Combined RSBI, TOF, and BIS for Prediction of Extubation Success

Safe extubation after general anesthesia requires adequate recovery in several physiological domains, including consciousness, neuromuscular function, and spontaneous ventilation. In routine anesthetic practice, extubation is rarely based on a single variable. Instead, clinicians integrate multiple clinical and monitor-based findings before deciding whether a patient is ready for tracheal extubation.

The bispectral index, train-of-four ratio, and rapid shallow breathing index represent three different components of extubation readiness. BIS reflects the depth of anesthesia and recovery of consciousness, TOF ratio indicates the degree of neuromuscular recovery, and RSBI reflects the adequacy of spontaneous breathing pattern. Although each of these parameters may provide useful information, their combined evaluation may offer a more comprehensive prediction of extubation success.

This prospective observational cohort study will include adult patients undergoing elective surgery under general anesthesia who are planned for extubation in the operating room. The study will be conducted without changing the standard anesthetic management. No randomization or study-related therapeutic intervention will be performed. The final decision to extubate will be made by the attending anesthesiologist according to routine clinical practice and will not be altered by the study protocol.

Pre-extubation data will include demographic variables, ASA physical status, body mass index, type and duration of surgery, anesthetic duration, neuromuscular blocking agent use, reversal agent use, respiratory rate, tidal volume, RSBI, TOF ratio, BIS value, peripheral oxygen saturation, and end-tidal carbon dioxide. RSBI will be calculated as respiratory rate divided by tidal volume in liters. TOF ratio and BIS values will be measured immediately before extubation.

Following extubation, patients will be monitored for 30 minutes for extubation-related respiratory or airway events. Successful extubation will be defined as the absence of reintubation, need for assisted mask ventilation, severe desaturation, laryngospasm, clinically significant respiratory distress, or other airway intervention within 30 minutes after extubation. Problematic extubation will be defined as the presence of any of these events.

The primary outcome of this study is the predictive performance of the combined RSBI, TOF ratio, and BIS model for successful extubation. Secondary outcomes include the individual predictive performance of RSBI, TOF ratio, and BIS; comparison of the combined model with each single-parameter model; extubation time; and the incidence of extubation-related complications such as desaturation, coughing, agitation, laryngospasm, need for airway intervention, assisted ventilation, and reintubation.

The main hypothesis is that the combined evaluation of RSBI, TOF ratio, and BIS provides superior predictive performance for extubation success compared with RSBI, TOF ratio, or BIS alone. Statistical analysis will include comparison of patients with successful and problematic extubation, receiver operating characteristic curve analysis for each parameter, and logistic regression analysis for the combined model. The area under the curve values of the single-parameter models and the combined model will be compared.