Delivering Confidence and Simplicity during Neuromuscular Blockade

TetraGraph is a quantitative neuromuscular transmission monitor based on electromyography (EMG). The TetraGraph monitor stimulates, measures, analyzes and displays muscle function in surgical patients receiving neuromuscular blocking agents (NMBAs). NMBAs are used in almost 50% of surgical cases. Inadequate reversal of NMBAs can lead to residual neuromuscular blockade (RNMB). RNMB delays recovery and can lead to life-threatening complications. To prevent complications, quantitative neuromuscular monitoring is rapidly becoming the standard of care when NMBAs are administered.

TetraGraph Features

The TetraGraph monitor is easy to use and features gold standard EMG technology for accurate measurements to bring confidence to the anesthesiology practice. The device has a quick start up time and does not require calibration. The arm can be tucked under surgical drape and can thus be used in all types of procedures, including cardiac, neuro, laparoscopic, robotic and bariatric surgeries. TetraGraph can be used from start to finish during the surgical procedure. The monitor enables objective assessment and facilitates titration of medication dosage to help clinicians determine when the patient’s neuromuscular block is sufficiently reversed to allow adequate spontaneous breathing. TetraGraph is small and portable and can travel with the patient to different settings like OR, PACU or ICU. The TetraGraph can be operated connected to mains electricity or battery operated.

TetraGraph Quantitative NMT Monitor

Neuromuscular Transmission is the transfer of an electrical impulse between a motor nerve and its associated muscle. A Neuromuscular Transmission (NMT) monitor indicates the depth of neuromuscular block by stimulation of a peripheral motor nerve and evaluating the evoked muscle response (compound muscle action potential, CMAP). Transmission of impulses from the nerve to the muscle is blocked by neuromuscular blocking agents (NMBAs) causing transient muscle weakness and preventing the patient from moving and breathing spontaneously.

Muscle relaxation is used during general anesthesia to enable endotracheal intubation and to provide optimal surgical conditions. In critical care, muscle relaxation may be used during mechanical ventilation. In these circumstances, TetraGraph can be used as an objective monitor of Neuromuscular Transmission.

EMG – The new Gold Standard in NMT monitoring

TetraGraph undertakes this function by periodically delivering electrical stimulation to the peripheral nerve and directly measuring the evoked electromyographic (EMG) response of the muscles (compound muscle action potential, CMAP). This provides a precise and automatic measurement of muscle response to a stimulus.

Like other technologies, EMG involves stimulation of a peripheral nerve and measurement of the response that is generated by the contraction of the innervated muscle. The difference from other technologies is that EMG measures an electrical event that occurs at the neuromuscular junction; the activation of postsynaptic receptors by acetylcholine (a chemical process) that converts it to a mechanical response (excitation- contraction coupling), that results in muscle contraction. Because measurement of function does not depend on physical movement (as MMG, AMG or KMG require), EMG is a better indicator of pure neuromuscular function- EMG is the new gold standard.

Neuromuscular Transmission Stages and related Neuromuscular Transmission Technologies

Neuromuscular Transmisson (NMT) is the transfer of an impulse between a nerve and a muscle in the neuromuscular junction. EMG measures the compound action potential, which is the first signal we are able to measure after neuromuscular transmission. Therefore, EMG is most specifically suited to monitor the effect of muscle relaxants without any mechanic interferences.


TetraSens electrode array has two proximal stimulating electrodes, one recording electrode and one reference electrode. The application is easy and quick. TetraSens electrode array is for single-patient use in order to avoid cross contamination. The electrodes can be applied on either hand, with the stimulation electrodes over the ulnar nerve at the wrist and the evoked response recorded from any of the hand muscles; typically, either the muscle at the base of the little finger (abductor digiti minimi muscle), or, more commonly, from the muscle at the base of the thumb, adductor pollicis muscle. TetraSens can also be placed on the FDI muscle (first dorsal interosseous). When the hand is inaccessible, the posterial tibial nerve (flexor hallucis brevis muscle), can be used for NMT monitoring.


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