What does a Train of Four (TOF) count of 1 indicate in a patient with neuromuscular blockade?

Train of Four Count = 1

A Train of Four (TOF) count of 1 indicates profound neuromuscular blockade where only the first of four twitches is present in response to peripheral nerve stimulation, representing deep paralysis that requires either continued waiting for spontaneous recovery or administration of high-dose reversal agents. 1

Clinical Significance

A TOF count of 1 means:

• Only one twitch (T1) is present out of four possible responses to nerve stimulation, indicating deep neuromuscular blockade 1
• The patient has profound paralysis with T2, T3, and T4 completely absent 1
• This level of blockade is too deep for safe reversal with neostigmine, which requires at least 4 twitches present (TOF count = 4) before administration 1

Management Algorithm

When TOF count = 1:

• Do not administer neostigmine - it is ineffective and contraindicated at this depth of blockade 1
• Wait and maintain anesthesia while reassessing TOF later to allow spontaneous recovery 1
• If using rocuronium, proceed to Post-Tetanic Count (PTC) evaluation at the adductor pollicis to determine if sugammadex can be used 1

For rocuronium-induced blockade specifically:

• If PTC = 1 or 2: administer sugammadex 4 mg/kg for deep blockade reversal, achieving TOF ratio ≥0.9 in 3-5 minutes 1, 2
• If PTC = 0: continue waiting and maintain anesthesia, then reassess PTC later 1

Critical Pitfalls to Avoid

• Never give neostigmine when TOF count < 4 - this represents inadequate spontaneous recovery and neostigmine has a ceiling effect that prevents reversal of deep blockade 1, 3
• Attempting reversal at TOF count = 1 with neostigmine can paradoxically induce muscle weakness and will not achieve adequate recovery 4, 3
• Failing to use quantitative monitoring leads to underestimation of blockade depth, as clinical assessment cannot detect this level of paralysis accurately 1, 2
• Extubating a patient at this depth of blockade would result in severe respiratory compromise, airway obstruction, and aspiration risk 1, 5

Monitoring Requirements

• Use quantitative neuromuscular monitoring (acceleromyography) at the adductor pollicis to accurately determine TOF count 1, 2
• Visual or tactile assessment alone is inadequate for detecting the difference between TOF counts and cannot guide appropriate reversal decisions 1
• Continue monitoring after any reversal agent administration to confirm achievement of TOF ratio ≥0.9 before extubation 1, 2