The primary objective of this prospective observational study is to evaluate the effectiveness of combining the Rapid Shallow Breathing Index (RSBI) and CRP-Albumin-Lymphocyte (CALLY) index to predict weaning success in adult patients within the intensive care unit. While weaning from mechanical ventilation is a critical clinical step, existing physiological metrics like RSBI do not fully capture a patient's inflammatory or nutritional status. This research introduces the CALLY index calculated as the ratio of the patient's immuno-nutritional reserve (Albumin and Lymphocytes) to systemic inflammation (CRP) as a complementary metabolic marker. By tracking approximately 105 participants at Basaksehir Cam and Sakura City Hospital, the study monitors weaning success over both a 48 hour and a 7 day period to identify both immediate and late phase extubation failures. The ultimate goal is to provide a more holistic prediction model that potentially reduces re-intubation rates and improves clinical outcomes by accurately identifying the optimal time for ventilator removal.

This prospective observational study aims to evaluate the combined predictive value of the Rapid Shallow Breathing Index (RSBI) and CRP-Albumin-Lymphocyte (CALLY) index in determining the success of weaning from mechanical ventilation in intensive care patients. While the RSBI focuses on physiological respiratory mechanics, the CALLY index serves as a non invasive biomarker reflecting the patient's immunonutritional and inflammatory status.

Data collection is deepened through systematic retrieval from the Hospital Information Management System. Researchers will record a wide range of parameters, including demographic data such as age, gender, and BMI alongside clinical severity scores including APACHE II, SOFA, and the Charlson Comorbidity Index. Real time respiratory profiling, including minute ventilation, tidal volume, and airway pressures, will be documented during the weaning process and the Spontaneous Breathing Trial (SBT).

Laboratory integration focuses on routine markers such as CRP, albumin, and lymphocyte counts to determine the patient's biological status at the time of the SBT. In this study, the CALLY Index is generalized as a ratio of the patient's immuno-nutritional reserve to systemic inflammation, calculated as: (Albumin x Lymphocyte Count) / CRP.

The primary outcome is defined as weaning success, characterized by the patient remaining free from invasive mechanical ventilation following extubation. To ensure a comprehensive evaluation of respiratory stability, this study extends the primary observation period to include both the initial 48 hour window and a 7 day follow-up. By incorporating the 7 day parameter, the researchers aim to capture both immediate and late-phase weaning failures, providing a more robust assessment of the combined indices' predictive power for long term extubation success. Secondary outcomes include 28 day mortality rates and total duration of intensive care stay.

Inclusion Criteria:

• Patients aged 18 years and older
• Patients who have received invasive mechanical ventilation for at least 24 hours in the general intensive care unit.

Patients who meet standard clinical weaning criteria (e.g., hemodynamic stability with minimal or no vasopressor support, adequate cough reflex, absence of excessive airway secretions).

Patients deemed ready for a Spontaneous Breathing Trial by the attending physician.

Exclusion Criteria:

• Patients under the age of 18.
• Patients with a known or detected pregnancy.
• Patients with a diagnosis of malignancy.
• Patients with neuromuscular diseases that could impair respiratory effort or muscle strength assessments (e.g., Myasthenia Gravis, Amyotrophic Lateral Sclerosis, Guillain-Barré syndrome).

The study population consists of adult patients hospitalized in the General Intensive Care Units of Basaksehir Cam and Sakura City Hospital who have been receiving invasive mechanical ventilation for at least 24 hours. Participants are identified from patients who meet the clinical requirements for a Spontaneous Breathing Trial and are considered candidates for weaning by the attending intensivist. The population represents a diverse group of critically ill patients requiring prolonged respiratory support, excluding those with specific confounding factors such as pregnancy, malignancy, or primary neuromuscular disorders

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