Acute Kidney Injury (AKI) Dr Svitlana Zhelezna Clinical Teaching Fellow UHCW NHS Trust 2013/2014 academic year

Objectives: Recognise AKI Investigate and decide on: pre-renal, renal and post renal causes Recognise and manage hypovolemia Manage hyperkalemia Indications for emergency dialysis and heamofiltration

Case 1 66 y.o. man presents to A&E at 10 am PC: increasing SOB for 7/7, coughing up phlegm and having fever. PMH: DM, HTN O/E: pale, sweaty, BP 85/50, HR 115, Sats 92% on air, RR 25, T 38.3, coarse crackles on the right side of his chest. CXR - RLL pneumonia. Blood results: Na 130, K 4.5, Urea 14.3, Cr 189 The nurse asks you to reassess the patient at 2 pm as he hasn't passed urine since admission. Current obs: HR 95, BP 95/55, Sats 96%, RR 22, T 37.5 What would be your actions?

Medical management Pt’s cardex: Stat: paracetamol 1g IV Oxigen 6 L Regular: Enoxaparin 40 mg metformin, aspirin, ramipril, atenolol and simvastatin Nebs with Soduim Chloride 0.9% Abx: Co-amoxiclave 1.2 g and Clarithromycin 500mg PRN: paracetamol 1g PO/IV, not more than QDS Salbutamol ml nebs

Definition of AKI (Kidney Disease: Improving Global Outcomes (KDIGO)) Acute kidney injury is defined when one of the following criteria is met Serum creatinine rises by ≥ 26µmol/L within 48 hours Serum creatinine rises ≥ 1.5 fold from the reference value, which is known or presumed to have occurred within one week urine output is 6 consecutive hours

Examples: Mr Smith U&E Mrs Dale Mr Hob (approximate weight 80 kg) - 40 ml per hour cut off – less then 240 ml per 6 hours Date14/06/1415/06/1416/06/14 Cr Date09/06/1415/06/14 Cr89135

Statistics: The reported prevalence of AKI from US data ranges from 1% (community-acquired) up to 7.1% (hospital-acquired) of all hospital admissions The incidence of AKI requiring renal replacement therapy (RRT) ranges from 22 per million population/year (pmp) to 203 pmp/year

Symptoms of Acute Kidney Injury: Raised Urea, Creatinine and Uric Acid: - Confusion - Drowsiness Failure to Excrete Normal Acidic Products: - Metabolic Acidosis - Respiratory Hyperventilation Electrolyte Imbalances (Hyperkalaemia): - Dysrhythmias

KDIGO staging system for acute kidney injury StageSerum creatinine (SCr)Urine output criteria 1 increase ≥ 26 μmol/L within 48hrs or increase ≥1.5 to 1.9 X reference SCr 6 consecutive hrs 2 increase ≥ 2 to 2.9 X reference SCr 12 hrs 3 increase ≥3 X reference SCr or increase ≥354 μmol/L or commenced on renal replacement therapy (RRT) irrespective of stage 24 hrs or anuria for 12 hrs

AKI risk factors: age > 75 yrs chronic kidney disease (CKD, eGFR < 60 mls/min/1.73m2) Cardiac failure Atherosclerotic peripheral vascular disease Liver disease Diabetes mellitus Nephrotoxic medications

Potential causes for AKI including reduced fluid intake increased fluid losses urinary tract symptoms recent drug ingestion sepsis

What to look for when clerking ? Ask about: family history of renal disease exactly when the presenting symptoms started, and which came first joint pains, or rash, or nose bleed, or ear trouble (vasculitis) backache or bone pains (myeloma and other malignancy) drugs taken (NSAID, ACEI ect.)

Assessment of volume status: Core temperature (raise due to dehydration) Skin Turgor/Mucus Membranes Peripheral perfusion (CRT raised) Pulse rate (raised) and volume (low) BP (low, postural drop) JVP (raised in fluid overload) Chest sounds (pulmonary oedema) Peripheral Oedema Urine output

Clinical examination must include (continuation): general Rash, uveitis, joint swelling signs of renovascular disease audible bruits impalpable peripheral pulses abdominal examination palpable bladder

AKI Outcomes: Renal function loss – i.e. persistent loss of renal function lasting > 4 weeks End Stage Kidney Disease – i.e. GFR 3 months Other associated complications – e.g. sepsis, bleeding, respiratory failure etc. Increased Mortality

Investigations: biochemistry Urea and electrolytes haematology FBC urinalysis (± microscopy) microbiology urine culture (if infection is suspected) blood culture (if infection is suspected)

Specific renal investigations (dependent upon the clinical presentation) renal immunology urinary biochemistry electrolytes osmolality ECG, Chest x-ray abdominal x-ray renal tract ultrasound ( within 24hrs if obstruction suspected or esoteric cause suspected requiring a kidney biopsy) kidney biopsy

Principles of Treatment: Check Medication! Stop all nephrotoxic ( Concurrent medications that interfere with GFR autoregulation or renal blood supply ) ACE inhibitors Angiotensin Receptor Blockers (ARBs) Ciclosporin (ulcerative colitis) NSAIDs Tacrolimus (immunomodulator) Check that the dosages of those remaining /commencing are correct in renal failure (Enoxaparin, some antibiotics)

Principles of Treatment: Treat lifethreatening hyperkalaemia first Correct hypovolaemia/hypoperfusion – restore pressure Exclude obstruction ASAP (Imaging) Treat the underlying cause Consider Renal replacement therapy if no response

Case 1 66 y.o. man presents to A&E at 10 am PC: increasing SOB for 7/7, coughing up phlegm and having fever. PMH: DM, HTN O/E: pale, sweaty, BP 85/50, HR 115, Sats 92% on air, RR 25, T 38.3, coarse crackles on the right side of his chest. CXR - RLL pneumonia. Blood results: Na 130, K 4.5, Urea 14.3, Cr 189 The nurse asks you to reassess the patient at 2 pm as he hasn't passed urine since admission. Current obs: HR 95, BP 95/55, Sats 96%, RR 22, T 37.5 What would be your actions?

Medical management: Pt’s cardex: Stat: paracetamol 1g IV Oxigen 6 L Regular: Enoxaparin 40 mg, metformin, aspirin, ramipril, atenolol and simvastatin Nebs with Soduim Chloride 0.9% Abx: Co-amoxiclave 1.2 g and Clarithromycin 500mg PRN: paracetamol 1g PO/IV, not more than QDS Salbutamol ml nebs

Initial management: Assess the patient (A-E) including volume status, check the catheter if in place (might be blocked or misplaced) CHECK CURRENT MEDICATIONS! Check patient’s base line U&E or previous if available Investigations: Urine dip (if not done already) Treatment: fluid resuscitation, call for senior help

Fluid balance (adults, resting state, mL per day) Totaling: in/out ~2500 ml/day

Maintenance fluids: WEIGHT RATE For the first 10 Kg 100 mL/kg/24hrs or 4 mL/kg/hr For the next Kg Add 50 mL/kg/24hrs or + 2 mL/kg/hr For each Kg above 20 Add 20 mL/kg/24hrs or +1 mL/kg/hr So, the maintenance fluid requirements for a 70-kg adult is = 2700 (mL/24hrs) Or = 110 (mL/hr)

Fluid requirements in illness: Missing maintenance is estimated by multiplying the normal maintenance volume by the length of the fasting period: Case: 89 yo male, was found lying on the floor in his flat for approximately 6 hours. He is know to have advanced dementia. Fluid requirements for 24 hours: Maintenance fluid 3L Missing maintenance 600 ml Total: 3600 ml

Fluid requirements in illness: Increased insensible losses due to hyperventilation, fever and sweating - an extra 500 ml/day is required for every degree Celcius above 37, ~20 ml/hr); Case: 60 yo. Female, admitted due to CAP, her temperature is 38.5 Fluid requirements for 24 hours: Maintenance fluid 3L Insensible loses 720 ml Total: 3720 ml

Fluid requirements in illness Maintenance requirements for an adult Na mmol/day K mmol/day In Iitres of water by the oral, enteral or parenteral route (or a combination of routes). Additional amounts should only be given to correct deficit or continuing losses

Contents of common crystalloids in mmol/L NaKCaClHCO3OsmpH Plasma Na Cl 0.9% Dextrose 5% Dex.Saline Hartmann’s Lactate 29 Ringer’s Lactate 28 Na Bicarb 1.2% Na Bicarb 8.4%

Fluid requirements in illness Excessive losses from gastric aspiration/vomiting crystalloid solution with K supplement. ↓Cl - 0.9% NaCl + K (sufficient amount) and care not to produce sodium overload. ↓Na (excessive diuretic exposure) - Hartmann's Diarrhoea, ileostomy, small bowel fistula, ileus, obstruction - volume for volume with Hartmann's.

What is Hyperkalaemia? Level of potassium above 5.5 mmol/l in venous blood ECG changes (peaked T waves and broadening of QRS complex) are important but may NOT be seen even if potassium level is life threatening May cause sudden death or progressive bradycardia and death

ECG Changes:

Causes of Hyperkalaemia: AKI/Renal failure Sepsis with acute kidney injury Drugs (spironolactone, ACE inhibitors, amiloride and OTHERS)

Treatment: K+ >6.0 mmol/l Calcium resonium 15G qds PO in water, recheck K+ after 2 hours K+ >6.5 mmol/l Above plus: Refer to a nephrologist, Dextrose-insulin (10U actrapid insulin in 50ml 50% dextrose, intravenously, over 5 minutes, check BM every 30min for 2 hours K+ >7.0 mmol/l Above plus: URGENT REFERRAL Neb Salbutamol 5mg and repeat in 2 hours IV Sodium Bicarbonate 500ml 1.26% over 30 mins OR If central line in situ: IV Sodium Bicarbonate 50ml 8.4% over 5 mins (not in pulmonary oedema) IV Calcium Gluconate 10ml 10% Recheck K+ and BM in 2 and 4 hours

Acute Renal Failure → Emergency Haemodialysis: K+ > 7mmol/L, resistant to medical therapy Pulmonary oedema refractory to medical therapy Metabolic pH < 7.2 or base excess < -10 Other possible indications include: Uraemic pericarditis Uraemic encephalopathy

Renal Replacement Therapy Dialysis: No clear proven advantage for either in treatment of renal failure Theoretical advantage of clearance of middle molecules Haemofiltration: No need to transfer patient to renal unit Can be continuous Improved haemodynamic stability Permits vasopressers and other drug therapies including TPN Reduced risk of disequilibrium syndrome

When to call nephrology? Any known dialysis patient admitted Any known renal transplant patient admitted Any case of AKI where cause is not clear Worsening AKI Emergency dialysis indications Suspect glomerulonephritis

Summary: worry if Patient has not passed urine or very little U&E creatinine is going up, check dynamics Patient is dehydrated plus cardiovascular compromised (past MI, CCF) remember Normal creatinine does not mean patient is not developing AKI Call early for senior or specialist help

Thank you! Any questions?