Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2006
Randomized Controlled TrialIntraoperative administration of tramadol for postoperative nurse-controlled analgesia resulted in earlier awakening and less sedation than morphine in children after cardiac surgery.
In adults, intraoperative administration of tramadol could result in earlier recovery and less sedation than morphine. In this controlled, randomized, double-blind study, we investigated whether an intraoperative initial dose of tramadol could cause more rapid awakening from general anesthesia, less sedation, and earlier tracheal extubation than morphine in children during the immediate postoperative period. Forty children aged 1-6 yr, scheduled for atrial or ventricular septal defect repair and tracheal extubation in the pediatric intensive care unit, were randomly allocated to receive morphine, initial dose 0.2 mg/kg, or tramadol 2 mg/kg given at the end of sternal closure, followed by nurse-controlled analgesia (bolus 0.02 mg/kg of morphine and 0.2 mg/kg of tramadol) with background infusions (0.015 mg x kg(-1) x h(-1) for morphine and 0.15 mg x kg(-1) x h(-1) for tramadol). ⋯ Times to first trigger of nurse-controlled analgesia bolus and objective pain scores during the 48 h observation period were comparable between groups. The incidence of desaturation and emesis were similar between groups. The patients ate well and did not differ on Day 1 or Day 2.
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Anesthesia and analgesia · Jun 2006
Randomized Controlled Trial Comparative StudyA comparison of epidural blockade produced by plain 1% lidocaine and 1% lidocaine prepared by dilution of 2% lidocaine with the same volume of saline.
Local anesthetics are commonly diluted with saline, but the influence of the dilution on the epidural anesthesia remains unclear. We randomized 40 patients scheduled for gynecological abdominal surgery under epidural anesthesia to one of two groups; those in group P received plain commercially prepared 1% lidocaine and those in group D received 1% lidocaine derived from 2% lidocaine and the same volume of saline was infused epidurally with an epidural catheter at L1-2. The pH and sodium and chloride ion concentrations of the solutions were measured. ⋯ The increase of foot temperature and decrease of mean arterial blood pressure were significantly faster in group P than in group D. Although the mean pH values of the two solutions were similar, sodium and chloride ion concentrations of the diluted solution were significantly larger than those of the plain solution. We conclude that 2% lidocaine diluted with the same volume of saline produces less potent epidural blockade than commercially prepared plain 1% lidocaine.
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Anesthesia and analgesia · Jun 2006
The differential effects of halothane and isoflurane on electroencephalographic responses to electrical microstimulation of the reticular formation.
Isoflurane and halothane cause electroencephalographic (EEG) depression and neuronal depression in the reticular formation, a site critical to consciousness. We hypothesized that isoflurane, more than halothane, would depress EEG activation elicited by electrical microstimulation of the reticular formation. Rats were anesthetized with either halothane or isoflurane and stimulating electrodes were positioned in the reticular formation. ⋯ At 1.2 MAC isoflurane, burst suppression occurred and microstimulation decreased the period of isoelectricity (24% +/- 19% to 8% +/- 7%; P < 0.05), whereas the spectral edge and median edge frequencies were unchanged. At anesthetic concentrations required to produce immobility, the cortex remains responsive to electrical microstimulation of the reticular formation, although the EEG response is depressed in the transition from 0.8 to 1.2 MAC. These data indicate that cortical neurons remain responsive to synaptic input during isoflurane and halothane anesthesia.
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Anesthesia and analgesia · Jun 2006
Controlled Clinical TrialThe effects of age on the median effective concentration of ropivacaine for motor blockade after epidural anesthesia with ropivacaine.
Minimal local analgesic concentrations have been defined as the median effective concentration (EC50). In this study, we sought to examine the effect of age on motor blockade and determine the motor block EC50 of elderly patients after epidural administration of ropivacaine in patients undergoing urological or minor lower limb surgery. ASA physical status I-II patients were enrolled in 1 of 2 age groups (Group 1: > or =70 yr; Group 2: <70 yr). ⋯ Effective motor blockade was defined as a modified Bromage score >0 within 30 min. The motor blockade EC50 of ropivacaine was 0.383% (95% confidence interval, 0.358%-0. 409%) in group 1 and 0.536% (95% confidence interval, 0.512%-0.556%) in group 2 (P < 0.01). We conclude that age is a determinant of motor blockade EC50 of ropivacaine with epidural administration.
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Anesthesia and analgesia · Jun 2006
ReviewMorphine-6-glucuronide: morphine's successor for postoperative pain relief?
In searching for an analgesic with fewer side effects than morphine, examination of morphine's active metabolite, morphine-6-glucuronide (M6G), suggests that M6G is possibly such a drug. In contrast to morphine, M6G is not metabolized but excreted via the kidneys and exhibits enterohepatic cycling, as it is a substrate for multidrug resistance transporter proteins in the liver and intestines. M6G exhibits a delay in its analgesic effect (blood-effect site equilibration half-life 4-8 h), which is partly related to slow passage through the blood-brain barrier and distribution within the brain compartment. ⋯ At analgesic doses, M6G causes similar reduction of the ventilatory response to CO2 as an equianalgesic dose of morphine but significantly less depression of the hypoxic ventilatory response. Preliminary data indicate that M6G is associated less than morphine with nausea and vomiting, causing 50% and 75% less nausea in postoperative and experimental settings, respectively. Although the data from the literature are very promising, we believe that more studies are necessary before we may conclude that M6G is superior to morphine for postoperative analgesia.