Development and Evaluation of a Remote Patient Monitoring System in Autologous Breast Reconstruction.

Flap monitoring after a deep inferior epigastric perforator flap breast reconstruction is crucial to detect complications in time. A novel and innovative wireless device has been developed and tested in a feasibility study. This study describes our experience with remote patient monitoring via this device in postoperative monitoring of deep inferior epigastric perforator flaps. METHODS: Following a deep inferior epigastric perforator breast reconstruction, the "Free Flap Patch" was adhered to the flap, continuously measuring temperature and tissue saturation. Data were stored locally on the patch and analyzed in a retrospective manner. Raw analog-digital-conversion values from the red- and infrared sensors, delta muscle saturation (dSmO2), and estimated tissue oxygenation (StO2) were assessed and compared with clinical records. RESULTS: No adverse events related to the device were recorded. One patient suffered flap loss; a decrease in estimated tissue oxygenation was measured with the device in situ. No deviations in clinical variables were recorded in the uncompromised flaps. CONCLUSIONS: A wearable patient monitoring device was successfully utilized in clinical practice. In one patient, a flap failure was recorded where the PPG-derived StO2 parameter was indicatory for this event. The Free Flap Patch has the potential of automatically predicting blood supply issues in an early stage. More data are needed for clinical validation.

Ex-vivo perfusion as a successful strategy for reduction of ischemia-reperfusion injury in prolonged muscle flap preservation - A gene expression study.

INTRODUCTION: With the introduction of vascularized composite allotransplantation (VCA) as new surgical technique, the need arose for strategies that could safely prolong graft preservation. Ex-vivo machine perfusion is a promising technique and is currently applied in solid organ transplantation. There is still limited evidence in the field of VCA and free flap transplantation. This gene expression study aimed to assess the degree of ischemia-reperfusion (IR) injury after preservation and replantation of free muscle flaps in a porcine model. MATERIALS AND METHODS: A microarray analysis was first conducted on muscle flaps preserved by ex-vivo perfusion versus cold storage, to select genes of interest for further investigation. The expression of these selected genes was then examined in a muscle flap replantation model after 18 hour ex-vivo perfusion (n = 14) using qRT-PCR. Two preservation solutions were compared to static cold storage: University of Wisconsin-mp (n = 5) and Histidine-Tryptophan-Ketoglutarate solution (n = 5). RESULTS: A selection of 8 genes was made based on micro-array results: Tumor necrosis factor receptor superfamily member 10-A like, Regulator of G-protein signaling 2, Nuclear factor kappa beta inhibitor zeta, Interleukin-1 beta, Fibroblast growth factor 6 and DNA damage-inducible transcript 4, Hypoxia-inducible factor 1-alpha and Caspase-3. The muscle flap replantation experiment compared their expression patterns before and after preservation and replantation and showed overall comparable gene expression between the preservation groups. CONCLUSIONS: The expression of genes related to ischemia, apoptosis and inflammation was comparable between the ex-vivo perfusion and static cold storage groups. These results suggest that ex-vivo perfusion might be a promising technique for 18 hour muscle preservation in terms of decreasing ischemia-reperfusion injury.