Comparison of phonomyography, kinemyography and mechanomyography for neuromuscular monitoring

Purpose: The gold standard of neuromuscular monitoring is mechanomyography (MMG). Phonomyography (PMG) and kinemyography (KMG) are new methods of neuromuscular monitoring. In this study, all three methods were compared to determine neuromuscular blockade at the adductor pollicis muscle. Methods: In 14 patients, phonomyography was recorded via a microphone taped to the thenar region. A standard mechanomyographic device was applied to the same thumb, and attached to the force transducer. On the contralateral side, a NMT-Mechanosensor(R) probe was attached to the thumb and forefinger (KMG). After induction of general anaesthesia, the ulnar nerves were stimulated supramaximally using superficial electrodes at the wrists using train-of-four (TOF) stimulation every 12 sec. Onset and recovery indices measured by the three methods after mivacurium 0.2 mg.kg(-1) iv were compared using ANOVA-multiple group comparisons. Agreement between methods was determined using Lin's concordance correlation coefficient. Results: Onset time and peak effect measured via MMG and PMG were similar. Recovery times from neuromuscular blockade (NMB) as measured via the three methods were not different. Agreement between PMG and MMG was excellent for onset and offset of NMB but unsatisfactory for peak effect. Agreement between MMG and KMG was satisfactory for TOF 0.25 and 0.50, and excellent for TOF 0.75 and 0.90 (onset and peak effect not determined for KMG). Agreement between PMG and KMG was satisfactory for TOF 0.25, 0.50 and 0.75, and excellent for TOF 0.90. Conclusion: Mechanomyography, PMG and KMG show satisfactory agreement for determination of recovery of NMB for clinical purposes.