Effect of xenon on central nervous system electrical activity during sevoflurane anaesthesia in cats: comparison with nitrous oxide

We have compared the effects of xenon and nitrous oxide on central nervous system (CNS) electrical activity during sevoflurane anaesthesia in cats by recording the electroencephalogram (EEG), multi-unit activity of the midbrain reticular formation (R-MUA) and somatosensory evoked potentials (SEP). Basal anaesthesia with 2% and 5% sevoflurane was used. With 2% sevoflurane, 70% xenon initially produced rhythmic slow waves which were followed by bursts of high-amplitude sharp waves interrupted by low amplitude slow waves on the EEG. Xenon induced an initial increase, followed by a decrease in R-MUA. Nitrous oxide 70% decreased the amplitude of the EEG activity which was associated with an increase in R-MUA. Xenon suppressed the amplitude of both the initial positive and negative deflections of the SEP to a greater extent than nitrous oxide. With 5% sevoflurane anaesthesia, both anaesthetics increased the frequency of spikes on the EEG and facilitated R-MUA. These findings indicate that xenon has a stimulatory action on CNS background activity and a suppressive action on CNS reactive capability which is more potent than that of nitrous oxide.     

Radip induction of ether anaesthesia and controlled maintenacne by a combination of intravenous and inhalation administration without the risk of explosion

The induction and maintenance of anaesthesia with ether using a combined intravenous infusion and a constant low inspired concentration are discribed. Predictions from a mathematical model were checked against animal experiments. Anaesthesia occurred within 5 min. The mehtod obviates the need for explosive mixtures.     

Recovery from sevoflurane anesthesia: a comparison to isoflurane and propofol anesthesia

BACKGROUND: Sevoflurane has a lower blood:gas partition coefficient than isoflurane, which may cause a more rapid recovery from anesthesia; it also might cause faster emergence times than for propofol-based anesthesia. We evaluated a database that included recovery endpoints from controlled, randomized, prospective studies sponsored by Abbott Laboratories that compared sevoflurane to isoflurane or propofol when extubation was planned immediately after completion of elective surgery in adult patients. METHODS: Sevoflurane was compared to isoflurane in eight studies (N=2,008) and to propofol in three studies (N=436). Analysis of variance was applied using least squares method mean values to calculate the pooled mean difference in recovery endpoints between primary anesthetics. The effects of patient age and case duration also were determined. RESULTS: Sevoflurane resulted in statistically significant shorter times to emergence (-3.3 min), response to command (-3.1 min), orientation (-4.0 min) and first analgesic (-8.9 min) but not time to eligibility for discharge (-1.7 min) compared to isoflurane (mean difference). Times to recovery endpoints increased with increasing case duration with isoflurane but not with sevoflurane (patients receiving isoflurane took 4-5 min more to emerge and respond to commands and 8.6 min more to achieve orientation during cases longer than 3 hr in duration than those receiving sevoflurane). Patients older than 65 yr had longer times to orientation, but within any age group, orientation was always faster after sevoflurane. There were no differences in recovery times between sevoflurane and propofol. CONCLUSIONS: Recovery from sevoflurane was 3-4 min faster than with isoflurane in all age groups, and the difference was magnified in longer-duration surgical cases (> 3 hr).     

A comparison of the effects of propofol and sevoflurane on the systemic toxicity of intravenous bupivacaine in rats

We compared the effects of propofol and sevoflurane on bupivacaine-induced central nervous system and cardiovascular toxicity in rats. Thirty-four male Sprague-Dawley rats were anesthetized with 70% N2O/30% O2 plus the 50% effective dose (ED50) of propofol (propofol group, n = 12); 70% N2O/30% O2 plus ED50 of sevoflurane (sevoflurane group, n = 11); or 70% N2O/30% O2 (control group, n = 11). Bupivacaine was infused at a constant rate of 2 mg x kg(-1) x min(-1) while electrocardiogram, electroencephalogram, and invasive arterial pressure were continuously monitored. The cumulative doses of bupivacaine that induced dysrhythmias, seizures, and 50% reduction of heart rate were larger in the propofol and sevoflurane groups than in the control group. The cumulative dose of bupivacaine that induced a 50% reduction in the mean arterial blood pressure was larger in the propofol group than in the sevoflurane and control groups. The margin of safety, assessed by the time between the onset of dysrhythmias and 50% reduction of mean arterial blood pressure, was wider in the propofol group than in the sevoflurane group. We conclude that propofol and sevoflurane attenuate bupivacaine-induced dysrhythmias and seizures and that propofol has a wider margin of safety than sevoflurane. IMPLICATIONS: In anesthetized patients, dysrhythmias may be the only warning sign of intravascular injection of bupivacaine. Because propofol has a wider margin of safety than sevoflurane, life-threatening cardiovascular depression may be prevented by stopping the injection of bupivacaine at the onset of dysrhythmias during propofol anesthesia.     

Rapid inhalation induction in children: 8% sevoflurane compared with 5% halothane

BACKGROUND: Ultrasonography (US) by acknowledged experts enhances the diagnostic performance and reduces the rate of negative laparotomies in patients with suspected acute appendicitis (AA). METHODS: The diagnostic accuracy and clinical impact of routine US performed by surgical residents was prospectively studied in 504 unselected patients admitted for AA. Clinical and US findings were correlated with laparotomy findings and pathological outcome in 135 patients (113 cases with proven AA, prevalence 22.4%) and clinical as well as follow-up data were compared in the remainder. RESULTS: The overall accuracy, sensitivity, and specificity of the clinical diagnosis of AA were 84.9%, 51.3%, and 94.6% and those of US were 93. 6%, 83.1%, and 96.6%. Joint evaluation of the results from clinical evaluation and US further improved diagnostic performance (accuracy 93.4%, sensitivity 84.1%, specificity 96.2) and significantly reduced the rate of diagnostic errors to 3.4% (p < 0.001) and unnecessary laparotomies to 9.6% (p < 0.01) in patients with suspected AA. CONCLUSIONS: Ultrasonographic evaluation of the patient with suspected AA is considered to be of value in surgical practice.     

Total intravenous anaesthesia with propofol or inhalational anaesthesia with isoflurane for major abdominal surgery. Recovery characteristics and postoperative oxygenation--an international multicentre study

Two hundred and ten adult patients undergoing open cholecystectomy, vagotomy or gastrectomy were included in a randomised multicentre study to compare postoperative nausea and vomiting, oxygen saturations for the first three postoperative nights, time to return of gastrointestinal function, mobilisation, and discharge from the hospital following induction and maintenance of anaesthesia with propofol and alfentanil or with thiopentone, nitrous oxide, isoflurane and alfentanil. Recovery from anaesthesia was significantly faster in the propofol group (mean (SD) times to eye opening and giving correct date of birth of 14.0 (SD 13.8) and 25.5 (SD 29.5) minutes, and 18.5 (SD 14.8) and 35.5 (SD 37.2) minutes in the propofol and isoflurane groups respectively). There was significantly less nausea in the propofol group (15.4%) than in the isoflurane group (33.7%) in the first two postoperative hours (p < 0.003) but not thereafter. There were no significant differences between the groups in any other recovery characteristics. The incidence of hypoxaemia (arterial oxygen saturation less than 93%) was close to 70% in both groups for the first three postoperative nights, indicating the need for oxygen therapy after major abdominal surgery.     

Positive pressure ventilation with the laryngeal mask airway in non-paralysed patients: comparison of sevoflurane and propofol maintenance techniques

Photofrin photodynamic therapy (PDT) has recently received FDA approval for the palliative treatment of totally and partially obstructing esophageal malignancies. However, there is a need for new PDT photosensitizers because Photofrin has a number of undesirable features. The purpose of this study was to evaluate the efficacy of four amine-bearing silicon phthalocyanines--Pc4, Pc10, Pc12 and Pc18--as potential PDT photosensitizers. Equimolar concentrations of these Pc were found to be highly effective at causing the regression of RIF-1 tumors transplanted to C3H/HeN mice. The amount of Pc4 necessary to cause an equivalent amount of tumor regression in this model system was substantially less than the amount of Photofrin. The cutaneous phototoxicity of the silicon Pc photosensitizer was assessed by the utilization of the murine ear-swelling model. When C3H mice were exposed to 167 J/cm2 of polychromatic visible light from a UVB-filtered solar simulator, which emitted UV radiation and visible light above 320 nm, the Pc produced little, if any, cutaneous photosensitivity. These results indicate that Pc4, Pc10, Pc12 and Pc18 are at least as effective as Photofrin in PDT protocols, while at the same time addressing many of the drawbacks of Photofrin.     

Assessment of intubating conditions in adults after induction with propofol and varying doses of remifentanil

We have assessed intubating conditions in three groups of 60 ASA I or II patients after induction of anaesthesia with propofol 2 mg kg-1 and remifentanil 0.5, 1.0 or 2.0 micrograms kg-1. Tracheal intubation was graded according to ease of laryn-goscopy, position of the vocal cords, coughing, jaw relaxation and movement of the limbs. Intubation was successful in 80%, 90% and 100% of patients after remifentanil 0.5, 1.0 or 2.0 micrograms kg-1, respectively. Overall intubating conditions were regarded as acceptable in 20%, 50% and 80% of patients, respectively. All three groups had a decrease in arterial pressure after induction but there was no difference between groups. The decrease in arterial pressure was not regarded as clinically significant. Intubating conditions were best after induction with remifentanil 2 micrograms kg and propofol 2 mg kg-1.     

A comparison of the induction characteristics of sevoflurane and halothane in children

The induction characteristics of sevoflurane and halothane were compared in 81 children aged 6 months to 6 years. The mean time taken to achieve loss of eyelash reflex was significantly shorter with sevoflurane than with halothane (sevoflurane, mean time (SD) 1 min 41 s (35 s), halothane, mean time (SD) 2 min 17 s (43 s), t = 4.11, p = < 0.01). The mean time taken to complete induction (to achieve steady spontaneous ventilation and small pupils with central gaze) was also shorter in children induced with sevoflurane (sevoflurane, mean time (SD) 3 min 58 s (1 min 8 s), halothane, mean time (SD) 4 min 50 s, (1 min 27 s), t = 2.29, p = 0.027). Effects on heart rate, blood pressure and oxygen saturation during induction were similar for both agents. There were no major complications during induction with either halothane or sevoflurane.     

Effect of anaesthesia with nitrous oxide in oxygen and fentanyl on renal function in the artificially ventilated dog

The effect on renal function of a large dose (25 micrograms kg-1) of fentanyl was investigated in 10 labrador dogs. The animals were anaesthetized with nitrous oxide in oxygen and a small supplement of fentanyl 0.4 microgram min-1 throughout the experiment, and muscular relaxation was provided by alcuronium, pulmonary ventilation being controlled. In the initial phase of each experiment, estimated renal plasma flow, glomerular filtration rate, urine volume, mean arterial pressure and renal vascular resistance were measured at 30-min intervals, three sets of samples being taken. Then the large dose of fentanyl was given over a 10-min period and the measurements were repeated at 30-min intervals for 90 min. Changes in renal function lasted for about 90 min; there was a significant decrease in estimated renal plasma flow (P less than 0.01), glomerular filtration rate (P less than 0.001), urine volume (P less than 0.01) and mean arterial pressure (P less than 0.001) together with an increase in renal vascular resistance (0.05 greater than P greater than 0.02). These changes were accompanied by bradycardia, but were still present when atropine was given.     

A comparison of 2% and 1% formulations of propofol for the induction and maintenance of anaesthesia in surgery of moderate duration

This study, conducted in 110 patients undergoing surgery of moderate duration, compared the pharmacodynamic equivalence, efficacy and safety of 1% and 2% formulations of propofol. Anaesthesia was induced with propofol 2 mg.kg-1 given over 40 s and supplementary bolus injections of propofol were given if needed. There were no significant differences between the groups in mean induction times, total induction doses of propofol, frequency and mean duration of apnoea, fentanyl requirements or mean recovery times (times to eyes opening and to orientation). Isolated statistically significant group differences in systolic and diastolic blood pressures and heart rates during induction were not considered clinically significant. Discomfort on injection occurred in 40% and 52% of those given 1% (n = 55) and 2% (n = 55) propofol, respectively; there was no statistically significant group difference in severity. No major adverse effects were reported. This study showed that the 2% formulation has a similar safety and pharmacodynamic profile to the 1% formulation.     

Economic considerations of the use of new anesthetics: a comparison of propofol, sevoflurane, desflurane, and isoflurane

Cost control in anesthesia is no longer an option; it is a necessity. New anesthetics have entered the market, but economic differences in comparison to standard anesthetic regimens are not exactly known. Eighty patients undergoing either subtotal thyroidectomy or laparoscopic cholecystectomy were randomly divided into four groups, with 20 patients in each group. Group 1 received propofol 1%/sufentanil, Group 2 received desflurane/sufentanil, Group 3 received sevoflurane/sufentanil, and Group 4 received isoflurane/sufentanil (standard anesthesia) for anesthesia. A fresh gas flow of 1.5-2 L/min and 60% N2O in oxygen was used for maintenance of anesthesia, and atracurium was given for muscle relaxation. Concentrations of volatile anesthetics, propofol, and sufentanil were varied according to the patient's perceived need. Isoflurane, desflurane, and sevoflurane consumption was measured by weighing the vaporizers with a precision weighing machine. Biometric data, time of surgery, and time of anesthesia were similar in the four groups. Times for extubation and stay in the postanesthesia care unit (PACU) were significantly longer in the isoflurane group. Use of sufentanil and atracurium did not differ among the groups. Propofol patients required fewer additional drugs in the PACU (e.g., antiemetics), and thus showed the lowest additional costs in the PACU. Total (intra- and postoperative) costs were significantly higher in the propofol group ($30.73 per patient; $0.24 per minute of anesthesia). The costs among the inhalational groups did not differ significantly (approximately $0.15 per minute of anesthesia). We conclude that in today's climate of cost savings, a comprehensive pharmacoeconomic approach is needed. Although propofol-based anesthesia was associated with the highest cost, it is doubtful whether the choice of anesthetic regimen will lower the costs of an anesthesia department. IMPLICATIONS: Cost analysis of anesthetic techniques is necessary in today's economic climate. Consumption of the new inhaled drugs sevoflurane and desflurane was measured in comparison to a standard anesthetic regimen using isoflurane and an IV technique using propofol. Propofol-based anesthesia was associated with the highest costs, whereas the costs of the new inhaled anesthetics sevoflurane and desflurane did not differ from those of a standard, isoflurane-based anesthesia regimen.     

Continuous thoracic epidural blockade in combination with general anesthesia with nitrous oxide, oxygen, and sevoflurane in two patients with myasthenia gravis

Continuous thoracic epidural anesthesia (T4/5) using 4-5 ml.h-1 of 1.5% lidocaine with 1:200,000 epinephrine and inhaled anesthesia using nitrous oxide, oxygen and sevoflurane were performed in two patients, (40 and 22 yr-old females) with myasthenia gravis. This combined anesthetic technique provided muscle relaxation for endotracheal intubation and optimal operating conditions, including muscle relaxation and stability of hemodynamics during transsternal thymectomy. Further, continuous epidural anesthesia using 4 ml.h-1 of 0.25% bupivacaine provided postoperative pain relief without other analgesics and stable postoperative respiratory conditions. In conclusion, we confirm the benefits of this technique which provides not only safe and stable conditions during the surgery, but also an improved comfort for patients in the postoperative period following transsternal thymectomy for myasthenia gravis.     

Administration of a crystalloid fluid preload does not prevent the decrease in arterial blood pressure after induction of anaesthesia with propofol and fentanyl

Five oligosaccharide alpha1-phosphates and one sulfated glycopeptide have been isolated from the hemofiltrate of one patient with end-stage renal disease. Isolation of these compounds has been achieved using reverse osmosis, ion-exchange and size-exclusion chromatography and high performance liquid chromatography. The structures were predominantly elucidated by one- and two-dimensional 1H and 31P NMR spectroscopy. The chemical structures were determined to be: 1 NeuAc alpha2-3Gal alpha1-OPO3H2; 2 NeuAc alpha2-6Galbeta1-4GlcNAc alpha1-OPO3H2; 3 NeuAc alpha2-3Galbeta1-3GalNAc alpha1-OPO3H2; 4 NeuAc alpha2-3Galbeta1-3[NeuAc alpha2-6]GalNAc alpha1-OPO3H2 (proposed structure); 5 Fuc alpha1-2Galbeta1-4[Fuc alpha1-3]GlcNAc alpha1-OPO3H2; 6 HOSO3-4Fuc alpha1-6GlcNAcbeta1-NAsn. While 2 and 3 have been previously characterized as compounds of urine and hemofiltrate, the oligosaccharide alpha1-phosphates 1, 4, and 5 could be isolated--to our knowledge--for the first time from biological material. Compound 6 is the first glycopeptide reported to contain a 4-sulfated fucose residue.     

Induction of anesthesia and tracheal intubation with sevoflurane in adults

BACKGROUND: The speed, quality, and cost of mask induction of anesthesia and laryngeal mask airway insertion or tracheal intubation were studied in young non-premedicated volunteers given high inspired concentrations of sevoflurane (6 to 7%). METHODS: Twenty healthy persons who were 19 to 32 years old participated three times, received 6 l/min fresh gas flow, and were randomized to receive 6 to 7% sevoflurane in 66% nitrous oxide/28% oxygen by face mask until tracheal intubation (treatment 1) or until laryngeal mask airway insertion (treatment 3), or 6 to 7% sevoflurane without nitrous oxide to tracheal intubation (treatment 2). Participants exhaled to residual volume and took three vital capacity breaths of the gas mixture; thereafter ventilation was manually assisted. The time of exposure to the inhaled gas was varied for consecutive participants. It was either increased or decreased by 30-sec increments based on the failure or success of the preceding volunteer's response to laryngoscopy and intubation after a preselected exposure time. Failure was defined as poor jaw relaxation, coughing or bucking, or inadequate vocal cord relaxation. RESULTS: Loss of the lid-lash reflex in unpremedicated young volunteers was achieved in 1 min and did not differ among groups. Average time (and 95% confidence interval) for acceptable conditions for LMA insertion was achieved in 1.7 (0.7 to 2.7) min, and all participants had an immediate return of spontaneous ventilation. The time for acceptable tracheal intubating conditions after manual hyperventilation by mask was 4.7 (3.7 to 5.7) min and 6.4 (5.1 to 7.7) min in treatments 1 and 2, respectively. There were no cases of increased secretions or laryngospasm. The incidence of breath holding and expiratory stridor ("crowing") was 7.5% and 25%, respectively, during treatment 1 and 15% and 40%, respectively, during treatment 2. CONCLUSIONS: The induction of anesthesia to loss of lid reflex in young non-premedicated adults approaches the speed of intravenous induction techniques. No untoward airway responses were noted during mask induction of anesthesia with a three-breath technique. In response to intubation, no adverse airway responses, including jaw tightness, laryngospasm, and excessive coughing or bucking, occurred in participants whose duration of mask administration of sevoflurane met the appropriate times (as determined in this study).     

A comparison between somatic symptoms with and without clear organic cause: results of an international study

BACKGROUND: The aim of this study was to determine differences between patients attending primary-care clinics with somatic symptoms for which no organic cause can be found, and those with a clear organic basis for their complaints. METHODS: Physical and psychiatric morbidity was measured in 5447 subjects presenting for primary care in 14 countries. Subjects were recruited using a two-stage design from 26,969 consecutive attenders and 25,916 (96.5%) subjects were successfully screened using the General Health Questionnaire (GHQ-12). The response rate for the second-stage assessment was 63% and consisted of the Composite International Diagnostic Instrument adapted for use in primary care (CIDI-PHC), the 28-item GHQ, the Groningen Social Disability Schedule (GSDS) and GP ratings to assess physical psychiatric and social status. Patients who reached the threshold for the number of somatic symptoms (five or more symptoms) were then divided into two groups on the basis of whether their somatic symptoms were medically explained or not. RESULTS: The presence of somatic symptoms, irrespective of aetiology, was associated with increased social and psychiatric morbidity. In the case of non-medically explained symptoms there was a clear linear relationship while with medically explained symptoms psychiatric morbidity rose sharply in the presence of more than 11 symptoms. Patients who had five or more non-medically explained symptoms were significantly younger, had greater psychiatric morbidity, were at greater risk of harmful use of alcohol and reported greater social disability than those with a medical explanation for their somatic symptoms. Patients who had an excess of somatic symptoms in both categories had especially high rates of social and psychiatric morbidity. CONCLUSIONS: These results show a strong association between somatic symptoms irrespective of aetiology and psychiatric morbidity across disparate cultures.     

Effects of mouth cleansing on the levels of exhaled nitrous oxide in young and older adults

Nitrous oxide (N2O) is produced by denitrification, i.e. by microbial reduction of nitrate (NO3-). Our previous studies have established an analytical method for demonstrating the existence of N2O in exhaled air, and we showed that levels of N2O in exhaled air increase with age after puberty. However, the source of this change and its biological significance are still unclear. The purpose of this study was to examine whether the oral microorganisms are the main source of N2O. We measured exhaled N2O in 35 young adults (aged 19-29 years) and 34 older adults (aged 61-79 years) before and after mouth cleansing. N2O was measured using an infrared-photoacoustic analyzer equipped with an optical filter (UA0985, 2215 cm-1). Participants were classified as producers and non-producers according to the levels of exhaled N2O relative to the level in the atmosphere. N2O production differed significantly between the young adult producers and the older adult producers. Mouth cleansing resulted in an immediate reduction in exhaled N2O in both groups. We only found seven (20.0%) producers in the young, and 32 (94.1%) producers in the older after mouth washing. The differences before and after mouth cleansing were significant in both groups (P < 0.01 in the young and P < 0.05 in the older). The oral cavity is a major source of N2O. However, since approximately half-levels of N2O were still observed in exhaled air after mouth, cleansing, there may exist another N2O source in the human body.