A-line autoregression index monitoring to titrate inhalational anaesthesia: effects on sevoflurane consumption, emergence time and memory.

BACKGROUND: A-line autoregression index (AAI) is a parameter derived from auditory evoked potentials proposed as depth of anaesthesia monitor. We evaluated the effects of AAI guidance on sevoflurane consumption, emergence time, explicit and implicit memory. METHODS: One hundred patients submitted to major abdominal surgery were randomized into two groups. In group A (n = 50), sevoflurane was titrated according to AAI (target = 20 +/- 5), in group B (n = 50) according to clinical signs. Anaesthesia was induced with fentanyl, propofol, atracurium and maintained with sevoflurane. The mean value of sevoflurane consumption (g/min) and emergence time has been assessed in both groups. After emergence, A test of explicit memory was administered. We assessed implicit memory using a category generation test. RESULTS: In group A, mean sevoflurane consumption was significantly (P = 0.0001) reduced by 20.4% and mean emergence time was significantly (P = 0.00012) shorter by 2 min with respect to group B. No patients experienced explicit memory while the difference between the two groups in implicit memory results was not significant (P = 0107). CONCLUSIONS: AAI titration of anaesthesia allows a significant reduction in sevoflurane consumption and emergence time without significant effects on the incidence of explicit and implicit memory. Nevertheless the relationship between AAI and memory requires studies in larger groups of patients.

Ethnic differences in propofol and fentanyl response: a comparison among Caucasians, Kenyan Africans and Brazilians.

BACKGROUND AND OBJECTIVE: Differences in sensitivity to anaesthetic drugs may exist among human races. Allelic variants for drug metabolizing isoenzymes and other pharmacokinetic/pharmacodynamic differences may account for a variable response to anaesthetic drugs. This study was designed to investigate comparatively the anaesthetic requirements and the recovery trends of three different ethnic groups: Caucasians, African blacks and Brazilians. METHODS: The anaesthetic depth and recovery of groups of 45 patients undergoing total intravenous anaesthesia with propofol and fentanyl were compared. The bispectral index and clinical parameters were used to assess the depth of anaesthesia. The bispectral index, the response to verbal stimuli and the eye opening time were used to assess recovery. RESULTS: After stopping propofol, the bispectral index values of Caucasians returned to the baseline in about 10.8 +/- 4 min, that of Kenyan African blacks in 18 +/- 7 min and that of Brazilians in a highly variable time ranging from 5 to 25 min, (14.9 +/- 9.9). The time from discontinuation of propofol and fentanyl infusion to eye opening was 18.8 +/- 7.1 min in African blacks (P < 0.01) and 13.5 +/- 8.8 min in Brazilians (P > 0.05) vs. 11.6 +/- 4.5 min in Caucasians. Time to respond to verbal commands was 16.8 +/- 8 min in African blacks (P < 0.01) and 12.8 +/- 8.1 min in Brazilians (P > 0.05) vs. 9.9 +/- 4.5 min in Caucasians. CONCLUSIONS: The recovery of Kenyan African blacks from anaesthesia with propofol and fentanyl is much slower, in comparison with Caucasians. The recovery time of Brazilians is much more variable, in comparison with Caucasians.

Comparison of propofol consumption and recovery time in Caucasians from Italy, with Chinese, Malays and Indians from Malaysia.

Differences in sensitivity to anaesthetic drugs may exist among different ethnic groups. Allelic variants for drug metabolizing isoenzymes and pharmacokinetic differences may account for a variable response to some anaesthetic drugs. This study was designed to compare propofol consumption and recovery characteristics in four ethnic groups: Chinese, Malays, and Indians in Malaysia and Caucasians in Italy. Patients undergoing total intravenous anaesthesia with propofol and fentanyl were evaluated for propofol consumption and recovery time. The Bispectral Index (BIS) was used to maintain the same anaesthesia depth in all patients. The BIS value, the response to verbal stimuli and eye-opening time were used to assess recovery. After propofol discontinuation the BIS values returned to baseline in 11+/-4.2 min for Caucasians, in 12.5+/-5.1 min for Chinese, 15.9+/-6.3 min for Malays and 22.1+/-8.1 for Indians. Time to eye-opening was 11.63+/-4.2 min in Caucasians, 13.23+/-4.9 min in Chinese, 16.97+/-5.2 min in Malays and 22.3+/-6.6 min in Indians. The propofol consumption was significantly lower in Indians compared to the other three groups (P<0.01). The recovery of Indians was much slower compared to Chinese, Malays and Caucasians. The recovery time of Malays is significantly slower compared to Chinese and Caucasians. Differences in propofol consumption and recovery time were not significant between Chinese and Caucasians, but the ratio recovery time/propofol consumption was significantly lower in Caucasians compared to all the other groups.

EEG signal processing in anaesthesia. Use of a neural network technique for monitoring depth of anaesthesia.

BACKGROUND: The Bispectral Index (BIS) is a proprietary index of anaesthesia depth, which is correlated with the level of consciousness and probability of intraoperative recall. The present study investigates the use of a neural network technique to obtain a non-proprietary index of the depth of anaesthesia from the processed EEG data. METHODS: Two hundred patients, who underwent general abdominal surgery, were recruited for our trial. For anaesthesia we used a total i.v. technique, tracheal intubation, and artificial ventilation. Fourteen EEG variables, including the BIS, were extracted from the EEG, monitored with an EEG computerized monitor, and then stored on a computer. Data from 150 patients were used to train the neural network. All the variables, excluding the BIS, were used as input data in the neural network. The output targets of the network were provided by anaesthesia scores ranging from 10 to 100 assigned by the anaesthesiologist according to the observer's assessment of alertness and sedation (OAA/S) and other clinical means of assessing depth of anaesthesia. Data from the other 50 patients were used to test the model and for statistical analysis. RESULTS: The artificial neural network was successfully trained to predict an anaesthesia depth index, the NED (neural network evaluated depth), ranging from 0 to 100. The correlation coefficient between the NED and the BIS over the test set was 0.94 (P<0.0001). CONCLUSION: We have developed a neural network model, which evaluates 13 processed EEG parameters to produce an index of anaesthesia depth, which correlates very well with the BIS during total i.v. anaesthesia with propofol.

The recovery of Senegalese African blacks from intravenous anesthesia with propofol and remifentanil is slower than that of Caucasians.

UNLABELLED: Differences in sensitivity to anesthetic drugs have already been described among races. This study was designed to comparatively investigate the anesthetic requirements of two different ethnic groups: Caucasians and African blacks. Forty-five Caucasians from Italy and 45 African blacks from Senegal, who underwent general IV anesthesia with propofol and remifentanil, were comparatively evaluated for anesthetic depth and time lapsed before recovery. We used an electroencephalographic-derived index of depth of anesthesia, the bispectral index (BIS), and evaluation of clinical variables to assess the depth of anesthesia and the recovery trend. Mean BIS values from Caucasians after propofol discontinuation returned to baseline (92-100) in approximately 8 min, whereas in African blacks BIS values remained <80 for some 30 min. Time to eye opening was 10.6 +/- 4.8 min in Caucasians versus 16.9 +/- 8.8 min in African blacks (P < 0.001). Time to respond to loud verbal commands was 14.8 +/- 9.1 min in African blacks versus 9.1 +/- 4.2 min in Caucasians (P < 0.01). During anesthetic induction, the mean arterial pressure decreased by 20% in Caucasians and by only 10% in African blacks. We conclude that the recovery from general anesthesia with propofol was slower in African blacks compared with Caucasian patients. IMPLICATIONS: This study demonstrates statistically significant differences between Caucasians and African blacks in the arousal time from IV anesthesia with propofol and remifentanil. The authors conclude that the recovery from general anesthesia was slower in African blacks compared with Caucasian patients.

The effect of glutathione and N-acetylcysteine on lipoperoxidative damage in patients with early septic shock.

Both the hyperproduction of oxygen free radicals (OFR) and the weakening of natural scavenging mechanisms have been implicated as contributors to multiple organ failure in septic shock. This study examined whether the antioxidants glutathione (GSH) and N-acetyl-L-cysteine (NAC) play a protective role against damage by OFR in early septic shock. We randomly entered 30 patients with septic shock into one of three groups within 24 h of diagnosis. All of the patients received septic shock therapy, including parenteral nutrition, antibiotics, and volume-expanding and inotropic agents. One group (Group B) also received 70 mg/kg/d of intravenous GSH, and a second group (Group C), 70 mg/kg/d of intravenous GSH and 75 mg/kg/d of intravenous NAC. The protection against OFR damage was evaluated by measuring expired ethane, plasma malondialdehyde, erythrocyte deformability, complement activation, and clinical scores at admission and on Days 3 and 5 of treatment. A significant decrease in peroxidative indexes was observed at Day 5 in Group B as compared with both the control group and basal values. The decrease in peroxidative indexes was even more marked in Group C. Clinical scores in this group were also significantly improved. In conclusion, the administration of high doses of NAC added to GSH significantly decreased the peroxidative stress of patients with septic shock.

Protective effects of N-acetylcysteine and rutin on the lipid peroxidation of the lung epithelium during the adult respiratory distress syndrome.

This study investigates the effects of N-acetylcysteine (NAC) and rutin on the lung oxidative burden of patients with early adult respiratory distress syndrome (ARDS). The protection was evaluated by measuring expired ethane and malondialdehyde (MDA), and oxidized (GSSG) and reduced glutathione (GSH) in the epithelial lining fluid of 36 patients who developed ARDS less than 24 hours before enrollment in the study. The patients were randomly assigned to 3 groups, receiving 250 mL 5% dextrose in water (group 1), NAC 50 mg/kg body weight in 5% dextrose (group 2), and NAC 50 mg/kg + rutin 5 mg/kg in 5% dextrose (group 3). Ethane and MDA concentrations were significantly reduced in the treatment groups after day 6. GSH was 30% increased in the treatment groups. No significant variations were observed in the control group until day 9. The trial confirms that NAC and rutin are efficient in protecting the lungs of patients with ARDS.

[Usefulness of the prevention of oxygen radical damage in the critical patient using the parenteral administration of reduced glutathione in high doses]. / L'utilità della prevenzione del danno ossiradicalico nel paziente critico attraverso la somministrazione parenterale di glutatione ridotto in alte dosi.

A hyperproduction of Oxygen Free Radicals (FRO) is frequently observed during stress, anoxia, hyperbarism and may worsen the clinical conditions of intensive care patients. The hyperproduction of FRO may be reduced by antioxidants. The glutathione (GSH) is frequently associated with organic antioxidant protective systems. Forty patients receiving a continuous infusion of 70 mg/Kg/die of GSH were compared with forty patients not receiving GSH; the patients in both groups were randomized for age, sex, and pathology. Some parameters which are indirect indexes of FRO hyperproduction were chosen: ethane in the expired air, plasma malondialdehyde, fibrinopeptide A and C5 activated complement fraction, also the erythrocyte membrane deformability was investigated. The results obtained in the group receiving GSH were compared with the control group and a significative difference was found indicating a reduced FRO production. These interesting results need more trials in order to confirm a real GSH involvement in the antioxidant organic protection. In any case the supplementation with antioxidants in the therapy of intensive care patients can be regarded as an interesting means to improve their clinical conditions.

Photooxidation of epinephrine sensitized by methylene blue as an assay for the evaluation of alpha-mercaptopropionylglycine as a free radical scavenger.

Free radicals, which are instable intermediates of some biochemical reactions, are produced everywhere in the living matter. They may induce cell membrane lipid peroxidation, with non reversible letal effects. Alpha-mercaptopropionylglycine capability of scavenging free radicals has been tested. H2O2 has been used as a free radical donor under actinic light, epinephrine oxidation to adrenochrome as a revealing system and methylene blue as sensitizing agent. alpha-MPG at 6 mM concentration showed the maximal inhibition of free radical formation in our system. Higher concentrations were unable to produce further inhibition.