Understanding the mechanisms of paracentesis-induced crculatory dysfunction.

Large-volume paracentesis induces early beneficial haemodynamic changes that may be shortly followed by a disorder known as paracentesis-induced circulatory dysfunction, characterized by a marked activation of the renin-angiotensin axis. Evidence is accumulating however that this disorder is secondary to an accentuation of an already established arteriolar vasodilatation. The causes of this syndrome are probably multiple and may include the dynamics of paracentesis (the rate of ascitic fluid extraction), release of nitric oxide from the vascular endothelium and mechanical modifications due to abdominal decompression. Patients developing this syndrome are prone to a faster reaccumulation of ascites, renal impairment and shorter survival. Plasma volume expansion after paracentesis reduces the incidence of this disorder. Preliminary evidence suggests that other approaches, such as the use of splanchnic vasoconstrictors or modulating the rate of ascitic fluid extraction, could be also effective, although more studies are needed.