Evaluation of different methods of securing cellophane bands for portosystemic shunt attenuation

Abstract

Objective: To compare mechanisms of and pressures at failure of 4 methods of securing 2 types of cellophane bands around a vein. Study design: Ex vivo mechanical evaluation. Methods: Cellophane bands composed of 3 or 4 layers were applied around a cadaveric external jugular vein (EJV) to create 25% or 50% attenuation. These bands were secured with a medium or medium-large polymer locking ligation clip (PLLC), or a medium or medium-large titanium ligation clip (TLC). Sterile saline 0.9% was instilled into the lumen of the EJV until a pressure of 100 mm Hg was reached. Failure mechanism and luminal pressure at failure were compared between groups. Results: Medium clips failed less often than medium-large clips (P < .001) and consistently sustained 100 mm Hg without failing. Three-layer cellophane bands were 4.1 times more likely to fail than 4-layer bands (P = .003, CI 1.6-10.2) and failed at lower pressures (28.32 ± 3.59 mm Hg and 44.81 ± 6.51 mm Hg, respectively, P = .027). Failure rates of the cellophane band constructs did not differ whether secured with PLLC or with TLC (P = .635) or with 25% vs 50% attenuation (P = .780). Conclusion: A single medium clip withstood physiological forces and secured a cellophane band at up to 50% attenuation. A 3-layer cellophane band was more likely to fail compared with a 4-layer cellophane band. Clinical significance: These ex vivo results provide evidence to support the application of a 4-layer cellophane band secured with a single medium PLLC or TLC for portosystemic shunt attenuation. A single medium PLLC should be used to eliminate computed tomography artifacts during postoperative evaluation of shunt closure.

Feasibility of thoracoscopic attenuation of the azygos vein as a model for portoazygos shunts: A canine cadaveric study

“…In the same study, four 11.5‐mm clips placed in alternating fashion achieved maximum security in securing cellophane bands 15 . The clinical importance of the clip size and orientation for securing thin film bands around CEPSS, however, has not been established 16 . Thus, the use of smaller clips in a nonalternating fashion may better facilitate thoracoscopic thin film band placement without jeopardizing the security of the band.…”

“…While they were held in apposition with the right‐angle forceps, the Kelly forceps were removed and a 12‐mm endoscopic hemostatic clip applicator (LIGACLIP endoscopic rotating multiple clip applier, medium/large; Ethicon, Somerville, New Jersey) was introduced through the cranial port. Each cellophane band was then secured via endoscopic clip placement as previously described 15,16 . Briefly, the surgeon attempted to place four 11.5‐mm clips in alternating fashion from both sides of the cellophane construct such that the inner diameter of the resulting cellophane band approximated the predissection diameter of the azygos vein segment around which it was placed.…”

“…In addition, the surgeon attempted to place all clips at a 90° angle to the long edge of the band while maintaining apposition and alignment of both ends of the cellophane band (Figure 2). 15,16 …”

“…Each cellophane band was then secured via endoscopic clip placement as previously described. 15,16 Briefly, the surgeon attempted to place four 11.5-mm clips in alternating fashion from both sides of the cellophane construct such that the inner diameter of the resulting cellophane band approximated the predissection diameter of the azygos vein segment around which it was placed. In addition, the surgeon attempted to place all clips at a 90 angle to the long edge of the band while maintaining apposition and alignment of both ends of the cellophane band ( Figure 2).…”

“…In addition, the surgeon attempted to place all clips at a 90 angle to the long edge of the band while maintaining apposition and alignment of both ends of the cellophane band ( Figure 2). 15,16 Ameroid constrictors were similarly introduced through the cranial port by using 10-mm right-angle forceps (Karl Storz Veterinary Endoscopy). The ameroid F I G U R E 2 Thoracoscopic placement of cellophane around the caudal azygos vein.…”