Risk Factors and Management of Acute Renal Injury in Cardiac Surgery

Transcription

1 Risk Factors and Management of Acute Renal Injury in Cardiac Surgery Robert S Kramer, MD, FACS Clinical Associate Professor of Surgery Tufts University School of Medicine Maine Medical Center, Portland Maine

2 I have nothing to disclose

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5 Objectives The nephron Definition of AKI Vulnerability of patients to AKI Setting and timing of surgery Pre- and intra-operative factors Intra-operative prevention strategies Treatment of post-op AKI

6 The Nephron

7 Acute Kidney Injury Network (AKIN) Definition of AKI Abrupt reduction (within 48 h) in kidney function defined by an increase in creatinine by 50% or 0.3 mg/dl over baseline

8 AKI duration predictive of increased short and long-term mortality following cardiac surgery Ann Thorac Surg 2010;90:1142 9

9 Development of AKI: Pre-op Intrinsic factors: CKD, renovascular disease Prerenal factors: Recent diuresis, NPO status, impaired LV function ACE Inhibitors and ARB s Nephrotoxins: IV contrast, meds Endotoxemia Inflammation Genetics Rosner and Okusa Clin J Am Soc Nephrol 1: 19 32, 2006

10 Prevention of AKI: Pre-op Strategies Readiness for Surgery (statins, infection, meds, etc) Anemia management Contrast induced nephropathy Maximal Allowable Contrast (MAC) Timing of surgery

11 Readiness for Surgery

12 Pre-op Anemia Management

13 Association between low pre-op Hb and AKI Karkouti Circ 2009:119:

14 Pre-op Cardiac Cath

15 Contrast Induced Nephropathy Calvin et al Nature Reviews Nephrology 6, (Nov 2010)

16 Rate of AKI (%) AKI Rate: Same or Separate Admissions Same admission cath and surg AKI = 50.2% Prior admit cath AKI = 33.7% P-value < Cath Prior Admit Cath Same Admit Kramer et al Ann Thorac Surg 2010;90:

17 Intra-operative Prevention of AKI

18 Intra-op events leading to AKI Ischemic damage to the vulnerable renal medulla Ischemia-reperfusion injury Emboli: Gas and particulate Inflammation: CPB-induced (SIRS) Nephrotoxins: Pigments (free Hb, myoglobin) Rosner and Okusa Clin J Am Soc Nephrol 1: 19 32, 2006 and Kaplan s Cardiac Anesthesia 6 th Edition, Elselvier, N.Y., 2011

19 Key intra-op strategies to prevent AKI Minimize Hemodilution Nadir Hematocrit: The sweet spot Optimize Oxygen Delivery

20 Minimize Hemodilution Small circuits Retrograde autologous priming Low crystalloid volume pre- and during CPB MUF Ultrafiltration

21 The Sweet Spot Loor, Koch et al J Thorac Cardiovasc Surg Sept 2012 p

22 O 2 Delivery During CPB Best predictor for AKI = lowest O 2 delivery Critical value = 272 ml/min/m 2 Ranucci, Ann Thorac Surg 2005;80:

23 Renal Oxygen Delivery From the Anita T.Layton Lab, Duke University

24 O 2 delivery during CPB and creatinine (CABG) Critical value = 272 ml/min/m 2 Peak Serum Creatinine (mg/dl) Oxygen Delivery ml/min/m 2 Ranucci, Ann Thorac Surg 2005;80:

25 O 2 delivery during CPB and ARF (CABG) Critical value = 272 ml/min/m 2 ARF Rate (%) O 2 Delivery ml/min/m 2 Ranucci, Ann Thorac Surg 2005;80:

26 O 2 delivery during CPB and AKI after CABG Hemodilution during CPB = risk factor for postop AKI Detrimental effects may be reduced by adjusting the three variables Ranucci, Ann Thorac Surg 2005;80:

27 Components of formula for O 2 delivery Pump flow Hemoglobin saturation Arterial oxygen content

28 DO2 Formula AKIN Stage II ( % increase in creatinine from baseline) DO 2 cut-off = 262 ml/min/m 2 de Somer et al. Crit Care Aug 10;15(4):R192

29 Goal Directed Perfusion Maintaining DO 2 level above the identified critical value might limit the incidence of postop AKI.

30 Nadir Hematocrit

31 Critical Threshold: Mortality R. H Habib J Thorac Cardiovasc Surg 2003;125: 1438

32 Critical Threshold: Renal and Multi-organ Failure R. H Habib J Thorac Cardiovasc Surg 2003;125: 1438

33 Anemia can be bad Transfusions can be worse Surgenor et al, Circulation. 2006; 114[suppl I]:I-43 I-48

34 CPB Strategies Avoid hyperthermic perfusion: 34% increase in AKI with each 10 min above 37 outlet temperature* Base flow on ideal body weight: Using BSA in obese patients can result in too high CPB flows. ** *Newland. Perfusion January 2013 **Santambrogio et al. J Card Surg 2009;24:

35 CPB Strategies Decreased CPB and X-clamp times are associated with lower incidence of AKI * Intra-op plasma preservation: Plasma vital in preserving endothelial vascular integrity (glycocalyx) ** *Del Duca D, et al Ann Thorac Surg 2007, 84(4): **Unpublished

36 CPB Strategies Minimize peri-op transfusions: Independent variable associated with AKI*. Decrease microemboli: Filters, single clamp technique, epiaortic echo ** BP management: ΔMAP (preop/cpb)*** *Karkouti, Circ 2009:119: **Groom et al Circ Cardiovasc Qual Outcomes 2009 ***Kanji et al. Journal of Cardiothoracic Surgery 2010, 5:71

37 Post-op AKI Management Vasoactive drips to maintain BP Minimize transfusions Diuretics will not reverse AKI Avoid NSAIDS & other nephrotoxins Normovolemia Rapid identification of hemorrhage sources, early decision for return to OR Renal replacement therapy (RRT)

38 Renal Replacement Therapy (RRT) Initiate RRT emergently when lifethreatening changes in fluid, electrolyte, and acid-base balance exist. Consider broader clinical context and trends rather than single BUN and creatinine thresholds alone when making decision to start RRT.

39 Summary Nephron & definition of AKI Vulnerability of patients Setting and timing of surgery Pre- and intra-operative factors Prevention strategies: Minimize hemodilution & maximize DO 2 Management of post-op AKI

40 Thank you