 Prior animal and clinical studies using similar devices have demonstrated that changes in the total hemoglobin concentration and percentage of oxygenated hemoglobin in the tissue transfer flap can be used to differentiate between arterial and venous occlusion. These other similar devices have been shown to be able to detect venous occlusion prior to clinical manifestations of venous occlusion using standard monitoring methods. This early detection of venous occlusion has important implications. It is well established that early detection and surgical re-exploration and correction of venous occlusion is associated with improved survival and salvage rates of tissue transfer flaps. It has been suggested in the reconstructive literature that the development of fat necrosis and flap atrophy are caused by a relative arterial or venous insufficiency, which could be detected using the MI device prior to the clinical manifestations of these complications.Patients undergoing reconstructive surgery at UCI Medical Center will be recruited for enrollment into the study. The study design requires following the patients and review their medical records in order to determine the clinical outcomes of their reconstructive surgery. The process of review of the medical record will require the review of both the in-patient medical record during the hospitalization in which the reconstructive surgery takes place and the outpatient medical record after surgery in order to observe for the possible development of the acute and delayed complications of reconstructive surgery. 