Canadian journal of anaesthesia = Journal canadien d'anesthésie
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A combination of lumbar plexus block, by a posterior technique, and sciatic nerve block can be a useful technique for outpatient anaesthesia. The purpose of this study was to examine the clinical characteristics of these blocks using lidocaine and to measure the serum lidocaine concentrations. Forty-five patients, undergoing lower extremity surgery, were studied. ⋯ This was associated with a contra-lateral extension of the block. We conclude that this combination of blocks is a valuable alternative for unilateral lower extremity anaesthesia. However, clinicians must be aware of the implications of a contra-lateral extension of the block.
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The purpose of this study was to describe the relation of the lumbar plexus with the psoas major and with the superficial and deep landmarks close to it. Four cadavers were dissected and 22 computed tomography files of the lumbosacral region studied. Cadaver dissections demonstrated that the lumbar plexus, at the level of L5, is within the substance of the psoas major muscle rather than between this muscle and the quadratus lumborum. ⋯ However, while the lateral femoral cutaneous nerve is in the same fascial plane as the femoral nerve, the obturator nerve can be found in the same plane as the two other nerves or in its own muscular fold. Radiological data provided the following measurements: the femoral nerve is at a depth of 9.01 +/- 2.43 cm; the psoas major medial border is at 2.73 +/- 0.64 cm from the median sagittal plane; and its lateral border is at 6.41 +/- 1.61 cm from the same plane. It is concluded that the lumbar plexus is within the psoas major, that the obturator nerve localization within the psoas major varies and that computed tomography data define precisely the relationship of the lumbar plexus with superficial and deep landmarks.
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Although spinal and epidural blocks provide excellent anaesthesia for many operations, they are frequently accompanied by hypotension. This is largely the result of sympathetic nerve blockade. Excessive hypotension may potentially produce myocardial and cerebral ischaemia, and is associated with neonatal acidaemia in obstetric practice. ⋯ In non-obstetric practice, ephedrine has a good track record but again its success rate is less than 100%. As there is no fetus to consider, it may be more appropriate to consider using a pure vasoconstrictor agent such as methoxamine or phenylephrine as a first-line therapy in such cases. This judgment can only be made on an individual patient basis as ephedrine produces a tachycardia while phenylephrine and methoxamine both produce bradycardia.