Monitoring Paralysis

Question 1

Train of four

Answer 1

Four stimuli given at 2 Hz every 5 sec

• potential for 4 twitches
• ratio indicates degree of block
• nondepolarizing: produce progressive reduction in magnitude, # of twitches indicates degree ofblockade
• depolarizing: produce equal but reduced twitches

Question 2

Tetanic stimulation

Answer 2

Concept that ACh is depleted by successive stimulations

• extent of fade is related to degree of block
• no fade = no block
• sustained response to tetanus present when tof >0.7

Question 3

Double-burst stimulation

Answer 3

2-bursts of 3 stimuli at 50 Hz

• decrease in second response indicates residual block
• rate is related to tof ratio but easier to interpret

Question 4

Post tetanic count

Answer 4

50 Hz tetanic stimulus given for 5 sec followed by 1 Hz

• # of responses detectable predicts time for spontaneous recovery
• fade response appears earlier than tof

Question 5

Phase 2 blockade with Sux

Answer 5

Postjunctional membranes repolarized but still not responding to ACh

• resembles blockade by nondepolarizing agents
• mechanism unknown, occurs when dose of Sux >3-5 mg/kg

Question 6

Technique

Answer 6

Peripheral nerve stimulator electrically stimulates motor nerve adductor pollicis, orbicularis oculi, posterior tibial, or perineal