Initiation of Pacing

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Refer to the Instruction Manual provided with each system for complete instructions on postoperative care and initiation of pacing.

Preparation

• Insert batteries into transmitter, turn both sides ‘OFF’.
• Set amplitude dials to 0.0 on both sides.
• Secure antennas over implanted receivers and connect to transmitter.
• Preoxygenate patient as necessary.

Amplitude Determination

Each hemidiaphragm is initially evaluated independently of the other.

• Discontinue alternate method of ventilation if required.
• Turn first side ‘ON’ and slowly increase amplitude control until threshold is reached.

Threshold is the lowest stimulus amplitude which results in a diaphragmatic response and can be observed by visual observation, manual palpation, respirometer, fluoroscopy, or patient sensation.

• Gradually increase amplitude until adding amplitude no longer increases tidal volume or diaphragm reaches maximum deflection.

Elevated Threshold Example


• Process should be repeated for the second side, allowing for the patient to rest on an alternative means of ventilation as necessary.
• Once unilateral amplitudes are determined and the patient is sufficiently oxygenated, both sides should be turned ‘ON’ and a bilateral tidal volume measured.
• Respiratory rate should be set so that minute volume is appropriate for the patient’s clinical needs.

Diaphragm Reconditioning

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Thresholds can vary by up to 20%, so readjustment of amplitudes may be occasionally required to maintain tidal volume and patient comfort.

• Patients should be allowed to pace until indications of diaphragm fatigue occur. This can be observed by a 50% decrease in tidal volume, decreasing oxygen saturation, or increasing CO2 retention.
• Pacing should be resumed daily until 24 hour pacing, or desired amount, is achieved.

For patients with little or no intraoperative response, or who have undergone a nerve grafting procedure, diaphragm reconditioning should take place asynchronously with a mechanical ventilator until such time as a sufficient tidal volume is obtained.


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