Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2002
Randomized Controlled Trial Comparative Study Clinical TrialDextromethorphan reduces immediate and late postoperative analgesic requirements and improves patients' subjective scorings after epidural lidocaine and general anesthesia.
Central N-methyl-D-aspartate receptors modulate postoperative pain. We compared the effects of preincision oral dextromethorphan (DM), an N-methyl-D-aspartate receptor antagonist, on postoperative IV patient-controlled analgesia morphine demand and on subjective variables in 80 patients undergoing lower-body procedures who were randomly assigned to epidural lidocaine (LA; 16 mL, 1.6%) or general anesthesia (GA). The patients were premedicated 90 min before surgery with placebo or DM 90 mg (20 patients per group) in a double-blinded manner. ⋯ All DM patients experienced significantly (P < 0.001) less pain, were less sedated, and felt better than their placebo counterparts; however, compared with placebo, DM improved subjective scorings in the GA patients more significantly (P < 0.05) than in the LA patients. We conclude that oral DM 90 mg in patients undergoing surgery under LA or GA reduces morphine and diclofenac use by approximately 50% in the immediate and late postoperative period compared with placebo. Subjectively scored levels of pain, sedation, and well-being were better as well.
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Anesthesia and analgesia · Jun 2002
Randomized Controlled Trial Clinical TrialOndansetron inhibits the analgesic effects of tramadol: a possible 5-HT(3) spinal receptor involvement in acute pain in humans.
To investigate a possible antinociceptive role of serotonin receptor subtype 3 (5-HT(3)), we evaluated the effects of a coadministration of ondansetron, a 5-HT(3) selective antagonist, and tramadol, a central analgesic dependent on enhanced serotonergic transmission. Fifty-nine patients undergoing ear, throat, and nose surgery, using tramadol for 24-h postoperative patient-controlled analgesia (bolus = 30 mg; lockout interval = 10 min) were randomly allocated either to a group receiving ondansetron continuous infusion (1 mg. mL(-1). h(-1)) for postoperative nausea and vomiting (Group O) or to a control group receiving saline (Group T). Pain and vomiting scores and tramadol consumption were evaluated at 4, 8, 12, and 24 h. Pain scores were never >4, according to a 0-10 numerical rating scale, in both groups. Group O required significantly larger doses of tramadol at 4 h (213 versus 71 mg, P < 0.001), 8 h (285 versus 128 mg, P < 0.002), and 12 h (406 versus 190 mg, P < 0.002). Vomiting scores were higher in Group O at 4 h (P < 0.05) and 8 h (P = 0.05). We conclude that ondansetron reduced the overall analgesic effect of tramadol, probably blocking spinal 5-HT(3) receptors. ⋯ Serotonin is an important neurotransmitter of the descending pathways that down-modulate spinal nociception. In postoperative pain, ondansetron, a selective 5-HT(3) receptor antagonist, increased the analgesic dose of tramadol. We suggest that, when antagonized for antiemetic purpose, 5-HT(3) receptors foster nociception, because of their site-dependent action.
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Anesthesia and analgesia · Jun 2002
Randomized Controlled Trial Clinical TrialThe hypnotic and analgesic effects of oral clonidine during sevoflurane anesthesia in children: a dose-response study.
Although clonidine has both hypnotic and analgesic actions, the dose relationship for each actions is still unknown in a clinical setting when clonidine is used as a premedication in children. We studied 80 ASA physical status I children (age range, 3-8 yr). Subjects were randomly divided into two groups (minimum alveolar anesthetic concentration [MAC]-Awake group, n = 40; MAC-Tetanus group, n = 40). Each patient received one dose of clonidine from 1 to 5 microg/kg orally, 100 min before arrival at the operating room. Anesthesia was induced and maintained with sevoflurane in oxygen and air. Before tracheal intubation, end-tidal sevoflurane was decreased stepwise by 0.2% at the start of 1.2%, a verbal command was given to the patients, and MAC-awake was determined in each patient. We also investigated MAC-tetanus, determined with transcutaneous electric tetanic stimulations, after tracheal intubation in each patient by observing the motor response to a transcutaneous electric tetanic stimulus to the ulnar nerve at a sevoflurane concentration decreased stepwise by 0.25% at the start of 2.75%. The initial reduction in MAC-tetanus was not as steep as that in MAC-awake. Clonidine reduced MAC-tetanus by 40% at the maximal dose of 5 microg/kg, whereas MAC-awake was already reduced by 50% at 2 microg/kg. We conclude that separate dose-response relationships for oral clonidine are present regarding the hypnotic and analgesic effects in children undergoing sevoflurane anesthesia. ⋯ Separate dose-response relationships for oral clonidine were found regarding the hypnotic and analgesic effects in children undergoing sevoflurane anesthesia.
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Anesthesia and analgesia · Jun 2002
Comparative Study Clinical TrialUpright posture reduces thermogenesis and augments core hypothermia.
We recently reported that baroreceptor-mediated reflexes modulate thermoregulatory vasoconstriction during lower abdominal surgery. Accordingly, we examined the hypothesis that postural differences and the related alterations in baroreceptor loading similarly modulate the thermogenic (i.e., shivering) response to hypothermia in humans. In healthy humans (n = 7), cold saline was infused IV (30 mL/kg at 4 degrees C) for 30 min to decrease core temperature. Each participant was studied on 2 separate days, once lying supine and once sitting upright. Tympanic membrane temperature and oxygen consumption were monitored for 40 min after each saline infusion. The decrease in core temperature upon completion of the infusion in the upright posture position was 1.24 degrees C +/- 0.07 degrees C, which was significantly greater than the 1.02 degrees C +/- 0.06 degrees C seen in the supine position. The core temperature was reduced by 0.59 degrees C +/- 0.07 degrees C in the upright position but only by 0.37 degrees C +/- 0.05 degrees C in the supine position when the increase in oxygen consumption signaling thermogenic shivering occurred. Thus, the threshold temperature for thermogenesis was significantly less in the upright than the supine position. The gain of the thermogenic response did not differ significantly between the positions (363 +/- 69 mL. min(-1). degrees C(-1) for upright and 480 +/- 80 mL. min(-1). degrees C(-1) for supine). The skin temperature gradient was significantly larger in the upright than in the supine posture, suggesting that the peripheral vasoconstriction was augmented by upright posture. Plasma norepinephrine concentrations increased in response to cold saline infusion under both conditions, but the increase was significantly larger in the upright than in the supine posture. Baroreceptor unloading thus augments the peripheral vasoconstrictor and catecholamine response to core hypothermia but simultaneously reduces thermogenesis, which consequently aggravated the core temperature decrease in the upright posture. ⋯ Upright posture attenuates the thermogenic response to core hypothermia but augments peripheral vasoconstriction. This divergent result suggests that input from the baroreceptor modifies the individual thermoregulatory efferent pathway at a site distal to the common thermoregulatory center or neural pathway.
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Anesthesia and analgesia · Jun 2002
Comparative StudyA comparison of the training value of two types of anesthesia simulators: computer screen-based and mannequin-based simulators.
In this study, we compared two different training simulators (the computer screen-based simulator versus the full-scale simulator) with respect to training effectiveness in anesthesia residents. Participants were evaluated in the management of a simulated preprogrammed scenario of anaphylactic shock using two variables: treatment score and diagnosis time. Our results showed that simulators can contribute significantly to the improvement of performance but that learning in treating simulated crisis situations such as anaphylactic shock did not significantly vary between full-scale and computer screen-based simulators. Consequently, the initial decision on whether to use a full-scale or computer screen-based training simulator should be made on the basis of cost and learning objectives rather than on the basis of technical or fidelity criteria. Our results support the contention that screen-based simulators are good devices to acquire technical skills of crisis management. Mannequin-based simulators would probably provide better training for behavioral aspects of crisis management, such as communication, leadership, and interpersonal conflicts, but this was not tested in the current study. ⋯ We compared two different training simulators (computer screen-based versus full-scale) for training anesthesia residents to better document the effectiveness of such devices as training tools. This is an important issue, given the extensive use and the high cost of mannequin-based simulators in anesthesiology.