Many patients with spinal cord injury (SCI) need mechanical ventilatory support. One type of support is diaphragm pacing, which stimulates the diaphragm, helping the person breathe. A minimally invasive form of diaphragm pacing via laparoscopically placed intramuscular diaphragm electrodes has “liberated thousands of patients from mechanical ventilation,” says Anthony DiMarco, MD. He and VA colleague Krzysztof Kowalski, PhD, have found a way to completely restore respiratory muscle function in patients with SCI safely and effectively.
In mid-thoracic and higher level SCIs, the expiratory muscles are paralyzed, putting patients at risk for respiratory tract infections and atelectasis, a major cause of morbidity and mortality in that population. The research team, led by DiMarco and Kowalski, combined diaphragm pacing with a minimally invasive system that allows the patient—simply with the press of a button—to cough effectively, reducing the risk of aspiration and infections. It is the first method in the world, says Dr. Kowalski, that activates abdominal and lower rib cage muscles to produce an effective cough.
An interventional clinical trial in 3 patients demonstrated that using the 2 systems in tandem was safe. The new system was implanted surgically, with disc electrodes placed on the dorsal surface of the spinal cord via laminectomy. Participants in the study used a stimulator to produce several different cough efforts from light to strong.
Mean peak expiratory airflow and airway pressure generation during spontaneous efforts were 1.7 ± 0.2 L/s and 31 ± 7 cmH 2O, respectively. After the spinal cord stimulation was applied, peak expiratory airflow was 9.0 ± 1.9 L/s and airway pressure generation was 90 ± 6 cmH 2O. In other words, results “characteristic of a normal cough,” the researchers concluded. Moreover, each patient raised secretions much more easily.
The research is being done at the Cleveland Functional Electrical Stimulation Center, a consortium of MetroHealth Medical Center, Case Western Reserve University, and Louis Stokes Cleveland VA Medical Center.
Army veteran David Powers, one of the study participants, in an interview with the VAntage Point blog, says, “Being a part of this research trial has made me feel great. For not only my own health but helping to improve the lives of others as well.”