Acute kidney injury is a common and important issue in critical care patients . Among different extra corporeal supporting modalities , continuous renal replacement therapy is a common selection especially in unstable conditions . As any other intervention , there are some related complications that should be diagnosed and treated as early as possible .

1. Complications & troubleshooting
in
Continuous Renal Replacement Therapy
Mansoor Masjedi MD
Associate prof. , Critical care consultant
Shiraz University of Medical Sciences
Shiraz - Iran
Jan 14th 2022

2. As with any procedure ,
certain complications & adverse events can be associated with CRRT
Vigilance for complications & immediate rectification are essential to
prevent life-threatening situations,
especially in vulnerable population of ICU
Complications & troubleshooting in CRRT

3. CRRT
often purported superiority in
hemodynamic stability , metabolic clearance & vol. control
compared with IHD
Trials failed to prove improvement in
morbidity & mortality
Complications & troubleshooting in CRRT
CRRT may increase renal recovery compared with IHD

4. Arterio–venous circuits : more complications & less efficacious
so
we will focus on complications of CVVH & CVVHD

5. Complications & troubleshooting in CRRT

6. • Catheter Related
• Hemorrhagic (the most significant problem)
• Hemodynamic ( HOTN ; the most common complication )
• Metabolic Disorder
• Electrolyte Imbalance
• Hypothermia
• Nutritional aspects
• Hypersensitivity
Complications & troubleshooting in CRRT

9. • IJV with Sono : the safest method & ↓ line malfunctions
• Femoral placement : ↑risk of infection only if BMI >28
• Subclavian access for hemodialysis : not recommended ( ↑risk of stenosis )
• Hemothorax , PTX , pericardial tamp. , arrhythmias , air embolism &
retroperitoneal hemorrhage
• Major local complications : Arterio-venous fistulas, aneurysms, thrombus formation
& hematomas
• Ensure proper connections
• Keep catheter in constant view ( severe blood loss , air embolism , .. )
Complications & troubleshooting in CRRT
Vascular access
Catheter Placement

10. Vascular access
Catheter dysfunction
Complications & troubleshooting in CRRT
 Recirculation results in :
hemoconcentration
reduced solute clearance
premature filter clotting
The shorter catheter the higher recirculation rate [ femoral catheters (15 cm) > (24 cm)]
Femoral catheters should extend into IVC to reduce malfunction & recirculation
 Any distortion or kinking of catheter → ↓ laminar blood flow & ↑ fibrin deposition
 Impaired flow →
↑negative arterial & ↑positive venous pressure →
↓ catheter & filter life & also ↓delivered dose of dialysis

11. How to reduce catheter related infections ?
 Sterile placement technique
 Appropriate local dressing & cath. care
 Avoidance of femoral site
 Use of antibiotic-coated cath.
 Antimicrobial locking solutions when not in use
Balance ; new line placement ≈ ↑risk of infection
Complications & troubleshooting in CRRT
Vascular access
Infection

13. Extracorporeal Circuit Considerations
Air Embolism
• System pressure monitoring is important throughout the entire extracorporeal
circuit.
• In the venous intake negative pressures can result in air entry
• Alarms in systems stop blood flow when air is detected
• Manifestations : chest pain, dyspnea, cyanosis, cough, hypoxia & cardiopul. arrest
Complications & troubleshooting in CRRT

14. Causes of decreased effective dialysis :
 Reduced filter life → ↓↓↓ effective dialysis time & delivered dialysis dose
 System malfunctions
 Time off for diagnostic procedures
 Limited expertise of the staff in troubleshooting problems
 ↓ Effectiveness of filter over time→
↓solute clearance ( ↓sieving coefficients) →
↓ultrafiltration (by increased protein layer deposition)
 Measurement of effective clearance & achieved dialysis dose becomes more difficult
Extracorporeal Circuit Considerations
Reduced filter life & Dialysis dose
Complications & troubleshooting in CRRT

15.  ↓Core body Temp. : 5–50% of pts.
 ↓Mean body Temp.
 Advantages
 ↓O2 consumption
 In some clinical situations, such as hyperthermia or post cardiac arrest
o Disadvantages
 heat loss → ↑energy requirements
 may mask fevers, delaying the recognition of infection
Complications & troubleshooting in CRRT
Extracorporeal Circuit Considerations
Hypothermia

16.  Extracorporeal exposure→
activate inflammatory mediators ( cytokines & proteases) →
↑ protein breakdown & ↑ energy expenditure
 Rare: anaphylactoid reactions to dialysis memb. (esp. in pts on ACEI )
Complications & troubleshooting in CRRT
Extracorporeal Circuit Considerations
Bioincompatibility and Immunologic Activation

18. • Critically ill pts , due to multiple factors , may not require anticoagulation for CRRT
• Systemic anticoagulation →↑risk of bleeding & may be contraindicated in some pts.
• Regional citrate anticoagulation (RCA) , complications :
• Hypocal.
• Met. Alk.
• Hypernat.
• Citrate intoxication
• Systemic or low dose heparin ≈ may develop HIT
Hematological complications
Anticoagulation
Complications & troubleshooting in CRRT
Repeated hemofiltration-filter clotting in less than 6 hrs was often associated with
the presence of anti-PF4/heparin antibodies ( 25% of pts ),
regardless of the platelet count

19.  Hemolysis occurs due to :
 shearing forces (extracorporeal circuit or passing through roller pump)
 treatment induced elect. abnl (hypophosph. , hypona. & hypokal.)
 If hemolysis is significant, a pigment-induced nephropathy → 2ndry renal inj.
CRRT
↓plts & impairs
aggregation
+
Clearance of
proinflammatory
platelet-
activating factors
potentially
balancing the
effects on plts
Hematological complications
Other hematologic complications

21. • Hemodynamic variability :
 On Initiation of CRRT ≈ often stabilizes if blood flows are steadily ↑ed
 Pt’s blood vol. which directly affected by UF rate
( Aggressive fluid removal → ↓intravas.vol.& hemodyn. Instability)
 Consider Impaired myocardial function
• Invasive & non-invasive hemodyn. monitoring ( IBP , CVP, CO ) are helpful
Hypotension
Complications & troubleshooting in CRRT

22. Testing for preload-dependence could help
avoiding unnecessary decrease of fluid removal in preload-independent HIRRT during CRRT.
PLR in the supine position or Trendelenburg maneuver in prone position combined with
measurement of cardiac output are highly reliable to identify preload-dependence and may provide new insights
into the mechanisms involved in hemodynamic instability related to CRRT (HIRRT).

23. Electrolyte & Acid–Base
Disturbances

24.  Less frequent with commercially available dialysate solutions
 Phosph clearance on CRRT >>> IHD (intercomp. mass transfer & larger filter pore size )
 Hypophosph & hypomg : the 2 most common elect dist.
 Replacement fluids do not contain Phosph or Mg → To be replaced
 Hypocal. & hypokal. are also common
 Hypona : if dialysate solutions do not adequately compensate it
 Hyperna : administration of trisodium citrate & saline solutions with RCA
Current recommendations : electrolyte & ABG q 6–8 h
Electrolyte and Acid–Base Disturbances
Complications & troubleshooting in CRRT

25.  Lactate-based vs bicarb - based solutions
( improved acid–base balance & ↓ cardiovas. events )
 Alkalemia if positive buffer balance between dialysate & replacement fluids ;
RCA ( citrate converted to 3 bicarb. by liver )
 Met. Acidosis (Anion-gap ) : Impaired breakdown of citrate in
severe hepatic dysfunction → citrate intoxication
Electrolyte and Acid–Base Disturbances
Complications & troubleshooting in CRRT

26. Nutritional losses

27. • Critically ill pts with AKI are hypercatabolic with ↑ed nutritional needs.
• Lean body mass 2ndry to protein breakdown due to :
 insulin resistance
 release of inflammatory mediators
 Met. Acid.
 growth factor resistance
• Amino acid loss in pts on CRRT : 10–20 g ⁄ day
• TPN amino acids ; 10% lost in hemofiltration
• Larger proteins ( e.g.albumin ) lost with CRRT
 As the filter ages
 Large ultrafiltration rates
 Use of newer membranes with ↑ed permeability
Hypoalb. & malnutrition are
independent predictors of mortality in AKI
Complications & troubleshooting in CRRT
Nutritional losses
Amino acids and protein

28.  Hyperglycemia : periph. insulin resistance & ↑ed hepatic gluconeog.
 Dialysate solutions : 100–180 mg ⁄ dl dextrose to prevent diffusive losses
(40–80 g ⁄ day does not induce hyperglycemia )
 Glucose-free solutions :
 hypoglycemia & inadequate nutritional supply
 induces gluconeogenesis using mainly amino acids
 their use is not recommended.
Close monitoring of blood glucose is necessary to achieve euglycemia
Complications & troubleshooting in CRRT
Nutritional losses
Glucose

29. • Water soluble vitamins & trace minerals → readily filtered → rapidly depleted
• Vit. A supplementation is not recommended : risk of toxic accumulation
• Active vitamin D is readily depleted → replacement
• Antioxidants ( zinc, selenium, Cu , mang. , chromium, vit. C & E ) freely lost
• Vit. C should not exceed 100–150 mg ⁄ day ( risk of Oxalosis)
Complications & troubleshooting in CRRT
Nutritional losses
Vitamins and Essential Minerals

30. Volume Management Errors

31. A separate CRRT flow sheet
and
well-trained dialysis personnel
help prevent errors
Complications & troubleshooting in CRRT
Volume management error

32. Recovery of Renal Function

33. Transient periods of hypotension,
prolonged exposure to extracorporeal membrane &
dialysis-catheter associated infections
are potential etiologies for ongoing kidney injury that delays recovery
Recovery of Renal Function
Complications & troubleshooting in CRRT

34. Thank you