Results of a kidney-protection strategy during open thoracoabdominal aortic surgery according to RIFLE criteria

Study Objective The replacement of a thoracoabdominal aortic aneurysm (TAAA) is a challenging intervention with major impact on the patient and a high risk of major complications such as bleeding, spinal cord problems, renal failure, respiratory failure, and death The aim of this study was to analyse and evaluate renal protection effectiveness of a single centre series in view of the implementation of a strict protocol of management based on left heart bypass and intermittent selective kidneys perfusion with cold crystalloid solution

Methods From January 2009 to November 2015, fifty-six patients with TAAA underwent open aortic repair in our centre. Three cases were excluded from this analysis: two were performed with cardiopulmonary bypass and deep hypothermic circulatory arrest, and one patient with contained aneurysmal rupture died at the opening for massive bleeding Final study population consisted of 53 patients operated with staged aortic clamp and left heart bypass (LHB), of which data- files were retrospectively collected and analysed. Kidney protection with intermittent 4°C Ringer’s acetate solution with mannitol 20% adjunct into renal ostia was used in 89%

Definitions For the definition of post-operative acute renal dysfunction we adopted the RIFLE criteria based on eGFR calculation, that proved to be the most reliable method to detect the occurrence of renal impairment and its prognosis in cardiac surgery

Study Population (n=53) Gender (Male) 77% (41) Mean Age (Yrs) 54±15 Obesity (BMI>30) 13% (7) Hypertension 62% (33) Diabetes 6% (3) Coronary Disease COPD 24.5% (13) Renal Insufficiency (GFR<60ml/h) 17% (9) Mean eGFR (mL/min) 79±23 Symptomatic Aneurysm 7.5%(4) Emergency 2% (1) Connective tissue disorder 34% (18) Redo

Intermittent cold kidney perfusion 89% Renal Ischemic time (min) 48±20 13.2% 60.4% 15.1% 9.4% 1.9% LHB Time (min) 155±44 Intermittent cold kidney perfusion 89% Renal Ischemic time (min) 48±20 Time for restart urinary output (min) 20±11 Lowest introperative Hb value (g/dl) 9±1 pRBC (units) PLT FFP 3±3 12±5 11±4 Cell-saver collected blood (L) 7±4 Minimum rectal temperature (°C) 33±1

Results 1 RIFLE scores I and F were observed in 15%, with need of continuous renal-replacement therapy in one patient (2%), no permanent dialysis. In-hospital mortality was 4%. Kidney Injury by RIFLE criteria % (n) No 63.3 (33) Class R 22.6 (12) Class I 11.3 (6) Class F 3.8 (2) Class L Class E

Results 2 At univariate analysis AKI was associated with hypertension (26% vs 0%, P=0.03), obesity (43% vs 12%, P=0.04), degenerative/post-dissection aneurysm (23% vs 0%, P=0.03), symptomatic aneurysm (50% vs 12%, P=0.04) Patients in any class RIFLE had significantly higher renal ischemic time than patients without renal dysfunction (56±43min, P=0.01) AKI was associated with increased occurrence of multi organ failure (25% vs 0%, P=0.001) and non-invasive ventilatory support (75% vs 31%, P=0.02)

Conclusions Renal dysfunction is a major comorbidity affecting TAAA open repair results RIFLE criteria are an objective and valid method for detection of acute kidney injury following TAAA surgery With the use of intermittent cold crystalloid renal perfusion and LHB support in aortic staged clamp technique is possible to achieve a good renal protection during TAAA open repair, despite the high blood products consumption and the visceral ischemic interval