Continuous Renal Replacement Therapy (CRRT) is a specialized form of dialysis used for individuals who are critically ill. This therapy is administered in intensive care units (ICUs) when a patient’s kidneys are not functioning properly. This article explores the life expectancy for patients undergoing CRRT, considering factors that influence their prognosis.
Understanding CRRT
CRRT is a continuous and slow form of dialysis, differing significantly from traditional intermittent hemodialysis, which is performed over a few hours. This gentle approach allows for the steady removal of waste products, excess fluids, and toxins from the blood over 24 hours or more. CRRT is employed for critically ill patients with acute kidney injury (AKI) who are too unstable to tolerate the rapid fluid shifts and blood pressure fluctuations associated with conventional dialysis.
The therapy continuously filters the patient’s blood through a specialized machine that mimics natural kidney functions. This process helps manage fluid balance, correct electrolyte imbalances, and remove accumulated toxins without imposing additional stress on the patient’s cardiovascular system. Patients often require a hemodialysis catheter, a large intravenous line usually placed in the neck or groin, to facilitate blood flow. CRRT serves as a supportive measure, providing kidney function while medical teams address the underlying severe condition causing the AKI.
Factors Affecting Life Expectancy
The life expectancy of patients on CRRT is primarily influenced by the severity and nature of their underlying critical illness. Conditions such as sepsis, multi-organ failure, severe heart failure, or respiratory failure are frequently the primary drivers of adverse outcomes, rather than the kidney injury itself. A greater extent of organ dysfunction generally leads to lower survival chances.
A patient’s baseline health also plays a substantial role in their prognosis. Older age is associated with increased in-hospital mortality among CRRT patients. Pre-existing chronic conditions, known as comorbidities, such as diabetes, chronic heart disease, liver disease, or chronic lung disease, significantly impact survival rates.
The extent and rapid development of acute kidney injury itself can affect outcomes. The degree of kidney damage and how quickly it occurred are important considerations. How well the patient responds to CRRT, including the effective correction of fluid imbalances, electrolyte levels, and removal of toxins, also influences their course. Patients with lower mean arterial pressure, lower arterial pH, and higher Sequential Organ Failure Assessment (SOFA) scores at the start of CRRT have been linked to increased early mortality.
The duration of CRRT therapy also correlates with outcomes. A longer duration often indicates a more severe and persistent underlying illness. Studies show that survival decreases significantly as the number of days on CRRT increases, particularly in patients with multi-system organ failure. For instance, in one study, in-hospital mortality for general surgical patients on CRRT for seven or more days was 100%.
Prognosis and Outcomes
The prognosis for patients undergoing CRRT is often guarded due to the severe nature of their underlying conditions. Short-term survival rates to ICU and hospital discharge are low, reflecting the high mortality associated with critical illness. In-hospital mortality rates for patients receiving CRRT range widely, from approximately 37% to over 80%. One study reported an overall in-hospital mortality rate of 84.1% in ICU patients on CRRT, with only about 24.8% surviving to 15 days post-CRRT initiation.
Long-term survival rates continue to decline over time. For patients with acute kidney injury requiring CRRT, overall survival has been reported to drop from around 46% at 90 days to about 30% at three years. Advanced age can become a stronger predictor of mortality in the period following hospital discharge.
Kidney function recovery after CRRT is possible, though rates vary. Some patients may become dialysis-independent, with studies indicating that approximately 25% of patients with acute kidney injury may achieve dialysis-free survival. The initial sign of kidney recovery is often an increase in urine output, although filtering capacity takes longer to recover, sometimes weeks or months. If a patient had healthy kidneys before their acute illness, their chances of recovery are significantly higher, potentially over 90%.
For patients whose kidney function does not recover sufficiently, a transition to other forms of chronic dialysis, such as intermittent hemodialysis or peritoneal dialysis, may be necessary. This transition occurs when the patient’s condition stabilizes enough to tolerate less continuous forms of renal support. The high mortality observed in CRRT patients is primarily attributed to the severe underlying illnesses and not CRRT itself, which serves as a life-sustaining supportive therapy.