Anesthesiology
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After severe hemorrhage, hypertonic saline restores systemic hemodynamics and decreases intracranial pressure (ICP), but its effects on regional cerebral blood flow (rCBF) when used for resuscitation of experimental animals with combined shock and intracranial hypertension have not been reported. We compared rCBF changes (by radiolabeled microsphere technique) after resuscitation from hemorrhage with either 0.8 or 7.2% saline in animals with and without a right hemispheric subdural mass. We studied 24 mongrel dogs anesthetized with 0.5% halothane and 60% nitrous oxide. ⋯ Once fluid resuscitation began, ICP was permitted to vary independently in both groups. Data were collected at baseline (before subdural balloon inflation in group 2), midway through the shock interval (T15), immediately after fluid infusion (T35), and 60 and 90 min later (T95, T155). In groups 1 and 2, ICP was significantly less in animals resuscitated with HS compared to those receiving SAL (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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The effects of topical application of local anesthetics on peripheral nerve blood flow (NBF) were studied in the rat sciatic nerve. Sciatic NBF was measured by laser doppler in 45 adult female Sprague-Dawley rats (90 nerves) after topical application of 25 microliter lidocaine and epinephrine, alone and in combination (lidocaine plus epinephrine), as well as bupivacaine, tetracaine, and normal saline, and studied in a randomized, blinded experimental design. NBF changes produced by lidocaine were dose-dependent. ⋯ Epinephrine 5.0 micrograms/ml and epinephrine 10.0 micrograms/ml produced reductions of 20% and 35%, respectively (P less than 0.05), which lasted throughout the study. The effects of each of the three concentrations were significantly different from the others. The combination of lidocaine plus epinephrine resulted in synergistic reduction of NBF for all drug concentrations (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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Comparative Study
Dose-response for atropine and heart rate in infants and children anesthetized with halothane and nitrous oxide.
The dose recommendations for atropine in anesthetized children vary, and the dose-response for heart rate has not been defined. We determined the dose-response for atropine and heart rate in 181 healthy children anesthetized with halothane and nitrous oxide. After induction of anesthesia, atropine in a dose of 5, 10, 20, 30, or 40 micrograms.kg-1 was administered by rapid intravenous infusion of each subject. ⋯ Subjects less than 6 months old had higher control and peak heart rates than did subjects greater than or equal to 2 yr old, but the older subjects had greater change in heart rate after atropine. For subjects greater than or equal to 2 yr old, all doses of atropine produced a significant increase in heart rate. The same was true for younger subjects, less than 6 months old, except that 5 micrograms.kg-1 did not increase heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)