Hydraulic occluders consist of an inflatable silicone membrane inside a polyester-reinforced stretch-resistant cuff. Inflation of the HO can be controlled percutaneously via injection of fluid into an SC injection port attached to the occluder by a length of actuating tubing (Figure 1). Chronic implantation of silicone HOs was first described in experimental models in 1969.1 More recently, clinical applications for HOs in dogs, including use as an artificial urethral sphincter2 and as a means of gradual venous occlusion for surgical treatment of adrenal gland neoplasia3 and congenital portosystemic shunts,4,5 have been reported.
Despite extensive experimental use, little information has been published regarding the precision and reliability of silicone HOs in situations requiring chronic implantation. Hydraulic occluders are individually hand assembled at present by gluing silicone sheets and tubing together in the desired size and configuration with liquid silicone. Early experiences with HOs raised concerns that manufacturing variability could lead to differences in initial lumen size and filling volumes, negatively affecting precision when planning partial occlusion or making adjustments in chronic applications. In addition, silicone acts as a semipermeable membrane, and the diffusion properties of various filling solutions may affect longterm maintenance of occlusion.6–11 To date, no standard filling solution has been evaluated for long-term maintenance of occlusion. The purposes of the present study were to evaluate different sizes of the same HO models, diffusion of various filling solutions (eg, saline [0.9% NaCl] solution, SH, and air), and maintenance of occlusion in 3 sizes of HO. Our hypotheses were that there would be considerable variation in occluder size as a result of the hand-manufacturing process, that high–molecular-weight filling solutions would undergo the least diffusion and yield the most reliable maintenance of long-term occlusion, and that air would diffuse rapidly through the HO membrane.
Simulated body fluid
DOCXS Biomedical Products and Accessories, Ukiah, Calif.
Surgilene, Davis and Geck, Wayne, NJ.
ROPAC-3.5, Access Technologies, Skokie, Ill.
Posi-Grip huber point needle, Access Technologies, Skokie, Ill.
HP Scanjet 4470 C, Hewlett-Packard Co, Palo Alto, Calif.
ImageJ 1.27Z, National Institutes of Health, Bethesda, Md.
Hylartin V, Pharmacia & Upjohn Co, Kalamazoo, Mich.
APX-203, Denver Instrument, Arvada, Colo.
T-5S-CS-UF, Access Technologies, Skokie, Ill.
Silastic, Dow Corning Corp, Midland, Mich.
PX 603-030G5V, Omega Engineering Inc, Stamford, Conn.
DP25 B-E-A, Omega Engineering Inc, Stamford, Conn.
IOX 220.127.116.11, EMKA Technologies, Falls Church, Va.
Bishop SP, Cole CR. Production of externally controlled progressive pulmonic stenosis in the dog. J Appl Physiol 1969;26:659–663.
Adin CA, Farese JP & Cross AR, et al. Urodynamic effects of a percutaneously controlled static hydraulic urethral sphincter in canine cadavers. Am J Vet Res 2004;65:283–288.
Peacock JT, Fossum TW & Bahr AM, et al. Evaluation of gradual occlusion of the caudal vena cava in clinically normal dogs. Am J Vet Res 2003;64:1347–1351.
Sereda CW, Adin CA & Ginn PE, et al. Evaluation of a percutaneously controlled hydraulic occluder in a rat model of gradual venous occlusion. Vet Surg 2005;34:35–42.
Sereda CW, Adin CA. Methods of gradual vascular occlusion and their applications in treatment of congenital portosystemic shunts in dogs: a review. Vet Surg 2005;34:83–91.
Tuncali D, Ozgur F. Spontaneous autoinflation of salinefilled mammary implants: postoperative volume determination by magnetic resonance imaging. Aesth Plast Surg 1999;23:437–442.
Yu LT, Latorre G & Marotta J, et al. In vitro measurement of silicone bleed from breast implants. Plast Reconstr Surg 1995;97:756–764.
Robinson OG Jr, Benos DJ. Spontaneous autoinflation of saline mammary implants. Ann Plast Surg 1997;39:114–121.
Edmunds LH, Rudy LW & Heymann MA, et al. An adjustable pulmonary arterial band. Trans Am Soc Artif Intern Organs 1972;18:217–223.
Oyane A, Kim HM & Furuya T, et al. Preparation and assessment of revised simulated body fluids. J Biomed Mater Res 2003;65A:188–195.
Gabriel SE. Soft tissue response to silicones. In: Black J, Hastings G, eds. Handbook of biomaterial properties. London: Chapman & Hall, 1998;556–571.
Leeuwenburgh BPJ, Schoof PH & Steendijk P, et al. Chronic and adjustable pulmonary artery banding. J Thorac Cardiovasc Surg 2003;125:231–237.
Jacobson ED, Swan KG. Hydraulic occluder for chronic electromagnetic blood flow determinations. J Appl Physiol 1966;21:1400–1402.
Solis E, Heck CF & Seward JB, et al. Percutaneously adjustable pulmonary artery band. Ann Thorac Surg 1986;41:65–69.
Park SC, Griffith BP & Siewers RD, et al. A percutaneously adjustable device for banding of the pulmonary trunk. Int J Cardiol 1985;9:477–484.
Peacock JT, Fossum TW & Bahr AM, et al. Evaluation of gradual occlusion of the caudal vena cava in clinically normal dogs. Am J Vet Res 2003;64:1347–1353.