NMBA Monitoring

Question 1

what is supra maximal stimulus?

Answer 1

peripheral nerve stimulating current that is sufficient to cause all NMJ to release ACh

Question 2

what is the supra maximal stimulus current?

Answer 2

> 30-50 mA

Question 3

what is TOF stimulus?

Answer 3

4 supramaximal neural stimuli at 2 Hz -> 4 muscular contractions

Question 4

what is the TOF ratio?

Answer 4

• amplitude of 4th twitch/amplitude of 1st twitch

- when TOF ration >70-80% then 20% of receptors are NOT blocked thus normal contraction should occur

Question 5

Post Tetanic Count (PTC)

Answer 5

• 50 Hz stimulation for 5 sec; wait 3 sec; then supra maximal stimulus at 1 Hz
• if 5-7 responses detected after tetnus -> return of TOF imminent

Question 6

Double Burst Stimulation (DBS)

Answer 6

• 2 bursts of 3 impulses; then 2 impulses at 50 Hz with 750 sec interval
• fade of second impulse series compared to first correlates with TOF ratio <0.6

Question 7

what is electromyography (EMG)?

Answer 7

measures muscle AP that occurs with muscle membrane DEPOLARIZATION

Question 8

what is the EMG amplitude?

Answer 8

constant amplitude of 20 mV at adductor pollicis & first dorsal interosseous muscle