title: Effect of isometric thumb preload on the evoked compound muscle action potential.
abstract: The effect of thumb preload on adductor pollicis muscle compound action potential (ECAP) was assessed after supramaximal ulnar nerve stimulus during steady isoflurane anaesthesia in 20 ASA I-II patients without neuromuscular block. During thumb preload, the peak-to-peak amplitude of the ECAP increased by 0.9 mV, to 9.5 (SD 2.2) mV (P < 0.01), because of the increased height of the negative half-wave. The positive half-wave amplitude did not change, but its duration was prolonged by 0.7 ms, to 6.4 (0.7) ms (P < 0.05). Consequently, there was a 15.9% increase in the area of the response curve (P < 0.01). Without preload, the first dorsal interosseus muscle peak-to-peak amplitude was 13.0 (4.3) mV. Thus thumb preload may not be the solution to improved monitoring of neuromuscular block by ECAP.
authors.affiliation: City Maternity Hospital, Department of Anaesthesia, Helsinki, Finland.
authors.forename: I
authors.initials: I
authors.lastname: Kalli
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000328:Adult; D000768:Anesthesia, General; D005260:Female; D006801:Humans; D008875:Middle Aged; D009469:Neuromuscular Junction / Q000502:physiology*; D013314:Stress, Mechanical; D013933:Thumb / Q000502:physiology*; D014459:Ulnar Nerve / Q000502:physiology