Anesthesiology
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A stimulation current of no more than 0.5 mA is regarded as safe in avoiding nerve injury and delivering adequate stimulus to provoke a motor response. However, there is no consistent level of stimulating threshold that reliably indicates intraneural placement of the needle. The authors determined the minimally required stimulation threshold to elicit a motor response outside and inside the most superficial part of the brachial plexus during high-resolution, ultrasound-guided, supraclavicular block. ⋯ Within the limitations of this study and the use of ultrasound, a stimulation current of 0.2 mA or less is reliable to detect intraneural placement of the needle. Furthermore, stimulation currents of more than 0.2 and no more than 0.5 mA could not rule out intraneural position.
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Randomized Controlled Trial Comparative Study
Is the performance of acceleromyography improved with preload and normalization? A comparison with mechanomyography.
Many studies have indicated that acceleromyography and mechanomyography cannot be used interchangeably. To improve the agreement between the two methods, it has been suggested to use a preload and to refer all train-of-four (TOF) ratios to the control TOF (normalization) when using acceleromyography. The first purpose of this study was to test whether a preload applied to acceleromyography would increase the precision and the agreement with mechanomyography. The second purpose was to evaluate whether normalization would improve the agreement with mechanomyography. ⋯ Preload increases the precision of acceleromyography, and normalization of the TOF ratios decreases bias in relation to mechanomyography. When both acceleromyography and mechanomyography are normalized, there is no significant bias between the two methods.