Functional electrical stimulation to enhance cough in quadriplegia

Respiratory problems are a major cause of death in the acute and chronic phases of cervical spinal cord injury (CSCI); CSCI paralyzes the intercostal and abdominal muscles, reducing ability to cough and clear secretions. Impaired cough due to neuromuscular disorders can be assessed with the maximum expiratory pressure (MEP). This study consists of two experiments with CSCI patients. In the first, MEP measurements were recorded with the following maneuvers performed: (1) spontaneous cough attempts, (2) manually assisted cough, and (3) cough attempts with functional electrical stimulation (FES) applied to the abdominal wall. In the second, spontaneous cough attempts and cough attempts with a portable FES unit were recorded. These CSCI patients were found to have a greatly reduced MEP when they coughed spontaneously. Either FES-assisted or manually assisted coughing increased the MEP in all patients studied. By increasing the MEP, abdominal muscle FES could enhance cough in quadriplegics.