NMB Management Flashcards
Which muscle is recommended to test neuromuscular block?
Adductor Pollicis muscle
ASA recommend against monitoring eye muscle responses to facial nerve stimulation
How can depth of neuromuscular block be assessed?
Depth of neuromuscular block can be defined based on:
1 TOF ratio
2. TOF count
3. Post Tetanic count PTC
When using quantitative monitoring
What are signs and symptoms of a minimal block (TOF ratio 0.4-0.9)
On the 4th twitch of TOF there are 2 levels of block
- Shallow block (TOF ratio <0.4)
- Minimal block (TOF ratio 0.4-0.9)
S&S of minimal block:
- Reduced vital capacity
- Reduced hand grip strength
- Impaired swallowing
- Increased Pulmonary Aspiration risk
- Upper airway obstruction
- Diplopia
- Subjective feeling of weakness
- Delayed recovery
- Reduced chemoreceptor mediated response to hypoxia
Which muscles are most sensitive to NMB? Which are least?
Ocular, pharyngeal and genioglossus are the most sensitive muscles to NMB and slowest to recover.
Larynx, diaphragm, upper abdominal and corrugator supercilii muscles are relatively resistant to NMB
Other factors such as no. of post synapatic receptors relative to muscle size contribute to differential muscle sensitivity
What are signs of inadequate recovery from NMB?
- Diplopia
- Difficulty swallowing
- Upper airway obstruction
- Pulmonary aspiration
What factors affect NMB speed of onset?
Rocuronium ranges from 2-3 mins but multiple factors affect it:
- Young age
- Female sex
- Rapid injection rate
- Priming
- Co-administration of Ephedrine
All shorten onset time
Esmolol increases onset time of NMB
What factors affecting NMB speed of onset?
Rocuronium ranges from 2-3 mins but multiple factors affect it:
- Young age
- Female sex
- Rapid injection rate
- Priming
- Coadministrarion of Ephedrine
All shorten onset time
Esmolol increases onset time of NMB
What factors affect duration of NMB?
- Increasing age
- Female sex
- Pregnancy
- Renal disease
- Hepatic disease
- Drugs - magnesium, esmolol, aminoglycoside antibiotics
Prolong duration of block
What factors affect duration of NMB?
- Increasing age
- Female sex
- Pregnancy
- Renal disease
- Hepatic disease
- Drugs - magnesium, esmolol, aminoglycoside antibiotics
Prolong duration of block
What is definition of residual NMB?
TOF ratio <0.9
What are clinical signs of recovery from NMB?
- Sustained head lift
- Sustained hand grip
- Tongue depression tests
Use of PNS allows subjective (tactile or visual) detection of TOF count and PTC
List some quantitative monitoring techniques to optomise and prevent residual NMB
- Acceleromyography
- Electromyography
- Kinemyography
- Compressomyopgraphy
List some quantitative monitoring techniques to optomise and prevent residual NMB
- Acceleromyography
- Electromyography
- Kinemyography
- Compressomyopgraphy
What is accelomyography?
Accelomyography devices utilise the principles of Newton’s law (force = mass x accelerarion).
When a piezoelectric sensor is applied to the thumb (fixed mass) and stimulated, the acceleration in response to stimulation is directly proportional to the force of contraction.
A resultant electrical signal is processed and displayed as a numeric value/ratio
What is Electromyography?
Electromyography devices measure the peak-to-peak amplitude or area under the waveform curve of the evoked muscle action potential to measure the intensity of the response.
EMG reflects more accurately the response at the NMJ than mechanical signals
Hypothermia and surgical electocautery interferes with EMG
