Acute Renal Failure

ACUTE RENAL FAILURE Vimar A. Luz, MD, FPCP, DPSN

OUTLINE Definition  Incidence  Causes/Pathophysiology  Phases  Evaluation  Management  Outcome 

RENAL FAILURE 

Acute  Rapid decline in GFR (Over Hours To Days)  Usually Reversible



Chronic  Kidney Damage for > 3 months  Irreversible

INCIDENCE 5% to 7% of hospital admissions  30% of ICU admissions 

ACUTE RENAL FAILURE

CATEGORIES

55% to 60%

35% to 40%

<5%

ACUTE RENAL FAILURE Prerenal

Due to decreased blood flow in the kidneys

ACUTE RENAL FAILURE

ACUTE RENAL FAILURE

PATHOPHYSIOLOGY

PATHOPHYSIOLOGY

Phases of Ischemic ARF

begins with renal insult hypothetical period of time S/S: Urine 400ml or less/24 hrs, Increasing BUN

Phases of Ischemic ARF

Period of ongoing renal failure and lasts 7-14 days S/S: Urine Output is Lowest

Phases of Ischemic ARF

Gradual return of renal function S/S: Can be complicated my marked diuretic phase

NEPHROLOGICAL EVALUATION Risk factors for ARF  Underlying CKD  Exposure to potential nephrotoxins  Recent disturbance of renal perfusion 

RISK GROUPS/FACTORS            

Hemodynamic instability Nephrotoxins Sepsis Post surgical Cardiovascular Elderly, HPN, Diabetics Trauma, Burns Neoplasia Pulmonary Muskuloskeletal Injury/Poisoning Gastrointestinal

Chertow GM et al, Toward and evidence based definition of hospital-acquired acute renal failure. J Am Soc Nephrol 2003; 8:1042A

MANAGEMENT PRIORITIES (I) 

Search for and correct prerenal and postrenal factors  Review medications and stop nephrotoxins  Optimize cardiac output and renal blood flow  Restore and/or increase urine flow  Monitor fluid intake and output, daily weight

MANAGEMENT PRIORITIES (II) Search for and treat acute complications (hyperkalemia, hyponatremia, acidosis hyperphosphatemia , pulmonary edema)  Provide early nutritional support  Search for and aggressively treat infections  Initiate dialysis before uremic complications emerge  Dose drugs appropriate for their clearance  Stop and repair ongoing intracellular injury 

MANAGEMENT Preventive  Resuscitative/Supportive 

Factors affecting choice of RRT modality 

Patient factors: - Hypercatabolism and abdominal surgery: no PD

a.The underlying disease process

isolated ARF: IHD MODS and hemodynamically unstable: CRRT, IHF, SLED Cerebral edema: continuous forms ARF and respiratory failure: continuous forms, SLED

b. The indications for dialysis

Rapid removal of solutes (life-threatening hyperkalemia):IHD Fluid removal in unstable patient: continuous forms

c. Location of the patient and duration of treatment Patient mobility: SLED ICU: Continuous, SLED Cardiac ICU: CRRT, SLED

Factors affecting choice of RRT modality 

Technique factors a. Solute and water clearance need for high urea clearance:IHD, SLED drug overdoses: drugs with large DV and easy dialysability: IHD, but rebound, thus: IHD followed by CRRT

b. Ease of application and local possibilities number of nurses, machines, training of nurses risk of bleeding: preferably IHD or SLED, PD?

ACUTE RENAL FAILURE Increase hospital length of stay  Associated with more than doubling of the cost of hospital care  Increased morbidity and mortality 

Chertow, et al. Toward and evidence-based definition of hospital acquired acute renal failure. J am Soc Nephrol 2003; 8:1042 A

OUTCOME 50% MORTALITY  Irreversible in about 5% of cases  About 5% suffer progressive deterioration in renal function  50% have subclinical functional defects 



*Dose of renal Replacement Therapy – The higher dose the better the survival

Ronco C et al. Effects of different doses in continous veno-venous hemofiltration on outcomes of acute renal failure: a prospective randomized trial. Lancet 2000;356:26-30

RECOVERY Severity of Creatinine Elevation  Requirement for Dialysis  Other organ system involvement 

Morgera et al. Long-term outcomes in acute renal failure patients treated with continous renal replacement therapies. Am J Kidney Dis 2002; 40:275-279 Bhandari S et al. Survivors of acute renal failure who do not recover renla function. Qjm 1996;89:415421 Salmanullah M et al. The effects of acute renal failure on long term renal function. Ren Fail 2003; 25:267-276

GOOD DAY!