AKI, or acute kidney injury, occurs in 18% of hospital admissions and can be caused by sepsis, hypovolemia, drugs, acute glomerulonephritis, or obstruction. Early signs include increased serum creatinine, low blood pressure under 90, and low urine output under 500ml in 24 hours. Treatment focuses on fluid management and supportive care; starting renal replacement therapy is based on fluid overload and high blood urea levels. Continuous renal replacement therapy is preferred for hemodynamic instability while intermittent hemodialysis enables faster clearance but is riskier for unstable patients.

1. +
AKI in a critically ill patient
Dr Ram

2. +
An abrupt (within days) reduction in kidney function currently
defined as an absolute increase in serum creatinine of either ≥
26.4µmol/L or a percentage increase ≥ 50% (1.5 fold from
baseline) or a reduction in urine output (documented oliguria of
<0.5 mL/kg/h for > 6 hours).

4. +
AKI Key Facts
 AKI occurs in 18% of all hospital admissions, in a range of
settings, where acutely unwell patients are managed
 “Minor” degrees of kidney dysfunction are associated with
prolonged lengths of stay and increased mortality
 AKI is often treatable or reversible using basic clinical tests and
steps
 Quality requirement of National Services Framework for Renal
Services (Part 2)

5. +
NCEPOD Findings &
Recommendations
 50% of cases with AKI documented as cause of death received
satisfactory or good care
 30% of cases inadequately investigated and managed
 20% of post-admission AKI is predictable and avoidable (or hospital
acquired AKI = HAAKI)
 Only 10% of AKI required RRT
 All emergency admissions should have electrolytes checked on admission
and appropriately thereafter
 All acute admissions should receive adequate senior reviews, with
consultant review within 12 hours of admission
 Implementation of NICE guidance CG50
RecommendationsFindings

6. Bagshaw et al, NDT
2008

7. AKI: causes
• Important to attempt to categorise broadly into
one of 3 groups
• sepsis/hypovolemia 70%
• drug related, acute GN 20%
• obstruction 10%
PRE-RENAL
RENAL
POST-RENAL

8. Cause of AKI – 3 tests
o Fluid/volume assessment PRE
o Urinalysis RENAL
o Ultrasound POST

9. +
3 Key early warning signs
 Increase in serum creatinine
 Systolic blood pressure <90
 Urine output <500ml in 24 hours

10. RISK FACTORS FOR AKI
Murugan R et al KI 2010

11. Pathophysiology of ATN

14. KI 2009(76)1089

15. KI 2009 (76) 1089

16. +
ANZICS data, NDT 2008

17. +Managing AKI - 1
Is your patient really sick? Get help
Volume assess + fluid challenge
Urine dip
U+Es + blood gas
Some important blood tests Calcium, CK, TSH
U/S abdo
Nephrology referral
PS: eGFR – used only in CKD

18. +
Tests
 Urine specific gravity
 Urine sodium
 Blood urea, creatinine

19. +
Managing AKI -2
 There is no pharmacological therapy for AKI
 Treatment is supportive

20. + Fluid management in the critically ill

21. Fluid management in the critically
ill

22. +
Fluid management in the critically ill
 FACTT trial: fluid conservative strategy had an increased
number of ventilator free days
 In the largest adult study focused on those with dialysis
requiring AKI, positive fluid balance was associated with
increased risk of death (secondary analysis of ANZICS-RENAL
study, Crit Care Med, 2012)
 Fluid overload at initiation of RRT is associated with lack of
renal recovery in patients with AKI (NDT 2012, 27, 956-61).
This is in contrast to PICARD study result and may be due to
the longer follow up in this study.

23. +
What fluid to use?
 When HES was compared to Ringer’s acetate in severe sepsis;
it was associated with increased mortality risk, need for RRT
and risk of severe bleeding (NEJM 2012, 367, 124-134)
 An ANZICS trial on 7000 patients managed in ICU, results were
similar (NEJM 2012, 367, 1901-1911)
 Albumin reduces mortality but does not achieve statistical
significance (NEJM 2014, 370, 1412-1421; Intensive Care Med
2011, 37, 86-96)

24. +
When to start RRT

25. +
(Traditional) indications for dialysis
 Acidosis
 Electrolyte imbalance
 Intoxication
 Overload
 Uraemic encephalopathy

26. +
When to start RRT
 Data from PICARD study was analysed. 243 patients. 2 groups
of patients with blood urea greater or less than 27mmol/L were
compared. Patients who started RRT at a higher urea had a
higher mortality at 60 days (CJASN 2011)
 1847 patients who received RRT for AKI in 22 ICUs in UK and
Germany were retrospectively analysed. Higher urea at the
time of RRT initiation was associated with reduced survival.
Higher blood pH was associated with better survival outcome
(Crit Care 2011)

27. +
What is the preferred dialysis modality

32.  SLED
 Considered a ‘hybrid’ of IHD and CRRT
 Administered using conventional dialysis technology but typical sessions
run for 8–12 h b
 Blood and dialysis flows that are intermediate to those prescribed in IHD
and CRRT

33. +What is the preferred dialysis modality –
CVVH v IHD
Crit Care, Systematic rev 2012

34. +
What is the preferred dialysis modality –
CVVH v IHD
 CVVH increases the clearance of middle and larger molecules
without increasing the clinical outcomes
 Filter life is shorter with CVVH thereby increasing the cost
 KDOQI recommendations suggest that CRRT is preferable with
haemodynamic instability, with cerebral oedema and with
metabolic disturbances like chronic hyponatraemia. In
intoxications IHD is preferable to ensure rapid clearance.

35. +
What is the preferred dialysis modality
SLED v CVVH

36. +
What is the preferred dialysis
modality SLED v CVVH
No difference in net UF or hypotensive episodes
SLED therapy was associated with fewer number of ventilator
days, fewer ICU days
Nursing time and treatment cost significantly lower with SLED
There was no difference in mortality

37. +
RRT Dosing
 IHD - Kt/V urea of at least 1.2 per treatment (ARF Trials
Network Study NEJM, 2008, 359, 7-20)
 CRRT should be prescribed at modest does, effluent flow rates
20-25ml/kg/hr. However careful attention should be paid to the
actual delivered dosage

39. +
It’s as easy as ABCDE!

40. What info to have when
calling the nephrologist
Your (boss') reason for referral
The history and background in your head –
don’t read the notes to me
The obs (MEWS, Urine output)
A urine dipstick result!!!
Your assessment of the patients fluid status
An up to date venous blood gas (that day)
PLEASE ENTER YOUR BLEEP NUMBER ON
THE YELLOW REFERRAL FORM

41. +
Question Time