Introduction:
- Neuromuscular monitoring devices were introduced into clinical practice in the 1970s
- Qualitative neuromuscular monitors, or peripheral nerve stimulators, provide an electrical stimulus to a motor nerve and the response of corresponding muscle subjectively evaluated
- MC (nerve + muscle) monitored: Ulnar nerve + Adductor pollicis.
Train of four (TOF):
Introduction:
- When train of four monitoring is used continuously, each set of stimuli is normally repeated every 10th to 20th second
- These sets are called trains because their shape bears the resemblance of a train
- Each stimulus in the train causes the muscle to contract, and ‘fade’ in the response provides the basis for evaluation.
Normal monitoring:
- Frequency of stimuli: 2 Hz = 2 stimuli/ sec
- Time gap between 2 stimuli = ½ = 0.5 sec
- Time gap between 2 TOF = 10-20 sec.
Application of Non-Depolarizing Muscle Relaxants (NDMR):
- Characterized by ‘fade‘ response
Application of Depolarizing Muscle Relaxants (NDMR):
- Fade response is absent
- T4/T1 ~ 1.
