Acute Kidney Injury Dr Alexis Missick FY2

Presentation Case Objectives Definition & Aetiology Investigation Management Complications

Clinical Scenario History: 55 year old lady presents to A&E with a 5 day history of diarrhoea and vomiting. She believes this was caused by a Chinese take away she had a day before developing symptoms. She has been unable to keep anything down including water and now feels very poorly. PMHx: HTN managed with ramipril. SHx: non-smoker, drinks alcohol occasionally. O/E: she appears very dry and has reduced skin turgor. BP is 100/70 and HR 95. Examination is otherwise unremarkable

Differentials?

Clinical Scenario History: 55 year old lady presents to A&E with a 5 day history of diarrhoea and vomiting. She believes this was caused by a Chinese take away she had a day before developing symptoms. She has been unable to keep anything down including water and now feels very poorly. PMHx: HTN managed with ramipril. SHx: non-smoke, occasional alcohol. O/E: she appears very dry and has reduced skin turgor. BP is 100/70 and HR 95. Examination is otherwise unremarkable Ix: normal FBC, Na 149, K 6.7, Urea 17.0 and Creatinine 258

Objectives Recognition of AKI Learn classification of causes and common examples Identification of appropriate investigations Understand principles of management of AKI Knowledge of indications for dialysis Awareness of complications and management of hyperkalaemia (common complication)

Definition Rapid impairment in renal function resulting in raised plasma urea/creatinine, fluid and/or acid-base imbalance which is reversible. AKIN Criteria for diagnosis of AKI 1.Time course – rapid (<48hours) 2.Reduction in Kidney function 1.Rise in serum creatinine (absolute increase of >0.3mg/dl or percentage increase of > 50%) 2.Reduction in urine output ( 6hours) RIFLE criteria (prosposed by ADQI) for staging of AKI: Risk, Injury, Failure, Loss, End stage kidney disease

Staging RIFLE Criteria Proposed by ADQI Severity (Stage 1-3) – Risk: GFR decrease >25%, serum creatinine increased 1.5 times OR urine production of 6 hours – Injury: GFR decrease >50%, doubling of creatinine OR urine production <0.5 ml/kg/hr for 12 hours – Failure: GFR decrease >75%, >tripling of creatinine or creatinine >355 μmol/l (>4 mg/dl) OR urine output below 0.3 ml/kg/hr for 24 hours Outcome – Loss: persistent AKI or complete loss of kidney function for more than 4 weeks – End-stage renal disease: need for renal replacement therapy (RRT) for more than 3 months

Aeitology

Presentation Symptoms – Malaise – Anorexia, Nausea and Vomiting – Pruritis – Dehydration – Confusion, convulsions Signs – Hypertension – Fluid overload: peripheral oedema, SOB/ bibasal crackles/raised JVP – Dehydration: postural hypotension, poor urine output (palpable bladder)

Investigations Bedside: BP (lying and standing), urine dip (?haematuria ?proteinuria), ECG Biochemistry: ABG, FBCs, U+Es, LFTs, CRP/ESR, Ca2+, blood culture Imaging: CXR, USS KUB or CT KUB Special tests: – CK, blood film, Myeloma screen (Bence-Jones protein), Renal Screen (ANA, ANCA, anti-BM) – Urine osmolality and cast cells – Renal biopsy – Doppler Renal USS and/or Angiography

Management Assess fluid status Fluid resuscitation Stop nephrotoxic drugs Treat the cause – Infection – give antibiotics, renal doses – Intrinsic renal disease – R/v medication – Obstruction- ?catheters ?calculus removal ?nephrostomies ?surgery

Complications – Indication for Immediate Dialysis!! Hyperkalaemia (persistent >7mmol/L) Metabolic Acidosis (if pH<7.2, bicarbonate <12) Pulmonary Oedema (refractory) Pericarditis Symptomatic ureamia - Encephalopathy

Hyperkalaemia Potassium range is 3.5 – 5mmol/L Rise in serum K+ >5mmol/l Signs/symptoms: muscle weakness ECG changes: – Flattened P waves – Broad QRS complex – Slurring of ST segment – Tall tented T waves

Hyperkalaemia Potassium >6.0 mmol/L – Calcium resonium 15g QDS PO – If septic or rising quickly treat as though K+ 6.5 Potassium >6.5 mmol/L – Dextrose-insulin (50ml 50% Dextrose with 10units Actrapid insulin, IV over 5mins) Monitor BM – Calcium resonium 15g QDS PO

Hyperkalaemia Potassium >7 mmol/L – Calcium gluconate (10ml of 10% solution into central vein or diluted into 40ml 0.9% saline into peripheral vein over 10mins, with cardiac monitor) – Dextrose insulin – Nebulised salbutamol 5mg – IV sodium bicarbonate (50ml 8.4% over 5mins centrally or 500mls 1.26% over 30mins peripherally – Calcium resonium