The purpose of this review was to synthesize the effects of IMT using a threshold device on physical function outcomes, as compared to usual care, in adults admitted to the ICU who required IMV for ≥24 hours.
We conducted a systematic review using Cochrane Handbook methods (PROSPERO: CRD 42023451809). Randomized controlled trials (RCTs) were included if they enrolled adults (≥18 years) admitted to the ICU who required IMV for ≥24 hours and assessed an intervention of IMT compared to usual care. Our primary outcome of interest was physical function. Secondary outcomes included IMV weaning time, reintubation rate, and mortality. We searched seven databases from their inception. All citations were imported into Covidence, where screening, study selection, and data extraction were completed independently and in duplicate. A third reviewer was available to arbitrate, if required. If results were sufficiently homogeneous, we conducted a meta-analysis and reported the mean difference (MD) for the same outcome measures or standardized MD (SMD) for similar outcome measures. Otherwise, results were reported narratively. We assessed risk of bias with version 2 of the Cochrane Risk of Bias Tools for randomized trials and evidence quality using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) tool.
We screened 12,950 studies and 23 met eligibility criteria. The eligible studies included a total of 1,115 participants among the treatment and control groups. Twenty-one (91%) studies initiated the IMT intervention prior to discontinuing IMV. Three (13%) studies reported physical function outcomes among 160 participants. When combined, we found that IMT may have no effect on physical function (SMD = -0.05, 95% confidence interval [CI]: -0.46 to 0.36). IMT may reduce IMV weaning time (MD = -1.85 days, 95% CI: -3.06 to -0.64), reintubation rate (Risk ratio [RR] = 0.73, 95% CI: 0.54 to 0.99), and mortality (RR = 0.56, 95% CI: 0.41 to 0.77). However, the evidence is very uncertain for all outcomes.
Our results suggest that IMT does not impact physical function; however, results are very uncertain due to few studies with small sample sizes. IMV weaning time, reintubation rate, and mortality may be reduced through IMT implementation.
The evidence of IMT on physical function is limited. High quality, appropriately powered RCTs are needed to determine the impact of IMT on physical function outcomes and to improve the precision of the effect estimate. Future studies should consider long-term follow-up and the inclusion of physiological outcomes, such as point-of-care ultrasound, to further evaluate the impact of IMT on physical function and diaphragmatic weakness.
Critical care
Physical function
