Using Near Infra-red Spectroscopy to Assess Oxygenation and Perfusion in Pre-operative Triage of Surgical Procedures

Introduction:  Near infra-red spectroscopy (NIRS) is a non-invasive imaging device that can measure oxygenated and de-oxygenated levels of hemoglobin in the wound and periwound tissues to calculate and create an image of tissue oxygen saturation. Incorporating NIRS imaging assessment in preoperative as well as intraoperative evaluation of patients can assist the surgeon in predicting which procedures will have optimal outcomes.   This study illustrates the use of NIRS in the OR to enhance operative decision making for several patients demonstrating the utility in predicting successful procedural outcomes.                                     Methods:  Three patients with diabetic foot ulcers that required surgical intervention were evaluated intraoperatively with NIRS (SnapshotNIR, Kent Imaging LLC, Calgary, Canada) to assess tissue STO2 in an effort compliment surgical decision making related to incisional closure techniques.  This case series demonstrates the predictive value of NIRS imaging in assessing a patient's healing potential when considering invasive wound care procedures.Results: NIRS imaging enhanced the surgeon’s ability to properly select patients that could be closed based on evaluation of the adequacy of the tissue STO2 to allow healing without incisional necrosis and breakdown.  Patients with poor STO2 based on NIRS imaging were either left open for later delayed closure or closed with loose tissue approximation.   Discussion: Surgical interventions including tissue resection, debridement and amputation all increase the metabolic demands on the involved tissues.  Adequate tissue perfusion and oxygenation are critical to support tissue healing following these interventions.  Tissue which lacks sufficient blood flow is at high risk for desiccation, necrosis and post operative complications such as failure to heal the incision following surgically intervention.   Proper preoperative assessment of adequacy of vascular perfusion is critical in-patient selection and screening. Until recently, ankle-brachial studies and transcutaneous oximetry have been used to assess blood flow and by association healing potential prior to invasive treatments. These studies are labor intensive and do not accurately or fully assess tissue oxygenation and perfusion. Additionally, these technologies cannot be used intraoperatively to assist in surgical decision making. Near infrared spectroscopic imaging (NIRS) is a novel imaging modality that provides instantaneous and useful information regarding a patient's tissue oxygenation. NIRS can screen patients for vascular insufficiency and thus prompt preoperative vascular optimization. NIRS is useful both preoperatively as well as intraoperatively and enhances surgical decision making to decrease the potential for postsurgical complications.References: