Anesthesia and analgesia
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Anesthesia and analgesia · Feb 2002
Comparative StudyElectrocardiographic electrodes provide the same results as expensive special sensors in the routine monitoring of anesthetic depth.
The Bispectral Index (BIS) is a mathematically derived electroencephalographic (EEG) derivative that has been introduced to monitor depth of anesthesia (1,2). The A-2000 BIS monitoring system (Aspect Medical Systems, Inc., Newton, MA) is currently the only commercially available system to monitor depth of anesthesia. In several studies, its propensity to optimize the use of hypnotics to maintain and achieve a certain depth of anesthesia has been described (3,4). Some studies have even proposed that the routine use of the monitoring system can decrease awareness (1,5), an increasing factor in malpractice claims. The cost-benefit calculations for BIS monitoring suffer from the fact that like its predecessor, the 1000-A BIS monitor, the A-2000 BIS monitoring system demands the use of expensive, special electrodes (6). Although the application of the single-use BIS sensor is very comfortable and easy to use, its high price of approximately $10-20 US prevents many anesthesiologists from using it. Furthermore, whereas the former model of the monitor (1000-A BIS monitor; Aspect Medical Systems, Inc.) used standardized connectors, which allowed the use of other electrodes such as electrocardiogram (ECG), the new monitoring system makes this very difficult because of special connectors that match the equivalent connector at the proximal BIS sensor site. The purpose of this prospective study was to compare BIS values derived from the original BIS sensor with BIS values derived from commercially available ECG electrodes. This comparison was made possible by designing and manufacturing a connector allowing the use of ECG electrodes. ⋯ The Bispectral Index (BIS) monitor adequately monitors depth of anesthesia. The routine use of this monitor has been hampered by the benefit-cost equation because only special expensive electrodes can be used. We examined the agreement of BIS values obtained by original sensor electrodes and commercial electrocardiogram (ECG) electrodes. These ECG electrodes can replace more expensive BIS sensors.
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Anesthesia and analgesia · Feb 2002
Randomized Controlled Trial Multicenter Study Clinical TrialThe efficacy and safety of three concentrations of levobupivacaine administered as a continuous epidural infusion in patients undergoing orthopedic surgery.
We evaluated the efficacy and safety of three concentrations of levobupivacaine infused epidurally as analgesia for patients undergoing orthopedic procedures. Patients undergoing elective hip or knee joint replacement were enrolled in the study (n = 105). Sensory blockade was established preoperatively with 10-15 mL of 0.75% levobupivacaine. Patients were then randomized to receive 0.0625%, 0.125%, or 0.25% levobupivacaine as a continuous epidural infusion at 6 mL/h for 24 h. IV morphine patient-controlled analgesia was given as rescue analgesia, and time to first request for analgesia and total dose of morphine consumed were recorded. Sensory blockade, motor blockade, visual analog scale pain score, and cardiovascular variables were also recorded at regular intervals postoperatively. Ninety-one patients were included in the primary intent-to-treat analysis. Total normalized dose of morphine, number of patient-controlled analgesia requests, and overall postoperative visual analog scale pain scores were significantly lower for the 0.25% group compared with the other two groups, and the time to first request for rescue analgesia was longer. There was no significant difference between the 0.125% and 0.25% groups in terms of maximum motor blockade achieved and time to minimal motor blockade. Safety data were equivalent among the three groups. We conclude that levobupivacaine as a continuous epidural infusion provided adequate postoperative analgesia and that the 0.25% concentration provided significantly longer analgesia than 0.125% or 0.0625% levobupivacaine without any significant increase in detectable motor blockade relative to the 0.125% group. ⋯ Postoperative epidural infusion of levobupivacaine can provide safe and effective analgesia for patients having hip or knee joint replacement. Of the three concentrations we infused at a constant rate, 0.25% provided significantly better pain relief.
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Anesthesia and analgesia · Feb 2002
Randomized Controlled Trial Comparative Study Clinical TrialRopivacaine undergoes slower systemic absorption from the caudal epidural space in children than bupivacaine.
We compared the systemic absorption of ropivacaine and bupivacaine after caudal epidural administration in children. Twenty ASA physical status I or II children aged 1-7 yr undergoing elective hypospadias repair were randomized after the induction of general anesthesia to receive a single caudal epidural injection of 2 mg/kg of either ropivacaine 0.2% (R) or bupivacaine 0.2% (B) in a double-blinded fashion. Peripheral venous blood samples (1 mL) were obtained before and 1, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, and 120 min after the caudal injection. The total R and B concentration was measured in plasma by using high-performance liquid chromatography. All blocks were successful, and there were no complications. The peak plasma concentration (mean +/- SD) (R = 0.67 +/- 0.16 and B = 0.73 +/- 0.23 microg/mL) and the area under the plasma concentration curve (R = 61.9 +/- 20.6 and B = 62.7 +/- 18.2 microg x mL(-1) x min(-1)) were comparable between the two study groups. The median (range) time to attain peak plasma concentration was significantly slower in children who received ropivacaine (R = 65 [10-120] min and B = 20 [15-50] min, P < 0.05). We conclude that ropivacaine undergoes slower systemic absorption from the caudal epidural space in children than does bupivacaine. ⋯ We compared the systemic absorption of ropivacaine (0.2%) and bupivacaine (0.2%) after caudal epidural injection of 2 mg/kg in children aged 1-7 yr. Our results show that ropivacaine undergoes slower systemic absorption from the caudal epidural space in children than does bupivacaine.