Year: 2026 | Month: April | Volume: 16 | Issue: 4 | Pages: 52-59
DOI: https://doi.org/10.52403/ijhsr.20260407
Assessment of Respiratory Muscle Strength in Mechanically Ventilated Patients
Sahana S1, Shaswat Verma2, Deepak T S3, Chaitali Kadam4, Veena Kiran Nambiar5
1,2,4,5M S Ramaiah College of Physiotherapy, 3Department of Critical Care Medicine,
M S Ramaiah Medical College, M S Ramaiah University of Applied Sciences Karnataka, Bangalore, India.
Corresponding Author: Shaswat Verma
ABSTRACT
Background: Respiratory muscle weakness is a prominent and well-recognized problem among mechanically ventilated patients, contributing significantly to delayed weaning, prolonged intensive care unit (ICU) stays, and reduced overall quality of life. Maximal Inspiratory Pressure (MIP) serves as a reliable and non-invasive indicator of respiratory muscle strength and can be easily assessed at the bedside using the end-expiratory occlusion technique. Recognizing its clinical value, this study aimed to measure the MIP of mechanically ventilated patients and examine its association with the duration of ventilator dependence.
Methods: An observational study was conducted among 75 patients receiving mechanical ventilation in the ICU who met the predefined inclusion criteria. MIP was measured using the end-expiratory occlusion method, and the value was calculated using the formula: MIP = Total PEEP – Maximal Negative Pressure. Demographic data were analyzed using descriptive statistics, while respiratory muscle strength was assessed in terms of median and interquartile range (IQR).
Results: The respiratory muscle strength of the study population, represented by MIP, showed a median value of 28 cm H₂O with an interquartile range of 26 to 29 cm H₂O. Patients who were on SIMV and CPAP mode of ventilation had an average MIP of 26.44 and 28.3 cm of H₂O. The correlation coefficient between length of stay on ventilator and MIP is -0.610 with a significant p value of <0.001. These findings indicate reduced inspiratory muscle strength among mechanically ventilated patients.
Conclusion: The study demonstrated that respiratory muscle strength in mechanically ventilated individuals is diminished, and a longer duration of ventilator support is associated with progressively lower MIP values. This negative correlation highlights the importance of routine monitoring of respiratory muscle strength and early rehabilitation strategies to facilitate timely weaning and improved patient outcomes.
Key words: Intensive Care Unit Acquired Weakness (ICU-AW); Respiratory muscle strength; Mechanical ventilator; Maximal Inspiratory Pressure; Ventilator-induced Diaphragm Dysfunction; Modes of Ventilator