Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Nov 2005
Vertical infraclavicular block of the brachial plexus: effects on hemidiaphragmatic movement and ventilatory function.
Several case reports have suggested that block of the brachial plexus by the vertical infraclavicular approach influences hemidiaphragmatic movement and ventilatory function. These effects have not been evaluated in a prospective study. ⋯ The vertical infraclavicular block can result in a change in ipsilateral hemidiaphragmatic movement, with a decrease of ventilatory function. Although a correlation between the presence of Horner's syndrome and hemidiaphragmatic dysfunction was observed, hemidiaphragmatic dysfunction also occurred independently.
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Reg Anesth Pain Med · Nov 2005
ReviewAcute toxicity of local anesthetics: underlying pharmacokinetic and pharmacodynamic concepts.
The risk of accidental intravascular injection and consequent acute toxicity is ever-present with most neural blockade techniques. The severity of cardiovascular and central nervous system (respectively, CVS and CNS) toxicity is directly related to the local anesthetic potency, dose, and rate of administration. Nonetheless, although the anesthetic potency of ropivacaine and levobupivacaine is similar to that of bupivacaine, at usual clinical doses, ropivacaine and levobupivacaine are less likely than bupivacaine to cause convulsions or lethal dysrhythmias. ⋯ This is an underlying tenet of dose fractionation, but the main advantage of dose fractionation is that the anesthesiologist is able to cease administration with less of the dose given if signs or symptoms of toxicity occur. Overall, it appears that the gains in safety from ropivacaine and levobupivacaine are due more to favorable pharmacodynamic enantioselectivity than to pharmacokinetic factors. This essay presents some pharmacokinetic aspects relevant to acute toxicity of local anesthetics, mainly using data from the authors' studies in a sheep model of simulated accidental intravenous administration.