Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1992
Comparative StudyProlongation of epidural anesthesia using a lipid drug carrier with procaine, lidocaine, and tetracaine.
This study evaluated the effect of a lipid drug carrier (iophendylate) on epidural anesthesia. The intensity and duration of motor blockade produced by aqueous and lipid preparations of local anesthetics were assessed in rabbits with long-term indwelling catheters in the epidural space. Motor blockades produced by procaine (1%, 2%, and 4%), lidocaine (1%, 2%, and 4%), and tetracaine (0.5%, 1%, and 2%) in normal saline solution were compared with the effects produced by equimolar amounts of the drug solutions in iophendylate. ⋯ A control group of animals that received normal saline solution or iophendylate alone did not exhibit motor blockade. These results may be attributed to sustained release of local anesthetics from the lipid vehicle. Hence, lipid drug carriers may be effective in prolonging epidural anesthesia.
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Anesthesia and analgesia · Dec 1992
Alfentanil-induced hypermetabolism, seizure, and histopathology in rat brain.
We evaluated the effect of alfentanil on hippocampal glucose utilization and histopathology associated with alfentanil-induced seizures. Three separate experiments were performed. First, anesthetized, paralyzed Long-Evans rats (n = 15; 5 rats per group) were mechanically ventilated and randomly assigned to three groups: (a) control, 70% N2O and 30% O2 continued for 1 h; (b) low-dose alfentanil (150 micrograms/kg i.v. bolus), followed by infusion at 15 micrograms.kg-1 x min-1 for 1 h without N2O; or (c) high-dose alfentanil (1000 micrograms/kg i.v. bolus), followed by infusion at 100 micrograms.kg-1 x min-1 for 1 h without N2O. ⋯ After tracheal extubation, the rats recovered overnight. Light-microscopic evaluation revealed hippocampal or amygdaloid damage in 6 of the 10 alfentanil-treated rats. High doses of alfentanil administered to rats can produce limbic system seizure activity with hypermetabolism associated with neuropathologic lesions.
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Anesthesia and analgesia · Dec 1992
Randomized Controlled Trial Clinical TrialEffectiveness of preoperative sedation with rectal midazolam, ketamine, or their combination in young children.
To determine which of three types of rectal sedation was most effective preoperatively in facilitating parental separation and intravenous cannulation in young children, 100 children 3.0 +/- 1.7 (mean +/- SD) yr of age were randomly assigned to four equal groups. One group (M-K-A) received rectal midazolam (0.5 mg/kg), ketamine (3 mg/kg), and atropine (0.02 mg/kg). The other sedation groups received the same doses of midazolam and atropine (M-A) or ketamine and atropine (K-A) alone, and the control group (A) received only rectal atropine. ⋯ Intravenous catheter placement was also successful significantly more often in the M-A (80%) and M-K-A (84%) groups than in the K-A (48%) or A (40%) groups. Complications were similar among the groups, but there was evidence that midazolam prolonged recovery time in some patients. Rectal midazolam with or without ketamine is a useful technique when intravenous catheter placement before induction of anesthesia is desired.
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Extracorporeal membrane oxygenation is still a relatively new technology that has recently achieved recognition after initial clinical disappointment in the late 1970s. At present, it is considered standard therapy for the full-term infant with PPHN who fails CMV and extraordinary, heroic therapy for older children and adults with ARF or cardiac failure, or both. ⋯ Areas of interest include heparinless circuits, carotid artery reconstruction, improved monitoring, and expanding applications of VV ECMO. As ECMO becomes safer and more effective, it is believed that new and expanding patient populations will emerge to include premature infants, earlier intervention in term infants, and more liberal application to pediatric and adult populations.
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Anesthesia and analgesia · Dec 1992
Thermoregulatory vasoconstriction during propofol/nitrous oxide anesthesia in humans: threshold and oxyhemoglobin saturation.
To determine the thermoregulatory effects of propofol and nitrous oxide, we measured the threshold for peripheral vasoconstriction in seven volunteers over a total of 13 study days. We also evaluated the effect of vasoconstriction on oxyhemoglobin saturation (SpO2). Anesthesia was induced with an intravenous bolus dose of propofol (2 mg/kg), followed by an infusion of 180 micrograms.kg-1 x min-1 for 15 min, and maintained with 60% nitrous oxide and propofol (80-160 micrograms.kg-1 x min-1). ⋯ These data suggest that anesthesia with propofol, in typical clinical concentrations, and 60% nitrous oxide substantially inhibits thermoregulatory vasoconstriction. Vasoconstriction increased SpO2 by approximately 2% without a significant concomitant change in PO2. The observed increase in SpO2 probably reflects decreased transmission of arterial pulsations to venous blood in the finger.