Electrical Impedance Characterization of in Vivo Porcine Tissue Using Machine Learning.

The incorporation of sensors onto the stapling platform has been investigated to overcome the disconnect in our understanding of tissue handling by surgical staplers. The goal of this study was to explore the feasibility of in vivo porcine tissue differentiation using bioimpedance data and machine learning methods. In vivo electrical impedance measurements were obtained in 7 young domestic pigs, using a logarithmic sweep of 50 points over a frequency range of 100 Hz to 1 MHz. Tissues studied included lung, liver, small bowel, colon, and stomach, which was further segmented into fundus, body, and antrum. The data was then parsed through MATLAB's classification learner to identify the best algorithm for tissue type differentiation. The most effective classification scheme was found to be cubic support vector machines with 86.96% accuracy. When fundus, body and antrum were aggregated together as stomach, the accuracy improved to 88.03%. The combination of stomach, small bowel, and colon together as GI tract improved accuracy to 99.79% using fine k nearest neighbors. The results suggest that bioimpedance data can be effectively used to differentiate tissue types in vivo. This study is one of the first that combines in vivo bioimpedance tissue data across multiple tissue types with machine learning methods.

Micro-CT imaging as a method for comparing perfusion in graduated-height and single-height surgical staple lines.

BACKGROUND: Wound healing is a goal for advanced technology in the surgical space to benefit clinical outcomes. Surgical staplers are commonly used in a variety of open and minimally invasive abdominal and thoracic procedures. Assessment of wound healing traits, such as perfusion, has been challenging due to technical limitations. A novel technique that utilizes micro-computed tomography methodology to measure perfusion was designed to compare the micro-perfusion of staple lines between commercial stapler reloads that employ different staple height strategies. MATERIALS AND METHODS: Following an Institutional Animal Care and Use Committee-approved protocol, rats were euthanized and immediately heparinized prior to a subtotal gastrectomy with either graduated-height or single-height staples. Rats were then perfused with barium, following which stomachs were removed and immediately fixed in formalin to prevent degradation. Stomachs were then imaged using micro-computed tomography and subsequent analysis was utilized to quantify fluid volume and patent vasculature proximity to staples within the staple line region for each group. RESULTS: Average perfusion volume was significantly higher with graduated-height staples (0.33% ± 0.18%) compared to single-height staples (0.16% ± 0.09%, P=0.011). Average vessel-to-staple line distance was not significant but trended lower with graduated-height staples (0.35±0.02 mm) compared to single-height staples (0.36±0.03 mm, P=0.18). DISCUSSION: Graduated-height staples had significantly higher perfusion volume than single-height staples, which likely has a downstream benefit on wound healing and clinical outcomes. CONCLUSION: This study shows a higher perfusion volume around the staple lines using graduated-height staples as compared to single-height staples and this may contribute to better wound healing in patients.

Potential role of proinflammatory cytokines in nerve damage related bone loss.

An estimated 375,000 people are currently suffering from spinal cord injuries and another 1.5 million are afflicted by peripheral nerve damage in the United States. Wolf's Law states that a bone grows or remodels in response to the stresses that are placed on it. Forces applied to bones that occur due to normal daily activity allow for healthy resorption and formation of bones. Periods of immobilization caused by nerve damage have a profound effect on the integrity of bone, causing an increased risk of bone fracture. The need for investigating ways of combating this secondary effect of nerve damage is imperative to the long-term health of spinal cord injury and peripheral nerve damage patients. Our lab uses two sciatic nerve damage models in mice to mimic the bone loss caused by recoverable, sciatic nerve crush (NC), and non-recoverable, sciatic neurectomy (NX), injuries. We are examining the hypothesis that recoverable damage actually causes an accelerated loss of bone mass compared to the permanently damaged nerve because of the transport of proinflammatory cytokines from the site of the nerve damage to the locally affected bone. This inflammatory response, and the hypothesized differences between the two models, will be examined via ELISA of the quadriceps to investigate the relative degree of proinflammatory cytokines local to the damage site. Understanding the cellular mechanisms that occur at nerve injury sites will allow for improved care and long-term treatment of patients. A preliminary analysis of the bone loss associate with these two nerve injury models indicate approximately a 50% greater decline in femoral mass of the NC femur compared to the NX limb, supporting the proinflammatory hypothesis.