Anesthesia and analgesia
-
Anesthesia and analgesia · Nov 1999
Randomized Controlled Trial Comparative Study Clinical TrialLidocaine plus ropivacaine versus lidocaine plus bupivacaine for peribulbar anesthesia by single medical injection.
This study was designed to compare the effects of ropivacaine and bupivacaine, each combined with lidocaine, during peribulbar anesthesia by single medial injection for cataract surgery. One hundred patients were included and randomly divided into two groups of 50, given a mixture of 50% bupivacaine (0.5%) and 50% lidocaine (2%) or 50% ropivacaine (1%) and 50% lidocaine (2%), and 25 U hyaluronidase per mL with each combination. After the first injection, patients given ropivacaine exhibited significantly better akinesia than those given bupivacaine, and significantly fewer were reinjected (19/50 vs 31/50). Among the patients reinjected, peroperative akinesia and analgesia proved satisfactory in both groups. We observed three cases of diplopia caused by retraction of the internal rectus muscle and two cases of moderate ptosis after superonasal reinjection. Hemodynamic profiles were similar in the two groups, and no major side effects were noted during the observation. One percent ropivacaine may be a more appropriate agent than 0.5% bupivacaine for peribulbar anesthesia by single medial injection. ⋯ One percent ropivacaine may be a more appropriate agent than 0.5% bupivacaine for peribulbar anesthesia by single medial injection. Combined with lidocaine, it provides better akinesia and similar analgesia.
-
Anesthesia and analgesia · Nov 1999
The performance of electroencephalogram bispectral index and auditory evoked potential index to predict loss of consciousness during propofol infusion.
The bispectral index (BIS) of the electroencephalogram and middle latency auditory evoked potentials are likely candidates to measure the level of unconsciousness and, thus, may improve the early recovery profile. We prospectively investigated the predictive performance of both measures to distinguish between the conscious and unconscious state. Twelve patients undergoing lower limb orthopedic surgery during regional anesthesia additionally received propofol by target-controlled infusion for sedation. The electroencephalogram BIS and the auditory evoked potential index (AEPi), a mathematical derivative of the morphology of the auditory evoked potential waveform, were recorded simultaneously in all patients during repeated transitions from consciousness to unconsciousness. Logistic regression procedures, receiver operating characteristic analysis, and sensitivity and specificity were used to compare predictive ability of both indices. In the logistic regression models, both the BIS and AEPi were significant predictors of unconsciousness (P < 0.0001). The area under the receiver operating characteristic curve for discrete descending index threshold values was apparently, but not significantly (P > 0.05), larger for the AEPi (0.968) than for the BIS (0.922), indicating a trend of better discriminatory performance. We conclude that both the BIS and AEPi are reliable means for monitoring the level of unconsciousness during propofol infusion. However, AEPi proved to offer more discriminatory power in the individual patient. ⋯ Both the bispectral index of the electroencephalogram and the auditory evoked potentials index are good predictors of the level of sedation and unconsciousness during propofol infusion. However, the auditory evoked potentials index offers better discriminatory power in describing the transition from the conscious to the unconscious state in the individual patient.
-
Anesthesia and analgesia · Nov 1999
Respiratory mechanics during sevoflurane anesthesia in children with and without asthma.
We studied lung function in children with and without asthma receiving anesthesia with sevoflurane. Fifty-two children had anesthesia induced with sevoflurane (up to 8%) in a mixture of 50% nitrous oxide in oxygen and then maintained at 3% with children breathing spontaneously via face mask and Jackson-Rees modification of the T-piece. Airway opening pressure and flow were then measured. After insertion of an oral endotracheal tube under 5% sevoflurane, measurements were repeated at 3%, as well as after increasing to 4.2%. Respiratory system resistance (Rrs) and compliance during expiration were calculated using multilinear regression analysis of airway opening pressure and flow, assuming a single-compartment model. Data from 44 children were analyzed (22 asthmatics and 22 normal children). The two groups were comparable with respect to age, weight, ventilation variables, and baseline respiratory mechanics. Intubation was associated with a significant increase in Rrs in asthmatics (17% +/- 49%), whereas in normal children, Rrs slightly decreased (-4% +/- 39%). At 4.2%, Rrs decreased slightly in both groups with almost no change in compliance system resistance. We concluded that in children with mild to moderate asthma, endotracheal intubation during sevoflurane anesthesia was associated with increase in Rrs that was not seen in nonasthmatic children. ⋯ Tracheal intubation using sevoflurane as sole anesthetic is possible and its frequency is increasing. When comparing children with and without asthma, tracheal intubation under sevoflurane was associated with an increase in respiratory system resistance in asthmatic children. However, no apparent clinical adverse event was observed.
-
Anesthesia and analgesia · Nov 1999
Depression of I waves in corticospinal volleys by sevoflurane, thiopental, and propofol.
Isoflurane depresses the number and amplitude of I waves of the motor-evoked potential produced by transcranial electrical stimulation of the motor cortex and thus affects components of the corticospinal volley that are believed to arise from Laminae III and V. This study extends these observations to sevoflurane (9 patients) and the two IV anesthetics, thiopental and propofol (10 sets of observations in 10 and 6 patients, respectively). The patients' ages ranged from 10 to 17 yr. Sevoflurane was administered to achieve end-tidal concentrations of 0.5%-3%. Thiopental and propofol were given as boluses of 5 mg/kg and 2 mg/kg, respectively, to patients anesthetized with nitrous oxide, fentanyl, midazolam, and a muscle relaxant. Sevoflurane had a depressant effect on I waves essentially similar to that of isoflurane; thiopental depressed I wave activity by an average of 33% (95% confidence interval: 20%-46%, P < 0.001) and propofol by 39% (95% confidence interval: 20%-40%, P < 0.001). With all three anesthetics, later I waves showed the most amplitude depression. The three anesthetics had qualitatively similar effects on I waves. ⋯ Sevoflurane, thiopental, and propofol depress components of the corticospinal volley produced by transcranial electrical stimulation of motor cortex in a manner qualitatively similar to isoflurane. The findings indicate that anesthetics with primarily hypnotic actions suppress interneuronal activity in cerebral cortex.