Predictors of Unilateral Spinal Block Success

This prospective observational study aims to determine the factors affecting the success of unilateral spinal anesthesia in patients undergoing orthopedic lower extremity surgery. Unilateral spinal anesthesia is preferred to minimize unwanted effects such as hypotension and to provide more stable hemodynamic conditions, especially in vulnerable patient populations. Unilateral spinal anesthesia is defined as achieving sensory and motor block predominantly on the operated side without significant contralateral spread. However, the factors influencing the success of this technique have not been fully clarified. This study will evaluate various patient-related and procedure-related factors, including age, sex, body mass index, patient positioning, needle type and orientation, injection technique and local anesthetic dose. The primary outcome is the success of unilateral spinal anesthesia, defined as the absence of contralateral block. The results of this study are expected to contribute to improving clinical practice by identifying major and minor factors affecting block success and optimizing anesthesia techniques.