Managing respiratory muscle weakness during weaning from invasive ventilation

Abstract

Weaning is a critical stage of an intensive care unit (ICU) stay, in which the respiratory muscles play a major role. Weakness of the respiratory muscles, which is associated with significant morbidity in the ICU, is not limited to atrophy and subsequent dysfunction of the diaphragm; the extradiaphragmatic inspiratory and expiratory muscles also play important parts. In addition to the well-established deleterious effect of mechanical ventilation on the respiratory muscles, other risk factors such as sepsis may be involved. Weakness of the respiratory muscles can be suspected visually in a patient with paradoxical movement of the abdominal compartment. Measurement of maximal inspiratory pressure is the simplest way to assess respiratory muscle function, but it does not specifically take the diaphragm into account. A cut-off value of −30 cmH2O could identify patients at risk for prolonged ventilatory weaning; however, ultrasound may be better for assessing respiratory muscle function in the ICU. Although diaphragm dysfunction has been associated with weaning failure, this diagnosis should not discourage clinicians from performing spontaneous breathing trials and considering extubation. Recent therapeutic developments aimed at preserving or restoring respiratory muscle function are promising.

Low-Medium and High-Intensity Inspiratory Muscle Training in Critically Ill Patients: A Systematic Review and Meta-Analysis

“…More recently, we noted that when IMT is performed with pressure threshold loading at a certain lung volume, the patient will not be able to overcome the initial loading of MIP (measured at the residual volume), especially if this is quite high. Thus, the inspiratory valve will close sooner in the breathing effort and limit the ability to perform full vital capacity inspirations [ 35 ]. This limits the loading and the training effect.…”

Critical illness-associated limb and diaphragmatic weakness

“…Managing CIDW can be done through preventive or curative approaches [85]. The preventive approach is based on promoting spontaneous ventilation within ranges of inspiratory efforts to maintain the diaphragm active (and minimize the risk of atrophy) while limiting excessive lung-distending pressures [86].…”

Non-Invasive Assessment of Abdominal/Diaphragmatic and Thoracic/Intercostal Spontaneous Breathing Contributions

“…Patient-specific drive has also been assessed using model-based methods [ 48 , 50 , 55 , 56 ]. The elucidation of muscular contributions and distribution of lung volume has now become a respiratory research focus [ 57 , 58 , 59 , 60 , 61 , 62 ]. However, to improve diagnosis, monitoring, and management, simple, non-invasive, and automated methods of assessing muscular recruitment and lung volume are required for the reliable differentiation of the causes of disordered breathing, particularly for use outside of fully equipped clinical settings.…”