Study Selection
Studies that were eligible for meta-analysis using the keywords/phrases, right phrenic nerve protection, right PNI, and CMAP were included under certain conditions: (1) reported clear, data that was easy to extract for further analysis, (2) studies were retrospective and observational in nature. The exclusion criteria included case studies, case reports, conference abstracts, and letters to the editor, incomplete and unclear data, studies on animals, or those not related to CBA procedures. All studies were independently evaluated for inclusion by two investigators. Any disparities arising during the assessment were resolved by a consensus among all the reviewers after consulting with the authors of the original study if possible.