Piezoelectric Neuromuscular Monitors
The technique of the piezoelectric monitor is based on the principle
that stretching or bending a flexible piezoelectric film, for example, attached to
the thumb, in response to nerve stimulation generates a voltage that is proportional
to the amount of stretching or bending.[81]
[82]
At least two devices based on the this principle are available commercially: The
ParaGraph Neuromuscular Blockade Monitor (Vital Signs, Totowa, NJ) and the M-NMT
MechanoSensor, which is a part of the Datex AS/3 monitoring system (Datex-Ohmeda,
Helsinki, Finland) ( Fig. 39-16
).
Few studies have evaluated the function of these monitors.[81]
[82]
[83]
The scarce
data indicate a good relationship between results obtained using PZ
EMG,
AMG and MMG, but also wide limits of agreement between the methods. Therefore,
Figure 39-15
Hand adaptor (elastic preload) for the TOF-Watch transducer.
(Accelleromyography, Organon Ltd., Dublin, Ireland.)
Figure 39-16
Datex-Engstrøm M-NMT MechanoSensor (a piezoelectric
neuromuscular monitor).
although PZ
EMG may be a valuable clinical tool, the values obtained in
the individual patient using this method may vary from those obtained using MMG or
AMG.
