Parasternal Intercostal Ultrasound vs RSBI for Weaning Prediction

Ultrasonographic Assessment of Parasternal Intercostal Muscle Thickness Versus Rapid Shallow Breathing Index for Predicting Weaning From Mechanical Ventilation

Mechanical ventilation is essential in the management of critically ill patients, but deciding the proper time to wean and extubate remains a significant challenge. Extubation failure is associated with poor outcomes, including prolonged intensive care unit stay, higher risk of complications, and increased mortality. The rapid shallow breathing index (RSBI) is widely used to predict weaning readiness, but its predictive accuracy is limited. Recently, ultrasound evaluation of respiratory muscles, particularly the parasternal intercostal muscle, has been proposed as a promising bedside tool to assess respiratory effort and load.

This comparative clinical trial was conducted on adult intensive care unit patients at Benha University Hospital who were mechanically ventilated for ≤24 hours and ready for a spontaneous breathing trial. Each patient underwent both rapid shallow breathing index (RSBI) measurement and parasternal intercostal muscle ultrasound prior to the trial. Patients were classified into successful or failed weaning groups based on trial outcome. The study compared the diagnostic accuracy of both methods and aimed to determine whether ultrasound assessment of the parasternal intercostal muscle offers a more reliable predictor of weaning success than rapid shallow breathing index (RSBI).

Inclusion Criteria:

• Age 18 years or older

• Both sexes

• Patients invasively mechanically ventilated for up to 24 hours and ready to undergo a spontaneous breathing trial

• Patients considered ready for spontaneous breathing trial if all of the following were met:

  • Alert and afebrile
  • Fraction of inspired oxygen less than 50 percent
  • Positive end-expiratory pressure less than or equal to 8 centimeters of water
  • Ratio of arterial oxygen partial pressure to fraction of inspired oxygen greater than 200
  • Arterial blood pH between 7.35 and 7.45
  • Respiratory rate less than or equal to 35 breaths per minute
  • Hemodynamically stable without vasopressor support

Exclusion Criteria:

• Age younger than 18 years
• Pregnancy
• Surgical dressings near or over the sternum that prevent ultrasound examination
• Body mass index less than 18.5 kilograms per square meter (underweight)
• Body mass index greater than or equal to 40 kilograms per square meter (morbid obesity)
• Primary neuromuscular diseases