GE CARESCAPE - NMT measurement basics; NMT measurement description

Neuromusculartransmission
1.Regionalblockadapter
2.Sensorcable
3.Sterileneedle
Preparingforlocalnerveorplexusstimulation
1.ConnecttheE-NMTregionalblockadaptertothesensorcable.
2.Connectadisposableneedleandsyringesettotheadapter.
3.PresstheStart-upmodulekeyandselectasuitablecurrentfromtheCurrentmA
listthatappearsonscreen.YoucanalsodothisbyselectingtheNMTparameter
window>RegionalBlocktab>CurrentmA.
4.StartstimulationbyselectingStart.
5.Whentheneedleapproachesthemotornerve,reducethecurrent.Thepulse
widthis40msandsomewhathighercurrentsmaybeneededthaninother
similarsystems.
6.Whenready,stopthestimulationbypressingtheStopContinuemodulekey,or
byselectingtheNMTparameterwindow>RegionalBlock>Stop.
NMTmeasurementbasics
NMTmeasurementdescription
TheGENMTmeasurementdevicesareusedformonitoringtherelaxationofthe
patientandregionalblockstimulationfornervelocation.
Neuromusculartransmissionisthetransferofamotornerveimpulseoverthe
neuromuscularjunction.TheGENMTdevicesdeliverstimulatingelectricalpulsestoa
motornerveandthemuscleresponsetothesestimulationsismeasured.
Twoelectrodesareneededforelectricalstimulationofaperipheralnerve.The
resultingresponsecanbemeasuredwitheithertwoelectrodesandaMechanoSensor,
whichmeasuresmovementsbetweenthumbandindexnger,oranElectroSensor
usingthreerecordingelectrodes.
Themonitorsearchesforthestimuluscurrentneededtoactivateallthebersofthe
stimulated(recorded)muscles.Thesearchbeginswitha10mAstimulusandthe
responseismeasured.Thecurrentisincreasedinstepsof5mAuntiltheincrease
inthecurrentnolongerincreasestheresponse.Thismaximalcurrentisthen
automaticallyincreasedby15%,resultinginthesupramaximalcurrent.
Ifthesupramaximalcurrentisnotfoundortheresponseistooweakforsearchinga
supramaximalcurrent,thecurrentissetto70mA.
MechanoSensorandkinemyography(KMG)
MeasurementwithMechanoSensorisbasedonkinemyographyprinciple.Two
electrodesareplacedontheulnarnerve,andtheinnervatingnerveisstimulated.
ThecoreoftheMechanoSensorisastripofpiezoelectricpolymer,housedinsidethe
sensor.Whenthispiezoelectricmaterialchangesshapeduetomusclecontraction
asaresultofnervestimulation,theelectricalchargeinthematerialisredistributed,
causinganelectronowtobalancethecharges.Thisowcanbemeasuredasa
potentialchange,whichisproportionaltotheamountofmaterialbending.
368CARESCAPEModularMonitors2062971-001