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.

FIGURE 1

The respiratory muscles involved in the generation of respiration. Figure created using BioRender.

FIGURE 2

Pragmatic approach for the diagnostic management of respiratory muscle weakness. SV: spontaneous ventilation; TEE: thickness at end expiration; TEI: thickness at end inspiration; US: ultrasound. Figure created using BioRender.

FIGURE 3

Interventions to manage respiratory muscle weakness in the intensive care unit. Figure created using BioRender.