Preoperative Evaluation of the Renal Function before the Treatment of Abdominal Aortic Aneurysms

BACKGROUND

Chronic impaired renal function constitutes a major risk factor of morbi-mortality during the treatment of an abdominal aortic aneurism (AAA). The inflammatory state due to the AAA could result in a reduction in the muscular mass and an overestimation of the glomerular filtration rate (GFR) with the usual formulas. The objective of this study was to determine if the formulas used to evaluate the estimated GFR were adapted in patients with AAA.

MATERIALS AND METHODS

Between August 2013 and November 2014, we conducted an exploratory study to evaluate the renal function before surgery for AAA in 28 patients. The renal function was evaluated by (1) the dosage of plasmatic creatinine, (2) the GFR estimated with the Cockroft-Gault, Modification of Diet in Renal Disease (MDRD), and chronic kidney disease epidemiology collaboration (CKD-EPI) formulas, (3) the creatinine clearance (CC), and (4) the direct measurement of the GFR with a reference method (iohexol clearance). Statistical analysis was carried out to compare and correlate the GFR estimated by the various formulas with the GFR measured by the reference technique.

RESULTS

The study included 21 men (75%) and 7 women (25%), with a median age of 76 years (58-89). The measured GFR was correlated with the GFR estimated from the CKD-EPI (rho = 0.78, P < 0.0001), the MDRD (rho = 0.78, P < 0.0001), the Cockroft-Gault (rho = 0.65, P = 0.0002), and CC (rho = 0.86, P < 0.0001). However, there were important individual variations between estimated and measured GFR. As regards the detection of the patients presenting a GFR <60 mL/min/1.73 m², the sensitivities of the CKD-EPI, MDRD, Cockroft-Gault formulas and CC were 64%, 64%, 71%, and 70%, respectively. Specificities were 71%, 79%, 57%, and 100%, respectively. The estimation of the GFR by the CKD-EPI formula had the lowest bias (-3.0). Bland-Altman plots indicated that the estimation of the GFR by the CKD-EPI formula had the best performance in comparison with the other methods.

CONCLUSIONS

This study found a statistical correlation between the measurement of the GFR and the various formulas available to estimation the GFR among AAA patients. The CKD-EPI formula is most appropriate. However, there were important individual variations between the measurement and the estimations of the GFR. A larger scale study is necessary to determine the profile of the patients with a risk of error in the estimation of the GFR. The French recommendations on the evaluation of the renal function before AAA treatment remain based on serum creatinine and should be revalued.

A systematic review and meta-analysis indicates underreporting of renal dysfunction following endovascular aneurysm repair

Deterioration in renal function has been described after endovascular repair of abdominal aortic aneurysms (EVRs). The etiology is multifactorial and represents an important therapeutic target. A need exists to quantitatively summarize incidence and severity of renal dysfunction after EVR to allow better-informed attempts to preserve renal function and improve life expectancy. Here a systematic search was performed using Medline and Embase for renal function after EVR applying PRISMA statements. Univariate and multivariate random-effects meta-analyses were performed to estimate pooled postoperative changes in serum creatinine and creatinine clearance at four time points after EVR. Clinically relevant deterioration in renal function was also estimated at 1 year or more after EVR. Pooled probability of clinically relevant deterioration in renal function at 1 year or more was 18% (95% confidence interval of 14-23%, I2 of 82.5%). Serum creatinine increased after EVR by 0.05 mg/dl at 30 days/1 month, 0.09 mg/dl at 1 month to 1 year, and 0.11 mg/dl at 1 year or more (all significant). Creatinine clearance decreased after EVR by 5.65 ml/min at 1 month-1 year and by 6.58 ml/min at 1 year or more (both significant). Thus, renal dysfunction after EVR is common and merits attention.

Endovascular aortic aneurysm repair with carbon dioxide-guided angiography in patients with renal insufficiency

OBJECTIVE

Renal dysfunction following endovascular abdominal aortic aneurysm repair (EVAR) remains a significant source of morbidity and mortality. We studied the use of carbon dioxide (CO(2)) as a non-nephrotoxic contrast agent for EVAR.

METHODS

Recorded data from 114 consecutive patients who underwent EVAR with CO(2) as the contrast agent over 44 months were retrospectively analyzed. CO(2) was used exclusively in 72 patients and in an additional 42 patients iodinated contrast (IC) was given (mean, 37 mL). Renal and hypogastric artery localization and completion angiography were done with CO(2) in all patients, including additional arterial embolization in 16 cases. Preoperative National Kidney Foundation glomerular filtration rate (GFR) classification was normal in 16 patients, mildly decreased in 52, moderate to severely decreased in 44, and two patients were on dialysis.

RESULTS

All graft deployments were successful with no surgical conversions. CO(2) angiography identified 20 endoleaks (two type 1, 16 type 2, and two type 4) and three unintentionally covered arteries. Additional use of IC in 42 patients did not modify the procedure in any case. When compared with a cohort of patients who underwent EVAR using exclusively IC, the operative time was shorter with CO(2) (177 vs 194 minutes; P = .01); fluoroscopy time was less (21 vs 28 minutes; P = .002), and volume of IC was lower (37 vs 106 mL; P < .001). Postoperatively, there were two deaths, two instances of renal failure requiring dialysis, and no complications related to CO(2) use. Among patients with moderate to severely decreased GFR, those undergoing EVAR with IC had a 12.7% greater decrease in GFR compared with the CO(2) EVAR group (P = .004). At 1, 6, and 12-month follow-up, computed tomography angiography showed well-positioned endografts with the expected patent renal and hypogastric arteries in all patients and no difference in endoleak detection compared with the IC EVAR group. During follow-up, eight transluminal interventions and one open conversion were required, and no aneurysm-related deaths occurred.

CONCLUSIONS

CO(2)-guided EVAR is technically feasible and safe; it eliminates or reduces the need for IC use, may expedite the procedure, and avoids deterioration in renal function in patients with pre-existing renal insufficiency. A prospective trial comparing CO(2) with IC during EVAR is warranted.