Overview

• Neuromuscular blockade (NMB) monitoring —> Used with anesthesia & sedation in critically ill patients

• NMB monitoring devices are expensive

• Prototype based on open-source hardware & software

• On-line peak detection

• Preliminary measurements in a healthy subject

Neuromuscular Blockade Monitoring

• ICU patients often need mechanical ventilation

• Why using Neuromuscular Blocking Agents (NMBAs)?

• They prevent muscle contractions and can improve tolerance and comfort

• Controlled doses increase chest compliance, improve oxygenation, reduce postoperative respiratory complications (PRC)

• Why NMB monitoring? Too little: residual paralysis. Too much: risk of PRC

• But careful: Qualitative assessment is unreliable —> Need quantitative NMB monitoring

Train-of-Four (ToF)

• Transcutaneous electrical stimulation applied to (ulnar) nerve —> measure muscle contraction (accelerometer)

• Four stimuli @ 2 Hz

• ToF Count: # of detected responses

• ToF Ratio: 4th to 1st response T4/T1

• ToF delivered at 15–20 s intervals to prevent potentiation

Commercially Available ToF Devices

• Need of Low-Cost Devices

Goal:

Design & implement a low-cost NMB monitoring device that may help reduce the economic burden of health-care institutions in low- and middle-income countries

Prototype Overview

• Arduino

• ADXL345 accelerometer

• TENS 3000 unit

• Relay

• LCD

Peak Detection Algorithm

• Normalized (z-score) signal over a time window

• Peak if exceeds a threshold

• Lag: window size

• Influence: weight [0-1] of past points

Adjusting Peak Detection Algorithm

Conclusions

• Inexpensive, modular, simple-to-build, open-source NMB monitoring device, able to display ToF Count & ToF Ratio

• Preliminary measurements showed great promise to transition into higher developing stages

• Exhaustive assessment needed to ensure safety and effectiveness in clinical settings