Monitoring
1.    Monitoring of thumb is preferred

• ulnar nerve at wrist
• vis/palp assessment of thumb adduction
• train-of-four; counting twitches = train-of-four count
• T1, T2, T3, T4

• ED95 (anesthesia background dependent)
• onset time
• duration

• T0 = unantagonizable block
• T1 only = antagonizable but difficult, drug dependent (pan, dtc, meto, longer than cis/roc/atr/vec) and takes 12-20 min
• T1, T2 present = antagonizable
• T1, T2, T3 or T1, T2, T3, T4 present = easily antagonizable

• measured train-of-four best > DBS "no fade" > train-of-four "no fade"... others unreliable.
• If in question, use clinical criteria: sustained head-lift x 5 sec, sustained hand grasp x 5 sec, sustained masseter muscle strength, or maximum NIF >= 50 cmH20 (i.e., more negative). 5-sec leg lift in pediatric patients.

Dosing:

1. Need to know ED95, onset time, duration of relaxation (see pharmacology)
2. Give ED95 x 1 initially (assuming patient already intubated using sux)
3. Wait duration of onset time, check train-of-four count
4. If train-of-four count > 2 at onset time dose ED95 x 1 again
5. Titrate drug to therapeutic window (T1-T2 present only) during period of required relaxation
6. Allow as much recovery as possible prior to antagonism of block
7. Antagonize block with neostigmine 0.04-0.07 mg/kg + glycopyrrolate 0.01 mg/kg
8. Use of volatile anesthetics reduce the requirement for neuromuscular blocking drugs in a dose-related fashion (1 MAC reduces ED95 by approx 1/3)

Drug Selection Principles

• In the elderly, those with impaired renal function, and/or complicated metabolic/electrolyte profile a drug which is independent of organ (kidney or liver) elimination is preferable (cisatracurium).
• Residual NMB in PACU increases portential for aspiration, hypoxia and other postop pulmonary complications
• Patient criteria: Age, renal function
• Indication of rapid sequence when sux contraindicated
• Case duration, extubation plans.
• Cost
• Liver disease is not considered a clinically meaningful selection criteria. If severe liver disease, cisatracurium is probably best.
• Potential cardiovascular effects are not a clinically meaningful drug selection criteria. They are, however,  important dosing considerations.

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Drug Selection Guidelines

• Pancuronium

1. when duration of relaxation needed is longer than 1 hour
2. when extubation is not planned immediately post-op
3. when renal function is normal
4. when patient < 70 years old
5. when no comorbidity factors are present. This incorporates the data that suggests the immediate-acting (duration drugs) are more easy to reverse than pancuronium.

• Cisatracurium

1. presence of renal failure
2. > 70 years old
3. when complete reversal of NMB is absolutely essential at end of case (e.g. full stomach, morbid obesity, difficult airway, etc.)
4. duration of case 35-60 minutes

• Vecuronium

1. when complete reversal of NMB is absolutely essential at end of case (e.g. full stomach, morbid obesity, difficult airway, etc.)
2. duration of case 35-60 minutes

• Mivacurium

1. profound relaxation needed in case no longer than 35 minutes
2. a succinylcholine drip, made by combining 5 (20mg/cc x 10cc) bottles is another valid alternative to mivacurium

• Rocuronium

1. when succinylcholine is contraindicated
2. when complete reversal of NMB is absolutely essential at end of case (e.g. full stomach, morbid obesity, difficult airway, etc.)

• d-tubocurarine - can be used to prevent fasciculations induced by succinylcholine when administered 3 to 5 minutes prior to the dose of succinylcholine

• doxacurium
• gallamine
• metocurine
• pipecuronium

Antagonism of Neuromuscular Blockade

1. ALL NDMR's SHOULD BE PHARMACOLOGICALLY REVERSED BEFORE EXTUBATION (with possible exception of mivacurium)
2. The most reliable signs of adequate restoration of neuromuscular function are CLINICAL signs: 5-sec head lift, 5-sec hand grasp, sustained masseter muscle strength, maximum NIF >= 50 cmH20 (i.e., more negative)
3. No twitches present in the TOF Count represents an unantagonizable block
4. Deeper blocks (e.g. T1 only present) are more difficult to antagonize than blocks where T2, T3 or T4 twitches are present in TOF Count
5. To maximize muscle recovery, reversal ought not be given till TOF Count is at least 2.
6. Longer-acting muscle relaxants (e.g. panc, curare, meto) are not as readily antagonized as intermediate or short duration muscle relaxants (e.g. vec, atra, roc, miv)
7. Neostigmine is more effective in antagonizing deep blocks
8. "No detectable fade" of DBS (Double Burst Stimulation) is the most reliable twitch monitoring sign of adequate restoration of neuromuscular function
9. Combining knowledge of # of twitches in TOF Count present at time of reversal, the relaxant being antagonized and time since reversal can enhance the accuracy of detecting adequate restoration of neuromuscular function