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Within-patient variability of myogenic motor-evoked potentials to multipulse transcranial electrical stimulation during two levels of partial neuromuscular blockade in aortic surgery.

Abstract：

UNLABELLED:Intraoperative recording of myogenic motor responses evoked by transcranial electrical stimulation (tcMEPs) is a method of assessing the integrity of the motor pathways during aortic surgery. To identify conditions for optimal spinal cord monitoring, we investigated the effects of manipulating the level of neuromuscular blockade (T1 response of the train-of-four (TOF) stimulation 5%-15% versus T1 response 45%-55% of baseline), as well as the number of transcranial pulses (two versus six stimuli) on the within-patient variability and amplitude of tcMEPs. Ten patients (30-76 yr) scheduled to undergo surgery on the thoracic and thoracoabdominal aorta were studied. After achieving a stable anesthetic state and before surgery, 10 tcMEPs were recorded from the right extensor digitorum communis muscle and the right tibialis anterior muscle in response to two-pulse and six-pulse transcranial electrical stimulation with an interstimulus interval of 2 ms during two levels of neuromuscular blockade. The right thenar eminence was used for recording the level of relaxation. The tcMEP amplitude using the six-pulse paradigm was larger (P < 0.01; leg and arm) compared with the amplitude evoked by two-pulse stimulation during both levels of relaxation. The within-patient variability, expressed as median coefficient of variation, was less when six-pulse stimulation was used. At a T1 response of 45%-55% of baseline, larger, less variable tcMEPs were recorded than at a T1 response of 5%-15%. Our results suggest that the best quality of tcMEP signals (tibialis anterior muscle) is obtained when the six-pulse paradigm is used with a stable level of muscle relaxation (the first twitch of the TOF-thenar eminence-at 45%-55% of baseline). IMPLICATIONS:This study shows that six-pulse (rather than two-pulse) transcranial electrical stimulation during a stable anesthetic state and a stable neuromuscular blockade aimed at 45%-55% (rather than 5%-15%) of baseline provides reliable and recordable muscle responses sufficiently robust for spinal cord monitoring in aortic surgery.

journal_name

Anesth Analg

journal_title

Anesthesia and analgesia

authors

van Dongen EP,ter Beek HT,Schepens MA,Morshuis WJ,Langemeijer HJ,de Boer A,Boezeman EH

doi

10.1097/00000539-199901000-00005

subject

Has Abstract

pub_date

1999-01-01 00:00:00

pages

22-7

issue

eissn

0003-2999

issn

1526-7598

journal_volume

pub_type

临床试验,杂志文章

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Within-patient variability of myogenic motor-evoked potentials to multipulse transcranial electrical stimulation during two levels of partial neuromuscular blockade in aortic surgery.