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

Matthew Eschbach,1 Gregory M Sindberg,2 Marisha L Godek,1 Matthew Nagelschmidt,1 Nicholas Paquette,3 Michael Wegener,1 James Alberino,1 Jane Mayotte,1 Amit Vasanji,4 Andrew M Miesse1 1Minimally Invasive Therapies Group, Medtronic, North Haven, CT, USA; 2Minimally Invasive Therapies Group, Medtronic, Plymouth, MN, USA; 3Minimally Invasive Therapies Group, Medtronic, Mansfield, MA, USA; 4Image IQ, Cleveland, OH, USA 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. Keywords: micro-computed tomography, wound healing, Tri-Staple, image processing, laparoscopic surgery, microvasculatur

Pathophysiology and management of hypokalemia: a clinical perspective

Potassium (K+) ions are the predominant intracellular cations. K+ homeostasis depends on external balance (dietary intake [typically 100 mmol per day] versus excretion [95% via the kidney; 5% via the colon]) and internal balance (the distribution of K+ between intracellular and extracellular fluid compartments). The uneven distribution of K+ across cell membranes means that a mere 1% shift in its distribution can cause a 50% change in plasma K+ concentration. Hormonal mechanisms (involving insulin, beta-adrenergic agonists and aldosterone) modulate K+ distribution by promoting rapid transfer of K+ across the plasma membrane. Extrarenal K+ losses from the body are usually small, but can be marked in individuals with chronic diarrhea, severe burns or prolonged sweating. Under normal circumstances, the kidney's distal nephron secretes K+ and determines final urinary excretion. In patients with hypokalemia (plasma K+ concentration <3.5 mmol/l), after the exclusion of extrarenal causes, alterations in sodium ion delivery to the distal nephron, mineralocorticoid status, or a specific inherited or acquired defect in distal nephron function (each of which affects distal nephron K+ secretion), should be considered. Clinical management of hypokalemia should establish the underlying cause and alleviate the primary disorder. This Review aims to inform clinicians about the pathophysiology and appropriate treatment for hypokalemia