Korean J Anesthesiol.  1997 Apr;32(4):553-560. 10.4097/kjae.1997.32.4.553.

The Train-of-Four Ratio Profile During Onset and Offset Following Administration of Neuromuscular Blocking Agents

• Kim SC
• Lee JS
• Yoon CS
• Kim MH
• Park W
• Kim SY
• Choi SJ

• KMID: 1934613
• DOI: http://doi.org/10.4097/kjae.1997.32.4.553

Abstract

BACKGROUND
The train of four (TOF) stimulation is valuable to study pharmacodynamics associated with the interaction between muscle relaxants and receptors in the neuromuscular junction. TOF fade expresses presynaptic effect diminished output of transmitters. The aim of this study was to examine differences in presynaptic effects of different relaxants by measuring the TOF ratio during the onset and offset of block.
METHODS
Eighty four healthy adult patients of ASA grades I or II were included in the study. The muscle relaxants studied were vecuronium (0.08 mg/kg), atracurium (0.5 mg/kg), mivacurium (0.15 mg/kg), rocuronium (0.6 mg/kg) and succinylcholine (1.0 mg/kg, 0.1 mg/kg, 0.2 mg/kg, 0.4 mg/kg). The TOF ratios were measured at approximate height of first response in the TOF (T1) of 75, 50 and 25% during onset and offset. Especially its ratios were measured at first depress of T1 during onset and its corresponding T1 during offset following administration of subclinical doses of succinylcholine.
RESULTS
In the non-depolarizing muscle relaxants, TOF fade is more evident during offset than onset (p<0.05). The extent of fade varies between muscle relaxants. The greatest TOF fade has been shown in rocuronium during onset. In the succinylcholine, the TOF fade is apparent during onset and related to doses given (p<0.05). However the significant TOF fade is not seen during offset.
CONCLUSIONS
All muscle relaxants, including both depolarizing and nondepolarizing agent, have predominantly postsynaptic and presynaptic effects. Furthermore, the fact that moderate TOF fade after subclinical doses of succinylcholine occurred obviously during onset of block is possibly indicating a greater presynaptic receptor blocking action.

Keyword

Neuromuscular relaxants; vecuronium; atracurium; mivacurium; rocuronium; Monitoring; train of four stimulation

MeSH Terms

Adult
Atracurium
Humans
Neuromuscular Blockade*
Neuromuscular Blocking Agents*
Neuromuscular Junction
Neuromuscular Nondepolarizing Agents
Receptors, Presynaptic
Succinylcholine
Vecuronium Bromide
Atracurium
Neuromuscular Blocking Agents
Neuromuscular Nondepolarizing Agents
Receptors, Presynaptic
Succinylcholine
Vecuronium Bromide