Wound Perfusion in High Risk Surgical Incisions

This is a prospective cohort pilot study. The primary purpose is to report the perfusion status of the surgical field in at risk surgical incisions. The secondary purposes are to describe the relationship between perfusion status and wound healing status and complications, and to describe the relationship between infrared digital thermography perfusion readings and the timing of propofol infusion. The research intervention will be photographs taken of the wound on the injured extremity, with a Forward-Looking Infrared (FLIR) camera, for the purpose of assessing perfusion status and skin temperature at the surgical site.

Patients with qualifying injuries will be identified at the time of injury. There will be no deviation from standard of care for these patients outside of the acquisition of the FLIR image. Standard emergent management of these injuries including but not limited to reduction, immobilization, and acquisition of advanced imaging will take place. Pre-operative discussion of the risks and benefits of surgical management will occur and informed consent obtained. Propofol is a commonly used anesthetic agent. However, propofol is also a vasodilating agent, which acts by blocking sympathetic tone. Limited worked has been done to evaluate the effects of propofol administration on the FLIR imaging data acquisition. A single study used FLIR to look at tissue perfusion after propofol infusion in children. In this study, the primary concern was whether infrared imaging could replace or augment, serial blood pressure and heart rate measurements, or other invasive monitoring measurements in patients undergoing general anesthesia with the use of vasodilatory agents, such as propofol. The authors' goal was to "assess the ability of the thermal imager to trend heat loss that registers as skin temperature from propofol-mediated vasodilation and study reversibility as propofol levels drop and vascular tone returns." This leaves a void regarding surgeons' understanding of the optimal timing of FLIR perfusion assessment and the reliability of measurements obtained pre and post propofol infusion. In order to better understand the effects of propofol and determine the optimal time for determining perfusion with the FLIR camera, the investigators will take a first reading in the pre-operative holding area, prior to the administration of any propofol or other vaso-active agent (as described below). Once in the operating room, after the induction of anesthesia but prior to application of any topical cleansing or cooling products to the skin, the participant will be transferred to the operating room table and placed on a clean, white sheet and blankets will be removed from both lower extremities. The planned surgical incision(s) to be used will be drawn on the skin by the most senior surgeon. Next, a clinical photo and a FLIR image will be obtained at 90 degrees to the skin, and 1 meter from the surface of the skin at the site of each planned incision. One researcher has successfully used a protocol of taking images at perpendicular to the skin and 1 meter distance and demonstrated that deviation of as much as 20 degrees from the perpendicular and 0.5m of distance has negligible effect on readings. A set of control photos, identical to the ones obtained on the injured extremity will be obtained on the contralateral, non-injured extremity. A physician who is part of the surgical team who is trained in the use of the FLIR camera will obtain the images. At the time of image acquisition, results of the wrinkle test at each incision, patient body temperature, room temperature and humidity will be recorded. Analysis of the FLIR images will involve averaging the tissue perfusion in a box drawn with 1 cm borders around the planned incision site as well as the entire area imaged. This will be compared to the control, the contralateral uninjured extremity. Participants will receive standard operative management of these injuries with standard of care post-operative management.