Rationale: Inspiratory muscle training (IMT) improves respiratory muscle function in patients with weaning difficulties. IMT protocols involve performing daily sets of breaths against external loads. However, the impact of IMT on weaning outcomes while incorporating sham control interventions remains unclear.
Objectives: To compare the effects of a high-intensity IMT (Hi-IMT) intervention with a sham low-intensity (Lo-IMT) control group on weaning outcomes, respiratory muscle and pulmonary function 28 days after inclusion, in patients with weaning difficulties.
Methods: Both groups underwent daily IMT sessions until successful weaning or a maximum of 28 days. The Hi-IMT group (n=44, 61% male, 57±15 years) performed maximal inspirations initiated from residual volume against an external load representing 30-50% of maximal inspiratory pressure (PImax), while the control group (n=46, 52% male, 60±12 years) performed maximal inspirations against a load ≤10% PImax.
Measurements and main results: Training adherence (completed/planned sessions) was comparable between the groups (Hi-IMT: 77±20%, Lo-IMT: 72±17%, p=0.25). Weaning success (64% Hi-IMT and 76% Lo-IMT; p=0.43) and weaning duration (Hi-IMT: 45±48 days, Lo-IMT: 37±26 days, p=0.33) were similar between groups. Both groups similarly improved PImax (Hi-IMT: +15cmH2O [95%CI: 9 ; 20], Lo-IMT: +14cmH2O [95%CI: 9 ; 19], p=0.72). Forced vital capacity improved more in the Hi-IMT than Lo-IMT group (Hi-IMT: +0.33L [95%CI: 0.22 ; 0.43], Lo-IMT: +0.16L [95%CI: 0.07 ; 0.25], p=0.04).
Conclusions: Both high-intensity IMT and sham low-intensity IMT, with high adherence to the protocol, resulted in similar weaning success rates and pronounced improvements in maximal inspiratory muscle strength. Clinical trial registration available at www.
Clinicaltrials: gov, ID: NCT03240263.
Keywords: Intensive Care Unit; Mechanical Ventilator Weaning; Respiratory Muscle; Respiratory Muscle Training.