Date Approved

4-2015

Graduate Degree Type

Thesis

Degree Name

Engineering (M.S.E.)

Degree Program

School of Engineering

First Advisor

Robert Bossemeyer

Second Advisor

Brian Lane

Third Advisor

Samhita Rhodes

Abstract

Laparoscopic partial nephrectomy (LPN) is an effective surgical procedure to remove a small renal tumor, while preserving the remainder of the kidney. However, it is a technically challenging procedure to maintain hemostatic condition on the kidney during LPN suturing. Three different experiments were conducted to explore the characteristics and limitations of the current mechanism for tissue approximation during LPN procedures.

During the first experiment, a standard suture anchor Hem-o-lok device, a standard stop knot, and three prototype devices were compared to each other based on the amount of tension that could be placed on a suture before there was a tear in renal tissue. The renal remnant of a standardized defect in porcine kidneys without an intact renal capsule was sutured using Vicryl 2-0 suture and different suture anchors. The approximate mean tensions at which the renal parenchymal tissue failed using these tested anchors was knots (2.7N ± 0.53N), Prototype 2(4.0 N± 1.6N), Hem-o-lok (5.4 N±0.72N), Prototype 1(5.6 N±0.75N), and Prototype 3(6.0 N±3.39N). Even with a small number of tests (8 for most configurations), there are significant differences at the 95% confidence level. Statistical analysis of the data, however, indicates that there is no significant difference between anchors Hem-o-lok, Prototype 1 and Prototype 3 with a significance level of 0.05.

The second experiment was conducted to determine if different types and sizes of absorbable suture used in partial nephrectomy can sustain a tension of 4N over a 21 day period, which is necessary to achieve hemostasis in the perfused kidney. The results indicate that the sutures commonly used in LPN, i.e. Vicryl 2-0 and Vicryl 3-0 do not break within the 21 day expected life and that failure of other sutures tested before 7 days is commonly due to knot slippage.

The final experiment measured and compared the holding strength of a common technique used in LPN surgery to provide anchoring of a suture, a Hem-o-lok device backstopped with a LAPRA-TY. Suture types Vicryl, Monocryl, Chromic, Stratafix and V-Loc were tested in common sizes. The results show that the holding strength of clips (Hem-o-Lok backstopped by LAPRA-TY) for Vicryl 4-0 sutures is the lowest of all types and sizes tested at a mean value of 4.2 N±1.36N and maximum for V-Loc 2-0 sutures at the mean value of 15.9 N±2.58N. The clips hold maximum tension for suture sizes “1” and “0”, whereas minimum tension for suture size 4- 0. This experiment indicates that the holding ability of these clips support the application of suture tension greater than 5.5N thought to be necessary for adequate hemostasis following LPN. However, suture types Vicryl 3-0 and Vicryl 4-0 may not be able to maintain hemostatic condition during LPN when used with this anchor method.

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