Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialNarcotrend or bispectral index monitoring during desflurane-remifentanil anesthesia: a comparison with a standard practice protocol.
Bispectral Index (BIS) (Aspect Medical Systems, Newton, MA) and Narcotrend (MonitorTechnik, Bad Bramstedt, Germany) are monitoring devices that were, as others, designed to assess the depth of anesthesia. Meanwhile, a number of studies indicate that with total IV anesthesia, BIS and Narcotrend have comparable effects on drug consumption and recovery times whereas comparative clinical data for volatile anesthetics are still missing. Therefore, we designed the present prospective, randomized, and double-blinded study to compare the effects of BIS and Narcotrend monitoring during desflurane-remifentanil anesthesia and versus a standard anesthetic practice protocol. One-hundred-twenty adult patients scheduled for minor orthopedic surgery were randomized to receive a desflurane-remifentanil anesthetic controlled either by Narcotrend or by BIS or solely by clinical variables. Anesthesia was induced with 0.4 microg x kg(-1) x min(-1) remifentanil and 2 mg/kg propofol. After tracheal intubation, remifentanil was infused at a constant rate of 0.2 microg x kg(-1) x min(-1) whereas desflurane in 1.5 L/min O(2)/air was adjusted according to clinical variables or the following target values: during maintenance of anesthesia to a value of "D(0)" (Narcotrend) or "50" (BIS), 15 min before the end of surgery to "C(1)" (Narcotrend) or "60" (BIS), whereas in the standard protocol group, desflurane was controlled according to clinical variables, e.g., heart rate, arterial blood pressure, movements. Recovery times and desflurane consumption were recorded by a blinded investigator. The desflurane vaporizer was weighed before and after anesthesia and consumption per minute was calculated. Data are mean +/- sd. The groups were comparable for demographic data, duration of anesthesia, and mean remifentanil dosages. Compared with standard practice, patients with Narcotrend or BIS monitoring needed significantly less desflurane (standard practice 443 +/- 71 mg/min, Narcotrend 374 +/- 124 mg/min, BIS monitoring 416 +/- 99 mg/min desflurane [both P < 0.05]). However, recovery times were not significantly different between the groups, e.g., opening of eyes 4.7 +/- 2.2 versus 3.7 +/- 2.0 versus 4.2 +/- 2.1 min. During desflurane-remifentanil anesthesia, Narcotrend and BIS monitoring seem to be equally effective compared with standard anesthetic practice: BIS and Narcotrend allow for a small reduction of desflurane consumption whereas recovery times are only slightly reduced. ⋯ Monitoring the electroencephalogram with Narcotrend or Bispectral Index during desflurane-remifentanil anesthesia only slightly reduces recovery times when compared with a standard practice protocol.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialRemifentanil as a single drug for extracorporeal shock wave lithotripsy: a comparison of infusion doses in terms of analgesic potency and side effects.
This randomized, double-blind study was designed to evaluate analgesic effectiveness and side effects of two remifentanil infusion rates in patients undergoing extracorporeal shock wave lithotripsy (ESWL) for renal stones. We included 200 patients who were administered remifentanil either 0.05 microg x kg(-1) x min(-1) (n = 100) or 0.1 microg x kg(-1) x min(-1) (n = 100) plus demand bolus of 10 microg of remifentanil via a patient-controlled analgesia (PCA) device. No other sedating drugs were given. The frequencies of PCA demands and deliveries were recorded. Arterial blood pressure, oxygen saturation, and respiratory rate were recorded throughout the procedure; postoperative nausea and vomiting (PONV), dizziness, itching, agitation, and respiratory depression were measured posttreatment. Visual analog scale (VAS) scores were taken preoperatively, directly postoperatively, and 30 min after finishing the procedure. There were no statistically significant differences in the frequency of PCA demands and delivered boluses or among perioperative VAS scores. The extent of PONV and frequency of dizziness and itching immediately after and dizziness 30 min after the end of treatment were significantly reduced in the smaller dose group. We conclude that a remifentanil regimen of 0.05 microg x kg(-1) x min(-1) plus 10 microg demands is superior to 0.1 microg x kg(-1) x min(-1) plus demands, as there was no difference in the VAS scores recorded between groups and it has a less frequent incidence of side effects in patients receiving ESWL. ⋯ Remifentanil is an appropriate analgesic choice for patients undergoing extracorporeal shock wave lithotripsy (ESWL) therapy, as it has both fast onset and offset times. We studied remifentanil as a sole drug for ESWL and have shown that an infusion rate of 0.05 microg x kg-1 x min-1 plus patient-controlled analgesia demands of 10 microg provides adequate analgesia and has significantly less side effects than a dose of 0.1 microg x kg-1 x min-1 plus 10 microg demands.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Comparative Study Clinical TrialThe influence of gender on loss of consciousness with sevoflurane or propofol.
Studies have suggested that hypnotic requirements for general anesthesia and emergence may be influenced by gender. In this study, we examined the effect of gender on the hypnotic requirement for loss of consciousness (LOC) using either a volatile (sevoflurane) or an IV (propofol) anesthetic. One-hundred-fifteen unpremedicated, ASA physical status I-II patients, aged 18-40 yr old, received either sevoflurane by mask to a predetermined end-tidal concentration (%ET(sevo)) or propofol by target-controlled infusion (effect site) while breathing spontaneously. After sufficient time for equilibration, LOC was assessed by lack of response to mild prodding. The up-down method of Dixon was used to determine the hypnotic target concentration at 50% response (LOC(50)). No statistically significant difference in LOC(50) was noted between men and women for sevoflurane (0.83% +/- 0.1% and 0.92% +/- 0.09% ET, respectively). Men required significantly more propofol than women (2.9 +/- 0.2 versus 2.7 +/- 0.1 microg/mL, respectively). However, there was no difference in the bispectral index (BIS) at LOC for men or women with either hypnotic anesthetic. This investigation identified a small, statistically significant difference in hypnotic requirement at LOC(50) between men and women with propofol but not with sevoflurane. As defined by BIS, men and women had equivalent hypnotic states at LOC(50), indicating that gender had no clinically significant effect on hypnotic requirements. However, BIS at a defined clinical end-point (LOC(50)) was significantly different between the sevoflurane and propofol groups, suggesting that neurophysiological effects of these anesthetics may be different. ⋯ Gender affects the dosing requirements for, and response to, many drugs used in anesthetic practice. Loss of consciousness is an early clinical marker of hypnotic drug effect. We found no significant difference to either an inhaled (sevoflurane) or IV (propofol) anesthetic related to patient gender.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Clinical TrialA rapid increase in the inspired concentration of desflurane is not associated with epileptiform encephalogram.
The large inspired concentration of sevoflurane (S) during mask induction of anesthesia can induce epileptiform electroencephalogram (EEG) associated with tachycardia. Tachycardia is also seen when the concentration of desflurane (D) is abruptly increased. It is not known whether this is associated with epileptiform EEG similar to S. We studied EEG and heart rate (HR) during rapidly increased concentrations of S or D in 31 females during the postintubation period of anesthesia. Anesthesia was induced with propofol and remifentanil, and the tracheas were intubated. Patients were randomized to receive either S or D in nitrous oxide-oxygen mixture after intubation, at a small dose first. After 10 min, S or D vaporizer was advanced to the highest reading of the vaporizer (7% for S, 18% for D) for 5 min. HR and EEG were recorded. Epileptiform EEG activity was recorded in eight of 15 patients in group S and in none in group D (P < 0.05). HR increased in both groups. In group S, HR increased gradually and the highest HR value was 84 bpm at 5 min after the increase in sevoflurane concentration. In group D, HR increased to 93 bpm 2 min after the increase in desflurane concentration (no significant difference, S versus D). A rapid increase in the concentration of S frequently induces epileptiform EEG during normoventilation. Tachycardia during increasing concentrations of D is not associated with epileptiform EEG. ⋯ A rapid increase in the concentration of sevoflurane induces epileptiform encephalogram (EEG) with tachycardia. A rapid increase in the concentration of desflurane also induces tachycardia but is not associated with epileptiform EEG.
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Anesthesia and analgesia · Aug 2005
Randomized Controlled Trial Clinical TrialDigital skin blood flow as an indicator for intravascular injection of epinephrine-containing simulated epidural test dose in sevoflurane-anesthetized adults.
I designed this study to determine the efficacy of heart rate (HR), systolic blood pressure (SBP), and digital skin blood flow (DSBF) in detecting intravascular injection after a simulated epidural test dose containing 15 mug of epinephrine in sevoflurane-anesthetized adults. In addition, the testing threshold using DSBF was derived. Eighty patients were randomized to receive either 0.5 minimum alveolar anesthetic concentration (MAC) sevoflurane or 1.0 MAC sevoflurane and nitrous oxide in oxygen (n = 40 for each sevoflurane concentration). Each group of patients was further randomized to receive either 3 mL of 1.5% lidocaine containing 15 mug of epinephrine IV or 3 mL of saline IV (n = 20 each). HR, SBP, and DSBF were monitored for 5 min after injection. By using the HR (positive if >or=10 bpm increase) and SBP (positive if >or=15 mm Hg increase) criteria, a positive response rate to epinephrine was 95% for both variables during 0.5 MAC and 90% during 1.0 MAC sevoflurane anesthesia. Injection of the test dose resulted in peak DSBF decrease by 87% +/- 8% and 81% +/- 12% at 52 +/- 10 and 53 +/- 13 s in the sevoflurane 0.5 and 1.0 MAC groups, respectively. Positive DSBF criterion, as determined from peak increases during saline administration, was a decrease in DSBF >or=15%. Using this value, the sensitivity, specificity, positive predictive value, and negative predictive value were 100% in both sevoflurane groups. In conclusion, DSBF was superior to conventional hemodynamic criteria for detection of an intravascular injection of epidural test dose. ⋯ This study examined the efficacy of digital skin blood flow to detect an intravascular injection of an epinephrine-containing epidural test dose. This new variable when measured with a laser Doppler flowmeter was superior to conventional hemodynamic criteria during sevoflurane anesthesia.