1. NIHR Clinical Lecturer in Nephrology University of Sheffield
Acute Kidney Injury
Tuesday 23 February 2016
Roslyn Simms
NIHR Clinical Lecturer in Nephrology
University of Sheffield

2. Overview of Acute Kidney Injury
Importance
Definition
Epidemiology
Causes
Clinical Assessment
Investigations
Management
Case
Summary

3. Control blood pressure Control Calcium + Phosphate
Acute Kidney Injury (AKI) – Importance?
Filter 180L fluid daily
Clear waste
Control blood pressure
Help to make blood
Control Calcium + Phosphate

4. Acute Kidney Injury (AKI) – Importance?
Associations with lots of Core Problems
Cause associated with:
Diarrhoea
Haematuria
Haemoptysis
Hypotension
Urine retention
Consequence
Fluid excess  SOB, Oedema

5. Definition of AKI
Sudden, sustained decline in renal function assoc. nitrogenous waste, electrolyte (K, HCO3) and fluid balance disorders
Based on: changes in serum Creatinine, urine output, need for dialysis

6. Measures of kidney function
Blood tests:
Creatinine
eGFR – estimated glomerular filtration rate
Urine output

7. AKI Definition - OLD International collaboration (ICU/Renal)
2004: Acute Dialysis Quality Initiative est.
RIFLE: 3 severities, 2 outcomes (duration) OLD
*End stage renal disease

8. AKI Definition modified
Criticised – not recognising SMALL (Creat)
changes
Different definitions
Timing? Size change?
Challenged epidemiology
NICE Guideline AKI (Aug 2013) inc. Detection

9. AKI – Early Identification
NHS England Patient Safety Alert (July 2014)
Biochem Lab software  AKI Stage 1-3 results
e-alert
KDIGO classification of AKI
Standardised across England
All patients (except dialysis units)
Recognition AKI

10. Staging system (Blood or Urine results)
AKI – Current definition
Staging system (Blood or Urine results)
Stage
Serum Creatinine
Urine output
1 (Early)
>26.5µmol/l or
1.5-2 fold rise
<0.5ml/kg/h >6h
2 (Moderate)
 by 2-3 fold baseline
<0.5ml/kg/h >12h
3 (Severe)
>3 fold baseline or
> 350µmol/l (>44µmol/l acute rise) or
Start RRT
<0.5ml/kg/h >24h or
≥ 12hr anuria
KDIGO 2012 – Used in Sheffield Teaching Hospitals

11. Improve recognition & appropriate actions
AKI - Definition
Now – AKI Alert system
Appear as lab result
Link direct to online “AKI Care bundle”
Step guidance on investigations/management
Improve recognition & appropriate actions

12. AKI – Epidemiology
AKI in 13-18% hospital admissions (esp. elderly) (incidence pmp/yr) (NICE, UK 2013)
Incidence AKI  dialysis 203pmp/yr (UK 2002)
20-60% critically ill patients have AKI (E, USA 2015)
4.9% AKI in ICU require CVVH (dialysis) (E 2002)
AKI inpatient mortality ~ 25-30% (NICE, UK 2013)
(UK) data, (E) European, USA data

13. AKI – Epidemiology £Lives
Independent risk for morbidity, kidney failure mortality
Comorbidities: bleeding (Plts/uraemic),
sepsis (immunodeficient/drugs)
cardiovascular risks
Costs NHS (2º care) - £ million/yr (UK)
Preventable…

14. National Confidential Enquiry Patient Outcomes & Death 2009
Deceased “AKI”: assoc. deficiencies in care
Only 50% received “good care”
Delays in recognition, Failures in prevention
Recommendations (2009):
All acute admissions – risk assess AKI (UEs)
Consultant review within 12hrs
Undergrad + Postgrad training: – detect, prevent, manage AKI
request NICE guideline on AKI

15. AKI - Causes Often multiple causes/exacerbating factors
Dehydration common
Fluid balance assessment  helpful clues
In hospital
Interventions eg contrast scans, new drugs
Sepsis
Systemic disorder/renal limited

16. AKI - Causes Pre-renal – renal perfusion Intrinsic Renal
renal parenchyma damaged
Post Renal – outflow obstruction

17. AKI – Causes – Pre-renal - FIRST
Commonest
F - Failure-cardiac/liver/skin (burns)
I - Infection/Sepsis + Intrarenal
haemodynamics (NSAIDs, ACEi)
R - Red cell haemorrhage
Volume losses
S - Sick –GI losses,
Stenosis (RAS) - Poor perfusion
T – Thrombosis

18. AKI – Causes – Intrinsic Renal
Renal parenchyma damaged
Vascular
Large: Renal artery/vein thrombosis
Cholesterol emboli
Small: Vasculitis, HUS/TTP, malignant Ht
Glomeruli: Glomerulonephritis, Nephrotic syndrome
Tubulointerstitium
Acute interstitial nephritis (drugs), cast nephropathy
(myeloma), contrast nephropathy, tumour lysis/urate,
Ischaemia, acute tubular necrosis (ATN)

19. AKI – Causes – Intrinsic Renal
Vasculitis: “inflammation” of blood vessels
Renal limited/Primary eg Post infectious GN
Systemic eg SLE
Haemolytic Uraemic Syndrome (HUS):
thrombotic microangiopathy: haemolytic anaemia, Plts, AKI. Diarrhoea +/-
Glomerulonephritis: “inflammation of glomeruli”, infections, inherited, autoimmune
Nephrotic syndrome: proteinuria (>3 g/24hrs), oedema, albumin, cholesterol

20. AKI – Causes – Intrinsic Renal
Acute tubular necrosis (acute tubular injury)
Very common, esp. in hospital patients
Oliguric/non-oliguric
Continuum from pre-renal
Dx of exclusion
Urine biochem: Una >40mmol/l FeNa>2
Ischaemic:   renal perfusion
Nephrotoxic: Hb, myoglobin, myeloma casts,
drugs, contrast
60% recover, 30% improve, 5-10% ESRF

21. AKI – Causes – Post-Renal
Urinary tract obstruction – any site
Ureter
Bladder
Prostate
Intrinsic/extrinsic
Stones
Tumour
Retroperitoneal fibrosis

22. AKI - Clinical Assessment - History
History: patient/collateral
Presenting symptoms (may be nonspecific – renal)
Uraemic: lethargy, nausea, anorexia, itch, confusion
Systemic: rash, joint pains, red eyes, nasal stuffiness /bleeding, haemoptysis
Ask: if reduced urine output/adequate fluid intake
PMH: comorbidites/risk factors eg
DM, CKD, prostate cancer, elderly
DH: current (dosing – may need to reduce/stop!),
Recent change in meds, INCLUDE over-the-counter

23. AKI - Clinical Assessment - Examination
Volume/haemodynamic status:
Pulse, JVP, Blood pressure (postural),
Oedema (sacral/peripheral), skin turgor
Urine volumes (if available)
Urinalysis
Airways: O2 sats, RR, chest (haemoptysis)
Pericardial rub (if very uraemic)
Abdomen: suprapubic percussion dull
Skin rash

24. AKI - Investigations Baseline UE, HCO3, bone, Glu, LFTs, CRP,
FBC, Coag, ± blood film
Urinalysis ± microscopy ± MSSU ± Urine:PCR
Renal ultrasound (PRIORITY if anuric)
ECG – hyperkalaemic changes?
CXR
If sick consider ABG (lactate, pH)

25. AKI – Investigations - ongoing
History suggestive/no obvious cause eg
Fall with “long lie”  CK (Rhabdo)
Lymphoma, recent chemo  (Tumour lysis)
GN screen: ANCA, Anti-GBM, Complement, ANA,
ENA, Igs, ASO, Cryoglobulins
Myeloma screen: serum+urine electrophoresis,
serum+urine free light chains
Renal referral  renal biopsy
Ideally avoid imaging requiring CONTRAST

26. Consider renal referral
AKI - Management
Identify precipitating cause
Stop nephrotoxins
Optimise fluid balance/haemodynamic support
Monitor UEs, urine output
Senior review
Print “AKI bundle” (checklist of investigations/management) & file in notes
Consider renal referral

27. AKI - Management Consider renal referral
AKI – poor response to management
AKI – cause unknown
Severe (stage 3) AKI (>3 fold baseline or
> 350µmol/l (>44µmol/l acute rise) or 12hrs anuric)
AKI in renal transplant patient
AKI on CKD (stages 4-5)
Need for dialysis

28. AKI – Management - Indications for dialysis
Suggestions?
K (resistant to med therapy)
Fluid overload (resistant to diuretics)
Metabolic acidosis
(not responding to medical therapy)
Complications of uraemia:
(pericarditis, encephalopathy)
Toxin removal – Li, ethylene glycol, salicylates

29. AKI – Management Indications for Urology referral
Infected, obstructed urinary tract - EMERGENCY
Obstructed urinary tract
Renal stones/urological malignancy
Renal trauma
Frank haematuria

30. AKI – Management Indications for Urology referral
Infected, obstructed urinary tract - EMERGENCY
Obstructed urinary tract
Renal stones/urological malignancy
Renal trauma
Frank haematuria

31. AKI – Spot Diagnoses Management

32. Interpret…

33. Interpret…

34. Severe Hyperkalaemia (K8.5mmol/l)

35. AKI - Management of Hyperkalaemia
Hyperkalaemic ECG changes (K>6.5mmol/l)
10ml 10% Calc gluconate (upto 40ml)
10U Actrapid + 50ml 50% dextrose
500ml 1.26% NaHCO3 (NOT if overloaded)
10-20ml Salbutamol nebuliser
15-30g rectal Calcium resonium
Haemodialysis – ESPECIALLY if dialysis patient!

36. AKI - Management of Pulmonary oedema
Diuretics (IV Furosemide)
Nitrates (GTN infusion)
Opiates (diamorphine mg) *
Venesection (rare nowadays)
Haemodialylsis ± Ventilatory support

37. AKI - Management – Other Features
Nutrition – dietician (Low K, appropriate calories, watch volume)
Sequelae & kidney function  recovery or CKD
Prevention – further complications/insults
Multidisciplinary team involvement – Critical care support/Urologists/Dieticians/Pharmacist/Nurse specialists, Physio, OT…

38. Case Discussion

39. 65yr old man presents to A&E with son
~3/52 diarrhoea, vomiting after pub meal
Last 1/52 symptoms settled but tired & SOB
Fell in bathroom last night, some abdominal pain  son concerned
PMH: DM2 (tablets  diet controlled)
Hypertension (lost weight, off meds)
DH: nil
Reviewed by surgeons - Awaiting abdominal CT
Anything you want to know?

40. On examination BP 150/80 P68 Afebrile O2 sats 94% air RR18 Chest clear
No ankle oedema, HS pure
Slightly tender abdomen assoc. fall? – nil specific
Catheterised in AE ~40ml clear urine
Urinalysis: 2+blood, 1+protein, 1+leucocytes
Anything you want to know?

41. Preliminary Investigations
K6.5 Urea 43 Creat 1050 (no previous biochem!)
HCO3 14
Hb 120 WCC Plts 350
CRP 120
Bone, LFTS normal
Anything you want to know?
ECG – Tall T waves
CXR - clear

42. Differential Diagnosis?
Initial Management
Treat hyperkalaemia:
Ca Cl, Ins/Dex, HCO3
IV fluid
Hourly urine output
IV Augmentin 1.2g bd
(cover for UTI – NB dose reduction!)
Differential Diagnosis?

43. Differential Diagnosis?
Excluded
Diarrhoea, BUT normal Plts, no anaemia (HUS)
Differentials?
Urosepsis & ATN (recent diarrhoea assoc. pre-renal insult) – need MSSU
Rhabdomyolysis – need to check CK
“Renal” cause – glomerulonephritis/renal limited vasculitis?

44. Bilateral hydronephrosis & ureteric stones
Further results
Non-contrast CT Abdomen
Bilateral hydronephrosis & ureteric stones
Urine output: 40/5/0/5/0/ml per hour
Repeat UEs: K6.1 Ur 42 Creat 1080

45. AKI - Cause Often multiple causes interacting In this case:
Pre-renal insult – recent diarrhoea/vomiting and low fluid intake, urosepsis
Intrinsic renal – possibly degree of ATN
Post-renal - bilateral ureteric obstruction

46. Management Any suggestions? Urology review
Plan for bilateral nephrostomies (next day!)
Anuric & obstructive AKI with hyperkalaemia
Femoral dialysis line & Haemodialysis

47. Outcome Post nephrostomies Polyuric IV fluids maintained
Renal function improved significantly within days
Transfer to Urology for management of ureteric stones

48. AKI - Summary
AKI abrupt decline in renal function identified by change in serum creatinine or urine output
Associated high morbidity and mortality
Guidelines now available for detection, investigations & management
AKI alert system ongoing in all English hospitals
Broad differential diagnosis – pre-renal insults commonest (careful Hx, PMH, DH, examination)
Importance of K, HCO3, fluid balance, haemodynamics
Exclude obstructive nephropathy

49. Thank you Any questions