Treatment of chronic ventilatory failure using a diaphragmatic pacemaker

Abstract

We present our series of patients with chronic ventilatory failure treated with electrophrenic respiration: 13 males and nine females with a mean age of 12+11.5 years. The etiology was, 13 tetraplegia, ®ve sequelae of surgical treatment of intracranial lesions, and four central alveolar hypoventilation. The mean duration of the conditioning period were 3 ± 4 months. Eighteen patients (81.8%) achieved permanent, diaphragmatically-paced breathing with bilateral stimulation and in four (18.2%) patients, pacing was only during sleep. Five patients died (22.7%): two during the hospital stay and three at home; two deaths had unknown cause and three were due respectively to, lack of at-home care, recurrence of an epidermoid tumor, and sequelae of accidental disconnection of the mechanical ventilation before beginning the conditioning period. Two cases were considered failures: One patient had transitory neurapraxia lasting 80 days, and the other had an ischemic spinal cord syndrome with progressive deterioration of the left-side response to stimulation. One patient had right phrenic nerve entrapment by scar tissue and four suered infections. The follow-up periods since pacemaker implantation are currently: 1, 11 years; 4, 10 years, and 17, less than 5 years. The results of our experience demonstrate that complete stable ventilation can be achieved using diaphragmatic pacing and that it improves the prognosis and life quality of patients with severe chronic respiratory failure.

Phrenic Nerve Pacing: Current Concepts

“…This is tested by cervical magnetic stimulation and/or electrical stimulation of the phrenic nerve in the neck (20,21,36,38,39). However a recent French series which looked at long term outcomes, found benefit in phrenic nerve pacing even in patients who had injuries dating back several years.…”

“…Pulmonary function tests, especially measurements of upright and supine vital capacity, are non invasive and may support or refute the diagnosis (2,14,38). Arterial blood gas values during mechanical ventilation (23,36,38) and a sleep study when possible, add diagnostic information (23).…”

“…Acceptable pulmonary function 5. Normal level of consciousness (36). Acquired CAHS has been described with medullary tumors, infection (particularly poliomyelitis), upper cervical trauma, some mitochondrial diseases, degenerative diseases (eg multiple sclerosis), and non-specific ischemic insults (12).…”

“…Thus, a strategy of minimizing diaphragm fatigue during pacing should involve the gradual conditioning with low-frequency stimulation and a slow respiratory rate (29). Diaphragmatic conditioning is a process by which the fast-contracting fibers (anaerobic, highly glycolytic fibers), which are highly susceptible to get fatigued, are converted to slow-contracting fatigue-resistant (aerobic oxidative fibers), which enable permanent ventilatory support using diaphragmatic pacing (4,36). While on mechanical ventilation, many patients are generally maintained with large tidal volumes.…”

“…When pacing on each side has been extended to 12 hours, while producing satisfactory minute volumes and normal arterial blood gases, the patient can be completely removed from mechanical ventilation. This weaning process usually takes 2 to 3 months, which is the time frame required for diaphragmatic fiber recovery (21,28,36,38,41). A considerably longer period of conditioning is required in children because of immaturity of respiratory components (21).…”