Managing respiratory muscle weakness during weaning from invasive ventilation

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.

Automated summary

Weaning is a critical stage in ICU care and respiratory muscles play a major role. Weakness of respiratory muscles, including diaphragm atrophy and dysfunction, as well as extradiaphragmatic inspiratory and expiratory muscles, is associated with significant morbidity in the ICU. Diagnosis of respiratory muscle weakness can be visually suspected through paradoxical movement of the abdominal compartment or measured using maximal inspiratory pressure. However, ultrasound may be a better option for assessing respiratory muscle function in the ICU. It is important to not let diaphragm dysfunction discourage clinicians from performing spontaneous breathing trials and considering extubation, as recent therapeutic developments show promise in preserving or restoring respiratory muscle function.