Salt and Diet in Patients with Heart Failure

Background: Over one million patients in the US are estimated to undergo mechanical ventilation every year, and approximately 300,000 of them fail attempts at weaning. The morbidity and mortality of these patients is greater than in patients who are successfully weaned. It follows that treatments aimed at reducing the duration of mechanical ventilation have the potential to benefit society both in terms of human suffering and cost. Patients who fail attempts at weaning assist their inspiratory muscles during inhalation by recruiting their expiratory muscles during exhalation. Unfortunately, this recruitment occurs relatively late during a weaning trial. The knowledge that (a) expiratory muscle recruitment can assist inspiration, (b) the recruitment of the expiratory muscles is delayed during weaning, and (c) that the respiratory muscles in patients requiring mechanical ventilation are in a catabolic state raises the possibility that strategies designed to produce an early recruitment, and improve the strength, of the expiratory muscles could improve weaning outcomes in difficult to wean patients. The current investigation, which will be conducted in healthy subjects and in ambulatory patients with chronic obstructive pulmonary disease (COPD) at Edward Hines Jr. VAH (Aims 1 and 2), and in patients who are difficult to wean from mechanical ventilation at RML Specialty Hospital, Hinsdale, IL (Aim 3), has been designed to develop and assess a novel triggering algorithm (VentFree), that controls the delivery of non-invasive neuro muscular electrical stimulation (NMES) to the abdominal-wall muscles during exhalation, and to study the physiological (respiratory) responses to such stimulation in assisting respiration in healthy subjects, in ambulatory patients with COPD and in patients requiring pronged mechanical ventilation.