Diaphragm pacing

A procedure to help patients with spinal cord injuries to breathe.

Their breathing is helped by setting the respiratory rate by electrical stimulation (pacing) of the phrenic nerve.

The pacing is accomplished via electrodes surgically implanted into the diaphragm, which is innervated by the phrenic nerve.

</P> This procedure is currently experimental.

It is being tested in patients with injuries that cut across (transect) the cervical spinal cord high in the neck and result in paralysis of all four limbs (tetraplegia) and respiratory failure requiring chronic mechanical ventilatory support.

For the procedure to work, the function of the phrenic nerve must be normal.

Diaphragm pacing originally required surgery opening the chest cavity (thoracotomy) to implant the electrodes.

It is now done by laparoscopy through small openings in the chest.

Patients undergo laparoscopic implantation of electrodes in the muscle of the diaphragm and initial electrical stimulation.

Following a recovery period of a week or so, diaphragm pacing is initiated.

Wires from the electrodes in the diaphragm run to and from a control box worn outside the body.

The pacing is performed according to a reconditioning program in which the duration and frequency of electrode stimulation is gradually increased until full-time diaphragm pacing is achieved.

How does diaphragm pacing work to help breathing? When the electrodes are stimulated by current, the diaphragm contracts and air is sucked into the lungs (inspiration).

When the nerve is not stimulated, the diaphragm relaxes and air moves out of the lungs (expiration).

The actor Christopher Reeve, who was paralyzed and on a respirator after fracturing his neck in a riding accident, underwent the procedure in 2003. The procedure is also known as electrophrenic respiration (abbreviated EPR) and diaphragmatic or phrenic pacing.