Anesthesia and analgesia
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe effect of cerebral monitoring on recovery after general anesthesia: a comparison of the auditory evoked potential and bispectral index devices with standard clinical practice.
The use of cerebral monitoring may improve the ability of anesthesiologists to titrate anesthetic drugs. However, there is controversy regarding the impact of the alleged anesthetic-sparing effects of cerebral monitoring on the recovery process and patient outcome. We designed this prospective double-blinded, sham-controlled study to evaluate the impact of intraoperative monitoring with the electroencephalogram bispectral index (BIS) or auditory evoked potential (AEP) device on the usage of desflurane and the time to discharge from the recovery room, as well as on patient satisfaction with their anesthetic experience and recovery. Ninety healthy patients undergoing laparoscopic general surgery procedures using a standardized anesthetic technique were randomly assigned to one of three monitoring groups: standard clinical practice (control), BIS-guided, or AEP-guided. Both the BIS and AEP monitors were connected to all patients before induction of general anesthesia. In the control group, the anesthesiologists were not permitted to observe the BIS or AEP index values during the intraoperative period. In the BIS-guided group, the volatile anesthetic was titrated to maintain a BIS value in the range of 45-55. In the AEP-guided group, the targeted AEP index range was 15-20. The BIS and AEP indices, as well as end-tidal desflurane concentration, were recorded at 3-5 min intervals. Recovery times to awakening, tracheal extubation, fast-track score >or=12, and postanesthesia care unit (PACU) discharge criteria were recorded at 1-10 min intervals. In addition, patient satisfaction with anesthesia and quality of recovery were evaluated on 100- and 18-point scales, respectively, at 24 h after surgery. The AEP- and BIS-guided groups were administered significantly smaller average end-tidal desflurane concentrations than the control group (3.8 +/- 0.9 and 3.9 +/- 0.6 versus 4.7 +/- 1.7, respectively) (P < 0.01). Although the emergence times to eye opening, tracheal extubation, and obeying commands were consistently shorter in the AEP and BIS groups (6 +/- 4 and 6 +/- 5 versus 8 +/- 8 min; 6 +/- 5 and 6 +/- 4 versus 11 +/- 10 min; and 8 +/- 4 and 7 +/- 4 versus 12 +/- 9 min, respectively), only the extubation times were significantly different from the control group (P < 0.05). More importantly, the length of the PACU stay was significantly shorter in both the AEP- and BIS-guided groups (79 +/- 43 and 80 +/- 47 versus 108 +/- 58 min, respectively) (P < 0.05). The patients' quality of recovery was also significantly higher in the two monitored groups (15 +/- 2 versus 13 +/- 3 in the control group, P < 0.05). We concluded that cerebral monitoring with either the BIS or AEP devices reduced the maintenance anesthetic (desflurane) requirement, resulting in a shorter length of stay in the PACU and improved quality of recovery after laparoscopic surgery. However, there were no significant outcome differences between the two cerebral monitored groups. ⋯ Compared with standard monitoring practices, use of an auditory evoked potential or bispectral index monitor to titrate the volatile anesthetic led to a significant reduction in the anesthetic requirement. The anesthetic-sparing effect of cerebral monitoring resulted in a shorter postanesthesia care unit stay and improved quality of recovery from the patient's perspective.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialPreincisional treatment to prevent pain after ambulatory hernia surgery.
We designed this study as a randomized comparison of postoperative pain after inguinal hernia repair in patients treated with triple preincisional analgesic therapy versus standard care. Triple therapy consisted of a nonsteroidal antiinflammatory, a local anesthetic field block, and an N-methyl-D-aspartate inhibitor before incision. The treatment group (n = 17) received rofecoxib, 50 mg PO, a field block with 0.25% bupivacaine/0.5% lidocaine, and ketamine 0.2 mg/kg IV before incision; controls (n = 17) received a placebo PO before surgery. The anesthetic protocol was standardized. Postoperative pain was treated by fentanyl IV and oxycodone 5 mg/acetaminophen 325 mg PO as required for pain. Pain scores (0-10) and analgesic were recorded for the first 7 days after surgery. Pain scores were 47% lower in the treatment group before discharge (3.1 +/- 0.6 versus 5.9 +/- 0.6, P = 0.0026) (mean +/- SE) and 18% less in the first 24 h after discharge (5.6 +/- 0.4 versus 6.8 +/- 0.5, P = 0.05); oral analgesic use was 34% less in the treatment group (4.6 +/- 0.8 doses versus 7.1 +/- 0.7 doses, P = 0.02) in the first 24 h after surgery. We conclude that triple preincisional therapy diminishes pain and analgesic use after outpatient hernia repair, and encourage further evaluation of this technique. ⋯ Outpatients undergoing inguinal hernia repair under general anesthesia report moderate-to-severe pain after surgery. Triple preincisional therapy that included rofecoxib, 50 mg PO, ketamine, 0.2 mg/kg IV, and local anesthetic field block reduced pain scores and analgesic use in the first 24 h after discharge.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialRopivacaine and fentanyl concentrations in patient-controlled epidural analgesia during labor: a volume-range study.
We enrolled nulliparous women in induced labor in a randomized study to determine whether increasing the concentration of the solution used in a patient-controlled epidural analgesia (PCEA) device was required as labor progressed. Patients were assigned to 6 groups (n = 25 in each group), receiving ropivacaine/fentanyl in concentrations of either 0.1%/0.5 microg/mL or 0.2%/1 microg/mL via a PCEA pump. Three groups received boluses of 12, 16, or 20 mL dilute solution in early labor (uterine contractions every 3 min and 4-cm cervical dilation) then 6, 8, and 10 mL concentrated solution in late labor. Three other groups received boluses of 12, 16, or 20 mL dilute solution during both periods. The lockout interval was 25 min. The primary outcome was time until the first request for staff-administered analgesia supplement. Hourly assessments included pain scores on a visual analog scale (VAS) graded from 0 to 10, satisfaction scores, arterial blood pressure, motor block intensity, and the upper sensory level of epidural anesthesia. Patients, midwives, and the observer were unaware of study solutions and PCEA settings. The maximum pain score was defined as the highest score experienced by each patient during each period. Duration of analgesia was defined as the time from the start of each period to the first injection of rescue analgesia and was compared using a survival analysis. There were no differences among the groups with regard to demographic and obstetric variables, arterial blood pressure, motor block intensity, upper sensory level, or satisfaction scores. At least 75% of the women rated their satisfaction as either good or excellent during each period. During late labor, the maximum pain score was lower in the group receiving 20 mL dilute solution compared with the group receiving 6 mL concentrated solution. Maximum pain score was not significantly different between 20 mL dilute solution and 10 mL concentrated solution (difference between VAS values = -0.4; 95% confidence limits, -1.599 and 0.799; P = 0.5055). During late labor, the duration of analgesia was longer in groups receiving 20 mL dilute solution (99 +/- 4 min) (mean +/- SD) than in those receiving 12 mL (77 +/- 30 min) and 16 mL (80 +/- 23 min). Duration of analgesia did not differ between groups receiving 20 mL and 10 mL (92 +/- 23 min) or between groups receiving 12 mL and 6 mL (78 +/- 30 min) of each respective solution. Duration of analgesia was longer in the groups receiving 8 mL concentrated solution (94 +/- 16 min) than in those receiving 16 mL dilute solution. We concluded that 0.1%/0.5 microg/mL ropivacaine/fentanyl was effective throughout labor when 20 mL was injected with each PCEA demand. With 16 mg ropivacaine and 8 microg fentanyl, the duration of analgesia was prolonged by doubling the concentration when labor became active. When 12 mg ropivacaine and 6 microg fentanyl were injected at each demand, analgesia was less satisfactory and doubling the concentration was not clinically effective. These results suggest that the effectiveness of PCEA is dependent on drug mass rather than the volume or concentration administered with each successful pump demand. ⋯ There is no clinical reason for increasing the concentration of the patient-controlled epidural analgesia (PCEA) solution when labor becomes active provided that an effective dose is already being administered with each demand. The quality of PCEA depends on the drug mass given with each demand rather than the concentration of the pump solution.
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To examine the physicochemical stability of combinations of propofol-lidocaine mixtures frequently used in clinical practice, we added lidocaine 5, 10, 20, or 40 mg to commercially available 1% propofol 20 mL. To assess chemical stability, propofol concentrations were determined by gas chromatography assay for 24 h after preparation of the mixture. In addition, scanning electron microscopy was used to determine the maximum detectable droplet size in randomly selected fields. Macroscopically, separate, colorless layers were first seen at 3 and 24 h after the addition of 40 and 20 mg of lidocaine to propofol, respectively, whereas the mixture with 5 or 10 mg of lidocaine was macroscopically stable. Propofol concentrations in the mixture with 40 mg of lidocaine decreased linearly and significantly from 4 to 24 h after preparation, whereas those combined with other lidocaine doses were unchanged compared with baseline concentrations. Scanning electron microscopy showed that droplets with diameters >or=5 microm first appeared 30 min after the addition of 40 mg of lidocaine to propofol, and the emulsion droplets were enlarged in a time- and dose-dependent fashion. Our results indicate that the addition of lidocaine to propofol results in a coalescence of oil droplets, which finally proceeds to a visible separate layer. Depending on the dose of lidocaine and the duration between its preparation and administration, this combination may pose the risk of pulmonary embolism. ⋯ The addition of lidocaine to propofol results in time- and dose-dependent increases in oil droplet diameters in emulsion. This mixture is physicochemically unstable over time and may cause pulmonary embolism, depending on the dose of lidocaine.
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Anesthesia and analgesia · Dec 2003
Randomized Controlled Trial Clinical TrialOptimizing the dose of intrathecal morphine in older patients undergoing hip arthroplasty.
Intrathecal (IT) morphine provides excellent postoperative analgesia but may result in many side effects, including postoperative nausea and vomiting, pruritus, and respiratory depression, particularly at larger doses. Older patients may be at particular risk. The optimal dose of spinal morphine in older patients undergoing hip arthroplasty is not known. We designed this prospective, randomized, controlled, double-blinded study to evaluate the analgesic efficacy and side effect profile of 50-200 microg of IT morphine in older patients undergoing elective hip arthroplasty. Sixty patients older than 65 years undergoing elective hip arthroplasty were enrolled. Patients were randomized to receive spinal anesthesia with 15 mg of bupivacaine and IT morphine in four groups: 1). 0 microg, 2). 50 microg, 3). 100 microg, and 4). 200 microg. IT morphine 100 and 200 microg produced effective pain relief and decreased the postoperative requirement for morphine compared with control. IT morphine 50 microg did not provide effective pain relief. Both 100 and 200 microg of IT morphine provided comparable levels of postoperative analgesia. There were no between-group differences in postoperative nausea and vomiting, sedation, respiratory depression, or urinary retention. Pruritus was significantly more frequent with 200 microg of IT morphine. In conclusion, 100 microg of IT morphine provided the best balance between analgesic efficacy and side effect profile in older patients undergoing hip arthroplasty. ⋯ The dosage of intrathecal morphine that provides the best balance between analgesic efficacy and side effect profile in the older patient undergoing hip arthroplasty is not known. This prospective, randomized, controlled, double-blinded clinical trial demonstrates that a dose of 100 microg of intrathecal morphine provides the best balance between efficacy and side effects, compared with doses of 0, 50, and 200 microg of morphine, in this patient population.