Diaphragm Pacing System Awaiting FDA Approval for ALS

The Synapse Biomedical NeuRx Diaphragm Pacing System (DPS), a device that stimulates the respiratory diaphragm with electrical signals, has received Humanitarian Use Device designation from the U.S. Food and Drug Administration (FDA), allowing it to be used by people with amyotrophic lateral sclerosis (ALS) who have a “stimulatable” diaphragm and are experiencing chronic breathing problems. Synapse Biomedical announced the HUD approval Oct. 8, 2010.

A diaphragm pacing system, such as this NeuRx DPS, uses electrodes to rhythmically stimulate the diaphragm. Illustration courtesy of Synapse Biomedical

Receiving a Humanitarian Use Device (HUD) designation is a first step toward a possible FDA Humanitarian Designation Exemption (HDE), which allows a company to market a device to a specific population.  The HUD designation establishes that the NeuRx diaphram pacing system is a medical device intended to benefit people with a condition that affects fewer than 4,000 people in the United States per year. (ALS affects greater numbers than that, but only a fraction of those have stimulatable diaphragms, meaning they have some preservation of the diaphragm muscle and the nerves that normally stimulate it.)

The NeuRx DPS already has been granted an FDA HDE for use by adults with spinal cord injuries who lack control of stimulatable diaphragms. According to an Oct. 8 statement from Synapse, the FDA will now determine whether NeuRx DPS is safe and has probable benefit for people with ALS who meet the humanitarian-use-device criteria.

"We anticipate that the HDE initial review will take 75 days, although FDA questions can result in additional review cycles," said Mike Fritz, vice president for clinical & regulatory affairs at Synapse, on Oct. 8.

About the diaphragm pacing system

The NeuRx Diaphragm Pacing System requires that electrodes be surgically implanted in the diaphragm, a dome-shaped sheet of muscle that extends across the bottom of the rib cage and plays an important function in respiration.

According to Synapse, the system is designed to activate the diaphragm muscle not only to supplement the patient's breathing ability but to delay diaphragm atrophy (shrinkage) and the need for invasive positive-pressure ventilation. The pacing device can be used in conjunction with noninvasive (such as oral or nasal delivery) positive-pressure ventilation (i.e., BiPAP).

In late 2008, Raymond Onders, director of minimally invasive surgery at University Hospital Case Medical Center in Cleveland, presented results from two clinical trials of people with ALS who received NeuRx systems. (See Surgeon reports on diaphragm pacing in ALS.)

At that time, he reported that the ALS-affected trial participants tolerated the device well and that those with declining respiratory capacity during the lead-in period to the study showed a slower rate of decline after they had pacing systems implanted. Onders will be reporting more about this research at the Motor Neurone Disease Association’s 21st International Symposium on ALS/MND in Orlando, Fla., Dec. 11-13, 2010.

Meaning for people with ALS

The HUD designation from the FDA brings this diaphragm pacing system one step closer to approval for use by people with ALS in the United States. Once the FDA has approved a device, government and private insurers are likely to cover it. For now, diaphragm pacing systems for people with ALS are considered experimental in the United States. It may be possible to obtain one, but only as part of a study, and insurance coverage is uncertain.

For some people with ALS, a diaphragm pacing system may provide an alternative to, or a delay in, the need for invasive ventilation via tracheostomy.

For those who do not have remaining phrenic nerves, which go to the diaphragm, or whose diaphragm muscles are too deteriorated, the device is not likely to have any benefit.

For more information, including a video and medical centers where the system is being implanted on an experimental basis, see Synapse Biomedical: ALS Clinical, or contact nurse practitioner Mary Jo Elmo at University Hospitals of Cleveland at (216) 844-8594 or maryjo.elmo@uhhs.com.

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