Mayo Clinic offers implantable diaphragmatic pacing system for spinal cord injury patients

Selected patients can reduce dependence on mechanical ventilators

Over the past two decades, researchers have explored the possibility of developing an implantable diaphragmatic pacing device to improve the quality of life for patients who are ventilator-dependent. In June 2008, the Food and Drug Administration approved the use of a diaphragmatic pacing stimulation system for ventilator-dependent patients with spinal cord injury (SCI) who lack voluntary control of their diaphragms. The goal of this pacing device is to reduce or end a person's dependence on a ventilator over time.

Implantable pacing device

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At Mayo Clinic, surgeons implant a pacing device as a minimally invasive procedure using a laparoscopic approach. Using direct visualization, surgeons place electrodes on the diaphragm in a location that elicits the optimal contraction. The electrodes are connected to wires that run through the skin to an external device about the size of a remote control. After implantation, the device provides electrical stimulation that induces diaphragm contraction and inhalation of air to fill the upper and lower parts of the lungs. Patients who use the device describe the impulse sensation as similar to a flick of the finger.

Mayo Clinic is one of a handful of centers offering a pacing device to selected patients with high cervical SCI who currently require ventilator support for breathing.

"The goal of implanting this device is to reduce the amount of time patients require mechanical ventilation," explains Ronald K. Reeves, M.D., a physiatrist at Mayo Clinic in Rochester, Minn., who is monitoring and training Mayo Clinic patients with spinal cord injury in the use of this device.

Reducing the number of hours spent on mechanical ventilation facilitates greater independence and other benefits for patients with SCI. Benefits include:

• Easier transfers
• Improved mobility without tubing or a ventilator to accommodate
• Reduced secretions
• Improved speech.

Additionally, because the pacing device is battery powered, it continues operating during power outages.

Candidates for device implantation at Mayo Clinic must be hemodynamically stable and have intact bilateral phrenic nerve function and support at their home or care facility to assist with the conditioning process. During conditioning, patients transition off the ventilator to the pacing device and then back to the ventilator several times a day for several days.

Dr. Reeves' team reports that two patients with SCI have undergone device implantation at Mayo Clinic thus far. During the first month after implantation, one of these patients was able to stay off the ventilator for up to eight hours a day, while the other was off the ventilator for two to three hours at a time.

Dr. Reeves expects that some patients will condition faster and remain off the ventilator for up to 24 hours using the pacing device. In the future, Dr. Reeves and colleagues are also hopeful that the pacing device can be implanted in patients with SCI acutely after injury to help wean them from ventilators during the days and weeks after injury, to help reduce the incidence of hospital-acquired pneumonia and other possible adverse effects associated with long-term use of a ventilator.