MARS Circuit System Setup and Monitoring
The MARS circuit operates as an albumin dialysis system that connects to standard continuous renal replacement therapy (CRRT) equipment, using albumin-enriched dialysate to selectively remove both albumin-bound toxins and water-soluble substances through a closed-loop recirculation system. 1
Circuit Components and Configuration
Primary Circuit Elements
Blood circuit: Connects directly to the patient via standard vascular access (typically femoral or internal jugular venous catheter), with blood flow rates maintained at standard dialysis parameters 1
Albumin dialysate circuit: Contains 20% albumin solution that circulates in a closed loop, separated from the patient's blood by a high-flux dialysis membrane 1
Secondary dialysis circuit: The albumin dialysate passes through conventional hemodialysis and charcoal/anion exchange columns to regenerate the albumin and remove accumulated toxins 1
Equipment Specifications
Standard MARS sets: Used for patients weighing 23.5-72 kg 2
MARS Mini sets: Available for smaller patients (2.8-13 kg), though efficacy data suggests inferior performance compared to standard sets 2
Treatment duration: Typically 6-24 hours per session, with average session length of 7-8 hours 3, 4
Critical Monitoring Parameters
Biochemical Monitoring (Before and After Each Treatment)
Bilirubin levels: Primary marker of toxin removal, though reductions may be modest (16.3 ± 6.5 to 13.8 ± 5.9 mg/dL with standard MARS) 2
Ammonia levels: Monitor for reduction from baseline (typical decrease from 113 ± 62 to 99 ± 68 μmol/L) 2
INR/coagulation: Note that INR may paradoxically increase during MARS therapy (1.5 ± 0.3 to 2.0 ± 1.1), unlike with plasma exchange 2
Electrolytes: Monitor albumin, total protein, sodium, potassium, and calcium (typically remain stable) 4
Neurological Monitoring
Glasgow Coma Score: Assess before and after each treatment 4
Hepatic encephalopathy grade: Document improvement in encephalopathy symptoms 3
EEG monitoring: Continuous or serial monitoring for patients with severe encephalopathy 4
Cerebral CT: As clinically indicated for patients at risk of cerebral edema 4
Hemodynamic and Organ Function Monitoring
Mean arterial pressure: Continuous monitoring during treatment 4
SOFA score: Calculate before and after treatment to assess multi-organ dysfunction trajectory 3
Acid-base status and blood gas analysis: Monitor throughout treatment 4
Renal function: Track creatinine and urine output 4
Liver ultrasound: Periodic assessment of hepatic status 4
Treatment Intensity and Frequency
Session Parameters
Average number of applications: 6.4 sessions per patient course 4
Continuous versus intermittent: Can be applied continuously for extended periods with high tolerance 4
Repeatability: System allows for repeated treatments over days to weeks, particularly useful in delayed non-function cases 4
Clinical Context and Limitations
Important Caveats
MARS does not improve overall survival compared to standard medical therapy in randomized controlled trials, despite biochemical improvements. 5 The RELIEF trial specifically failed to demonstrate survival benefit at 28 days despite documented biochemical improvement 5
However, MARS may provide short-term survival improvement (14-day and 28-day) in highly selected patients with ACLF and multiple organ failure, potentially serving as a bridge to transplantation 5
Optimal Patient Selection
Inclusion criteria: Bilirubin >15 mg/dL, ammonia >160 μg/dL, Glasgow Coma Score 6-11 4
Best candidates: Patients with fulminant hepatic failure awaiting transplantation who need neurological stabilization 6
Early referral: Patients should be referred to expert centers at early stages after decompensation for optimal outcomes 5, 6