Shu-Jane Wang ¹ Tien-Pei Fang ² Daniel D Rowley ³ Nan-Wei Liu ⁴ Jui-O Chen ⁵ Jui- Fang Liu ⁶ Hui-Ling Lin ^7*

• ¹ Department of Respiratory Therapy, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan
• ² Department of Respiratory Therapy, Chiayi Chang Gung Memorial Hospital, Chiayi City, Taiwan
• ³ Respiratory Therapy Services, University of Virginia Health System, Charlottesville, Virginia, United States
• ⁴ Department of English, National Chengchi University, Taipei, Taiwan
• ⁵ Department of Nursing, Tajen University, Yenpu Township, Taiwan
• ⁶ Department of Respiratory Care, Chang Gung University of Science and Technology, Taoyuan, Taiwan
• ⁷ Department of Respiratory Therapy, College of Medicine, Chang Gung University, Taoyuan, Taiwan

Background: Patients undergoing mechanical ventilation often develop rapid diaphragmatic atrophy, respiratory muscle weakness, and dysfunction, which are associated with prolonged duration of ventilation. This study aimed to evaluate whether Inspiratory Muscle Training (IMT) facilitates weaning from mechanical ventilation and enhances muscle strength in critically ill, subacute adult patients, while examining the relationship between IMT and relevant clinical laboratory values. Methods: In this randomized clinical trial, patients admitted to the intensive care unit requiring mechanical ventilation for more than two days, with stable hemodynamics and resolved acute conditions, were enrolled. Participants were randomly assigned to the IMT or no-IMT group. The IMT group received training twice daily, five days a week, for three consecutive weeks. The primary outcome was ventilator duration. The primary outcome measure was the number of days until liberation from mechanical ventilation. The secondary outcomes of interest were respiratory muscle strength and biomarker levels.Results: Thirty-three subjects (17 in the IMT group, 16 in the no-IMT group) were included in the final analysis. The IMT group had significantly shorter ventilator days (12.6 ± 5.2 vs. 18.1 ± 8.8, P = 0.04). IMT intervention significantly reduced rapid shallow breathing index and improved respiratory muscle strength, with greater maximum inspiratory pressure (P < 0.01), maximum expiratory pressure (P = 0.03), and peak expiratory flow (P = 0.01). A moderate positive correlation was observed between IMT and increased creatinine levels (rs = 0.54, P = 0.01), whereas the no-IMT group showed a reduction. Conclusion: IMT significantly shortened ventilator duration and improved respiratory muscle strength. A moderate correlation between increased creatinine levels and respiratory muscle strength was observed, suggesting that creatinine may be a potential biomarker for muscle recovery during IMT. (This study was registered at ClinicalTrials.gov (NCT06611683).