Biomedical subjects

Guy Derose

Publications and source records attributed to Guy Derose.

5 recordsLinked to original sources

PubMed2006

Examination of the trend in Canada toward geographic centralization of aneurysm surgery during the endovascular era.

Unlike in the United States, endovascular aneurysm repair (EVAR) has not been widely disseminated in Canada but has remained limited to large-volume vascular surgery units. Since the development of the endovascular program at our hospital, we have experienced a growth in our aneurysm practice and the area of referral. The purpose of this study was to compare the geographic referral area of our aneurysm practice between 1997 (prior to the introduction of EVAR) and 2003 (EVAR and open surgery). Our prospective database was reviewed to identify patients who underwent elective open aneurysm repair in 1997 and 2003 and those who underwent EVAR in 2003. Each patient's county of residence was identified, allowing for grouping of patients into one of four geographic regions (I-IV) increasingly more distant from our hospital. Proportions were compared with the chi(2) test. In 1997, 105 patients underwent open abdominal aortic aneurysm repair, with the majority of patients originating from the two regions in closest proximity to our hospital (I, 34%; II, 46%; III, 18%; IV, 2%). This contrasts with the 2003 EVAR group (n = 63), which had a higher proportion of patients referred from greater distances (I, 13%; II, 27%; III, 27%; IV, 33%) (p < 0.001). The 2003 open group (n = 165) did not differ statistically with respect to region of origin (I, 18%; II, 41%; III, 21%; IV, 19%) compared to their 2003 EVAR counterparts (p = 0.075) but did have a higher proportion of patients from the more distant regions compared to the 1997 open group (p < 0.001). During the last 5 years, we have experienced a doubling of our elective aneurysm case volumes as well as a trend for patients to be referred from greater distances for both EVAR and open repair. This suggests a trend in Canada toward increased centralization of aneurysm care in centers providing both endovascular and open surgical alternatives.

Aortic Aneurysm, Abdominal↗

PubMed2006

Comparison of renal function after endovascular aneurysm repair with different transrenally fixated endografts.

OBJECTIVE: Transrenal fixation of abdominal aortic endografts may provide a more secure proximal attachment with few deleterious effects with respect to renal function. This study's purpose was to determine whether different metals used in two commercially available endografts (Cook Zenith and Medtronic Talent) result in different effects on renal function when placed across renal ostia. METHODS: A total of 140 consecutive patients, between August 2003 and April 2005, who underwent elective endovascular repair of an aortic aneurysm with a nitinol or stainless steel-based endograft with transrenal fixation were reviewed with a mean follow-up period of 5.5 months (range, 1-22 months). The main outcome variable was the percentage change in creatinine clearance (CrCl), which was determined before surgery and at the most recent follow-up. Multiple regression analysis was performed to analyze the contribution of various factors to any deterioration in renal function. RESULTS: The 140 patients were predominantly male (86%), with a mean age of 75 years (range, 56-92) and a mean aneurysm diameter of 62 mm (range, 42-110 mm). The mean intraoperative contrast use was 67 mL (range, 45-160 mL), and after surgery these patients received a mean of 3 surveillance computed tomographic scans (range, 1-7). Nineteen cases (13.6%) required deliberate accessory renal artery coverage. CrCl did not change significantly after surgery; the mean change in CrCl at the end of follow-up was a 2.5% decrease. There was no difference in the reduction in CrCl between endograft types. Only 14.3% of patients experienced a greater than 20% decrease in CrCl. Multiple regression analysis failed to show a relationship between change in renal function and age, sex, aneurysm diameter, infrarenal neck dimensions, endograft type, coverage of accessory renal arteries, intraoperative contrast volume, preoperative CrCl, and postoperative computed tomographic scans. Length of follow-up was an independent predictor (P = .04). CONCLUSIONS: Transrenal endograft fixation results in little deterioration in renal function during intermediate follow-up. The few patients who do experience a decline in renal function do so independently of any features related to the initial endovascular repair, and there is no difference in renal deterioration between endografts with nitinol and stainless steel transrenal bare metal stents.

Aged↗

PubMed2006

A screening program to identify risk factors for abdominal aortic aneurysms.

BACKGROUND: We aimed to explore the feasibility of a nurse-supervised aneurysm screening program to identify any independent risk factors for abdominal aortic aneurysm (AAA) formation in high-risk patients. METHODS: We conducted a prospective observational study of 90 male patients in a university- affiliated hospital in southern Ontario. The patients were prospectively evaluated and all underwent abdominal ultrasonography, with the main outcome measure being detection of an AAA. RESULTS: AAAs were identified in 18 patients (20%) and had a mean diameter of 3.6 (range 2.8-6.0) cm. A separate analysis was performed to identify risk factors for the presence of an aneurysm. The presence of carotid artery disease proved to be the only statistically significant independent predictor of the presence of AAA (odds ratio 2.23, 95% confidence interval 1.76-2.56). CONCLUSIONS: This study confirms the feasibility of a nurse-supervised AAA screening program, and on the basis of these results we recommend ultrasonographic screening for AAA in patients with a history of carotid artery disease.

Aged↗

PubMed2005

Risk-adjusted analysis of early mortality after ruptured abdominal aortic aneurysm repair.

PURPOSE: Ruptured abdominal aortic aneurysms (RAAAs) continue to result in early mortality in up to 50% of patients. Additionally, it remains difficult to compare outcomes given the variability in patient comorbidities and presentation. The purpose of this study was to describe an instrument that permits the prospective analysis of outcomes after RAAA repair while adjusting for the variability in preoperative risk. METHODS: Consecutive patients undergoing attempted open RAAA repair over a 5-year period (1999 to 2003) at our center were reviewed. Thirty-day or in-hospital mortality was the main outcome variable. Preoperative mortality risk was estimated for each patient by using a validated modification of the POSSUM scoring system (V-POSSUM). A risk-adjusted cumulative sum method (RA-CUSUM) was used to compare observed versus predicted outcomes by assigning a risk-adjusted score, based on log-likelihood ratios, to each patient. These scores were sequentially plotted with preset control limits to allow for "signaling" when results were substantially different from expected (doubling or halving of odds ratios). RESULTS: A total of 136 patients were reviewed, with an early mortality rate of 45.6%. V-POSSUM scores were accurate in predicting mortality for the entire cohort, with an observed-to-predicted mortality ratio of 0.92 (P = .80). Each patient's risk-adjusted score was plotted sequentially. In one segment of the resulting plot, the graph adopted a negative slope and crossed the lower control limit, indicating improved results compared with predicted. CONCLUSIONS: V-POSSUM scores in this series accurately predicted early mortality after RAAA surgery. The RA-CUSUM method allows for the prospective evaluation of outcomes, while taking into account patient variability. In the current study, this resulted in the identification of a series of patients who had improved outcomes compared with predicted.

Adult↗

PubMed2005

National audit of the recent utilization of endovascular abdominal aortic aneurysm repair in Canada: 2003 to 2004.

OBJECTIVES: Worldwide, increasing proportions of aortic aneurysms are repaired electively via the endovascular route. The purpose of this study was to report the recent utilization of endovascular repair in Canada by reviewing a national administrative database. METHODS: The Canadian Institute for Health Information database (a collection of all acute care hospitalizations) was reviewed to identify patients who received nonemergent repair of an abdominal aortic aneurysm (AAA) between April 1, 2003 and March 31, 2004. During this 1-year period, differentiation between endovascular (EVAR) and open repair was possible using ICD-10-CA procedural codes in eight of ten provinces. Case volumes, patient age, length of hospitalization, and mortality were stratified by method of repair, province, and size and teaching status of hospitals. RESULTS: In this 1-year period, 1996 patients in eight provinces (representing 72% of Canada's population) underwent open repair (n = 1818, 91.1%) or EVAR (n = 178, 8.9%) of a nonruptured AAA. National utilization rates were 8.4 and 0.8 per 100,000 population for open repair and EVAR. These rates were more constant for EVAR (0 to 1.3) then for open repair (4 to 18.3) when analyzed on a provincial basis. Mean patient age did not differ between EVAR and open repair (73.7 vs 71.9 years, P = 0.4) while mean length of stay (5.8 vs 11.9 days, P = 0.03) and in-hospital mortality (0.6% vs 4.6%, P = .025) were significantly lower for EVAR than for open repair. Most EVAR (96%) and more than half of open repairs (56%) were performed in academic teaching centers. CONCLUSIONS: Although EVAR results in significant reductions in length of hospitalization and early mortality, it continues to be underutilized in Canada compared with other national reports involving administrative databases.

Aged↗