The Splanchnic Hematocrit in Man

Abstract The aim of the present work was to study to what extent the difference between the total body hematocrit and the hematocrit of the blood in the large vessels is caused by a low hematocrit in the splanchnic area. 131 I‐labelled albumin and 51 Cr‐labelled red cells were injected into an antecubital vein and samples were drawn simultaneously from the femoral artery and a hepatic vein. The plasma and red cell volumes of the body and the body hematocrit were determined from the activity injected and the calculated initial concentrations. The splanchnic hematocrit was calculated from the arterio‐hepatic venous activity differences. The hepatic plasma flow was determined by the bromsulfalein method for calculation of the splanchnic plasma and red cell volumes. In 10 normal subjects the splanchnic hematocrit was not significantly different from the body hematocrit. The difference between large vessel hematocrit and body or splanchnic hematocrit may be expressed as an amount of ‘extra’ plasma, which in the body on the average was 450 ml, and in the splanchnic area 105 ml. The results indicate that the ‘extra’ plasma is evenly distributed throughout the smaller vessels in the body, or that a substantial amount of ‘extra’ plasma exists in some parts of the body, not examined so far.