Association Between Abdominal Muscle Weakness and Weaning Failure in Mechanically Ventilated Critically Ill Patients: An Ultrasound Assessment

Background Assessing cough effectiveness and abdominal muscle strength in critically ill patients is difficult, despite their significant impact on weaning outcomes. Ultrasound evaluation of abdominal muscle activity during a cough may help identify patients at risk of weaning failure. We investigated how abdominal muscle weakness (AMW), assessed via ultrasound during coughing, relates to weaning failure at 48 hours and 7 days, and explored its links with diaphragm dysfunction (DD) and ICU-acquired weakness (ICUAW). Methods Patients at high risk for weaning failure, who were intubated or tracheostomized and had been ventilated for at least 48 hours, successfully completed the spontaneous breathing trial (SBT), and were attempting their first disconnection, were included. Before the disconnection attempt, all patients were tested for AMW, defined as the overall thickening fraction of the abdominal muscles during cough (TF _abs ). DD was explored using ultrasound, and ICUAW was assessed using the Medical Research Council scale or the peripheral nerve test in uncooperative patients. Results Among the 46 patients, weaning was successful at 48 hours in 30 (65.2%) and failed in 16 (34.7%). Nine (20.5%) patients had AMW, ICUAW, and DD simultaneously, whereas 10 (22.9%) patients developed isolated AMW. Pearson's chi-square test confirmed that AMW was not associated with ICUAW (p = 0.28) or DD (p = 0.97). The multivariable logistic regression analysis revealed a greater probability of weaning failure at 48 hours (OR 9.4, CI 1.1–75.2, p = 0.03) and 7 days (OR 14.8, CI 1.6–136.1, p = 0.02) for patients with AMW than for patients without AMW. ICUAW was also associated with weaning failure at 48 hours (OR 8.5, CI 1.5–46.8, p = 0.01) and 7 days (OR 20.4, CI 2.7–155.0, p < 0.01), whereas the presence of DD was not related to either weaning failure at 48 hours or 7 days. Conclusions An ultrasound evaluation of abdominal muscle function during cough, together with an assessment of ICUAW, could help assess ventilator disconnection readiness.