The role of diaphragm and rectus abdominis muscle thickness in predicting mortality, morbidity, and weaning success from mechanical ventilation in ICU patients

Purpose: This study aimed to evaluate the relationship between diaphragm and rectus abdominis (RA) muscle thickness and mortality, morbidity, and weaning success from mechanical ventilation in intensive care unit (ICU) patients. Materials and methods: A total of 87 adult ICU patients were included. Diaphragm and RA muscle thicknesses were measured via ultrasound on the 1st, 3rd, 7th, and discharge days of ICU stay. Clinical data, including mechanical ventilation status, weaning outcome, infections, and the use of sedation, inotropes, and steroids, were recorded. Results: Invasive mechanical ventilation (IMV) was applied in 82.7% of patients. Weaning was successful in only 15.2% of IMV patients. On the discharge day, diaphragm and RA thicknesses were significantly lower in the IMV group than in the non-IMV group (p=0.029, p=0.004, respectively). RA thickness was significantly higher on day 1 in the successfully weaned group (p=0.03). Diaphragm thickness showed a weak positive correlation with BMI. A weak negative correlation was found between RA thickness and NUTRIC score. No correlation was observed between muscle thicknesses and age, APACHE-II or SOFA scores. Conclusion: Monitoring diaphragm and RA muscle thickness may guide the assessment of weaning and mortality risk in ICU patients. Particularly, RA thickness may serve as a potential biomarker for predicting weaning success.