How to Train for Use of TOF Peripheral Nerve Stimulator

The purpose of the Peripheral Nerve Stimulator (PNS) is to monitor the degree of neuromuscular blockage by stimulating a nerve and gauging the response in patients receiving Non-Depolarizing Neuromuscular Blocking Agents (NMBA) to allow administration of the optimal dose possible to achieve the desired effect. The following steps are used in an intensive care setting for patients who require monitoring.

Things You'll Need

• Peripheral nerve stimulator (with lead wires and batteries)
• 2 electrode pads (pediatric preferred)
• Alcohol wipes

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Instructions

Peripheral Nerve Stimulator/Train of Four Monitoring

• 1

  Explain procedure to patient and family. Inform them that the PNS may cause tingling or discomfort.

• 2

  Wash hands. Select monitoring site. Choose a site free from injury, inflammation and edema. Possible sites include the ulnar nerve (preferred), facial nerve or posterior tibial nerve.

• 3

  Prepare the monitoring site by washing vigorously with an alcohol pad. Remove hair if necessary. Allow site to dry.

• 4

  Place electrode on selected site.

• 5

  Attach lead wires to the electrodes. Use caution to prevent lead wires from coming in contact with external pacemaker catheter/wires.

• 6

  Turn on the PNS. Select a low numerical energy setting.

• 7

  Determine baseline response to neuromuscular stimulation.

• 8

  Determine the supramaximal stimulation (SMS) prior to initiating NMBAs. The SMS is the level at which additional stimulating current elicits no further increase in the intensity of the four twitches. Increase the mA dial in increments of 1 and repeat TOF until you observe four vigorous twitches. (Allow 10 seconds before repeating.) Document the number that corresponds to four vigorous twitches. Administer an additional TOF to verify the SMS.

• 9

  Retest the TOF 10 to 15 minutes after giving the bolus dose of NMBA and initiating continuous infusion.

• 10

  Retest every one to two hours until the patient is stable and the desired level of blockade is achieved. Retest every four hours thereafter.

Troubleshooting If No Twitches Are Seen

• 11

  Retest another nerve.

• 12

  Change electrodes.

• 13

  Check lead connections and PNS for mechanical failure or low battery.

• 14

  Increase the stimulating current.

• 15

  Check the infusion for rate, dose and concentration if there are no explanations for a zero response. If the zero response continues, notify the physician/Advanced Practice Registered Nurse.