Inspiratory Muscle Training in Difficult to Wean Patients

Prolonged mechanical ventilation secondary to weaning failure demands a significant amount of intensive care unit (ICU) resources, thus increasing the economic burden of public healthcare costs. One of the proposed mechanisms accounting for weaning failure is the concept that excessive work of breathing for weak respiratory muscles during the liberation from mechanical ventilation compromises cerebral blood flow, thereby predisposing the brain to dysfunction. Restriction in brain perfusion could have an adverse impact on the function of the respiratory muscles by impairing the output of the respiratory centre thus promoting respiratory muscle fatigue, leading to weaning failure. Inspiratory muscle training (IMT) has been shown to improve the functional capacity of the inspiratory muscles in patients with respiratory muscle weakness whilst has been recently proposed as a possible additional component of weaning strategies. Therefore, this project aims to identify both a mechanism that might be linked to prolong ICU length of stay and that at the same time might be amenable to treatment.