ABSTRACT
BACKGROUND AND OBJECTIVES: We evaluated the location and structure of the fibrous sheath formed after the placement of tunneled, cuffed hemodialysis catheters in large animals, 70 kg pigs. We focused on describing the location of the fibrous sheath in relation to the catheter. Its location explains the fibrous sheath's ability to cause catheter dysfunction by covering the catheter exit ports located at the catheter's tip. DESIGN: We used three animals. Each animal had a tunneled, cuffed, 15-French diameter hemodialysis catheter placed in the external jugular vein, with the tip at the junction of the superior vena cava and the right atrium. Two animals were sacrificed at 5 weeks and one animal at 17 weeks after catheter placement. The catheter and surrounding tissues were removed in one block. The fibrous sheath was dissected and longitudinally cut along the catheter to evaluate its extension in relation to the catheter. Relevant portions of the fibrous sheath were sent for pathology examination. RESULTS: The fibrous sheath covered the catheter in its entire length and circumference. It started at the entry site and continued without any interruption along the entire length of the catheter, including the tip. Its average thickness is 1 mm and has an inner cellular/inflammatory layer comprising lymphocytes, plasma cells, neutrophils, macrophages, multinucleated giant cells, and spindled cells and an outer layer comprising a mixture of collagen and fibroblasts. CONCLUSION: Our model showed that the fibrous sheath forms around all catheters and covers them in their entire length and circumference without any gaps.
Subject(s)
Catheterization, Central Venous/adverse effects , Catheterization, Central Venous/instrumentation , Catheters, Indwelling/adverse effects , Central Venous Catheters/adverse effects , Foreign-Body Reaction/etiology , Jugular Veins/pathology , Renal Dialysis , Animals , Catheter Obstruction/etiology , Equipment Design , Fibrosis , Foreign-Body Reaction/pathology , Models, Animal , Risk Factors , Sus scrofa , Time FactorsABSTRACT
BACKGROUND: Currently, there is insufficient knowledge about the surgical anatomy and surgical techniques in large animals that can be used to test medical devices designed for human use. We encountered this problem in our study requiring the placement of jugular vein, tunneled, cuffed hemodialysis catheter in 70 kg pigs. Despite the operator's extensive expertise in placing tunneled hemodialysis catheters in humans, the important differences in anatomy made the procedure and choosing the appropriate catheter length challenging. METHODS: The following article describes the anatomy and our technique for the placement of tunneled hemodialysis catheter in the pig model. RESULTS: We consider our surgical technique to be sound because in all animals the catheters were placed in the desired location, the procedures were well tolerated by the animals, and there were no immediate or late complications. CONCLUSION: We present our experience to help other researchers who might encounter the same problem.
Subject(s)
Catheterization, Central Venous/instrumentation , Catheterization, Central Venous/methods , Catheters, Indwelling , Central Venous Catheters , Jugular Veins/surgery , Renal Dialysis , Animals , Equipment Design , Models, Animal , Sus scrofaABSTRACT
Current models of animal arteriovenous fistula (AVF) are swine models of femoral vein terminolaterally anastomosed to femoral artery, creating a deep AVF. This feature sets it aside from human AVFs using superficial veins. Our AVF model uses sheep superficial veins to create an AVF almost identical to human model. AVFs were created in six sheep using basilic veins sutured terminolaterally to brachial artery. Presurgery vein and artery diameters were measured. We measured AVFs and feeding arteries blood flows and diameters at 1, 3, and 5 weeks postsurgery. At 5 weeks we performed angiograms, euthanized animals, and harvested AVFs. Four animals completed the study. Three AVFs developed and were patent at 5 weeks; one thrombosed. Animal weight and presurgery vessels diameters predicted AVFs blood flows and diameters. Despite using vessels with diameters smaller than the ones recommended for human AVF, the Fistulas developed. Two animals died before the study conclusion for causes unrelated to surgery. This AVF model is anatomically almost identical to the human AVF and has a good maturation rate. It is a viable model for studying AVF maturation, devices intended to improve AVF maturation, AVF related procedures and can even support hemodialysis needles.
