Fig. 5. Relation of intraabdominal caval vein pressure to intraabdominal cavity pressure. Data from eight patients undergoing intraperitoneal carbon dioxide insufflation showing a linear association between both variables (r = 0.99 ± 0.006) with the regression equation: intraabdominal caval vein pressure = 0.85 (± 0.09) × intraperitoneal pressure + 7.39 (± 2.7) (P < 0.001).