Acute Kidney Injury


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Acute Kidney Injury

  1. 1. Dr. Michel Helmy Marketing Manager – Acute Therapies South East Europe, Middle East & Africa CRRT Workshop AKI Acute Kidney Injury AKIAKI Acute Kidney InjuryAcute Kidney Injury
  2. 2. © 2012 – Michel Helmy 2 Anatomy of the Kidney Approximately 1,200 ml of blood or 25 % of Cardiac Output flows through the kidney in one minute Renal artery and vein Fibrous capsule Cortex Pyramid (medulla) Ureter Pelvis Deep inside the cortex and the medulla regions are long hairpin-like structures called nephrons, these are the functional urine producing unit of the kidney
  3. 3. © 2012 – Michel Helmy 3 The Nephron The urine producing part of the kidney Distal tubule Collecting duct Loop of Henle Peritubular capillaries Proximal tubule Bowman’s capsule Glomerulus Afferent arteriole (wider) Efferent arteriole (narrow) There are one million Nephrons in each kidney The efferent arteriole, which is narrower than the afferent arteriole, creating a hydrostatic pressure in glomerulus
  4. 4. © 2012 – Michel Helmy 4 Renal Function Secretion of three different hormones: SECRETORY FUNCTIONEXCRETORY FUNCTION Renin: regulate blood pressure Vitamin D: regulate calcium uptake Excretion product of the kidney: urine EPO: regulate red blood cell production Remove excess fluid Remove waste products Regulate acid/base balance Regulate electrolyte levels Urea & Creatinine
  5. 5. © 2012 – Michel Helmy 5 ARF… Definition . • Definition: • A clinical syndrome characterized by rapid reduction in renal excretory function underpinned by variety of causes. Serum creatinine & urine output should continue to be viewed as the best existing markers for AKI • Acute kidney injury causes are generally divided into • Pre-renal • Renal (intrinsic) • Post-renal relative incidence of each of these is dependent on age, gender and clinical setting. • Glomerular Filtration Rate is reduced ….decreased urine excretion • Nitrogenous wastes accumulates in the body (uremia) • Metabolic & electrolytes disturbances
  6. 6. © 2012 – Michel Helmy 6 Definition: AKI = ARF? ARF = Acute Renal FailureAKI = Acute Kidney Injury Intended to describe the entire spectrum of disease from being relatively mild to severe. Defined as renal function inadequate to clear the waste products of metabolism despite the absence of correction of hemodynamic or mechanical causes. Clinical manifestations of renal failure include the following: •Uremic symptoms (drowsiness, nausea, hiccough, twitching) •Hyperkalemia •Hyponatremia •Metabolic acidosis Defined as an abrupt change in serum creatinine and/or urine output and classified according the RIFLE criteria
  7. 7. © 2012 – Michel Helmy 7 Definition of AKI 2.1.1:2.1.1: Acute kidney injury (AKI) is defined as any of the following (Not Graded): • Increase in SCr by ≥ 0.3 mg/dl (≥ 26.5 µmol/l) within 48 hours; OROR • Increase in SCr to ≥ 1.5 times baseline, which is known or presumed to have occurred within prior 7 days OROR • Urine volume <0.5 ml/kg/h for 6 hours
  8. 8. © 2012 – Michel Helmy 8 Conclusion: AKI is not ARF As you have seen, the terms acute kidney injury (AKI) and acute renal failure (ARF) are not synonymous. While the term renal failure is best reserved for patients who have lost renal function to the point that life can no longer be sustained without intervention, AKI is used to describe the milder as well as severe forms of acute renal dysfunction in patients. Let us have a deeper look at the classification of AKI…
  9. 9. © 2012 – Michel Helmy 9 Diagnosis ARF If the cause of ARF is not apparent, a large amount of blood tests and examination of a urine specimen is typically performed. • Urea in blood • Creatinine in blood • Urine analysis • Urine volume output • Ultrasound of kidneys Conventional Units < 1.5 mg 10 - 20 mg/dl International Units 50 - 100 μmol /L 2.6 - 6.8 mmol /L Normal adult blood values Creatinine BUN (Blood Urea Nitrogen) Acute Renal Failure
  10. 10. © 2012 – Michel Helmy 10 Diagnosis AKI If the cause of ARF is not apparent, a large amount of blood tests and examination of a urine specimen is typically performed. • Urea in blood • Creatinine in blood • Urine analysis • Urine volume output • Ultrasound of kidneys Normal adult blood values Conventional Units International Units Creatinine < 1.5 mg 50 - 100 μmol /L BUN (Blood Urea Nitrogen) 10 -20 mg 2.6 - 6.8 mmol /L Creatinine Clearance 90 – 130 16 -26 mg/kg/24 hrs GFR 120 ml/min 180 L/day
  11. 11. © 2012 – Michel Helmy 11 AKI … in the ICUs . • An estimated 5–20% of critically ill patients experience an episode of AKI during the course of their illness • AKI requiring RRT has been reported in 4·9% of all admissions to intensive-care units(10) • Data from the Intensive Care National Audit Research Centre suggests that AKI accounts for nearly 10% of all ICU bed days (11). • AKI is common in hospitalized patients and also has a poor prognosis. • Non-ICU AKI, in which the kidney is usually the only failed organ, carries a mortality rate of up to 10% (12,13). • ICU AKI is often associated with sepsis and with non-renal organ system failure (14), with mortality rates of over 50%. These rates rise to 80% when RRT is required (15). Predictably, death rates increase with an increasing number of failing organ systems but over 65% of survivors recover renal function and discontinue RRT(1). • AKI in ICUs is often only one facet of MOF, and frequently results from systemic inflammatory reaction or sepsis.
  12. 12. © 2012 – Michel Helmy 12 Incidence ARF Study • Close to 30.000 patients were studied • Sept. 2000 to December 2001 • 54 hospitals in 23 countries Conclusion: The period prevalence of ARF requiring RRT i between 5% - Hospital m JAMA n ICU was 6 % and was associated with high ortality rate. 2005; 294:813-818
  13. 13. © 2012 – Michel Helmy 13 Incidence of ARF Publication This article states: Acute renal failure complicates the course of 7 - 23 % of patients in the Intensive Care Unit Referring to publications 1 -4 in the reference list Intensive Care in Nephrology (Taylor & Francis Group - 2005) Pages 99-111
  14. 14. © 2012 – Michel Helmy 14 Incidence of ARF in US. Publication This publication states: The annual incidence of community-acquired ARF is approximately 100 case per 1 m diagnosed in only 1% o sentation. On the other hand, hospital-acqu any as 4% of hospital ad ad Published on illion population, and it is f hospital admissions at pre ired ARF occurs in as m missions and 20% of critical care missions Author: Richard Sinert, DO A Professor of M Coauthor(s): Peter R. Peacock, University of New York Health ssociate Professor of Emergency Medicine, Clinical Assistant edicine, State University of New York College of Medicine; Jr, MD Assistant Professor of Emergency Medicine, State Sciences Center at Brooklyn,
  15. 15. © 2012 – Michel Helmy 15 Traditional classification of ARF Pre-renal ARF Post-renal ARFIntrinsic-renal ARF The causes of ARF are traditionally divided into three categories. Although this division is useful for classification, all three categories may occur simultaneously in a given patient. ARF is a complication that can occur following any medical condition. It can result from pre-renal causes, intrinsic renal causes or post-renal causes. Acute Renal Failure
  16. 16. © 2012 – Michel Helmy 16 Pre-renal ARF Kidney hypoperfusion (reduced blood supply) results in both renal ischemia (reduced supply of oxygenated blood) and low GFR By far the most commonly type of ARF seen in ICU Common causes: • intravascular volume depletion dehydration, hemorrhage • decreased cardiac output congestive heart failure, infarct • systemic vasodilatation (dilation of blood vessels) anaphylactic shock, sepsis Acute Renal Failure
  17. 17. © 2012 – Michel Helmy 17 Intrinsic ARF Possible causes: • miscellaneous renal diseases • toxins Necrosis (is Greek for dead) = death of cell and living tissue Tubule is part of the Nephron, the urine forming part of the kidney Acute Renal Failure Intrinsic renal causes account for 35-40% of ARF cases. The causes of intrinsic renal failure are diseases or toxins causing damage of the small renal vessels and glomeruli, commonly resulting in acute tubular necrosis.
  18. 18. © 2012 – Michel Helmy 18 Post-renal ARF Increased pressure on the Bowman’s capsule offers a resistance to normal filtration pressure, which causes an acute reduction in GFR Cause: acute obstruction of the flow of urine Acute Renal Failure Post-renal causes account only for about 5% of ARF cases. They are associated with acute obstruction of the flow of urine which can occur at any point in the urinary tract. The obstruction creates a back flow of urine in the kidney which results in an increased pressure on The Bowman’s capsule. The constant pressure offers a resistance to the normal filtration pressure, which causes an acute reduction in GRF.
  19. 19. © 2012 – Michel Helmy 19 Causes of AKI Volume-responsive AKI Postoperative AKIHypotension Sepsis-induced AKI AKI is common in the critically ill, especially in patients with sepsis and other forms of systemic inflammation (e.g. major surgery, trauma, burns), but other causes must be considered. Let us look at the 4 most common causes first: Now let’s go back to the concept of AKI!
  20. 20. © 2012 – Michel Helmy 20 • ADQI (Acute Dialysis Quality Initiative) is a process initiated by a group of physicians from different parts of the world, with the objective to seek consensus and evidence and establish guidelines towards AKI. • They have proposed the RIFLE classification as a definition of AKI. RIFLE defines three grades of severity of ARF on the basis of either an acute increase in serum creatinine, decrease in GFR or decreased urine output. •• ClassificationClassification •• RRiskisk •• IInjurynjury •• FFailureailure Outcome:Outcome: •• LLossoss •• EEndnd--stage renal diseasestage renal disease AKI … Stages (RIFLE Criteria) .
  21. 21. © 2012 – Michel Helmy 21 Classification of AKI according to RIFLE criteriaRIFLE criteria RIFLE defines three grades of severity of AKI on the basis of either: • acute increase in serum creatinine • decrease in GFR • decreased urine output. Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group. Crit Care. 2004 Gambro Acute Therapies supports the RIFLE definition of AKI
  22. 22. 22 Staging of AKI 2.1.2:2.1.2: AKI is staged for severity according to the following criteria (below). (Not Graded) Stage Serum Creatinine Urine Output 1 1.5-1.9 times baseline OR ≥0.3 mg/dl (≥ 26.5 µmol/l) increase <0.5 ml/kg/h for 6-12 hours 2 2.0-2.9 times baseline <0.5 ml/kg/h for ≥12 hours 3 3.0 times baseline OR increase in serum creatinine to ≥4.0 mg/dl (≥ 353.6 µmol/l) OR initiation of renal replacement therapy OR, in patients <18 years, decrease in eGFR to <35 ml/min per 1.73 m2 <0.3 ml/kg/h for ≥ 24 hours OR Anuria for ≥ 12 hours
  23. 23. © 2012 – Michel Helmy 23 RIFLE criteria: Urine Output • Approximately 50-60% of AKI cases are non-oliguric • Patients may continue to make urine despite an inadequate glomerular filtration • Although prognosis is often better if urine output is maintained, use of diuretics to promote urine output does not seem to improve outcome (and some studies even suggests harm) Anuria: <100 ml/24 hour Oliguria: 100-400 ml/24 hour Nonoliguria: >400 ml/24 hour Definition Now when do we talk of ‘Oliguria’? And when is a patient ‘non-oliguric’?
  24. 24. © 2012 – Michel Helmy 24 Initial treatment of AKI Focused on fluid management 1. Hypovolemia potentiates and exacerbates all forms of ARF 2. Reversal of hypovolemia by rapid fluid infusion can be sufficient to treat many forms of ARF 3. Rapid fluid infusion can result in life-threatening fluid overload 4. Urinary Catheter for measurement of Urine Output 5. Section 3 of the KDIGO Guideline addresses approaches to prevent progression of AKI. An important recommendation supported by 1B evidence is not to use diuretics to prevent AKInot to use diuretics to prevent AKI. This continues to be a first line therapy used by many physicians upon suspicion of AKI. Challenging fluid management problems 2- Renal Replacement Therapy in AKI
  25. 25. © 2012 – Michel Helmy 25 Classification of RRT RRT Dialysis Modalities Intermittent Continuous IHD SLEDD / EDD PD CRRT PD is an intra-corporeal (inside the body) treatment all other modalities are extra-corporeal (outside the body) treatments
  26. 26. © 2012 – Michel Helmy 26 Continuous renal replacement therapy (CRRT) has become the preferred treatment of acute kidney injury CRRT has been proven to be suitable in patients with hemodynamic instability in the intensive care setting and studies have confirmed its benefits with respect to solute and fluid removal. History of AKI Management . CRRT 5% peritoneal dialysis 5% intermittent hemodialysis 90% CRRT 27% intermittent hemodialysis 73% late 90’s IHD 10 to 20% CRRT 80 to 90% 3rd MillenniumARF in the ICUARF in the ICU mid 80’s
  27. 27. © 2012 – Michel Helmy 27 Outcomes of AKI Outcomes (or endpoints) regarding AKI can either be defined as a measurement (i.e. serum creatinine) or an event (i.e. death or need for dialysis). Some of these endpoints are: Survival / Mortality Recovery of Renal Function Economic Analysis Morbidity Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group. Crit Care. 2004 Can be defined as lack of need for Renal Replacement Therapy. Therefore it is important to know when a kidney has recovered completely or partial. Let us see how this works!
  28. 28. © 2012 – Michel Helmy 28 Renal Recovery: How to define? Complete recovery: Return to near baseline GFR Partial recovery: Failure to return to baseline but without the need for chronic renal replacement Complete Renal Recovery is defined when: Serum Creatinine (SCrt) is not more than 50% increased from baseline example: if baseline SCrt is 1 mg/dL (88 mmol/L) complete recovery is said to occur if the new steady state SCrt is <1.5 mg/dL (133 mmol/L) Partial Renal Recovery is defined when: The above condition for complete recovery is not met but the patient does not require chronic dialysis (i.e. renal ‘loss’ has not occurred) Second International Consensus Conference of the Acute Dialysis Quality Initiative (ADQI) Group. Crit Care. 2004