The Role of Peripheral Perfusion Index as a Predictive Factor During Weaning Process

Study Protocol This prospective observational study will be conducted in the Anesthesia Intensive Care Unit of Istanbul Gaziosmanpaşa Training and Research Hospital (SUAM) between March 2025 and June 2025 following approval from the Ethics Committee. Written informed consent will be obtained from the patients' legal representatives prior to enrollment.

Readiness for weaning from mechanical ventilation will be evaluated by the same attending intensivist throughout the study, in accordance with the local protocol. Criteria for readiness include resolution of the underlying cause of mechanical ventilation, ability to tolerate temporary discontinuation of mechanical ventilation, absence of frequent endotracheal suctioning needs, adequate oxygenation (PaO₂ > 60 mmHg with FiO₂ ≤ 0.5 and PEEP ≤ 8 cmH₂O), acceptable pH and PaCO₂ based on the patient's baseline respiratory condition, and stable cardiovascular status. In patients at high risk for upper airway edema, a cuff leak test will be performed by the intensivist.

The spontaneous breathing trial (SBT) will be performed using the Pressure Support (PS) mode with 5 cmH₂O PS and 5 cmH₂O PEEP. After 30 minutes, weaning parameters will be reassessed and the intensivist will make the extubation decision.

SBT failure will be defined by the presence of one or more of the following criteria: altered mental status, respiratory rate > 35 breaths/min, RSBI > 105, signs of increased respiratory effort (use of accessory muscles, thoracoabdominal asynchrony, intercostal retractions), SpO₂ < 90% or PaO₂ < 60 mmHg on FiO₂ of 0.4, or hemodynamic instability (heart rate > 140 bpm, systolic blood pressure > 180 mmHg or < 90 mmHg, or a change in either > 20% from baseline).

Patients with successful SBT will be extubated and monitored for 48 hours for the need for reintubation. Supplemental oxygen will be provided via a simple oxygen mask (4-6 L/min) to maintain SpO₂ > 92%.