Inspiratory muscle training shows no clear effect on physical function in critically ill adults on mechanical ventilation

PurposeThe onset of diaphragmatic weakness begins within hours of commencing invasive mechanical ventilation (IMV), which may contribute to the physical disability that can persist at five years after intensive care unit (ICU) discharge. Inspiratory muscle training (IMT) has the potential to alleviate the negative effects of IMV.MethodsWe conducted a systematic review and meta-analysis with an approach consistent with Cochrane methods. We registered our review a priori (PROSPERO: CRD 42023451809) and published our protocol. Randomized controlled trials (RCTs) which enrolled adults (≥18 years) admitted to ICU who required IMV for ≥24 h were eligible if they delivered an IMT intervention using an external device that provided airway resistance (eg, threshold device, tapered flow resistive device) compared to usual care. Our primary outcome was physical function. Secondary outcomes included respiratory muscle strength, mortality, length of stay, IMV weaning time, reintubation rate, dyspnea and endurance. We searched Medline, Embase, Emcare, AMED, CINAHL, CENTRAL and clinicaltrials.gov from inception and used the Covidence platform for study selection and data extraction. We reported results as standardized mean difference (SMD) if outcome measures were similar. We used the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) to assess the certainty of evidence.ResultsWe screened 12 945 studies and 18 met the inclusion criteria. Three studies reported the effects of IMT on physical function. IMT may have no effect on physical function (SMD = -0.05, 95% confidence interval: -0.46 to 0.36) however results are very uncertain.ConclusionOur results suggest physical function is not impacted by IMT; however, our results are based on a limited number of studies with small samples sizes. High quality, appropriately powered RCTs are needed to improve the precision of the effect estimate.