Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2001
The effect of large-dose intrathecal opioids on the autonomic nervous system.
Decreases in blood pressure after the spinal injection of opioids suggest that intrathecal (IT) opioids may have a sympatholytic effect similar to that of local anesthetic drugs. We compared two groups of patients aged 10-16 yr (n = 10 in each group). Group One (IT group) received IT opioids. Group Two (Epidural group) received 0.5% bupivacaine epidurally. The sympathetic effects of IT opioids and epidural bupivacaine were monitored by the changes in toe relative to calf temperature and by the changes in pulse wave gradients with digital plethysmography. Changes in temperature gradients comparing calf to toe and increases in pulse amplitude indicate vasodilatation caused by sympathetic blockade in this model. Calf to toe temperature gradients (Deltacalf-Deltatoe) were evaluated by subtracting the two measurements. Pulse wave plethysmography was recorded before and after spinal and epidural injection at intervals of 10 min for 40 min. All patients demonstrated changes in their calf to toe gradients after IT and epidural injections (-3.2 +/- 1.6). Systolic blood pressure decreased from a mean of 70 +/- 15 mm Hg to 55 +/- 10 mm Hg. Pulse wave plethysmography amplitude increased after the intrathecal opioid and epidural bupivacaine injection similarly. We conclude that the increases in pulse wave amplitude and decreases in calf-toe gradients indicate a sympatholytic effect after IT opioids similar to that of local anesthetics. ⋯ The sympatholytic effects of neuraxial opioids were compared with those of local anesthetics. Two groups of patients were assigned to receive a neuraxial opioid or bupivacaine. Our results demonstrate that opioids cause hypotension and peripheral vasodilatation similar to bupivacaine. This finding suggests that neuraxial opioids have a sympatholytic effect comparable to that of local anesthetic drugs.
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Anesthesia and analgesia · Aug 2001
Case ReportsUnmasked residual neuromuscular block after administration of vecuronium for days.
Significant neuromuscular block may be present in patients who have received vecuronium for days.
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Anesthesia and analgesia · Aug 2001
Designing meaningful industry metrics for clinical productivity for anesthesiology departments.
Clinical productivity measurements that account for differences in clinical settings and concurrencies provided more precise comparisons between two anesthesiology groups. The data show that different concurrencies confound the current industry standard, "per full-time equivalent" measurements, whereas "per operating room site" and "per case" measurements allowed for more meaningful comparisons.
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Anesthesia and analgesia · Aug 2001
The pharmacokinetics and pharmacodynamics of bupivacaine-loaded microspheres on a brachial plexus block model in sheep.
We evaluated bupivacaine-loaded microspheres (B-Ms) using a brachial plexus block model in sheep. In the first step, pharmacokinetic characterization of 75 mg bupivacaine hydrochloride (B-HCl) (IV infusion and brachial plexus block) was performed (n = 12). In the second step, a brachial plexus block dose response study of B-HCl was performed with 37.5 mg, 75 mg, 150 mg, 300 mg, and 750 mg. As a comparison, evaluations were performed using a 750-mg bupivacaine base (B). In the third step, evaluations of brachial plexus block were performed with B-Ms (750 mg of B as B-Ms) using two formulations, 60/40 and 50/50 (w/w %); drug-free microspheres were also evaluated. Toxicity evaluations were also performed after IV administration of B-HCl (750 mg and 300 mg), B-Ms (750 mg), and drug-free microspheres (30 mL over 1 min). As the B-HCl dose increased, the time of onset of block decreased and the duration of complete motor blockade increased at the expense of an increase in bupivacaine plasma concentrations. The time of maximum concentration appeared to be independent of the B-HCl dose. In brachial plexus block, a 37.5-mg dose of B-HCl did not induce motor blockade whereas a dose of 750 mg of B-HCl was clinically toxic. In the case of IV administration, doses of 300 mg of B-HCl were as toxic as 750 mg of B-HCl. Compared with the 75 mg of B-HCl administration for brachial plexus block, administration of 750 mg of B as B-Ms increased the duration of complete motor blockade without significant difference in maximum concentration. No significant clinical difference between the two formulations of B-Ms was demonstrated. The IV administration of B-Ms was safe. We conclude that the controlled release of bupivacaine from microspheres prolonged the brachial plexus block without obvious toxicity. ⋯ Administration of 750 mg of bupivacaine as loaded-microspheres resulted in prolongation of brachial plexus block in sheep. The peak plasma concentration was not significantly larger than that obtained with 75 mg of plain bupivacaine. The motor blockade was increased more than six times compared with 75 mg plain bupivacaine.