Articles: anesthetics.
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Anesthesia and analgesia · Sep 1983
Evaluation of neurotoxicity after subarachnoid injection of large volumes of local anesthetic solutions.
Recent case reports describing prolonged neurologic deficit after accidental spinal anesthesia with large volumes of 2-chloroprocaine have led to the suggestion that chloroprocaine may be more likely to cause such complications than other local anesthetics. We evaluated the neurologic effects of lumbar puncture alone and of large-volume subarachnoid administration of 2-chloroprocaine (3%), bupivacaine (0.75%), lidocaine (2%), Elliott's solution B (which is similar to CSF), or the carrier solution of 2-chloroprocaine (Nesacaine) in 48 sheep and 8 monkeys. Cerebrospinal fluid of sheep was collected on days 1 and 7 for biochemical and biological analyses, and CSF pressures of monkeys were recorded before and after injection. ⋯ Three of the eight monkeys had lumbar subpial demyelination with macrophage invasion; two had received bupivacaine, and one received 2-chloroprocaine. No solution produced significant abnormalities in sheep CSF composition. We conclude that no local anesthetic or solution was more neurotoxic than another when injected in large volumes into the subarachnoid space of sheep or monkeys.
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Alphadione, a steroidal anesthetic formulation containing alphaxalone (3 alpha-hydroxy-5 alpha-pregnane-11, 20-dione) and alphadolone acetate (21-acetoxy-3 alpha-hydoroxy-5 alpha-pregnane-11, 20-dione) in polyoxyethylated castor oil (Cremophor EL) owes its short duration of action to rapid metabolic transformation rather than the redistribution into the body fat. Treatment of rats with alphadione (1 ml/kg; intraperitoneal route) induced an increase in the cytochrome P-450 content of the liver. The difference spectra were obtained only when alphadione or alphaxalone was added to the liver microsomal suspension while neither alphadolone acetate nor Cremophor EL induced any spectral changes. The spectral dissociation constant (Ks) for alphaxalone was 2.5 X 10(-3) mM suggesting that hydroxylation of alphaxalone is a cytochrome P-450 dependent reaction.
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Randomized Controlled Trial Clinical Trial
Cardiovascular response to intubation. A comparative study of thiopentone and midazolam.
The cardiovascular response evoked by tracheal intubation was observed in 20 patients undergoing elective abdominal surgery in whom anaesthesia was induced with either midazolam 0.3 mg/kg or thiopentone 4.5 mg/kg followed by pancuronium 0.1 mg/kg. In the thiopentone group, intubation caused a mean rise in systolic arterial pressure from 141 to 193 mmHg (p less than 0.0005) and in the heart rate-systolic pressure product from 11101 to 21763 (p less than 0.05); 5 minutes later the mean values were still 173 mmHg and 19030 respectively. In the midazolam group systolic arterial pressure and the rate pressure product increased from 138 to 151 mmHg and 10960 to 14267 respectively in response to intubation. These values were significantly lower than the thiopentone group (p less than 0.005 in each case) and were relatively transient and returned to control values within 5 minutes.
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Review
General kinetic and dynamic principles and their application to continuous infusion anaesthesia.
The use of intravenous anaesthetic agents by continuous infusion requires knowledge of their pharmacokinetic properties. In this article, the general pharmacokinetic principles behind the use of infusions of intravenous agents are presented and the literature with regard to the individual drugs used in this way is reviewed.