Regional-Anaesthesie
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Regional-Anaesthesie · Sep 1990
[In electric nerve stimulation can the distance from the nerves be inferred from the intensity of muscle contraction? Possible parameters and sources of error].
Electrical nerve stimulation is a useful tool in regional anesthesia; it assists in locating the nerves. This investigation deals with electrical resistances at adhesive electrodes attached to the skin. The influence of external electrical resistance on the stimulating impulse is demonstrated. ⋯ Axillary puncture of the brachial plexus resulted in the following values: (1) A stimulating impulse (cross-wave) of 1 mA and 1 ms exerted at a distance of 4 mm to the nerve induced a contraction of strength 3. (2) Reducing the impulse at this site by one-half (0.55 mA) resulted in just-visible contractions (strength 1). (3) Advancing the cannula at a stimulating impulse of 0.55 mA inside the neurovascular sheath again produced contractions of strength 3. (4) Performing the puncture with a blunt needle and tracing a distinct resistance, the impulse of 0.6 mA elicited contractions of strength 2. The needle tip was still outside the vascular nerve sheath. If this resistance was overcome and the needle tip lay inside the neurovascular sheath, the impulse could be reduced by one-half (0.32 mA) to produce contractions of strength 2.
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Regional-Anaesthesie · Sep 1990
Randomized Controlled Trial Clinical Trial[The effect of volume and dosage of isobaric bupivacaine on the sensory spread of spinal anesthesia].
There is some controversy about the relationship of volume, concentration and total dose of bupivacaine in the sensory spread of spinal anesthesia. In this study the effects of volume and dose were investigated. MATERIAL AND METHODS. ⋯ Earlier studies on the effects of changes in volume, concentration and dose of bupivacaine showed similar "jumps of blockade" between 2 ml and 3 ml injected volume. Assembling the results the relation between volume and total dose does not suggest a no linear dependence. The anatomic configuration of the spinal cord at the conus medullaris may affect the distribution of the solution.