Assessment of respiratory muscle strength during extubation in critically ill patients

Background: Mechanical ventilation is associated with mechanical ventilator (MV)-induced diaphragmatic dysfunction, which leads to respiratory muscle weakness, the inability to sustain spontaneous breathing, prolonging ventilatory weaning, a longer stay in the intensive care unit (ICU), and an increased risk of in-hospital mortality. Purpose: We wished to compare MIP measurements obtained via a one-way valve and mechanical ventilator software in critically ill patients, in order to determine the interchangeability of these methods and explore the utility of the ventilator method as a screening tool. Methods: A crossover study was conducted in an ICU with patients ≥18 years of age after 48 h of mechanical ventilation. The participants were randomized in receiving the two different methods for measuring MIP: a manometer coupled to the one-way valve (MIP-OWV) and the MV (MIP-MV). Results: Thirty-two patients of both sexes were assessed. No significant difference was found between the MIP-OWV and MIP-MV methods (p = 0.77), with strong correlation (r = 0.70; p < 0.001) and minimal mean bias (−1.0 cmH2O). However, the wide limits of agreement (−38.8 to +36.8 cmH2O) indicated clinically relevant individual variability. Conclusions: While not interchangeable for precise clinical decisions due to individual variability, ventilator software shows promise as an efficient screening tool for inspiratory muscle strength assessments in ICU settings, offering practical advantages over the traditional method.