Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2003
Randomized Controlled Trial Clinical TrialThe dose effect of ephedrine on the onset time of vecuronium.
A small dose of ephedrine decreases the onset time of rocuronium and cisatracurium; however, ephedrine might be associated with adverse hemodynamic effects. The appropriate dose of ephedrine has not been determined. We, therefore, studied 120 patients anesthetized with fentanyl 2 microg/kg and propofol 2-2.5 mg/kg who were randomly divided to receive either ephedrine (30, 70, or 110 microg/kg) or saline. During propofol anesthesia, the neuromuscular block was monitored by mechanomyography by using submaximal current of train-of-four stimulation every 10 s. To determine cardiac output, a transcutaneous Doppler probe was placed externally at the suprasternal notch. Tracheal intubation was performed by a blinded investigator at 2 min after vecuronium. Neuromuscular block, intubating conditions, and hemodynamic effects were measured during the induction of anesthesia. Both ephedrine 70 and 110 microg/kg improved intubating conditions at 2 min after vecuronium; however, 110 microg/kg was associated with adverse hemodynamic effects. We conclude that ephedrine 70 microg/kg given before the induction of anesthesia improved intubating conditions at 2 min after vecuronium, probably by increased cardiac output without significant adverse hemodynamic effects. ⋯ Ephedrine 70 microg/kg given before the induction of anesthesia improved tracheal intubating conditions at 2 min after vecuronium by increased cardiac output without significant adverse hemodynamic effects.
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Anesthesia and analgesia · Apr 2003
Sevoflurane exposure generates superoxide but leads to decreased superoxide during ischemia and reperfusion in isolated hearts.
Reactive oxygen species (ROS) are largely responsible for cardiac injury consequent to ischemia and reperfusion, but, paradoxically, there is evidence suggesting that anesthetics induce preconditioning (APC) by generating ROS. We hypothesized that sevoflurane generates the ROS superoxide (O(2)(.-)), that APC attenuates O(2)(.-) formation during ischemia, and that this attenuation is reversed by bracketing APC with the O(2)(.-) scavenger manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) or the putative mitochondrial adenosine triphosphate-sensitive potassium (mK(ATP)) channel blocker 5-hydroxydecanoate (5-HD). O(2)(.-) was measured continuously in guinea pig hearts by using dihydroethidium. Sevoflurane was administered alone (APC), with MnTBAP, or with 5-HD before 30 min of ischemia and 120 min of reperfusion. Control hearts underwent no pretreatment. Sevoflurane directly increased O(2)(.-); this was blocked by MnTBAP but not by 5-HD. O(2)(.-) increased during ischemia and during reperfusion. These increases in O(2)(.-) were attenuated in the APC group, but this was prevented by MnTBAP or 5-HD. We conclude that sevoflurane directly induces O(2)(.-) formation but that O(2)(.-) formation is decreased during subsequent ischemia and reperfusion. The former effect appears independent of mK(ATP) channels, but not the latter. Our study indicates that APC is initiated by ROS that in turn cause mK(ATP) channel opening. Although there appears to be a paradoxical role for ROS in triggering and mediating APC, a possible mechanism is offered. ⋯ Reactive oxygen species (ROS) are implicated in triggering anesthetic preconditioning (APC). The ROS superoxide (O(2)(.-)) was measured continuously in guinea pig isolated hearts. Sevoflurane directly increased O(2)(.-) but led to attenuated O(2)(.-) formation during ischemia. This demonstrates triggering of APC by ROS and clarifies the mechanism of cardioprotection during ischemia.
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Anesthesia and analgesia · Apr 2003
Case ReportsBispectral index-derived facial electromyography-guided fentanyl titration in the opiate-exposed patient.
A 34-yr-old man, possibly opiate tolerant, underwent the second part of a scoliosis repair. We describe a narcotic titration protocol by using facial electromyography data derived from the bispectral index monitor that resulted in a good clinical outcome.
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Anesthesia and analgesia · Apr 2003
Randomized Controlled Trial Clinical TrialContinuous interscalene brachial plexus block for postoperative pain control at home: a randomized, double-blinded, placebo-controlled study.
In this study, we investigated the efficacy of patient-controlled regional analgesia for outpatients undergoing moderately painful orthopedic surgery of the shoulder. Preoperatively, patients (n = 20) received an interscalene nerve block and perineural catheter. Postoperatively, patients were discharged home with both oral opioids and a portable infusion pump delivering either 0.2% ropivacaine or 0.9% saline, determined randomly in a double-blinded manner. Daily end points included pain scores, opioid use and side effects, sleep quality, and technique complications. Ropivacaine (n = 10) infusion significantly reduced pain compared with saline (n = 10) infusion. The average pain at rest (scale: 0-10) on postoperative day 1 (median, 25th-75th percentiles) was 4.8 (4.0-5.0) for the saline group, versus 0.0 (0.0-2.0) for the ropivacaine group (P < 0.001). Oral opioid use and related side effects were also significantly decreased in the ropivacaine group. On postoperative day 1, median tablet consumption was 8.0 (6.5-9.5) and 0.5 (0.0-1.0) for the saline and ropivacaine groups, respectively (P < 0.001). Sleep disturbance scores were nearly threefold greater on the first postoperative night for patients receiving saline (P = 0.013). We conclude that after moderately painful orthopedic surgery of the shoulder, ropivacaine infusion using a portable infusion pump and an interscalene perineural catheter at home decreased pain, opioid use and related side effects, and sleep disturbances. ⋯ This randomized, double-blinded, placebo-controlled study demonstrated that ropivacaine, infused with a portable infusion pump via an interscalene perineural catheter for 3 days at home, significantly decreased postoperative pain after orthopedic surgery of the shoulder. In addition to providing potent analgesia and increasing patient satisfaction, perineural infusion decreased opioid requirements and their associated side effects.
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Anesthesia and analgesia · Apr 2003
Randomized Controlled Trial Comparative Study Clinical TrialThe anesthetic conserving device compared with conventional circle system used under different flow conditions for inhaled anesthesia.
The Anesthetic Conserving Device (ACD) is a high-flow anesthesia system closed to volatile anesthetics only. We compared the ACD with a circle system under different fresh gas flow (FGF) conditions. Eighty-one patients undergoing major surgery were randomly allocated to receive sevoflurane from a circle circuit combined either with the ACD placed at the Y-piece (n = 41) or with a vaporizer (n = 40). The FGF was set to 8 L/min in the ACD system, where the circle circuit served as a nonrebreather. In the conventional circle system without ACD, the vaporizer was supplied with 1-, 1.5-, 3-, and 6-L/min FGFs. We compared the ACD with the circle system under the four FGFs in terms of sevoflurane dosing, sevoflurane consumption, humidification efficiency, and environmental pollution. The ACD and the low-flow circle system (1.5- and 1-L/min FGFs) resulted in the smallest sevoflurane consumption. The increase in inspired sevoflurane concentration was faster with the circle system than with the ACD only with FGFs > or =3 L/min. The removal of ACD from the circuit allowed the fastest washout of sevoflurane. Respiratory gas humidification was always adequate. Sevoflurane ambient concentration with the ACD was 1-70 ppb. The ACD is a valid and simple alternative to low-flow systems. ⋯ The Anesthetic Conserving Device (ACD) is a new device for anesthetic vapor delivery. We demonstrated that the ACD reduces anesthetic consumption and environmental pollution similarly to a low-flow circle system, offering advantages such as simplicity, no toxicity from compounds produced in the absorber, and potential cost savings.