Michelle T. Mueller

A design modification to minimize tilting of an inferior vena cava filter does not deliver a clinical benefit.

OBJECTIVE In July 2007, our group began to use a modified conical inferior vena cava filter with additional stabilizing struts designed to reduce tilting of retrievable filters. We analyzed our experience with this modified filter (Cook Medical, Bloomington, Ind) from July 1, 2007 to December 31, 2008 and compared it to our experience with the standard filter (Günther Tulip, Cook Medical, Bloomington, Ind) from January 1, 2006 through December 31, 2008 to determine if adoption of the modified filter reduced tilting and delivered a discernible clinical benefit. METHODS The primary outcome measure was tilt angle after deployment. Secondary outcomes were change in tilt angle between deployment and retrieval (self-centering) and retrieval failure due to inability to engage the filter hook. Measurements were retrospectively determined using the anteroposterior venogram at the time of placement and removal. Tilt angle was defined by the center line of the filter relative to the center line of the inferior vena cava (IVC). Statistical significance was assumed for P ≤ .05. RESULTS During the study period, a total of 302 IVC filters were placed. Retrieval was attempted for 85 of 194 (44%) standard filters and 52 of 108 (48%) modified filters. The overall difference in tilt angle (degrees) between the standard (median [interquartile range] = 5 [3, 8]) and modified (5 [3, 8]) filters at the time of placement was not statistically significant (P = .44). Modified filters deployed through a femoral route (8 [4, 11]) had significantly greater tilt angles than modified filters deployed using jugular access (4 [2, 6]; P < .0001). At the time of retrieval, evidence of self-centering was observed more often with modified (32 of 52 [62%]) than standard (36 of 85 [42%]) filters (P = .03). Overall, there were only four failures to retrieve the filter due to excess tilting (standard, 3 of 85 [4%], modified, 1 of 52 [2%]; P = .59). CONCLUSION Overall, tilt angle at insertion did not differ between the modified and standard filters, although more modified filters displayed self-centering. There was no difference between the groups in retrieval failure due to excess tilting. Despite its greater tendency to self-center, we did not recognize a measurable clinical advantage of the modified filter.

A novel perfused porcine simulator for teaching aortic anastomosis increases resident interest in vascular surgery

Objective: This report describes a novel simulator, euthanized pigs on cardiopulmonary bypass, and validates this simulator with a controlled trial in general surgery residents learning aortic anastomosis. We evaluated this novel simulator with the following hypothesis: our porcine perfused simulator is as good as or better than the standard rubber tubing, low‐fidelity models used for vascular anastomotic training. Methods: Euthanized pigs were placed on cardiopulmonary bypass, creating a perfused, ex vivo model on which to perform surgical procedures. The participants in the study were postgraduate year 2, 3, and 4 general surgery residents. Residents were randomized to practice aortic anastomosis in the pig laboratory (PL) simulator or in a dry laboratory. The PL residents and control residents performed a first vascular anastomosis on the rubber tube model. Anastomosis creation was filmed. The anastomosis and video were stored for later grading. Next, all residents underwent an ungraded, one‐on‐one training session with the attending vascular surgeon. After the training session, all residents completed a second videotaped rubber tubing anastomosis. The grading scales used were validated by other authors: Global Assessment Score, Final Product Score, and Checklist Scoring Instrument. Survey data describing this experience were collected using a 13‐question prelaboratory and 16‐question postlaboratory questionnaires consisting of yes/no, multiple selection, and 5‐point Likert‐type scale questions. Results: All residents had a statistically significant improvement in time to completion and in the Global Assessment Score with tutored practice. The PL residents showed statistically significant improvement in completion time between the first and second videotaped anastomosis; however, there was no statistically significant improvement in the scoring metrics. The control residents showed statistically significant improvement in all three scoring metrics, but no statistically significant difference was found in completion time. The survey data showed a statistically significant shift in considering vascular surgery as a career after the experience in the PL group (P = .05) compared with the control group, who had no change in interest (P = .91). Conclusions: Our prospective, randomized clinical trial shows that the porcine cardiopulmonary bypass model achieves similar results to a previously validated bench top model while improving general surgery resident interest in vascular surgery as a career.

DELAYED ABDOMINAL CLOSURE IN THE MANAGEMENT OF RUPTURED ABDOMINAL AORTIC ANEURYSM.: 144-S

The objective of this study was to compare initial use of the open abdomen using the vacuum-pack technique followed by delayed abdominal closure with standard primary abdominal closure in the treatment of ruptured abdominal aortic aneurysm (rAAA) repair. A retrospective review identified 122 rAAA cases, which were divided into two management eras: era 1 (primarily closed) and era 2 (47% open abdomen).One hundred three patients were included in this review: 58 in era 1 and 45 in era 2. Evidence of one of three ischemia-reperfusion (IR) criteria, preoperative hypotension, estimated blood loss > or = 6 L, or intraoperative resuscitation with > or = 12 L, predicted mortality. These criteria were also used as surrogate clinical markers for abdominal compartment syndrome. The in-hospital mortality was higher in those with at least one IR criterion: 43% versus 10% (p = .0003). In those with at least one IR criterion, the initial 24-hour mortality was 21% for era 1 versus 0% for era 2 (p = .03), and the 30-day mortality was 40% for era 1 and 32% for era 2 (p = .77).Three IR criteria were identified and were associated with increased mortality. Patients with these risk factors who were treated with delayed abdominal closure had an improved acute survival rate and a trend for improved long-term survival.