Acute Renal Failure

1. Acute Renal Failure

2. A sudden deterioration of function of both kidneys leading to an inability to maintain the normal internal physiological environment. Products of metabolism normally removed by the kidney are retained leading to a condition that resembles systemic intoxication. A syndrome characterised by a sudden decrease of the GFR and consequently an increase in blood nitrogen products Liano & Pascual, 1999 The RIFLE classification of ARF is as follows: Risk (R) - Increase in serum creatinine level X 1.5 or decrease in GFR by 25%, or UO <0.5 mL/kg/h for 6 hours Injury (I) - Increase in serum creatinine level X 2.0 or decrease in GFR by 50%, or UO <0.5 mL/kg/h for 12 hours Failure (F) - Increase in serum creatinine level X 3.0, decrease in GFR by 75%, or serum creatinine level > 350umol/l; UO <0.3 mL/kg/h for 24 hours, or anuria for 12 hours Loss (L) - Persistent ARF, complete loss of kidney function >4 wk End-stage kidney disease (E) - Loss of kidney function >3 months Definition

3. Renal Function • Regulate fluid balance • Regulate blood pressure • Regulate electrolytes • Remove products of metabolism • Metabolise and remove toxins • Maintain normal blood pH • Regulate Calcium & Phosphate balance • Activate vitamin D3 • Produce Erythropoietin

4. Epidemiology • ARF is common • ARF found in approximately 5% of hospital admissions. Renal Association (2002) • Community based ARF- 172 pmp (Creat >500), 22 pmp need dialysis, referral rate 70pmp. (Feest,et al, 1993) • Metcalfe et al (2002) Incidence RRT for ARF 131 pmp, 72 pmp ARF on CRF • Median age 60-65 years. Turney et al (1990) • Madrid ARF study (1996) incidence 209 pmp or 1.5/1000 hospitalised patients

5. Classification of ARF

6. ARF Relative to Age

7. Predisposing Factors to ARF

8. Pre-Renal ARF • Cardiac: • Heart failure, MI, arrhythmia, PE, shock, tamponade • Volume: • haemorrhage, GI loss, Renal loss, skin loss, sequestration, inadequate hydration, diuretics • Vasomotor factors: • Afferent Constriction- sepsis,drugs (NSAIDS), hypercalcaemia, Postop., Hepatorenal syndrome. • Efferent Dilation- ACEI, AII RAs • Obstruction: • Thrombosis, embolism, hyperviscosity

9. Renal ARF

10. Renal Causes of ARF • Glomerular: • GN, vasculidites (polyarteritis, SLE) • Tubular: • ATN, nephrotoxins, HUS, myoglobin, sepsis • Interstitial: • infection, inflammation, drugs

12. Glomerular Disease Normal Glomerulus Rapidly Progressive Glomerulonephritis

13. Nephrotoxins

14. Post-Renal ARF Urinary Tract Obstruction

15. Family History Ethnic: inherited disorders Hereditary: APKD Diabetes, IHD, R D Social History Smoking Occupation Foreign travel waterway or sewage exposure Rodent exposure History Past Medical History Previous U & E’s Previous Health checks Systemic conditions Previous urinary conditions Recent procedures or instrumentation Known immunosuppression Drug History Toxic drugs, OTC, herbal remedies Clinical Assessment

16. Assessment • Priority: Risk of Death • Vital signs • Level of consciousness • Assessment of intravascular volume status 1. Mucous membrane & skin turgor(skin twist on forehead or anterior chest 2. Heart rate: lying and standing: postural drop in dehydration 3. JVP assessment: normal 0-3 cm 4. Examine peripheries: capillary return of nail bed, hand venous filling 5. Weight, assessment of fluid output

17. Blood Specimens • Potassium: high or low • Sodium: normal or high • Bicarbonate: low, metabolic acidosis • Urea: high • Creatinine: high • Phosphate: normal or low • Calcium: normal or low • Full Blood Count: infection, anaemia • Immunological assessment: for glomerular/vasculitic disease

18. Additional Assessment • Chest X-ray • Plain abdominal • Renal Ultrasound • Renal Biopsy • CT Scan

19. Should be examined in all ARF cases 50% of patient have oliguria as the earliest sign. Other sign/symptoms may take 2-3 days to appear Very variable: 800-2500ml/24hr Reflect water intake Urine output controlled by ADH, aldosterone, ANP, Na+ Low normal output is 400-500mls/24hr or 30ml/hr Measurement is useful for initial fluid resuscitation response Establised oliguria/anuria- remove catheter Anuria is usually post ARF unless proven othetrwise Polyuria can be normal or follow the oliguric phase. Daily weight is more accurate than fluid balance Urine Biochemistry In pre-renal failure Urine specific gravity - >1.016 Low urinary sodium - <20 mmol/l High urinary urea - >250 mmol/l High osmolality - > 500 mosm/kg In intrinsic renal failure Urine specific gravity - <1.010 High urinary sodium - >40 mmol/l Low urinary urea - <185 mmol/l Isotonic urine - 300-350 mosm/kg Urine Assessment

20. Urinalysis • Cloudy: pyuria, bacteruria, chyluria, amorphous phosphate (alkaline urine) • Smell: (not taste!) ketones, ammonia/fish-pseudomonas • Dipstick: Blood: free Hb or Mb cause diffuse green, intact RBC cause green spots Albumin: >250mg/l, not immunoglobulins and B-J Proteins Glucose: Exceeds renal threshold (10mmol/l) found in hyperglycaemia, pregnancy, Fanconi syndrome, ATN pH: normal 4.5-7.8. Systemic acidosis pH 5.3 or less, if not renal RTA Ketones: DM, starvation, alcoholism. Levadopa & captopril give false positives. SG: water SG is 1.0. Each 30-35mOsm/kg rise in osmolality increases the SG by 0.001, therefore an SG of 10.10 is an osmolality of 300-350mOsm/kg. Normal range is 1.002-1.30. Falsely high when urine pH <6.0 and falsely low when pH is >7.0

21. Urine Microscopy Red Cellular Casts Red Blood Cells

22. Anorexia Nausea & Vomiting Gastritis Constipation Diarrhoea Pancreatitis GI bleeding Hiccup Stomatitis Parotitis Uraemic Fetor GI Ulcers Anaemia: normocyctic, normochromic, RBC life Platelet Dysfunction White Cell Dysfunction Uraemic Symptoms

23. Pruritis: uraemic toxins, allergy, calcium phosphate Dry Skin: Reduced Sweat & sebaceous glands Pigmentation: Urochrome, Melanin Hypothermia Fatigue & Malaise Thirst Weight Loss Cramps Restless Limbs Uraemic Symptoms

24. Subdural Haematoma Polyneuritis Peripheral Neuropathy Autonomic Neuropathy Headache Irritability Tics Erratic memory Motor Weakness Insomnia Drowsiness Slurred Speech Convulsions Coma Stupor Tremor Low attention span Uraemic Symptoms

25. Management of ARF • Priority: Risk of death: Potassium management • Maintain volume: Low- JVP, postural drop in BP, High- cardiac gallop, pulmonary creps • Avoid nephrotoxins • Avoid hypotension • Fluid input & output • Daily weight, CVP • BP lying & standing (where possible) • Daily U&Es • Sodium Management • Protein management • Nutrition: 35kcal/kg CHO, Protein 1gm

26. Management of ARF • Volume: 500ml + previous days output + any other loss. Keep output 1-2ml/min • Dopamine: “renal” dose 1-3µg/kg/min, No evidence! • Frusemide: ? Reduce workload, flush tubules, increase Cl- delivery, decrease renal vascular resistance • Mannitol: ?increase tubular flow, RBF, prevent renal cell swelling, expands iv volume, preserves mitochodrial function, free radical scavenger. • Pulmonary Oedema: usually iatrogenic • Bleeding • Sepsis • Uraemic symptoms: headache, nausea, vomiting, coma, dry skin, itching, pallor etc.

27. Cause of Death in ARF Fernando Liaño