https://doi.org/10.1177/1089253218790270 Seminars in Cardiothoracic and Vascular Anesthesia 1–7 © The Author(s) 2018 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/1089253218790270 journals.sagepub.com/home/scv Original Article Introduction Renal function is often affected after open abdominal aor- tic aneurysm (AAA) repair 1,2 and may be related to reduced renal blood flow. 3,4 Renal and cerebral blood flow are autoregulated and cerebral perfusion is considered to be maintained when mean arterial pressure (MAP) is kept between 60 and 150 mm Hg, 5 whereas the lower limit for renal autoregulation is reported as high as 80 mm Hg. 6,7 Accordingly, postoperative affected renal function may be related to perioperative hypotension. 8 Renal blood flow is high and yet in the medulla oxygen tension is low 9 and a reduction in flow may affect renal function. 10,11 Also, infrarenal aortic cross-clamping reduces cardiac output (CO) 12,13 and could affect tissue oxygenation. Cerebral oxygenation (S c O 2 ) may be monitored by near-infrared spectroscopy (NIRS), while evaluation of renal oxygen extraction as an index of renal blood flow requires an arterial and renal venous catheter. The S c O 2 is taken to indicate whether cerebral blood flow is adequate during surgery, 14,15 and during nonvascular surgery S c O 2 is maintained even if MAP is reduced to below 60 mm Hg. 16 Patients undergoing AAA repair may present other athero- sclerotic manifestations and the lower level of both cere- bral and renal autoregulation could be elevated. 7,17 We evaluated whether the increase in plasma creatinine after 790270SCV XX X 10.1177/1089253218790270Seminars in Cardiothoracic and Vascular AnesthesiaOlesen et al research-article 2018 1 Rigshospitalet, Copenhagen, Denmark 2 Bispebjerg and Frederiksberg Hospitals, Copenhagen, Denmark Corresponding Author: Niels Damkjær Olesen, Department of Anesthesia, Rigshospitalet, Blegdamsvej 9, Copenhagen 2100, Denmark. Email: niels.damkjaer.olesen.01@regionh.dk Elevated Renal Oxygen Extraction During Open Abdominal Aortic Aneurysm Repair Is Related to Postoperative Renal Dysfunction Niels Damkjær Olesen, MD 1 , Thomas Bech Jørgensen, MD 2 , Jonas Eiberg, MD, PhD 1 , Ulf Johan Vilhelm Helgstrand, MD, DMSc 1 , Henrik Hegaard Sillesen, MD, DMSc 1 , Pernille Cedergreen, MD 1 , Niels Henry Secher, MD, DMSc 1 , and Henning Bay Nielsen, MD, DMSc 1 Abstract Background. Open abdominal aortic aneurysm repair is often followed by elevated plasma creatinine, likely due to impaired renal blood flow. We evaluated whether postoperative elevation in creatinine relates to renal oxygen extraction during surgery as an index of renal blood flow and also monitored frontal lobe oxygenation. Methods. For 19 patients (66 ± 10 years; mean ± SD) undergoing open infrarenal abdominal aortic aneurysm repair, renal oxygen extraction was determined by arterial and renal vein catheterization. Near-infrared spectroscopy determined frontal lobe oxygenation. Results. During surgery mean arterial pressure (from 102 ± 14 to 65 ± 11 mm Hg; P < .0001), arterial hemoglobin (from 7.7 ± 0.7 to 6.6 ± 0.8 mmol/L; P < 0.0001), and frontal lobe oxygenation (from 74 ± 6% to 70 ± 6%; P = .0414) decreased, while renal oxygen extraction increased (from 5.3% [4.3-8.1]; median [interquartile range] to 10.8% [5.8- 17.5]; P = .0405). Plasma creatinine became significantly elevated on the second day after the operation (from 83 [73- 101] to 105 μmol/L [79-143]; P = .0062) with a peak increase observed after 2 days (1-2). The peak increase in creatinine correlated to intraoperative renal oxygen extraction (r = 0.51; P = .026). Conclusion. Kidney function was affected after open abdominal aortic aneurysm repair likely related to limited renal blood flow. We take the increase in renal oxygen extraction and reduction in frontal lobe oxygenation to suggest that mean arterial pressure and hemoglobin were too low to maintain renal and cerebral circulation in vascular surgical patients. Keywords abdominal aortic aneurysm, cerebrovascular circulation, near-infrared spectroscopy, renal circulation