Comparative Study of TetraGraph and Mechanomiograph Neuromuscular Monitors in Clinical Settings

"The gold standard of quantitative monitoring is mechanomyography (MMG), which measures the force of contraction of the adductor pollicis muscle following ulnar nerve stimulation. MMG responses are accurate and reproducible. However, the complex and bulky devices are only suitable for research use, are not suitable for clinical use and are not commercially available."

Another type of monitor is the electromyograph, which can be seen as an alternative to mechanomyography because of its accuracy. This technique measures muscle activity as a summation of the action potentials of muscle fibres. This activity is proportional to the strength of the muscle contraction. The most commonly innervated nerve is also the ulnar nerve, which innervates the abductor digiti minimi and the first dorsalis interosseus muscles. During the measurements, electrical signals from these muscles are detected. EMG has several advantages over other monitoring techniques. It does not require immobilisation of the hand, thumb immobility is not a problem, no preload is required, and hypothermia does not affect the hand as much as other neuromuscular monitors. The TetraGraph (Senzime AB, Sweden) is a portable EMG-based neuromuscular minitor for which the manufacturers received marketing approval from the U.S. Food and Drug Administration (FDA) in 2019.