Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Clinical TrialThe effect of fresh gas flow and anesthetic technique on the ability to control acute hemodynamic responses during surgery.
We evaluated the effect of the fresh gas flow (FGF) rate and the anesthetic technique on the ability to control the acute hyperdynamic response to a specific surgical stimulus during surgery in 90 consenting ASA physical status I-III patients undergoing lower abdominal procedures. After the administration of midazolam 2 mg IV, anesthesia was induced in all patients with propofol 1.5 mg/kg IV and fentanyl 1 microg/kg IV and was initially maintained with desflurane or isoflurane, 0.7 minimum alveolar anesthetic concentration, at total FGF rates of either 1 or 3 L/min. In response to the surgical stimulation of skin incision and retropubic dissection, an increase in mean arterial pressure (MAP) >20% above the preincision baseline MAP value provoked a stepwise increase in the inspired concentration of the volatile anesthetic or the IV administration of a variable-rate infusion of esmolol. At both FGF rates, the acute hemodynamic response to surgical stimulation was more efficiently treated by increasing the inspired concentration of desflurane than isoflurane. At 1 L/min, the average time to control the increase in MAP was significantly shorter with desflurane (17+/-12 min) compared with isoflurane (29+/-16 min), with 60% of the patients in the isoflurane group requiring rescue therapy. When an esmolol infusion was used to control the increase in MAP, supplementation with fentanyl was required in 40% and 53% of patients anesthetized with desflurane and isoflurane, respectively. In conclusion, desflurane provided more rapid and reliable control of acute hemodynamic responses to surgical stimulation than isoflurane or esmolol when the volatile anesthetics were administered at low FGF rates. ⋯ At low fresh gas flow rates (1 L/min), desflurane more successfully and rapidly controlled the acute hemodynamic responses to painful surgical stimuli than isoflurane.
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Clinical TrialEpidural fentanyl reduces the shivering threshold during epidural lidocaine anesthesia.
Epidural local anesthetics and IV opioids both decrease the core temperature that triggers shivering. However, the effect of epidural opioids on shivering thresholds has not been assessed. In this study, we tested the hypothesis that adding epidural fentanyl to epidural lidocaine decreases the shivering threshold compared with epidural lidocaine alone. Fourteen healthy male patients undergoing extracorporeal shockwave lithotripsy under epidural anesthesia were randomly assigned to receive either epidural lidocaine or epidural lidocaine plus epidural fentanyl. Ice-cold lactated Ringer's solution was given IV before epidural blockade, and the core temperature that triggers shivering was established. Then epidural anesthesia was induced, and the shivering threshold was established again after lithotripsy. Results were analyzed using paired or unpaired t-tests. Reduction in the shivering threshold by epidural anesthesia was significantly greater when fentanyl was added to lidocaine than when lidocaine was used alone (mean +/- SD: -0.6+/-0.4 degrees C versus -0.1+/-0.4 degrees C; P < 0.02). We conclude that patients are at increased risk of hypothermia when fentanyl is added to epidural lidocaine. ⋯ Fentanyl is often added to lidocaine to improve the quality of epidural blockade and to reduce side effects. However, this study shows that patients are at increased risk of hypothermia when fentanyl is added to lidocaine.
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Anesthesia and analgesia · Sep 1998
Randomized Controlled Trial Comparative Study Clinical TrialA double-blind comparison of ropivacaine, bupivacaine, and mepivacaine during sciatic and femoral nerve blockade.
No study has evaluated the efficacy of ropivacaine in peripheral nerve block of the lower extremity. The purpose of this prospective, randomized, double-blind study was to compare ropivacaine, bupivacaine, and mepivacaine during combined sciatic-femoral nerve block. Forty-five ASA physical status I or II patients scheduled for elective hallux valgus repair with thigh tourniquet were randomized to receive combined sciatic-femoral block with 0.75% ropivacaine (ROPI, n = 15), 0.5% bupivacaine (BUPI, n = 15), and 2% mepivacaine (MEPI, n = 15). Time required for onset of sensory and motor block on the operated limb (readiness for surgery) and resolution of motor block, as well as onset of postsurgical pain and time of first analgesic requirement, were recorded. The three groups were similar with regard to demographic variables, duration of surgery, and measured visual analog pain scores. Onset of sensory and motor blockade was similar in Groups ROPI and MEPI and significantly shorter than in Group BUPI (P = 0.002 and P = 0.001, respectively). Resolution of motor block occurred later in Groups ROPI and BUPI than in Group MEPI (P = 0.005 and P = 0.0001, respectively). Duration of postoperative analgesia was significantly longer in Groups ROPI (670+/-227 min) and BUPI (880+/-312 min) compared with Group MEPI (251+/-47 min) (P = 0.0001), with a significant decrease in postoperative pain medication requirements (P < 0.05). We conclude that for sciatic-femoral nerve block, 0.75% ropivacaine has an onset similar to that of 2% mepivacaine and a duration of postoperative analgesia between that of 0.5% bupivacaine and 2% mepivacaine. ⋯ Quick onset of block with prolonged postoperative analgesia is an important goal in peripheral nerve blockade. We evaluated the clinical properties of 0.5% bupivacaine, 2% mepivacaine, and 0.75% ropivacaine for sciatic-femoral nerve block and demonstrated that ropivacaine has an onset similar to that of mepivacaine but allows for postoperative analgesia between that of bupivacaine and mepivacaine.