [BIS group – 10, 5; ETAG group – 10, 5 (median, inter-quartile range, IQR), P = 0.32] and time to recovery (min) [BIS group – 14, 6; ETAG group – 13.5, 7 (median, IQR), P = 0.34] did not differ significantly between the two groups. The EtSevo concentration (vol%) was significantly higher in the BIS group at 5 min [BIS group – 1.2, 0.4; ETAG group – 1.0, 0.4 (median, IQR), P < 0.001], 30 min [BIS group – 1.1, 0.4; ETAG group – 1.0, 0.3 (median, IQR), P = 0.002] and 120 min [BIS group – 1.11 ± 0.28; ETAG group – 0.96 ± 0.27 (mean ± standard deviation), P = 0.014] after induction of anaesthesia.Conclusions:BIS and ETAG monitoring are associated with comparable recovery profiles. ETAG monitoring is associated with significantly less sevoflurane consumption.

Background anaesthetic agents do not influence the impact of arginine vasopressin on haemodynamic states and cerebral oxygenation during shoulder surgery in the beach chair position: a prospective, single-blind study

BackgroundAdministration of arginine vasopressin (AVP) is associated with reducing jugular venous (SjvO2) and regional cerebral (rScO2) oxygen saturation under propofol-remifentanil (P/R) anaesthesia. We determined whether background anaesthetics modulate the effect of AVP on cerebral oxygenation and haemodynamics.MethodsWe randomly allocated 60 adult patients scheduled for shoulder surgery in the beach chair position (BCP) into 4 groups, to receive either an intravenous bolus of saline (groups PR-S and SN-S) or 0.05 U/kg AVP (groups PR-AVP and SN-AVP) under P/R or sevoflurane-nitrous oxide (S/N) anaesthesia (n = 15 each). Haemodynamic variables, SjvO2 and rScO2 were measured.ResultsAVP significantly increased mean arterial blood pressure (MAP) and decreased rScO2 in either anaesthetic group. AVP also decreased SjvO2 in the P/R groups but not in the S/N groups. The AVP-treated groups showed higher MAP and cerebral desaturation (>20% rScO2 decrease from baseline), along with lower HR and rScO2 in the BCP than those in the saline-treated groups. In contrast, AVP did not affect SjvO2 values or the incidence of SjvO2 < 50%. Baseline SjvO2 was lower and the magnitude of its reduction in the BCP was greater in the PR-AVP group than in the SN-AVP group, and the lowest SjvO2 values were 37 ± 6 and 57 ± 8%, respectively (P < 0.001).ConclusionsThe choice of anaesthetic regimen did not affect cerebral oxygenation or haemodynamics of AVP in the BCP. However, the negative effect of AVP on cerebral oxygenation should be considered, especially under P/R anaesthesia.Trial registrationClinicalTrials.gov identifier: NCT01687894, registered on September 18, 2012.

Spinal anaesthesia for orthopaedic surgery in children with cerebral palsy: analysis of 36 patients

Background and Objective: Cerebral palsy is one of the most common childhood neuromuscular diseases in the world. Spinal anaesthesia in children is an evolving technique with many advantages in perioperative management. The aim of this retrospective study was to provide first-hand reports of children with cerebral palsy who underwent orthopaedic surgery under spinal anaesthesia.Methods:Records of the children with cerebral palsy who underwent orthopaedic surgery under spinal anaesthesia between May 2012 and June 2013 at Selcuk University Hospital were investigated. In all patients, lumbar puncture was performed in lateral decubitus position with mask sevoflurane-nitrous oxide anaesthesia. In patients who were calm prior the spinal block, inhalation anaesthesia was terminated. In patients who were restless before the spinal block, anaesthesia was combined with light sevoflurane anaesthesia and a laryngeal mask. From anaesthesia records, the number of attempts required to complete the lumbar puncture, and the success rates of spinal anaesthesia and perioperative complications were noted. Data were expressed as numbers and percentages.Results:The study included 36 patients (20 girls and 16 boys). The mean age was 71 months. The rate of reaching subarachnoid space on first attempt was 86%. In all patients, spinal anaesthesia was considered successful. In 26 patients, laryngeal mask and light sevoflurane anaesthesia were required to maintain ideal surgical conditions. No major perioperative complications were observed.Conclusion:Spinal anaesthesia alone or combined with light sevoflurane anaesthesia is a reliable technique with high success rates in children with cerebral palsy undergoing orthopaedic surgery.

Impaired Spatial Learning and Memory after Sevoflurane–Nitrous Oxide Anesthesia in Aged Rats Is Associated with Down-Regulated cAMP/CREB Signaling

Neurocognitive deficits arising from anesthetic exposure have recently been debated, while studies have shown that the phosphorylation of cyclic AMP response element-binding protein (CREB) in the hippocampus is critical for long-term memory. To better understand the neural effects of inhalational anesthetics, we studied the behavioral and biochemical changes in aged rats that were exposed to sevoflurane (Sev) and nitrous oxide (N2O) for 4 h. Eighteen-month-old rats were randomly assigned to receive 1.3% sevoflurane and 50% nitrous oxide/50% oxygen or 50% oxygen for 4 h. Spatial learning and memory were tested with the Morris water maze 48 h after exposure, and the results showed that sevoflurane–nitrous oxide exposure induced a significant deficit in spatial learning acquisition and memory retention. Experiments revealed that the cAMP and pCREB levels in the dorsal hippocampus were decreased in rats with anesthetic exposure in comparison with control rats 48 h after anesthesia as well as 15 min after the probe trial, but there were no significant differences in CREB expression. Besides these, the current study also found the DG neurogenesis significantly decreased as well as neuronal loss and neuronal apoptosis increased in the hippocampus of rats exposed to Sev+N2O. The current study demonstrated that down-regulation of cAMP/CREB signaling, decrease of CREB-dependent neurogenesis and neuronal survival in the hippocampus contributed to the neurotoxicity and cognitive dysfunction induced by general anesthesia with sevoflurane–nitrous oxide.

Composite-, plain-auditory evoked potentials index and bispectral index to measure the effects of sevoflurane

The composite auditory evoked potentials index (cAAI) uses both cortical electroencephalogram (EEG) and response to auditory stimuli, while the bispectral index (BIS) uses only the cortical EEG and auditory evoked potentials index (AAI) uses only response to auditory stimuli. We expected that the cAAI was more useful to monitor anesthetic effect of sevoflurane than the BIS and AAI. The present study compared the changes of cAAI, AAI, and BIS in different sevoflurane concentration. Forty-five adult patients were anesthetized with sevoflurane in 50 % nitrous oxide. AAI (AEP version 1.4), cAAI (AEP version 1.6), and BIS (A-2000) were compared (each 15 patients in AAI, cAAI, and BIS groups) before induction, just before and after intubation, at 10 min since sevoflurane was set to 1.0, 1.5 and 2.0 %, and after extubation. All three indices decreased significantly before intubation. The cAAI was significantly higher than the AAI at sevoflurane 1.0 and 1.5 %. The AAI and BIS were significantly lower at sevoflurane 2.0 % than those at sevoflurane 1.0 %, but the cAAI did not. The cAAI had the largest and AAI had the smallest inter-individual variation. In sevoflurane-nitrous oxide anesthesia, cAAI was inferior to AAI and BIS to discriminate different anesthetic effect. The cAAI had larger inter-individual variation than the AAI and BIS.

Notice of Retraction

The following article from Acta Anaesthesiologica Scandinavica "Haemodynamics and cerebral oxygenation during arthroscopic shoulder surgery in beach chair position under general anaesthesia" by Jeong H, Lee SH, Jang EA, Chung SS, Lee J, Yoo KY. Acta Anaesthesiol Scand. 56 (7): 872–9(August 2012). DOI: 10.1111/j.1399-6576.2012.02716.x. and published online on 10 May 2012 in Wiley Online Library (wileyonlinelibrary.com) has been retracted at the request of the Editor-in-Chief Lars S. Rasmussen by agreement with Blackwell Publishing Ltd. The retraction has been decided based on redundancy because very similar findings have been published in the following article: "Cerebral oxygen saturation measured by near-infrared spectroscopy and jugular venous bulb oxygen saturation during arthroscopic shoulder surgery in beach chair position under sevoflurane-nitrous oxide or propofol-remifentanil anesthesia". Jeong H, Jeong S, Lim HJ, Lee J, Yoo KY. Anesthesiology; 116 (5): 1047–56 (May 2012) from the same institution. The two articles do not cite each other. The corresponding author has acknowledged that data from some patients appear in both articles and the study design was misrepresented.

Cerebral Oxygen Saturation Measured by Near-infrared Spectroscopy and Jugular Venous Bulb Oxygen Saturation during Arthroscopic Shoulder Surgery in Beach Chair Position under Sevoflurane-Nitrous Oxide or Propofol-Remifentanil Anesthesia

We examined the effects of different anesthetics on cerebral oxygenation and systemic hemodynamics in patients undergoing surgery in beach chair position (BCP). Jugular venous bulb oxygen saturation (SjvO2) and regional cerebral tissue oxygen saturation (SctO2) were determined while patients were placed from the supine to BCP. Whether SctO2 and SjvO2 are interchangeable in assessing the cerebral oxygenation was also examined. Forty patients undergoing shoulder surgery in BCP were randomly assigned to receive sevoflurane-nitrous oxide (S/N) or propofol-remifentanil (P/R) anesthesia. Four patients taking angiotensin II receptor antagonists were excluded post hoc. Mean arterial pressure and heart rate, as well as SjvO2 and SctO2, were measured before (postinduction baseline in supine position) and after BCP. Mean arterial pressure decreased by BCP in both groups. It was, however, significantly higher in S/N (n = 19) than in P/R group (n = 17) at 7 to 8 min after the positioning. SjvO2 also significantly decreased after BCP in both groups, the magnitude of which was lower in S/N than in P/R group (11 ± 10% vs. 23 ± 9%, P = 0.0006). The incidences of SjvO2 <50% and mean arterial pressure less than 50 mmHg were lower in S/N group, but SctO2and the incidence of cerebral desaturation (more than 20% decrease from baseline) did not significantly differ between the groups. SctO2 and SjvO2 were only weakly correlated (β = 0.218, r2 = 0.133). Bland-Altman analysis showed a mean difference of -7.2% with 95% limit of agreement between -38.2% and 23.8%. The margin of safety against impaired cerebral oxygenation is greater and SjvO2 is more preserved with S/N than with P/R anesthesia. SctO2 may not be reliable in detecting a low SjvO2 during the surgery in BCP.

Accuracy of BIS value for monitoring depth of sevoflurane-nitrous oxide anesthesia in children

Objective To evaluate the accuracy of BIS value for monitoring the depth of sevoflurane-nitrous oxide in children. Methods Seventy-two ASA Ⅰ or Ⅱ children aged 1-14 yr undergoing abdominal surgery were randomly assigned into 3 groups （ n = 24 each） ：sevoflurane group （group S）, sevoflurane ＋ 30% N2O group （group SN1 ）and sevoflurane ＋ 60% N2O （group SN2 ）. Anesthesia was induced with atropine, lidocaine, propofol, rocuronium and remifentanil. After tracheal intubation, the patients were mechanically ventilated. PETCO2 was maintained at 35-45 mm Hg. Anesthesia was maintained with 2.5% sevoflurane combined with 0, 30% and 60% nitrous oxide in group S, SN1 and SN2 respectively. The end-tidal sevoflurane concentration （CETSev） was maintained at 2.5%, 2.0% and 1.5%. Each CETSev was maintained for at least 10 min after the begining of the surgery. Then the CETSev was modified to maintain BIS value at 40-60. BIS value was recorded before anesthesia induction and each stable CETSev. CETSev was recorded at maintaining BIS value of 40-60 for at least 20 min （ C50 ）.Results BIS value and C50 were significantly lower in group SN2 than in group S and SN1 （ P 〈 0.05）, while no significant difference was found between group S and SN1 （ P 〉 0.05）. BIS value was negatively correlated with CETSev in all 3 groups （r = -0.736, -0.817, -0.729, P 〈 0.01）.There was no significant difference in the correlation coefficients among the 3 groups （ P 〉 0.05 ）. Conclusion BIS value can accurately reflect the depth of sevoflurane-nitrous oxide anesthesia in children. Key words: Electroencephalography; Monitoring, intraoperative; Anesthetics, inhalation; Nitrous oxide; Child

Cerebral state index vs. bispectral index during sevoflurane–nitrous oxide anaesthesia

The cerebral state index (CSI) is a low-cost and compact electroencephalographic monitor alternative to the bispectral index (BIS). Although both indices are shown as the number between 0 and 100, owing to the different calculation algorithms, both indices might be different during anaesthesia. The present study was performed to compare the BIS and CSI during sevoflurane-nitrous oxide anaesthesia. Forty patients scheduled for abdominal surgery aged 30-70 years were enrolled. The electrodes of both the cerebral state monitor and BIS were attached simultaneously. Anaesthesia was induced with midazolam and fentanyl, and was maintained with sevoflurane with 50% nitrous oxide in oxygen and intermittent epidural mepivacaine. During surgery, end-tidal sevoflurane concentration was kept at 0.5, 1.0, and 1.5% for more than 10 min to measure CSI and BIS. The duration of signal disturbance by electric cautery was 12.6 +/- 4.2 min in the BIS and 3.9 +/- 1.8 min in the cerebral state monitor (P < 0.05) for 9.5 +/- 4.3 min duration of electric cautery. The recovery time from disturbance by electric cautery was 37 +/- 12 s in the BIS and 4 +/- 2 s in the cerebral state monitor (P < 0.05). The absolute values of the BIS and CSI were not significantly different. Both BIS and CSI decreased significantly when end-tidal sevoflurane concentration increased from 0.5 to 1.0%, but did not significantly change when end-tidal sevoflurane concentration increased from 1.0 to 1.5%. The BIS and CSI correlated well. The Bland-Altman plot showed good agreement between the BIS and CSI. During sevoflurane-nitrous oxide anaesthesia, the CSI was not significantly different from the BIS in the awake state and with sevoflurane concentration 0.5-1.5%.

Differential electroencephalographic response to tracheal intubation between young and elderly during isoflurane– and sevoflurane–nitrous oxide anaesthesia

Age-associated differences in the electroencephalographic (EEG) response to noxious stimuli with the presence of nitrous oxide (N(2)O) are unknown. We compared the EEG response with tracheal intubation between young and elderly. Sixty young (<40 yr) and elderly (>70 yr) patients were randomly allocated to one of the four groups. Anaesthesia was induced with 66% N(2)O and isoflurane in oxygen (Young-isoflurane and Elderly-isoflurane groups) or 66% N(2)O and sevoflurane in oxygen (Young-sevoflurane and Elderly-sevoflurane groups). Inhaled isoflurane and sevoflurane concentrations were gradually increased and the end-tidal concentrations were maintained at 1.1% and 1.7%, respectively. Tracheal intubation was performed 12 min after induction of anaesthesia. There were significant differences in the overall changes in bispectral index (BIS) and 95% spectral edge frequency (SEF95) between young and elderly (P<0.001 for both), but not between patients receiving isoflurane and sevoflurane (P=0.4 and 0.3, respectively). Both BIS and SEF95 were significantly decreased after tracheal intubation in Young-isoflurane and Young-sevoflurane groups (P<0.05 for all). In sharp contrast, BIS and SEF95 remained unchanged in Elderly-isoflurane and Elderly-sevoflurane groups (P>0.7 for all). These results suggest that both BIS and SEF95 significantly decreased, despite the presence of increased sympathetic activity after tracheal intubation in young patients. A significant difference was detected in EEG response to tracheal intubation between young and elderly. BIS does not reflect the depth of anaesthesia after tracheal intubation during anaesthesia with isoflurane or sevoflurane with 66% of N(2)O in young patients.

A randomised placebo‐controlled trial of the effects of midazolam premedication on children's postoperative cognition

This randomised, placebo-controlled study assessed the effects of midazolam premedication on children's postoperative cognition and physical morbidity. In all, 179 children aged 5-10 years were randomly assigned to receive buccal midazolam (0.2 mg x kg(-1)) or placebo before sevoflurane-nitrous oxide anaesthesia for multiple dental extractions. They performed tests of choice reaction time, attention, psychomotor co-ordination and memory pre-operatively (baseline), before discharge and at 48 h. The reaction time of both groups was significantly slower before discharge compared to baseline, with the midazolam group being significantly slower than placebo. Psychomotor co-ordination was also significantly impaired postoperatively after midazolam. Performance on both tests had recovered to baseline by 48 h. Midazolam was also associated with significant anterograde amnesia, both postoperatively and at 48 h, for information presented in the interval between premedication and surgery. The results show significant short-term impairment of children's cognitive function and amnesia enduring for 48 h after low-dose midazolam premedication.

The effects of brief sevoflurane‐nitrous oxide anaesthesia upon children's postoperative cognition and behaviour

This study assessed the effects of brief sevoflurane-nitrous oxide anaesthesia on children's postoperative cognition, behaviour and physical morbidity. Forty-eight children aged 5-10 years undergoing anaesthesia without premedication for multiple dental extractions, and 48 control children, performed tests of choice reaction time, attention, psychomotor co-ordination and memory pre-operatively (baseline), prior to discharge and at 48 h (anaesthesia group only). Physical and psychological morbidity were recorded at 1 week. Mean choice reaction time and psychomotor co-ordination were significantly impaired postoperatively but had recovered at 48 h. However, measures of performance variability suggested the presence of residual impairment. Profound retrograde amnesia affected postoperative and 48-h recall of pictorial stimuli presented prior to anaesthesia, but recognition memory was unimpaired. Attention-seeking, tantrums, crying and nightmares were occurring more frequently in some 8-20% of children 1 week after the procedure.

A Comparative Study of Recovery Characteristics between Propofol-Remifentanil and Sevoflurane-Nitrous Oxide Anesthesia in Children

Background: Remifentanil and sevoflurane are characterized by rapid emergence from anesthesia. Therefore, propofol-remifentanil anesthesia (PR) and sevoflurane-nitrous oxide anesthesia (SN) were compared with regard to the recovery characteristics in children. Methods: Sixty children scheduled for tonsillectomy were randomly assigned to receive PR (n = 30) or SN (n = 30). The PR group was induced by remifentanil, propofol and vecuronium, maintained with infusion of remifentanil and propofol. The SN group was induced by sevoflurane, nitrous oxide, vecuronium maintained with sevoflurane in 50% nitrous oxide. At the end of operation, all anesthetics were discontinued and 100% oxygen was inspirated in both groups. The times to spontaneous breathing, extubation, eye opening, PACU discharge were assessed and postoperative nausea/vomiting, agitation were noted. Results: Spontaneous breathing occurred after 9.29 1.02 minutes (PR) versus 6.85 0.60 minutes (SN) (P ＜ 0.05), extubation after 9.19 0.91 minutes versus 8.87 0.67 minutes, eye opening after 9.47 1.01 minutes versus 14.85 0.80 minutes (P ＜ 0.05) and PACU discharge after 21.32 2.01 minutes versus 27.55 1.72 minutes (P ＜ 0.05). The occurrence of postoperative nausea/vomiting was 7% (PR) versus 13% (SN), and the incidence of agitation was 60% (PR) versus 83% (SN). Conclusions: It was observed that the recovery of propofol-remifentanil anesthesia was faster than that of sevoflurane-nitrous oxide anesthesia, except spontaneous breathing. The incidences of postoperative nausea/vomiting were low in both groups, and the incidences of agitation were higher in SN group than in PR group.

Stress hormone changes in general anesthesia of long duration: isoflurane–nitrous oxide vs sevoflurane–nitrous oxide anesthesia

Study Objective There are few comparative studies of stress hormone changes during general anesthesia with long duration between isoflurane–nitrous oxide and sevoflurane–nitrous oxide anesthesia. We investigated perioperative changes of stress hormone in these two anesthetic methods with duration of more than 10 hours. Design Prospective study. Setting Operating room and high care unit of a university hospital. Patients Twenty patients with ASA physical status I or II for surgery for laryngeal or pharyngeal cancer with expected duration of more than 10 hours. Interventions Anesthesia was induced with midazolam, thiopental, and vecuronium and was maintained with sevoflurane (sevoflurane group) or isoflurane (isoflurane group) with nitrous oxide 4 L/min in oxygen 2 L/min. Measurements and Main Results Plasma concentrations of epinephrine, norepinephrine, cortisol, adrenocorticotropic hormone, and anti-diuretic hormone (ADH); serum concentrations of glucagon and insulin; and blood glucose concentration were measured before inhalation of anesthetics, after 5 and 10 hours, and at 1, 6, and 12 hours after the end of inhalation. Epinephrine and norepinephrine concentrations increased continuously during and after surgery in the isoflurane group whereas it increased only after surgery in the sevoflurane group. Both concentrations were higher in the isoflurane group during anesthesia. Cortisol increased continuously whereas adrenocorticotropic hormone increased only during surgery. Anti-diuretic hormone increased with its peak during surgery and the isoflurane group had significantly higher values than the sevoflurane group. Glucose increased both during and after surgery, insulin increased only after surgery, and glucagon decreased during surgery in both groups. Conclusions In inhalation anesthesia with the duration of more than 10 hours, isoflurane–nitrous oxide and sevoflurane–nitrous oxide had the same effects on stress hormone changes except for epinephrine, norepinephrine, and ADH. Epinephrine, norepinephrine, and ADH concentrations were higher in isoflurane–nitrous oxide anesthesia.

Comparison of the Eeg-Based SnapTM Index and the Bispectral (BisTM) Index During Sevoflurane - Nitrous Oxide Anaesthesia

The BIS monitor (Aspect Medical Inc, Newton, USA) was the first electroencephalogram (EEG)-based monitor of the hypnotic effect reflected by a dimensionless figure ranging from 100 (awake state) to 0 (flat line EEG). Its widespread use makes it the most-studied and the best-known among same intended devices. Its algorithm processes low-frequency EEG oscillations in order to provide the Bispectral index. A BIS index ranging from 40 to 60 has been established as the proper for surgical performance. The BIS monitor permits a closer approach to the hypnotic component of anaesthesia beyond clinical signs and may reduce the probability of intraoperative awareness; therefore, it has become a recommended monitoring tool in routine practice. The SNAP monitor (Nicolet Biomedical, Madison WI, USA) is also intended for monitoring the hypnotic effect of anaesthetics, which is in turn displayed as an index ranging from 100 to 0, with 100 meaning a fully awake state and 0 meaning no brain activity. The algorithm of the SNAP monitor is featured by its additional processing of ultra-high EEG frequencies, which seem to be involved in the formation of consciousness. The use of these frequencies would theoretically improve responsiveness during increased brain activity. We studied its behaviour patterns and capability to monitor the hypnotic effect induced by sevoflurane-nitrous oxide by comparison with the BIS index. Seventy patients ASA I-III were induced with propofol, fentanyl and rocuronium, and maintained with sevoflurane-N(2)O. BIS and SNAP indices were simultaneously recorded before induction, after intubation, after incision, at the following 10, 30 and 50 minutes, awakening and extubation time points, together with heart rate and blood pressure. The Pearson correlation was R(2) = 0.68 (p < .05). The Bland and Altman test showed a bias of 14.3 for SNAP index values with respect to BIS index values. We concluded that the SNAP index correlates with variations in the hypnotic effect induced by sevoflurane-nitrous oxide anaesthesia when compared with the BIS index. In this context, a SNAP index ranging from 58 to 70 would be equivalent to the BIS index range 40 to 60 and, therefore, the accurate for surgical performance.

Effect of sevoflurane/nitrous oxide versus propofol anaesthesia on somatosensory evoked potential monitoring of the spinal cord during surgery to correct scoliosis

Use of intraoperative somatosensory evoked potential (SSEP) monitoring is helpful in spinal corrective surgery but may be affected by anaesthetic drugs. An anaesthetic technique that has less effect on SSEP or allows faster recovery is an advantage. We compared the effects on SSEP and the clinical recovery profiles of sevoflurane/nitrous oxide and propofol anaesthesia during surgery to correct scoliosis. Twenty adolescent patients were randomized into two groups of 10. One group received sevoflurane-nitrous oxide anaesthesia and the other received propofol i.v. anaesthesia. An alfentanil infusion was used for analgesia in both groups. Changes in anaesthetic concentration produced little effect on the latency of SSEP, but the effect on the variability of SSEP amplitude was significant (P<0.05). Sevoflurane produced a faster decrease in SSEP and a faster recovery than propofol (P<0.05). On emergence, patients who received sevoflurane tended to have shorter recovery times to eye opening (mean 5.1 vs 20.6 min, P=0.09) and toe movement (mean 7.9 vs 15.7 min, P=0.22). Those who had received sevoflurane were significantly more lucid and cooperative in recovery. Sevoflurane produces a faster decrease and recovery of SSEP amplitude as well as a better conscious state on emergence than propofol.

Stress hormone responses to major intra-abdominal surgery during and immediately after sevoflurane-nitrous oxide anaesthesia in elderly patients

We studied the responses of plasma epinephrine, norepinephrine, adrenocorticotropic hormone (ACTH), cortisol, and antidiuretic hormone (ADH) during and immediately after sevoflurane-nitrous oxide anaesthesia supplemented with vecuronium in seven elderly patients (mean 76.6 +/- 1.7 SEM) who underwent major intra-abdominal surgery. The plasma concentrations of norepinephrine, ACTH, cortisol, and ADH increased in response to surgical procedures (P < 0.05). The plasma concentration of ADH increased to a peak concentration of 189.1 +/- 20.7 pg.ml-1 30 min after skin incision (P < 0.05). The plasma concentrations of epinephrine, norepinephrine, ACTH, and cortisol increased to peak concentrations of 408.6 +/- 135.5 pg.ml-1, 635.7 +/- 167.8 pg.ml-1, 222.6 +/- 48.0 pg.ml-1, and 113.6 +/- 67.5 micrograms.dl-1, respectively immediately after tracheal extubation (P < 0.05). We conclude that, in the elderly patients, the responses of stress hormones to major intra-abdominal surgery were preserved during sevoflurane-nitrous oxide anaesthesia sufficient to prevent increases in arterial pressure and heart rate. The strongest responses of epinephrine, norepinephrine, ACTH, and cortisol were elicited immediately after tracheal extubation.