PURPOSE: Respiratory insufficiency is the major cause of mortality in patients with ALS. Ventilators, although life-saving, are inconvenient and associated with significant risks and alternate therapies to prevent or manage respiratory muscle decline in ALS is needed. The motor point diaphragm pacing stimulation (DPS) system has become a standardized minimally invasive laparoscopic technique that can provide ventilation in spinal cord injured patients. We postulate that therapeutic DPS will delay respiratory failure in ALS patient.
METHODS: As part of an FDA trial, patients underwent outpatient laparoscopic diaphragm motor point mapping with electrode implantations. Stimulus/output characteristics of each electrode were determined and diaphragm conditioning initiated. ALS patients conditioned their diaphragms with 5 daily stimulation sessions of 30 minutes each . Each patient had three extensive lead-in assessments that were continued post implantation of the DPS system.
RESULTS: Sixteen patients have been safely implanted with no adverse events. Feeding tubes were safely simultaneously placed in 7 patients. In all patients, more fluoroscopically observed diaphragm excursion occured with diaphragm stimulation than under maximal voluntary effort. DPS significantly increases muscle thickness when assessed with ultrasound (p-value 0.02). After conditioning the diaphragm with the DPS, preliminary results show an average rate of decline in FVC of 1.3% per month from the pre-implantation decline of 3.1% a month, which extrapolates to an additional 15 months of ventilator free survival. Additional findings include: DPS can convert fast twitch glycolytic (IIb) to functional slow twitch oxidative muscle (I) fibers; DPS improves posterior lobe lung ventilation; DPS increases lung compliance leading to decreased work of breathing; and patients have started utilizing DPS to improve nighttime ventilation.
CONCLUSION: The DPS system can be safely implanted and utilized in ALS patients, with a documented decrease in the decline of respiratory failure leading to increased survival. A multi-center pivotal trial is now enrolling patients and collecting data.
CLINICAL IMPLICATIONS: The ability to specifically target and improve diaphragm function with the DPS system will increase therapeutic options in these patients.
DISCLOSURE: Raymond Onders, No Product/Research Disclosure Information; Shareholder Myself, my university and my hospital have intellectual property rights and founded a company that manufactures some technology used in this study