Role of nephrologists in the ICU AKI in the ICU

1. Critical Care Nephrology
Eman Elrefaie

2. AKI in ICU
 Definition
 Staging
 Epidemiology
 Risk factors
 AKI Risk Stratification(Biomarkers)
 Causes
 Systemic effect of AKI
 Management

3. Acute kidney injury (AKI) (formerly acute renal failure) is
the syndrome arising from a rapid fall in GFR (over hours
to days). It is characterized by
 Retention of both nitrogenous and non nitrogenous
waste products of metabolism.
 Electrolyte , acid –base, and fluid homeostasis
disorders.
Definition

4. Definitions Of AKI

5.  AKI is defined as any of the following (Not Graded):
• Increase in SCr by ≥ 0.3 mg/dl within 48 hours; or
• Increase in SCr to ≥ 1.5 times baseline, which is known
or presumed to have occurred within the prior 7 days; or
• Urine volume < 0.5 ml/kg/h for 6 hours.
AKI –KDIGO Definition

6. Stages of AKI

7. Stage-based management of AKI

8. • AKI of any stage developed within 1 week of admission in 57%
of patients.
• Sever (stage 2 or 3) AKI occurred in 39%, and 13.5% required
renal replacement therapy (RRT).
• AKI in the ICU is an independent risk factor for death.
Epidemiology

9. AKI Risk factors
Age
S Cr > 1.3 mg/dl
Serum bilirubin > 1.5 mg/dl
Proteinuria
Hyperglycemia
Sepsis
Hemodynamic instability
Active cancer
High intra abdominal pressure

10. AKI Risk Stratification in the ICU

11. Biomarkers

12. AKI Risk Stratification in the ICU

13. AKI causes

14. Causes of AKI

15. Common causes of AKI in the ICU
KDIGO AKI in the
setting of “life
threatening organ
dysfunction caused
by a dysregulated
host response to
infection”; SOFA
score increase ≥ 2
points or qSOFA ≥ 2

16. Scoring Systems
o The SIRS score was calculated according to the following criteria:
 Body temperature >38 C0 or <36 C0 (1 point),
 Heart rate > 90 bpm (1 point),
 Respiratory rate > 20 breaths/min (1 point),
 White blood cell count >12,000/ mm3 or<4000/mm3 (1 point).
o The qSOFA score was calculated according to the following
criteria:
 systolic blood pressure ≤100 mmHg (1 point),
 respiratory rate ≥ 22 breaths/min (1 point),
 and altered mental status (1 point).

17. Scoring Systems
o The SOFA score is an organ-failure scoring system comprising six
domains
 (respiration, coagulation, liver, cardiovascular, central nervous system, and renal).
Each organ system earns a score out of 4 (range, 0–4, with 4 being the worst) and
with a maximum score out of 24.

18.  Sepsis accounts for 2% of all hospital admissions, but 25% of
admissions to ICU.
 Sepsis associated AKI (SA-AKI)
occurs in 10% to 20% of all patients
admitted to the ICU due to infection.
 Patients with septic shock 50% to 70%.
 Patients whose renal failure is sepsis-related have a mortality of up
to 75%.
Epidemiology

19. Sepsis pathophysiology

20. Sepsis Management
During the first 6h of resuscitation, the goals include
CVP
>8mmHg
MAP ≥
65mmHg Central venous
(superior vena
cava) oxygen
saturation ≥ 70%
UO ≥
0.5mL/kg/h

21. Sepsis Management
 Fluid therapy:
 Give an initial fluid challenge of ≥ 1000mL crystalloids (to achieve a
minimum of 30mL/kg in the first 4 – 6h).
 Consider adding albumin to the initial fluid resuscitation regimen if
serum albumin is low.
 Avoid sodium bicarbonate therapy for the correction of
hypoperfusion-induced lactic acidaemia with pH ≥ 7.15.

22. Sepsis Management
Vasopressor therapy:
 Use vasopressor therapy to target an initial MAP of ≥ 65mmHg.
 Noradrenaline is first-line.
 Adrenaline can be added or substituted if an additional agent is required to
maintain BP.
 Vasopressin (0.03 units/min) can also be added to, or substituted for,
noradrenaline.
 Dopamine is an alternative to noradrenaline in selected patients at low risk of
arrhythmias who have low COP and low heart rate. Do not use low-dose
dopamine for ‘renal protection ’ .

23. Sepsis Management
Inotropic therapy:
 Add dobutamine to vasopressor therapy (if administered) in the presence of:
(i) myocardial dysfunction (as suggested by elevated cardiac filling pressures and
low CO); or (ii) ongoing signs of hypoperfusion despite adequate intravascular
volume and MAP.
Corticosteroids:
 If patients require persistent high doses of vasopressors for maintenance of
adequate BP despite adequate fluid resuscitation.
 Consider a continuous infusion of IV hydrocortisone (200 – 300mg daily — no
higher) for a minimum of 5 days.
 Hydrocortisone is now recommended alone, rather than in combination with
fludrocortisone.

24. Sepsis Management
Glucose control:
 Hyperglycemia impairs leucocyte function..
 Commence insulin when two consecutive blood glucose levels are ≥ (180mg/dL),
and aim to keep blood glucose levels ≤ (180mg/dL).
 All patients receiving IV insulin should receive a glucose calorie source.
 Blood glucose values should be monitored every 1 – 2h until glucose values and
infusion rates have stabilized and then at least every 4h ( 1 point-of-care testing
of capillary blood should be interpreted with caution, as they may overestimate
plasma glucose concentration).

25. Blood product administration:
 Transfuse to maintain Hb >7.0g/dL.
 Do not administer FFP to correct laboratory clotting abnormalities unless
bleeding or planned invasive procedures.
 Consider platelet administration if:
• Counts are <5000/mm 3 (5 x 10 9 /L), regardless of bleeding.
• Counts are 5000 – 30,000/mm 3 (5 – 30 x 10 9 /L) and bleeding risk.
Sepsis Management

26. Systemic effect of AKI

27. Treatment of AKI in the ICU
Treatment of
AKI in the
ICU
Non dialytic
fluids causes others
Dialytic
Renal
replacement
therapy

28. Fluid replacement
Treatment of
AKI in the
ICU
Fluid
replacement
Strategy of
administration
Type of fluid
Renal
replacement
therapy

29.  Phase A :initial aggressive Volume
resuscitation (e.g., 30 mL/kg of intravenous
crystalloid),
 Phase B : fluid is often still required, but fluids should only be
provided as needed to maintain organ perfusion in a targeted
manner.
 Phase C : equilibrium phase; fluid administration is stopped.
 Phase D : mobilization, deresuscitation, or flow phase; fluids are
with held to allow for spontaneous diuresis. If failed,
pharmacologic diuresis or ultrafiltration can be provided to achieve
euvolemia.
Fluid replacement

30. Fluid replacement
Synthetic colloid
Crystalloids
Sodium
bicarbonate
Hypotonic
Colloid

31.  Saline vs balanced crystalloids
Types of Fluid

32. Types of Fluid
Balanced crystalloids
 Lower rate of death
 Lower use of RRT
 Lower renal dysfunction
Isotonic crystalloids : Excessive
use of saline can result in
hypercholeramic acidosis
Balanced solution :
Recommendation that balance
solution are used unless patients
are hypocholermic or hyperkalemic

33.  Colloids Versus Crystalloids :
Types of fluid (KDIGO)

34.  N=6997 Patients
 Outcome : no difference
 Length of ICU stay
 Length of hospitalization
 Duration of MV
 Duration of RRT-day
 Mortality

36.  Albumin use in AKI in critically ill and septic patients:
 Isotonic crystalloids for initial management for
expansion of intravascular volume in patients at risk for
AKI or with AKI
 In sever sepsis and septic shock when patients require
substational amounts of crystalloids as apart of initial
volume replacement
 May have role in low serum albumin < 2-2.5 gm/dl.

37.  Sodium bicarbonate
 Weak ’ NaHCO3 solutions (e.g. 1.26% or 1.4%) can be useful in
 volume-depletion
 acidotic (pH <7.15)
 hyperkalemic patients
 Use with crystalloid, e.g. in a ratio of 1L NaHCO3 to every 2 – 3L of NaCl.
 Avoid stronger (4.2% or 8.4%) solutions, and monitor for Ca.

38. ICU patients with
 pH < 7.2
 Pa CO2< 45mmhg,
 Serum bicarbonate < 20mmol/l
(the bicarbonate infusion was titrated to increase
the arterial PH to 7.30)
• Decrease rate of AKI requiring RRT
• Improve mortality
• Lower rate of hyperkalemia
• Higher incidence of metabolic alkalosis ,
hypernatremia, hypocalcemia .

39. In bicarbonate group :
Increase all mortality causes
Risk of hypocalcaemia

40.  To minimize complication of Sodium bicarbonate
 Consider base therapy when systemic blood Ph ≤7.10 or at level ≤7.20in
presence of underlying CVS diseases or haemodynamic instability.
 Using bicarbonate formula:HCO3 deficit = 0.4 x Weight {kg} x (desired HCO3
{mmol/L} - measured HCO3 {mmol/L}).
 Initate therapy based on calculation using
bicarbonate spacing 50% body weight
 Consider administration at slow rate 0.1mEq/kg per min
 Assess response with measurement every 2-4 h
 Consider administration of ca++
if hypocalcemia developed

41.  Synthetic colloid (starch)
 Solutions contain oncotically active ingredients
(e.g. hydroxyethyl starch or gelatin) that remain in
the intravascular compartment and pull in
extravascular water.
 Effective volume expanders, may worsen AKI.
 May deplete clotting factors and i bleeding risk.
 Severe allergic reactions have been reported to all types of colloid.
 The recent UK consensus statement on AKI and guidelines from the European
Society of Intensive Care Medicine recommends that colloid (including gelatin-
based) solutions be avoided.
 Hypotonic fluid Limited use for restoration of intravascular volume.

42. Complications of fluid overload

43. Treatment of AKI in the ICU
Treatment of
AKI in the
ICU
Non dialytic
Fluids Causes Others
Dialytic
Renal
replacement
therapy

45.  Studies aimed at determining the optimal time for starting RRT have
evaluated various arbitrary cut-offs for: serum creatinine, serum urea,
urine output and time from icu admission or duration of AKI
 The time of RRT initation dose not affect survival in critically ill patients
with sever AKI in absence of urgent indication for RRT
 Delayed RRT with close patient monitoring might lead to a reduced use of
RRT saving health resources.

46. KDIGO Guidelines
 Fluid overload
 Hyperkalemia
 Sever metabolic acidosis
 Signs of uremia
 Certain alcohol and drug
intoxication
 Diuretic - resistant cardiac failure
 Complication of dialysis access
insertion .
 Sever hypotension in already
sick patient
 Electrolyte imbalances
 Complication of anticoagulation
 Dialysis disequilibrium.
Indications for RRT Complications of RRT

47. Modalities of RRT

48. CRRT and Prolonged Intermittent RRT
• CRRT is preferred over IHD in the ICU because it is associated
with less hemodynamic instability.
• Prolonged intermittent RRT is another RRT option in the ICU.
 consists of treatment over 6 to 12 hours with blood and dialysate
flow rates that are higher than CRRT but lower than IHD.
 It may replace CRRT or be used as a bridge between CRRT and
IHD for patients recovering from critical illness

49. Vascular access

51.  Nearly 3.4% of all ICU admissions are ESRD.
 Annual rate of ICU admission among adult patients with ESRD
was more than 25 times that of the general adult population.
Patients with ESRD had:
 more than two-fold the rate of peripheral vascular disease, were
more likely to require ICU care.
 more than double the rate of sepsis than the general ICU
population.