Effects of Interscalene Block on Visual Clarity in Arthroscopic Surgery

Arthroscopic rotator cuff repair (RCR) has become the predominant technique for managing patients with full-thickness rotator cuff tears. Optimizing visual clarity is crucial for performing shoulder arthroscopy safely, precisely, and successfully. However, intraoperative bleeding remains the most significant factor impairing visual clarity. The interscalene brachial plexus block (ISB) technique is widely employed in shoulder joint and upper extremity surgeries. However, ISB may lead to hypertension due to the spread of local anesthetic to adjacent structures, such as the carotid sinus baroreceptors. Hypertension-induced microbleeding can obstruct the surgical field of view. Our hypothesis suggests that arthroscopic visual clarity may be compromised in awake patients receiving ISB for anesthesia. This study aims to compare the effects of interscalene brachial plexus block and general anesthesia on hemodynamic parameters and visual clarity in patients undergoing arthroscopic rotator cuff repair surgery.

Our study will be conducted prospectively, and no additional medication or interventional procedure will be administered to the patients. A total of 80 patients, 40 from the general anesthesia group and 40 from the interscalene block anesthesia group, who meet the inclusion criteria, will be included in the study. In both groups, systolic arterial blood pressure (SAB), diastolic arterial blood pressure (DAB), mean arterial blood pressure (MAP), and heart rate (HR) values will be recorded every 5 minutes throughout the operation after the surgical procedure begins. At the end of the operation, visual clarity will be assessed by the same surgeon (M.O) using a Numeric Rating Scale (0 = very poor, 10 = excellent). To detect a 2-point (20%) difference in the NRS score for visual clarity, a total of 37 patients are required with 80% power and a significance level of 0.05. This calculation assumes that such an effect is clinically significant and that the standard deviation is 2.21. Assuming a 10% dropout rate, we calculated that a total of 80 patients would be needed for two groups, with 40 patients per group. Descriptive statistics, including mean, standard deviation, median, minimum, maximum, frequency, and percentage, will be used to summarize the data. The Kolmogorov-Smirnov test will be employed to assess the distribution of variables. For the comparison of quantitative data, the Independent Samples t-test and Mann-Whitney U test will be utilized. For the comparison of qualitative data, the Chi-Square test will be used. A p-value less than 0.05 will be considered statistically significant. The cut-off values of quantitative parameters will be determined using ROC analysis.