iTOF®

The iTOF is a wireless neuromuscular transmission (NMT) monitor that measures muscle acceleration in response to electrical stimulation to monitor the depth of neuromuscular blockade in patients during anesthesia in operating theaters, recovery rooms, and intensive care units. It consists of a mobile app interface, a Bluetooth-connected nerve stimulation device with a 9V battery, an accelerometer sensor, and stimulation cables with an included splint.

Both iTOF and predicate (ToFscan) use 3-D accelerometry to measure thumb movement in response to electrical stimulation patterns. Key differences: iTOF delivers up to 70 mA (370V) versus predicate's 60 mA (300V); iTOF includes 2 Hz single twitch stimulation and uses 3.3 DBS only versus predicate's 3.3 and 3.2; iTOF has manual mode selection only without automatic twitch pursuit; iTOF uses a standard 9V non-rechargeable battery and mobile app via Bluetooth rather than predicate's built-in interface; iTOF allows customizable repeat frequency intervals (10s–1h) versus predicate's fixed intervals.

IEC 60601-1 (general electrical safety), IEC 60601-1-2 (electromagnetic compatibility), IEC 60601-2-10 (peripheral nerve stimulators), IEEE/ANSI C63.27-2017 (wireless coexistence), and ISO 10993-1 (biocompatibility testing including cytotoxicity, sensitization, and irritation). Software verification and validation and cybersecurity testing were performed per FDA guidance.

Both devices measure thumb movement via 3-D accelerometry in response to defined electrical stimulation patterns to monitor neuromuscular blockade—the same technological principle and intended diagnostic use. Although the iTOF has higher stimulation voltage/current, additional stimulation modes, manual-only selection, a non-rechargeable battery, and wireless connectivity, these differences do not raise new safety or effectiveness questions because hardware and software verification and validation testing, along with biocompatibility and electrical safety testing, demonstrate the iTOF performs as intended in specified conditions. The performance characteristics support equivalent safety and effectiveness to the predicate device.