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.

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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 Technology

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. 


Operating Modes

TOF mode, is the TetraGraph®’s main mode of operation. A sequence of four stimuli, at a frequency of 2 Hz, referred to as Train-of-Four (TOF) is delivered to the peripheral nerve and the Train-of-Four Ratio (TOFR, or the ratio of the amplitude of the fourth twitch T4, to that of the first twitch, T1) and the TOF Count (TOFC, or the number of discernable twitches) of the evoked EMG responses are calculated and displayed. TOF stimulation is used to assess the depth of neuromuscular blockade and gauge the degree of recovery after reversal. Other operating modes are Post-Tetanic Count (PTC), which is used to determine NMBA management during surgeries that require deep block, and Single Twitch, which is used to deliver a single stimulus and display a single muscle response in millivolt (mV).