Anesthesiology
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Continuous epidural infusion of bupivacaine is widely practiced for postoperative pain relief in pediatric patients. However, bupivacaine may induce adverse effects in infants (convulsions or cardiac arrhythmias), likely because of decreased hepatic clearance and serum protein binding capacity. The authors wanted to examine the complex relations between age, alpha-1 acid glycoprotein (AAG) concentration, and unbound and total bupivacaine serum concentrations in infants receiving bupivacaine epidurally for 2 days. ⋯ Because of a low AAG concentration and a low intrinsic clearance, unbound bupivacaine increased to concentrations greater than 0.2 microg/ml in two infants younger than 2 months, after 2 days of infusion at a rate of 0.375 mg x kg(-1) x h(-1). The increase in AAG observed after surgery did not fully buffer this unbound fraction. Similarly, the buffer capacity of erythrocytes did not sufficiently increase at high concentration to compensate the saturation of the AAG system. Thus, we propose the use of a maximum dose of 0.25 mg x kg(-1) x h(-1) in infants younger than 4 months and a maximum of 0.3 mg x kg(-1) x h(-1) in infants older than 4 months.
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Randomized Controlled Trial Clinical Trial
Moderate hypothermia depresses arterial baroreflex control of heart rate during, and delays its recovery after, general anesthesia in humans.
Effects of hypothermia on arterial baroreflex function during, and on its recovery after, general anesthesia were examined in humans. ⋯ The results indicate that moderate hypothermia enhances anesthesia-induced depression of baroreflex function in anesthetized humans and delays its recovery after general anesthesia.
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Volatile anesthetics relax airway smooth muscle (ASM) by altering intracellular Ca2+ concentration ([Ca2+]i). The authors hypothesized that relaxation is produced by decreasing sarcoplasmic reticulum Ca2+ content via increased Ca2+ "leak" through both inositol trisphosphate (IP3) and ryanodine receptor channels. ⋯ The authors conclude that halothane reduces sarcoplasmic reticulum Ca2+ content in ASM cells via increased Ca2+ leak through both IP3 receptor and ryanodine receptor channels. Effects on IP3 receptor channels are both direct and indirect via elevation of IP3 levels.
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Comment Letter Biography Historical Article
Thomas Drysdale Buchanan or Henry Isaiah Dorr: give credit to both.