title: Intraperitoneal pressure: ascitic fluid and splanchnic vascular pressures, and their role in prevention and formation of ascites.
abstract: Seventeen patients with ascites due to cirrhosis underwent hepatic venous catheterization and pressure measurement in the ascitic fluid. Intraperitoneal fluid hydrostatic pressure (IFP) ranged 3.5-22, mean 11.2 mm Hg, and correlated closely to the pressure in the inferior vena cava (r = 0.97, P < 0.001), which was on average 1.8 mmHg above that of ascitic fluid (P < 0.005). Wedged hepatic venous pressure (WHVP) (range 19-43, mean 32 mmHg) correlated directly to IFP (0.89, P < 0.001) and was significantly higher than that of ten cirrhotic patients without ascites (range 12-27, mean 20 mmHg, P < 0.005). After diuretic therapy WHVP decreased to an average of 20 mmHg. Mean plasma colloid osmotic pressures were 20 mmHg (range 18-24 mmHg)( and 23 mmHg (range 19-29 mmHg) in patients with and without ascites, the values being significantly different (P < 0.05). Colloid osmotic pressure of ascitic fluid ranged 1-14, mean 4.9 mmHg. Mean ratio between albumin concentration in ascitic fluid and plasma was 0.31 (range 0.12-0.77). In five pigs portal venous pressure (PVP) increased during infusion of fluid into the peritoneal cavity. The increase in PVP was smaller than that of IFP (P < 0.02), indicating that ascitic fluid stems the pressures in the splanchnic venous vascular bed up to a higher level, but that the transmural hydrostatic pressure difference decreases simultaneously. The results are discussed in relation to the local 'oedema-preventing' mechanisms: (a) increased interstitial hydrostatic fluid pressure, (b) decreased interstitial fluid colloid osmotic pressure, (c) increased lymph flow, and it is concluded that the peritoneal space can be considered as a special part of the interstitium in which IFP is considered to play an important role in regulation of ascitic fluid.
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001201:Ascites / Q000209:etiology* / Q000517:prevention & control; D001202:Ascitic Fluid / Q000502:physiology*; D001794:Blood Pressure; D005260:Female; D006801:Humans; D006874:Hydrostatic Pressure; D008103:Liver Cirrhosis / Q000150:complications / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009997:Osmotic Pressure; D011312:Pressure; D013152:Splanchnic Circulation; D013552:Swine; D014690:Venous Pressure