Regional anesthesia and pain medicine
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Reg Anesth Pain Med · May 2007
Clinical TrialHigh-resolution ultrasound-guided high interscalene plexus block for carotid endarterectomy.
High-resolution ultrasound imaging (HRUI) allows real-time visualization of peripheral nerves, needle insertion, and the spread of local-anesthetic (LA) solution. We evaluated the feasibility of performing a high interscalene brachial-plexus block for carotid endarterectomy by means of HRUI, thereby limiting the amount of LA to the dose required to sufficiently surround the relevant nerve structures. ⋯ High-resolution ultrasonic imaging allows clear depiction of the target tissues and facilitates accurate needle placement during high interscalene brachial-plexus blocks. This technique may minimize the risk of direct puncture-related complications, as well as accidental intravascular injection of LA. The observation of LA spread in all patients, even in small increments of less than 1 mL might enhance safety by limiting the injected LA to the actual demand. Well-placed LA spread could potentially avoid central nervous toxicity caused by intravascular injection or resorption of inadequately high dosages, in particular in nerve blocks of the highly vascularized neck region.
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Reg Anesth Pain Med · May 2007
Comparative StudyComparison of different injectate volumes for stellate ganglion block: an anatomic and radiologic study.
Volumes from 5 to 20 mL of local anesthetic are used for stellate ganglion block. The variation of practice gave us the impetus to investigate the distribution of 3 different volumes of solution. We documented the regions reached by each volume to assess the possibility to reduce the injectate to 5 mL. ⋯ The use of 5 mL results in an almost ideal vertical distribution in most of the cadavers, whereas high volumes--20 mL more so than 10 mL--are at risk of spreading extensively in both the vertical direction and also uncontrollably to other regions of the neck.
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Reg Anesth Pain Med · May 2007
Altered blood flow in terminal vessels after local application of ropivacaine and prilocaine.
Ropivacaine is primarily a local anesthetic, but it also acts as a vasoactive agent. Case reports have described a critical reduction in blood flow when higher concentrations of ropivacaine were used for peripheral-nerve blocks. One hypothesis is that local application of ropivacaine in tissues supplied by end arteries reduces tissue blood flow because of arterial vasoconstriction. ⋯ The application of ropivacaine directly to a rat's tail artery diminished blood flow and lowered regional skin temperature. These effects were dose related. The use of ropivacaine at higher concentrations can, therefore, not be recommended if tissues supplied by end arteries might be affected.