Continuous Renal Replacement Therapy (CRRT)

1. Continuous Renal Replacement Therapy (CRRT) Maureen Walter,Raquel Lomeli Anika Stevenson,Nellie Preble Intensive Care; Acute Renal Failure

2. What is CRRT • Continuous Dialysis of Critically Ill Patients in the ICU • The concept behind CRRT is to dialyse patients in a more physiologic way, slowly over 24 hours, just like the kidney. Intensive care patients are particularly suited to the techniques as they are by definition, bed bound and when acutely sick, intolerant of fluid swings associated with IHD • What is the difference between CRRT and IHD • Slow continuous natural like the kidneys vs rapid/qod • Why is it necessary in the ICU • Patients are hemodynamically unstable Intensive Care; Acute Renal Failure

3. IHD vs CRRT • While IHD is an important treatment therapy for patients with ESRD it may be contraindicated for patients in the ICU suffering from ARF due to their other disease processes. • IHD is done only 3-4 times a week in order to extract 2 days worth of accumulated fluid. The process takes about 3-4 hours. • CRRT is a continuous process that slowly and gently provides for the removal of fluids electrolytes and uremic toxins. Intensive Care; Acute Renal Failure

4. Indications for RRT in Critically Ill Patients • Oliguria (urine output <200ml/12hr) • Anuria (urine output <50ml/12hr) • Hyperkalemia (K+>6.5mmol/l and rising) • Severe acidemia (pH<7.1) • Azotemia (urea>30mmol/l or creat >300umol/l) • Pulmonary edema • Uremic encephalopathy • Uremic pericarditis • Uremic myopathy or neuropathy • Severe Dysnatremia (Na+>160 or <115mmol/l) • Hyperthermia • Drug overdose with filterable toxins (Lithium,Vancomycin,Procainamide etc.) • Anasarca • Imminent/ongoing massive blood product administration Intensive Care; Acute Renal Failure

5. Major complications of IHD • Intermittent hemodialysis (IHD) for critically ill patients may be limited or ineffective due to the critical nature of their ilness. Volume overload and hemodynamic instability may not be treated adequately with conventional forms of dialysis. • Complications of IHD: • Systemic hypotension(leads to Multi organ dysfunction • Arrhythmias • Hypoxemia • Hemmorrhage • Infection • Line related complications (e.g. pneumothorax) • Seizure/dialysis disequalibrium • Pyrogen reaction or hemolysis • ? Delay in recovery of renal function(r/t ischemia) • Fluid overload between treatments(Acute respiratory distress syndrome) Intensive Care; Acute Renal Failure

6. Why CRRT--Treatment Goals • Reduces hemodynamic instability preventing secondary ischemia • Precise Volume control/immediately adaptable • Ensures creatinine clearance • Uremic toxin removal • Effective control of uremia,hypophosphatemia,hyperkalemia • Acid base balance • Rapid control of metabolic acidosis • Electrolyte Management/dialisate to mirror ideal blood composition • Allows for provision of nutritional support • Management of sepsis/plasma cytokine filter • Safer for patients with head injuries • Probable advantage in terms of renal recovery • Improved nutritional support(full protein diet) Intensive Care; Acute Renal Failure

7. Accute Renal Failure • Acute renal failure is a common complication of critically ill patients in today’s intensive care units. • Three types • Pre-decline in renal blood flow resulting in decreased renal perfusion • Intra—injury to kidneys by nephrotoxins resulting in tubular cell injury • Post– obstruction to outflow • In the ICU most ARF is associated with prerenal and intrarenal failure. Intensive Care; Acute Renal Failure

8. Mortality related to ARF • 40%-70% • Factors • Increased age of patient population and multi system organ failure • How soon CRRT was started after admission* • In one study Patients who survived were started on CRRT 8 days earlier than those who died • Comorbidities—DM,HTN,CVD,ESRD,Malignancy etc • Gender--Male>Female Intensive Care; Acute Renal Failure

9. Summary of CRRT • Although ARF mortality remains high, CRRT is becoming the therapy of choice for the treatment of ARF in the critically ill patient. • Timely initiation of CRRT may improve patient survival • Surviving patients (without preexisting ESRD) are likely to experience recovery of renal function. • CRRT has many benefits including • Hemodynamic stability • Excellent fluid and solute removal • Enhanced cytokine removal and prevention of sepsis Intensive Care; Acute Renal Failure

10. Question • Prerenal failure occurs in response to: • A. Uncontrolled hypertension • B. Decline in renal blood flow • C. Exposure to nephrotoxins • D. Obstruction to urine outflow Intensive Care; Acute Renal Failure

11. Question • Intermittent hemodyalisis of critically ill patients results in hemodynamic instability due to: • A. Rapid urea removal • B. Excessive urea losses • C. Rapid fluid removal • D. excessive urine output Intensive Care; Acute Renal Failure

12. Question • The key indication for CRRT is: • A. Respiratory failure on mechanical ventilation • B.Multisystem organ failure on vasopressors • C. Anuria with refractory hypertension • D. Fluid overload with hemodynamic instability Intensive Care; Acute Renal Failure