Extracorporeal blood therapy in sepsis and acute respiratory distress syndrome: the "purifying dream".

Objective: To discuss the rationale, hypothesis, modality of extracorporeal blood purification (EBP) techniques for the critically ill animal models or patients, and to summarize the experimental and clinical studies with inconsistent data which explored the EBP's efficacy in the areas of critical care medicine.

Data Sources: Articles referred in this review were collected from the database of PubMed published in English up to June 2014.

Study Selection: We had done a literature search by using the term "(sepsis OR acute lung injury OR acute respiratory distress syndrome) AND (extracorporeal blood purification OR hemofiltration OR hemoperfusion OR plasma exchange OR plasmapheresis OR adsorpiton)". Related original or review articles were included and carefully analyzed.

Results: Acute cellular and humoral immune disturbances occur in both sepsis and acute respiratory distress syndrome (ARDS). Treatments aimed at targeting one single pro-/anti-inflammatory mediator have largely failed with no proven clinical benefits. Such failure shifts the therapeutic rationale to the nonspecific, broad-spectrum methods for modulating the over-activated inflammatory and anti-inflammatory response. Therefore, EBP techniques have become the potential weapons with high promise for removing the circulating pro-/anti-inflammatory mediators and promoting immune reconstitution. Over the years, multiple extracorporeal techniques for the critically ill animal models or patients have been developed, including hemofiltration (HF), high-volume hemofiltration (HVHF), high-cutoff hemofiltration (HCO-HF), hemo-perfusion or -adsorption (HP/HA), coupled plasma filtration adsorption (CPFA), and plasma exchange (PE). These previous studies showed that EBP therapy was feasible and safe for the critically ill animal models or patients. However, data on their efficacy (especially on the clinical benefits, such as mortality) were inconsistent.

Conclusions: It is not now to conclude that EBP intervention can purify septic or ARDS patients with high clinical efficacy from current experimental and clinical practice. Prospective, randomized controlled, and well-designed clinical or experimental studies and most suitable EBP modalities should be further developed.