Breathing induced by abdominal muscle stimulation in individuals without spontaneous ventilation

The purpose of the study was to determine if functional electrical stimulation of abdominal muscles (FESAM) could maintain pulmonary ventilation at acceptable levels in individuals with spinal cord injury (SCI) who are unable to breathe spontaneously. This is the first published investigation of this technique in this subject population. This case series study included three individuals with SCI; two were on mechanical ventilation (MV), and one used mechanical ventilation and also had an implanted phrenic nerve stimulator (PNS). Using surface electrodes, stimulation was applied to the rectus abdominis and lateral group of abdominal muscles. Repetitive trains of pulses produced a breathing frequency of 20 breaths/min. The longest periods of breathing using only FESAM-supported ventilation for the three subjects were 30, 40, and 210 s, respectively. Airflow at the mouth and volumes were measured with a pneumotachograph and/or optoelectronic plethysmography. Oxygenation was monitored with a pulse oximeter. The tidal volumes generated exclusively by FESAM were sufficient to maintain adequate oxygenation during the periods of stimulation. When oxygenation measured with pulse oximetry dropped to 92% saturation, FESAM was discontinued, and MV or PNS was resumed. This is the first report of achieving successful ventilation in individuals with SCI who have zero tidal volume using FESAM. These preliminary results indicate the clinical potential of FESAM as an additional tool in the armamentarium of supported ventilation.