The subject of intra-abdominal pressure falls naturally under four heads, namely:
Except in so far as the pressures within the hollow viscera and the blood-vessels affect or are affected by the intraperitoneal pressure proper, they will not be treated of in this study. The pressures on the viscera must be identical with the pressure conditions of the cavity within which they are exposed wholly or in part, except where there is
Pressure on solid viscera (liver, kidney, spleen), which cannot be other than that existing in the free peritoneal cavity.
Pressures within hollow viscera; which have been fairly established under a variety of conditions, and may be wholly independent of the pressure in the abdominal cavity.
Pressures within blood and lymph spaces which have been accurately determined, and are modified by the pressure in the abdominal cavity.
Pressures within the peritoneal space proper.