BackgroundMaintaining a sufficiently high systolic blood pressure is essential for free flap perfusion after microsurgical breast reconstruction. Yet, many women undergoing these procedures have low postoperative systolic blood pressure. Intravenous volume administration or vasopressors may be needed to maintain systolic blood pressure above a predefined threshold. However, excessive volume administration may lead to volume overload and flap stasis, and the postoperative use of vasopressors may be limited depending on institutional standards. Additional nonpharmacological measures to raise blood pressure might be beneficial. Evidence suggests that the Red Bull energy drink could raise blood pressure. It has been shown to increase systolic and diastolic blood pressure in healthy volunteers and athletes.ObjectiveThe primary objective of this study is to determine the difference in systolic blood pressure between an intervention group receiving Red Bull and a control group receiving still water after microsurgical breast reconstruction. Secondary objectives include postoperative heart rate, 24-hour fluid balance, pain level, or necessity for revision surgery due to flap complications.MethodsThe Red Bull study is a prospective, multicenter randomized controlled trial comparing the effect of postoperative ingestion of Red Bull energy drink against still water in female patients undergoing unilateral microsurgical breast reconstruction. A total of 250 mL of Red Bull (intervention group) or 250 mL of still water (control group) will be administered to the study participants 2 hours postoperatively as well as for breakfast and lunch on postoperative day 1, amounting to a total volume of 750 mL per 24 hours. Female patients between 18 and 70 years of age undergoing unilateral microsurgical breast reconstruction will be included. Exclusion criteria are a history of arterial hypertension, cardiac rhythm disorder, diabetes mellitus, gastric or duodenal ulcer, thyroid disease, and current use of antihypertensive or antiarrhythmic drugs or thyroid hormones, as well as intolerance to Red Bull.ResultsRecruitment for the study started in June 2020 and was completed in December 2022. There is evidence that the Red Bull energy drink increases blood pressure in healthy volunteers and athletes. We hypothesize that postoperative ingestion of Red Bull will increase systolic blood pressure in women after microsurgical breast reconstruction. Red Bull could hence be used as a nonpharmacological adjunct to vasopressors or volume administration in women with hypotensive blood pressure after microsurgical breast reconstruction.ConclusionsThis paper describes the Red Bull study trial protocol and analysis plan. The information will increase the transparency of the data analysis for the Red Bull study.Trial RegistrationClinicalTrials.gov NCT04397419; https://clinicaltrials.gov/ct2/show/NCT04397419International Registered Report Identifier (IRRID)DERR1-10.2196/38487