• Anesthesiology · May 1993

    Effect of vecuronium-induced neuromuscular blockade on cortical motor evoked potentials.

    • T B Sloan and R Erian.
    • Department of Anesthesiology, University of Texas Health Science Center, San Antonio 78284-7838.
    • Anesthesiology. 1993 May 1;78(5):966-73.

    BackgroundNeuromuscular blockade (NMB) is a frequent component of anesthetic techniques used during surgery in which monitoring of the nervous system is desirable. Because NMB should affect the evoked muscle response to transcranial magnetic stimulation (tcMMEP), their relationship in a primate model was characterized.MethodsTranscranial magnetic stimulation was characterized during NMB using an infusion of vecuronium in ten adult cynomologous monkeys during anesthesia with a continuous ketamine infusion. Neuromuscular blockade was measured by peak-to-peak amplitude of the evoked muscular activity (compound muscle action potential [m-response]) of the thenar muscles and mechanical muscle action (ratio of the fourth to first peak in the train of four [TOF]) after direct stimulation of the median nerve. Neuromuscular blockade was increased incrementally to complete block and then allowed to decrease until complete resolution of measurable block. Transcranial magnetic stimulation was assessed by measuring the onset latency (time from stimulation to beginning response) and amplitude of the thenar EMG response. Cortical stimulation was accomplished using a Cadwell MES-10 magnetic stimulator at 80% of full output (1.6 Tesla).ResultsThe tcMMEP, m-response amplitude, and mechanical muscle action, unblocked, were reduced with increasing NMB. Transcranial magnetic stimulation amplitude was more variable than was onset latency. Transcranial magnetic stimulation amplitude reduction from the baseline value did not achieve statistical significance until the m-response amplitude was reduced to 0.2 of baseline or until the TOF ratio was reduced to 0.1. Transcranial magnetic stimulation onset latency prolongation from baseline was not significantly affected by declining TOF ratios, but was prolonged when the m-response declined to 0.1 of baseline.ConclusionsThis study indicates that tcMMEP onset latency is not significantly affected by NMB if the degree of blockade in the muscles used for tcMMEP monitoring is not extreme (greater than 0.2 of baseline by m-response amplitude or a TOF ratio of 0.1 or greater). If monitoring of tcMMEP amplitude is desired, partial neuromuscular blockade may be acceptable. However, amplitude reduction may occur during partial NMB. Maintenance of a constant degree of NMB is suggested to minimize amplitude fluctuations.

      Pubmed     Full text   Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…