Safety and effectiveness of regional anesthesia compared with anesthetic techniques not using regional anesthesia on outcomes after free tissue flap surgery: a systematic review protocol.

[OBJECTIVE] This systematic review will aim to evaluate the evidence on the effectiveness of regional anesthesia, when compared with general anesthesia alone, on the outcomes of free flap surgeries.

[INTRODUCTION] Free flap procedures involve complete separation of a flap of tissue from its native vascular bed, followed by reimplantation to a recipient site on the body. Optimal perfusion and successful neovascularization are crucial to survival of the grafted flap. Currently, no best-practice recommendations exist regarding the use of regional anesthesia in free flap surgeries. Regional anesthesia techniques have the potential to alter blood flow and neuroendocrine responses to surgical stress, which may impact perfusion and survival of free flap grafts. This potential for augmentation or hindrance of flap perfusion may have a significant impact on patient outcomes, thus meriting systematic review.

[INCLUSION CRITERIA] The review will include both experimental and observational (analytical only) study designs that examine the vascular outcomes of regional anesthesia compared with general anesthesia alone in free flap surgery.

[METHODS] The databases to be searched include PubMed, CINAHL, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science Core Collection, Embase, and gray literature sources. Identified studies will be independently assessed by two reviewers utilizing JBI critical appraisal tools. Data will be extracted using a standardized data matrix. Certainty of findings will be conducted using the Grading of Recommendations Assessment, Development and Evaluation approach. Narrative synthesis will be compiled and meta-analysis completed, where possible.

[SYSTEMATIC REVIEW REGISTRATION NUMBER] PROSPERO CRD42021283584.