Complications of Continuous Renal Replacement Therapy (CRRT)
What complications should be expected when using CRRT?
The most common complications of Continuous Renal Replacement Therapy are:
- • Hypotension
- • Bleeding
- • Electrolyte imbalances
- • Infection
- • Hypothermia
Hypotension is the most common complication of dialysis, occurring in around 30% of treatments. Several factors associated with the dialysis treatment can cause hypotension (partial list):
• Cardiac events
• Electrolyte imbalances
• Elevated dialysate temperature
• Bacterial contamination of system
• Low dialysate sodium concentration
• Clearance of vasoactive drugs
• Use of antihypertensive medications prior to treatment
However, hypotension is most often related to the imbalance between fluid removal and fluid replacement by the extravascular compartment. A large amount of fluid removal is a major risk factor for hypotension, especially in patients with compromised refilling capacity, as in diabetic neuropathy, low cardiac ejection fraction, diastolic dysfunction, and sepsis. Although CRRT has been demonstrated to reduce episodes of hypotension and to allow better acid-base and electrolyte control, the prolonged time of therapy increases the risk of volume and electrolytes depletion. In spite of the expected safety of obtaining fluid removal over a longer period of time with CRRT, careful monitoring is mandatory. Hypotension and hemodynamic instability are still frequent in CRRT. In intensive and/or prolonged treatment, CRRT results in overcorrection of electrolyte imbalances, especially when non-physiologic solutions are used, such as dialysate or replacement fluids. Hypocalcemia, hypophosphatemia, and hypokalemia are common complications associated with higher doses of CRRT, requiring careful electrolyte monitoring during the procedure. The use of peritoneal dialysate fluids used for CRRT can cause hyperglycemia, demanding special attention with potassium imbalance. Patients receiving CRRT are at increased risk for hypothermia as blood circulates in the extracorporeal circulation for a prolonged time. Dialysate and replacement fluids should be warmed prior to administration, and the patient’s body temperature should be frequently monitored. Because CRRT requires anticoagulation for a prolonged time, the risk of bleeding is also increased. The monitoring of hemoglobin and hematocrit is important to detect hidden bleeding. Patients on RRT are vulnerable to catheter-related infections, including systemic infections and those local to the vascular access site. The cooling effect of prolonged extracorporeal circulation in CRRT may mask fever; special monitoring for other signs of infection is mandatory.
