Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2002
Randomized Controlled Trial Clinical TrialSlow rewarming has no effects on the decrease in jugular venous oxygen hemoglobin saturation and long-term cognitive outcome in diabetic patients.
The purpose of this study was to examine the effects of rewarming rate on internal jugular venous oxygen hemoglobin saturation (SjvO(2)) during the rewarming period, and long-term cognitive outcome in diabetic patients. We studied 30 diabetic patients scheduled for elective coronary artery bypass graft surgery. As a control, 30 age-matched nondiabetic patients were identified. The diabetic patients were randomly divided into two groups: the Slow Rewarming group (n = 15) (mean rewarming speed: 0.22 degrees +/- 0.07 degrees C/min, mean +/- SD) or the Standard Rewarming group (Standard group) (n = 15) (mean rewarming speed: 0.46 degrees +/- 0.09 degrees C/min, mean +/- SD). After the induction of anesthesia, a fiberoptic oximetry catheter was inserted into the right jugular bulb to monitor SjvO(2) continuously. Hemodynamic variables and arterial and jugular venous blood gases were measured at nine time points. All patients underwent a battery of neurologic and neuropsychologic tests on the day before the operation and at 4 mo after surgery. The SjvO(2) values in the Standard group were decreased during the rewarming period compared with at the induction of anesthesia (P < 0.05). There was a significant difference in the SjvO(2) value in the Control group between standard rewarming and slow rewarming during rewarming periods (Standard Control group: 51% +/- 8%, Slow Control groups: 58% +/- 5%) (P < 0.05). However, there was no difference in the SjvO(2) value in diabetic patients between standard rewarming and slow rewarming during the rewarming period. The rewarming rates (odds ratio: 0.8; 95% confidence interval: 0.5-1.3; P = 0.6) had no correlation with cognitive impairment at 4 mo after the surgery. Diabetes (odds ratio: 1.6; 95% confidence interval: 0.9-2.6; P = 0.04) was a factor in relation to cognitive impairment at 4 mo after the surgery. We concluded that a slow rewarming rate had no effects on the reduction in SjvO(2) value and long-term cognitive outcome in diabetic patients. ⋯ We examined the effects of rewarming rate on internal jugular venous oxygen hemoglobin saturation in diabetic and nondiabetic patients during the rewarming period and long-term cognitive outcome. Slow rewarming could not prevent the frequency of the reduction in internal jugular venous oxygen hemoglobin saturation and adverse cognitive outcome in diabetic patients.
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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
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.
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Anesthesia and analgesia · Jun 2002
Comparative StudyThe bispectral index and explicit recall during the intraoperative wake-up test for scoliosis surgery.
In this prospective study, we evaluated the bispectral index (BIS) and postoperative recall during the intraoperative wake-up examination in 34 children and adolescents undergoing scoliosis surgery. Each anesthesiologist was blinded to BIS values throughout surgery and the wake-up test. The BIS, mean arterial blood pressure, and heart rate were compared at: before starting the wake-up test, patient movement to command, and after the patient was reanesthetized. The anesthetic technique for Group 1 was small-dose isoflurane, nitrous oxide, fentanyl, and midazolam and for Group 2 was nitrous oxide, fentanyl, and midazolam. Controlled hypotension was used for all cases. At patient movement to command, the patients were told a specific color to remember (teal) and on the second postoperative day were interviewed for explicit recall of the color and other intraoperative events. A total of 37 wake-up tests were performed in 34 patients. There was a significant increase in both groups of BIS (P < 0.001), mean arterial blood pressure (P < 0.001), and heart rate (P < 0.01) at the time of purposeful patient movement followed by a significant decline in BIS after reintroduction of anesthesia (P < 0.01). No patient recalled intraoperative pain, one patient recalled the wake-up test but not the color, and five patients recalled the specified color. We conclude that BIS may be a useful clinical monitor for predicting patient movement to command during the intraoperative wake-up test, particularly when controlled hypotension is used and hemodynamic responses to emergence of anesthesia are blunted. ⋯ The relationship between bispectral index (BIS) and purposeful intraoperative patient movement is consistent with previous BIS utility studies. We conclude that BIS may be a useful clinical monitor for predicting patient movement to command during the intraoperative wake-up test, particularly when controlled hypotension is used and hemodynamic responses to emergence of anesthesia are blunted.