Objective neuromuscular monitoring is strongly recommended when administering
neuromuscular blocking agents (NMBA). However, objective neuromuscular monitoring may be
challenging, especially in smaller children due to the limited size of their extremities
which often are not easily accessible due to issues such as sterile draping and surgical
equipment. Consequently, paediatric anaesthesia care providers often experience problems
with neuromuscular monitoring.
NMBAs improve intubating conditions and prevent airway injury in children and infants
(<12 months of age). However, both patient age and type of anaesthesia influence onset
and duration of action. Infants have shorter onset time of NMBAs compared to older
children, and a higher proportion of infants had excellent intubating conditions compared
to older children at two minutes after a dose of 0.15 mg/kg cisatracurium. Inhalation
anaesthetics prolong recovery from cisatracurium compared to total intravenous
anaesthesia and a longer duration of action is seen in infants compared to older
children. However, as compared to adults, less profound neuromuscular blockade may be
sufficient in children to establish satisfactory intubating conditions.
In children < 3 years old, a study reported residual neuromuscular blockade (TOF (Train
Of Four) ratio < 0.9) among 8% of the included patients after administration of a single
bolus of 0.1 mg/kg cisatracurium, but the actual proportion may have been as high as 20%.
To prevent residual neuromuscular block, objective neuromuscular monitoring is
recommended. In adults residual neuromuscular block may result in respiratory events
(hypoxaemia and airway obstruction), unpleasant symptoms of muscle weakness, prolonged
post-anaesthesia care unit stay, and an increased risk of postoperative pulmonary
complications.
It is possible to monitor onset time and duration of action of NMBAs with
electromyography (EMG) or acceleromyography (AMG) by train-of-four (TOF) stimulation of a
peripheral nerve. Typically, the ulnar nerve is stimulated. In smaller children the
tibial nerve can be used as an alternative. However, a recent study in adults reports
that there may be important differences when comparing EMG and AMG TOF monitoring at the
ulnar nerve with EMG detecting recovery of neuromuscular function later than AMG. Only
one study in infants has reported that monitoring of neuromuscular function with AMG
applied on the first toe may be a suitable alternative when the thumb is inaccessible.
One recent study has reported the feasibility of monitoring the depth of neuromuscular
block in infants using electromyography. No study has to our knowledge compared AMG to
EMG in infants and small children.
The investigators hypothesize that AMG will indicate faster recovery (time to return to
TOF 90%) from neuromuscular block than EMG A secondary aim of this study is to
investigate agreement between the two monitors using a Bland Altman analysis comparing
onset time and recovery from deep to moderate rocuronium-induced neuromuscular block with
EMG and AMG.