1. Patients can be paced unilaterally for many years.
2. Patients with complex neuromuscular disease, including spinal muscular atrophy, MS, and so on, can be paced.

Diagnosis
Phrenic-nerve paralysis is suspected when the patient exhibits inward movement of the abdomen during inspiration (especially in the supine position) and when there is difficulty weaning the patient from the ventilator. Diagnosis is based on clinical presentation, chest radiography findings (diaphragmatic elevation), pulmonary function test results, blood gas levels, ultrasonography and fluoroscopy of the diaphragm, phrenic-nerve-conduction studies, and diaphragmatic electromyography.

Sometimes, the clinical signs of diaphragmatic dysfunction are difficult to diagnose in the early postoperative period because of mechanical ventilation, the presence of chest tubes, postoperative pain, and abdominal muscle recruitment. This partly explains the delay in the diagnosis of postoperative diaphragmatic dysfunction observed in some cases.

Key words: diaphragm dysfunction; neurofibromatosis; phrenic nerve; respiratory failure

On examination, there was evidence of severe diaphragmatic dysfunction with dullness at the bases of the lungs, diminished excursion of the diaphragm, and marked paradoxical inward motion of the anterior abdominal wall on deep inspiration. In addition, the patient was unable to remain in the supine position for more than a few seconds because of severe dyspnea. He claimed that he had been forced to sleep in an upright position for several weeks. A workup was undertaken to confirm the clinical suspicion of bilateral diaphragmatic paralysis. Spirometry and lung volumes revealed a moderately severe restrictive pattern, with FVC of 2.32 L (48% of predicted value) in the upright position and 1.51 L (31% predicted) in the supine position. [FEV.sub.1] was 1.69 L and 0.86 L in the upright and supine positions, respectively. Maximal inspiratory and expiratory forces were -61 (58% predicted) and +84 (42% predicted) cm [H.sub.2]O pressure, respectively, confirming severe respiratory muscle dysfunction. Transdiaphragmatic pressure, assessed by esophageal and gastric balloon pressure monitoring, revealed a significantly decreased pressure of 31 cm [H.sub.2]O. Fluoroscopic examination of the diaphragm (the "sniff test") --Revealed marked decrease in diaphragm motion bilaterally. Electromyographic studies of the diaphragm after stimulation of the phrenic nerves on both sides revealed no response. MRI of the cervical spine, obtained for a complaint of arm pain and paresthesias 4 months prior to the development of dyspnea, had revealed enlargement of the nerve roots within and lateral to the neural foramen at the levels of C3-4 and C6-7 on the right, and bilaterally at the levels of C4-5 and C5-6, most consistent with multiple neurofibromas (Fig 3). In summary, the radiographic, physiologic, and electrophysiologic studies were all consistent with severe bilateral diaphragm paralysis, which was believed to be secondary to involvement of the phrenic nerve roots (C3 to C5) with neurofibromas. For the past 3 years, the patient has been able to sleep flat at night with the assistance of noninvasive ventilation (bilevel pressure ventilation), and exertional dyspnea has remained stable

Conclusion
Patients with phrenic-nerve paresis or paralysis, especially those with unilateral paresis, have good prognoses.

The Mark IV Breathing Pacemaker System is an implantable diaphragmatic/phrenic nerve stimulator. Phrenic pacing, also referred to as diaphragm pacing, provides support for patients with chronic ventilatory insufficiency whose diaphragm, lungs, and phrenic nerves have residual function.

The external transmitter and antennas transmit energy to the bilaterally implanted receivers, which convert the radio signals into stimulating pulses delivered to both phrenic nerves by the electrodes. The hemidiaphragms then contract, producing inhalation. The train of impulses then stops, allowing the diaphragm to relax and exhalation to occur. Cyclic repetition of pulse trains, followed by no pulses, produces a normal breathing pattern. Some of the earliest patients have been pacing for more than 30 years, and many for more than two decades.

These pacemakers have full PMA approval by the US FDA and have qualified for the CE Mark under the European Active Implantable Medical Device Directive. Because of their reliability and cost effectiveness, they are approved by the Center for Medicare & Medicaid Services (formerly HFCA) for Medicare reimbursement and by most other private and government insurance plans throughout the world. Refer to the instruction manual, which is provided with each device, for detailed instructions for use, warnings, precautions, and adverse side effects. Federal law (USA) restricts this device to sale by or on the order of a physician.

This website was last updated on January 25, 2005

The quality management system of Avery Laboratories is certified in compliance with CAN/CSA ISO13485:1998 which is a requirement for distribution in Canada. However, breathing pacemakers are not currently licensed by Health Canada for sale or distribution within Canada. This licensing is in process, and is expected to be completed shortly.

NEW YORK, NY -- March 9, 1998 -- The Food and Drug Administration has given marketing approval to a new breathing pacemaker for patients who have lost neurological control of respiration. The portable device can significantly improve the quality of life and dramatically reduce the cost of care of people who are dependent on mechanical ventilators, including those with brain-stem or spinal cord injuries or with sleep apnea.

The Mark IV pacemaker was developed by the Dobelle Institute through its affiliates on Long Island and in Switzerland.

The pacemaker controls breathing by delivering repetitive electrical impulses to the phrenic nerves, which control movement of the diaphragm. Implantation of the device takes about an hour and can be performed on an outpatient basis.

Two patients implanted at Columbia-Presbyterian are among the first in the United States to receive the new system. One of the recipients is a seven-year-old boy who has had sleep apnea since birth and stops breathing whenever he falls asleep. Another recipient is a retired telecommunications professional, age 64, who had a small stroke in 1996 and suffers from intractable hiccups, which interrupt his breathing thousands of times a day.
A third patient, age 33, was paralysed from the neck down in a 1993 wrestling accident. After initial implant surgery, in Virginia, he came to Columbia-Presbyterian for pacemaker tuning at the Dobelle Institute.

The Mark IV completely supersedes earlier versions of the device, which affiliates of the Dobelle Institute have been making since 1971. Patients in 24 foreign countries have been using the new system during the FDA review, through the Institute Dobelle AG of Zurich. Most patients implanted with the earlier models can now be upgraded to the Mark IV without surgery.

In the future, by changing electrodes and the nerves selected for stimulation, the device will also be used to control many types of intractable pain, movement disorders such as Parkinson's disease, urinary incontinence and male sexual dysfunction.

The Mark IV is the direct outgrowth of ongoing research into artificial vision for the blind (TV camera and computer connected to the brain), conducted by Dr. Dobelle and his collaborators, beginning in 1968 at the
University of Utah.

Now, the sisters say they are normal teenagers and able to participate in any activity including long-distance running. They state that, although it took a long time to reach their goals, the breathing pacemakers have proven "even better than

Prior to her breathing pacemaker, Michaelene had been hospitalized several times each year for pneumonia, sleep studies, etc. According to her mother, she now goes years between such episodes. Additionally, since her breathing pacemaker does not require the routine maintenance and disposable supplies of a mechanical ventilator, it saves over ,000 every year for trest of her life.

Michaelene is now able to attend sleep-over parties and overnight camping trips. She enjoys snowboarding, skiing, and surfing. Her mother states that the portability of her Mark IV breathing pacemaker system has dramatically improved her quality of life and increased her self-esteem.

Adam was diagnosed with Central Hypoventilation Syndrome soon after his birth in July 1990. Like many children with his condition, Adam spend much of his early childhood in a hospital. All non-invasive treatments including Bi-Pap, C-Pap, and negative pressure ventilation eventually proved unsuccessful Although his parents considered resorting to a tracheostomy and positive-pressure ventilation, they opted instead to have him implanted with a breathing pacemaker.

His surgery was performed in March 1998. Adam no longer requires nighttime nursing assistance and is able to care for himself independently. He was recently chosen as an All-Star for his Little League baseball team, is a member of his school's gymnastic team, and has his artwork shown at local colleges and fine arts centers.

Jocelyn was born in March 1984 and quickly diagnosed with Congenital Central Hypoventilation Syndrome, or Ondine's Curse. She required mechanical ventilation every night, and occasionally during the day. As she approached adolescence, Jocelyn's ability to breathe effectively while awake began to deteriorate. She became completely dependent on her ventilator, which severely limited her activity.

Jocelyn has been able to take advantage of the portability of the breathing pacemaker to return to the level of social and athletic activity typical of teenage children. Today, Jocelyn is a senior in high school and is interested in pursuing a career in modeling or fashion.

After confirming the diagnosis, a tracheostomy was placed as Lukas would not tolerate ventilation by mask. Although he was able to return home with a ventilator, he suffered from repeated episodes of pneumonia as well as some developmental difficulties. In May 1999, Lukas returned to the Kinderklinik where he was implanted with a breathing pacemaker.

Lukas carries his Mark IV transmitter, which weighs approximately one pound, in a backpack as shown in the photo. His doctors report that Lukas is treated at home and doing well, with notable improvements in his mental and motor development

In 1977, Colin was born with Central Hypoventilation Syndrome (Ondine's Curse). For the next year-and-a-half Colin lived in the ICU at a children's hospital on a ventilator, unable to go home with his family. In 1979, at 19 months of age Colin was implanted with a breathing pacemaker.

During subsequent years, Colin used his pacer everynight during sleep as well as during the day, at times. In 1992, Colin was updated with a new, smaller I-110A/S-232G system, which is now superceded by the 1-110A/Mark IV system. These system consist of implanted receivers, electrodes on the phrenic nerves, and a silent external transmitter the size of a paperback book which weigh about 1 lb.