Complications & troubleshooting in continuous renal replacement therapy

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 1 4 th 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 CRR T

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

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

8. 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

9. How to reduce catheter related infections ? S terile placement technique A ppropriate local dressing & cath. care A voidance of femoral site U se of antibiotic-coated cath. A ntimicrobial locking solutions when not in use Balance ; new line placement ≈ ↑ risk of infection Complications & troubleshooting in CRRT Vascular access Infection

10. 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

11. Causes of decreased effective dialysis : Reduced filter life → ↓↓↓ effective dialysis time & delivered dialysis dose S ystem malfunctions Time off for diagnostic procedures L imited expertise of the staff in troubleshooting problems ↓ E ffectiveness of filter over time → ↓ s olute 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

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

13. 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

14. Critically ill pts , due to multiple factors , may not require anticoagulation for CRRT S ystemic anticoagulation →↑ risk of bleeding & may be contraindicated in some pts. R egional citrate anticoagulation (RCA) , complications : Hypocal . Met. Alk . Hypernat . C itrate intoxication S ystemic 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

15. H emolysis occurs due to : shearing forces ( extracorporeal circuit or passing through roller pump) treatment induced elect. a bnl ( hypophosph . , hypona . & hypokal .) I f hemolysis is significant, a pigment-induced nephropathy → 2ndry renal inj. Hematological complications Other hematologic complications

16. Hemodynamic variability : On Initiation of CRRT ≈ often stabilizes if blood flows are steadily ↑ ed P t’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

17. 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) .

18. Electrolyte & Acid–Base Disturbances

19. L ess 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. R eplacement fluids do not contain Phosph or Mg → T o 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

20. 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

21. Nutritional losses

22. 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 a cids ; 10 % lost in hemofiltration Larger proteins ( e.g.albumin ) lost with CRRT A s the filter ages Large ultrafiltration rates U se 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

23. 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 ) G lucose-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

24. 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

25. Volume Management Errors

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

27. Recovery of Renal Function

28. 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

29. Thank you