Articles: nerve-block.
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Acta Anaesthesiol Scand · May 2002
Case ReportsTachycardia and convulsions induced by accidental intravascular ropivacaine injection during sciatic block.
Ropivacaine, a recently introduced local anesthetic of the amide family (1), seems to show less toxicity than bupivacaine (2-4). Nevertheless, both neurologic and cardiovascular toxicities are possible. Six cases of ropivacaine-induced convulsions have previously been reported (5-10), of which three cases also showed cardiovascular toxicity. In three cases, total plasma concentrations were measured (Table 1).
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Anesthesia and analgesia · May 2002
Comparative StudyA comparison of intertendinous and classical approaches to popliteal nerve block using magnetic resonance imaging simulation.
The classical approach to sciatic nerve block in the popliteal fossa (popliteal block) often requires multiple attempts to localize the sciatic nerve. Recently, it has been suggested that an intertendinous approach to popliteal block may result in a more consistent localization of the sciatic nerve. In the current study, we compared anatomical landmarks for the intertendinous and classical approaches to popliteal block with respect to the accuracy in localizing the sciatic nerve using magnetic resonance imaging simulation. Two anesthesiologists experienced in popliteal block drew landmarks for the intertendinous and classical approaches on 10 volunteers; a 1.5 Tesla superconducting magnet was used to obtain simultaneous, 10-mm thick, fast-spin echo proton density transverse axial sequences of the lower extremities. Using these acquired images, the two approaches were simulated off-line using previously identified landmarks. The spatial relationships of the simulated needle paths to the nerves and vessels in the popliteal fossa, as well as other relevant structures, were measured and compared. Simulation of the intertendinous approach to popliteal block resulted in needle-to-sciatic nerve contact in 14 legs (70%) versus 5 legs (25%) when the classical approach was used (P < 0.05). We conclude that the intertendinous approach might result in a more consistent localization of the sciatic nerve and may decrease the risk of sciatic vessel puncture. ⋯ A simulation of popliteal block using magnetic resonance imaging in volunteers suggests that using tendons of the hamstring muscles as the anatomical landmarks yields a more consistent localization of the sciatic nerve.
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Anesthesia and analgesia · May 2002
The effects of age on neural blockade and hemodynamic changes after epidural anesthesia with ropivacaine.
We studied the influence of age on the neural blockade and hemodynamic changes after the epidural administration of ropivacaine 1.0% in patients undergoing orthopedic, urological, gynecological, or lower abdominal surgery. Fifty-four patients were enrolled in one of three age groups (Group 1: 18-40 yr; Group 2: 41-60 yr; Group 3: > or=61 yr). After a test dose of 3 mL of prilocaine 1.0% with epinephrine 5 microg/mL, 15 mL of ropivacaine 1.0% was administered epidurally. The level of analgesia and degree of motor blockade were assessed, and hemodynamic variables were recorded at standardized intervals. The upper level of analgesia differed among all groups (medians: Group 1: T8; Group 2: T6; Group 3: T4). Motor blockade was more intense in the oldest compared with the youngest age group. The incidence of bradycardia and hypotension and the maximal decrease in mean arterial blood pressure during the first hour after the epidural injection (median of Group 1: 11 mm Hg; Group 2: 16 mm Hg; Group 3: 29 mm Hg) were more frequent in the oldest age group. We conclude that age influences the clinical profile of ropivacaine 1.0%. The hemodynamic effects in older patients may be caused by the high thoracic spread of analgesia, although a diminished hemodynamic homeostasis may contribute. ⋯ Analgesia levels after the epidural administration of 15 mL of ropivacaine 1.0% increase with increasing age. This is associated with an increased incidence of hypotension in the elderly, although an effect of age on the hemodynamic homeostasis may have contributed. It appears that epidural doses should be adjusted for elderly patients.
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Anesthesia and analgesia · May 2002
Case ReportsProjected complex sensations after interscalene brachial plexus block.
The development of projected complex sensations mimicking phantom pain after interscalene block is reported. The recognition of this entity is important because it may be confused with some other cardiac, esophageal, or visceral pathologies.