Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe synergistic effect of combined treatment with systemic ketamine and morphine on experimentally induced windup-like pain in humans.
In this study, we evaluated whether combined treatment with ketamine (KET), an N-methyl-D-aspartate receptor antagonist, and morphine (MO) results in positive analgesic effects. Eleven volunteers were exposed to a skin burn injury on the leg. The effects of IV KET (9 microg. kg(-1). min(-1); 45 min) and MO (10 microg. kg(-1). min(-1); 10 min) alone and in combination, as well as placebo (saline; 10 min), were studied in a randomized, crossover, double-blinded design. The area of secondary hyperalgesia (SH) for mechanical stimulation was diminished by KET as compared with placebo. Mechanical pain thresholds were increased severalfold with KET and with KET plus MO, both in the primary hyperalgesic (PH; burn injury) and SH area. MO infusion showed no effect on the SH area or pain threshold. Windup-like pain was evaluated by continuous assessment on a visual analog scale during 30 s of repetitive stimulation (40-g load at 3 Hz) and analyzed as a sum of pain scores. The combined treatment (KET plus MO) almost abolished windup-like pain both in the PH and the SH areas, an effect that was not present with monotherapy with KET or MO. This study provides experimental support for a positive analgesic interaction between an N-methyl-D-aspartate receptor antagonist and an opioid on central summation of pain. ⋯ This is the first experimental study in humans to find synergistic analgesic effects with coadministration of the N-methyl-D-aspartate receptor antagonist ketamine and morphine on pain involving central sensitization phenomena.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe relative motor blocking potencies of intrathecal ropivacaine: effects of concentration.
This study established the median effective dose (ED(50)) for motor block of intrathecal 1% and 0.1% ropivacaine and determined the effects of the concentration of the solution injected on the motor block obtained. We enrolled into this prospective, randomized, double-blind, sequential allocation study 54 parturients undergoing elective Cesarean delivery under combined spinal-epidural technique. Parturients were randomized to receive intrathecal ropivacaine either 1% or 0.1%. The initial dose was chosen to be 4 mg, with subsequent doses being determined by the response of the previous patient (testing interval, 1 mg). The occurrence of any motor block in either lower limb within 5 min from the intrathecal injection of the study solution was considered effective. The motor block at 5 min was 6.1 mg for 1% ropivacaine (95% confidence interval [CI], 5.1-7.1) and was 9.1 mg (95% CI, 7.8-10.3) for 0.1% ropivacaine (P = 0.0013; 95% CI difference, 1.3-4.7). The relative efficacy ratio of the 2 concentrations was 1.5 (95% CI difference, 1.2-1.9) in favor of the larger concentration. The ED(50) of spinal ropivacaine to produce motor block in pregnant patients was significantly influenced by the concentration of the local anesthetic, with dose requirements being increased by 50% for the smaller concentration. ⋯ The minimum local anesthetic dose for motor block with 0.1% ropivacaine is 50% larger than the 1% concentration with a relative efficacy ratio of 1.5. Our findings suggest that more diluted local anesthetic solutions determine less motor block, and this may be considered in ambulant laboring parturients.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialProphylaxis of postoperative nausea and vomiting with oral, long-acting dimenhydrinate in gynecologic outpatient laparoscopy.
Dimenhydrinate is an inexpensive antiemetic with few side effects available as an oral, long-acting (LA) formulation (Gravol L/A) containing 25 mg of immediate and 50 mg of sustained release drug. We designed this double-blind comparison trial to assess the efficacy of dimenhydrinate LA versus droperidol alone and the combination for prophylaxis of nausea, vomiting, and retching in outpatient gynecologic laparoscopy. One-hundred-forty-one women were randomized into 3 groups: 1) droperidol (placebo capsule preoperatively and IV droperidol 0.625 mg before induction), 2) dimenhydrinate LA preoperatively and IV placebo before induction, or 3) combination. Information regarding nausea, vomiting, retching, pain, and sedation was recorded in the postanesthesia care unit (PACU) and collected by telephone for the presence of symptoms: on arrival home; at bedtime; upon arising, and at lunchtime the following day. The overall incidence of complete treatment failure (rescue medication in PACU or nausea, vomiting, or retching at any time point) was 28 of 46 (61%), 28 of 48 (58%), and 22 of 47 (47%); and for treatment failure vomiting (rescue medication in PACU or vomiting or retching at any time point) was 16 of 46 (35%), 11 of 48 (23%), and 5 of 47 (11%), for the droperidol, dimenhydrinate, and combination groups, respectively (P = 0.007 for droperidol versus combination). There were no differences in sedation or pain. Preoperative administration of an oral dose of LA dimenhydrinate in combination with droperidol when compared with droperidol alone effectively reduced the incidence of vomiting but not nausea in women undergoing elective outpatient gynecologic laparoscopy. ⋯ Dimenhydrinate is an inexpensive antiemetic with few side effects available as a long-acting oral formulation. Women undergoing outpatient gynecologic laparoscopy were given droperidol, an effective antiemetic, dimenhydrinate alone, or the combination of the two drugs. Dimenhydrinate plus droperidol significantly reduced the overall incidence of vomiting, but not nausea, when compared with droperidol alone.
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Factor V Leiden (FVL) is the most common known inherited cause of thrombophilia; it is present in approximately 5% of the Caucasian population. Although the risk of venous thrombosis associated with this polymorphism in various medical settings is well described, its effect on perioperative risk is only beginning to be explored. ⋯ This review will describe the physiology of the FVL mutation, briefly clarify its risk in the nonsurgical setting, and assess current data regarding FVL in noncardiac and cardiac surgery. Finally, a summary of current clinical evidence and a plan for more detailed investigation of this potentially significant risk factor will be proposed.
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Anesthesia and analgesia · Jun 2004
Randomized Controlled Trial Comparative Study Clinical TrialIntrathecal midazolam II: combination with intrathecal fentanyl for labor pain.
Recent investigations have sought to improve intrathecal analgesia by combining opioids with other classes of analgesics. In this study we assessed the ability of intrathecal midazolam to increase the potency and duration of the analgesic effects of intrathecal fentanyl without causing adverse effects. Thirty parturients with cervical dilations 2-6 cm were randomized to receive either intrathecal midazolam 2 mg, fentanyl 10 micro g, or both combined to initiate analgesia. Pain scores were recorded before and at 5-min intervals for 30 min after the injection and then every 30 minutes until the patient requested further analgesia. The presence and severity of nausea, emesis, pruritus, headache, and sedation, in addition to arterial blood pressure, heart rate, respiratory rate, sensory changes to ice, motor impairment, cardiotocograph, and Apgar score were also recorded. The parturients were assessed after 2 days and 1 mo for neurologic impairment. Preinjection pain scores were unaltered by intrathecal midazolam alone and moderately decreased by fentanyl. Intrathecal midazolam increased the analgesic effect of fentanyl. No treatment altered cardiorespiratory variables or caused motor impairment. The addition of intrathecal midazolam to fentanyl did not increase the occurrence of any maternal adverse event or abnormalities on the cardiotocograph. We conclude that intrathecal midazolam enhanced the analgesic effect of fentanyl without increasing maternal or fetal adverse effects. ⋯ Treatment of labor pain with epidural injections of local anesthetic is complicated by decreases in arterial blood pressure and leg weakness. This study showed that a mixture of two drugs, fentanyl and midazolam, could provide powerful pain relief when the drugs were given together spinally without such side effects.