Validation of a Muscle Relaxation Monitor

Validation of a Device to Monitor Muscle Relaxation During Surgery

The objective of this study is to determine the accuracy of a hydraulically coupled twitch monitor compared to the EMG twitch monitor in current use to measure the extent of neuromuscular blockade in patients undergoing general anesthesia.

Neuromuscular blockade (paralysis) is necessary for many surgical procedures to provide optimal surgical conditions. The extent of paralysis typically assessed during routine clinical care by examining the muscle response of the thumb ("twitch") following delivery of a series of the "train-of-four".

Quantitative assessment of neuromuscular block can be assessed using electromyography (EMG) This technique measures action potential in the muscles of the thumb.

The proposed method is a simple technique that can constructed with equipment that is readily available in most operating rooms. If validated, it would provide a simple method to assess quantitatively the extent of neuromuscular blockade and recovery of muscle strength.

1. Age >18
2. Surgery is elective
3. Subject has been NPO for fluids for >2 hours and for solids >8 hours
4. General anesthesia with tracheal intubation is required
5. Mask ventilation is expected to be without difficulty
6. Subject voluntarily consents in writing to the protocol
7. ASA Physical Status 1-III (healthy individuals, those with mild comorbid conditions, or those with more serious co-morbid conditions that are well controlled)

Exclusion Criteria:

1. Lack of ability to provide written, informed consent
2. Airway examination indicates a likelihood of difficult mask ventilation
3. Symptoms of active reflux at the time of induction, at risk of having food in their stomach at the time of induction, expected abnormal response to non-depolarizing neuromuscular blockers
4. Age ≤18 years
5. Pregnant women
6. Presence of carpal tunnel syndrome
7. Prisoners
8. General anesthesia not being provided
9. Tracheal intubation will not be performed
10. Anticipated length of surgery <60 minutes
11. Emergent or urgent surgery
12. Disease that might alter the normal neuromuscular response to electrical stimulation (e.g., muscular dystrophies, myasthenia gravis, quadriplegia).
13. ASA Physical Status IV or V (individuals with major comorbid conditions that are a constant source of risk to health)