Abdominal Functional Electrical Stimulation To Assist Ventilator Weaning In Critically Ill Patients: a randomised controlled trial

The abdominal muscles are the primary muscle group used during forced exhalation. We have shown that surface Functional Electrical Stimulation (FES) of the abdominal muscles, termed Abdominal FES, can improve respiratory function and assist weaning from mechanical ventilation in spinal cord injury. A pilot study of 11 ventilated critically ill patients found Abdominal FES maintained abdominal muscle thickness and decreased ventilation duration. We hypothesise that Abdominal FES in critically ill patients will reduce mechanical ventilation duration. Two hundred and fifty four critically ill patients being treated in the Intensive Care Unit (ICU) of the Prince of Wales Hospital, Sydney, and Royal North Shore Hospital, Sydney, will be recruited to this randomised, placebo controlled trial. Participants will be recruited who are mechanically ventilated and are expected to remain that way for at least 48 hours. 127 patients will be randomly allocated to receive Abdominal FES and 127 will receive a placebo. In the Abdominal FES group, Abdominal FES will be applied for 45 minutes per day, 5 days per week, until the patient is discharged from the ICU, by a local physiotherapist. Specifically, Abdominal FES will be delivered, via electrodes placed over the posterolateral surface of the abdomen. The stimulation amplitude will initially be set to 60 mA (50 Hz), which corresponds to 90% of the maximum amplitude that was tolerated by healthy volunteers in a previous study. If this amplitude results in discomfort to the patient (based on clinical judgement) then it will be reduced as necessary. In addition, the stimulation amplitude will be evaluated every five minutes to ensure that stimulation is still tolerable and causing a suitable muscle contraction.