Abdominal Functional Electrical Stimulation To Assist Ventilator Weaning In Critically Ill Patients

INTERVENTION: 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, however the sample size was too small to achieve statistical significance. We hypothesise that Abdominal FES in critically ill patients will reduce diaphragm and abdominal muscle atrophy, with the long term goal of this project to demonstrate reduced mechanical ventilation duration. Twenty critically ill patients being treated in the Intensive Care Unit (ICU) of the Prince of Wales Hospital, Sydney, will be recruited to this randomised, placebo controlled pilot trial. Participants will be recruited who are mechanically ventilated and are expected to remain that way for at least 48 hours. Ten patients will be randomly allocated to receive Abdominal FES and 10 will receive a placebo. In the Abdominal FES group, Abdominal FES will be applied for 30 minutes, twice per day, 5 days per week, until the patient is discharged from the ICU. Specifically, Abdominal FES will be delivered, via electrodes placed over the surface of the abdomen, at a frequency of 30 Hz and a pulse width of 350 µs. These settings are based on previous trials. The stimulation amplitude will initially be set to 60 mA, 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 five and 20 minutes after the start of each session to ensure that stimulation is still tolerable and causing a suitable muscle contraction. Ultrasound will be used to verify whether stimulation results in a contraction of the abdominal muscles during the first Abdominal FES session. CONDITION: Critical Illness Sepsis Stroke Traumatic Brain Injury PRIMARY OUTCOME: Feasibility as measured by patient compliance, time needed to recruit patients, time needed to collect data, proportion of eligible patients of total ICU population, withdrawal rate and effectiveness of blinding Thickness of the abdominal muscles as measured by ultrasound SECONDARY OUTCOME: Echogenicity of the abdominal wall muscles as measured by ultrasound Maximum expiratory pressure (MEP) measured using spirometry Maximum inspiratory pressure measured using spirometry Number of Re‐intubations in intensive care Peak expiratory flow measured using spirometry Quality of Life during and after mechanical ventilation as measured by SF‐36 questionnaire Systemic inflammatory markers (IL‐6, IL‐1, IL‐8) as measured by blood test Thickness of the diaphragm as measured by ultrasound Time in Intensive Care Unit (ICU) Time spent dependent on mechanical ventilation Vital capacity measured using spirometry INCLUSION CRITERIA: mechanical ventilation dependence due to critical illness