The Impact of Pelvic Venous Pressure on Blood Loss during Open Radical Cystectomy and Urinary Diversion: Results of a Secondary Analysis of a Randomized Clinical Trial

Abstract

Blood loss and blood substitution are associated with higher morbidity after major abdominal surgery. During major liver resection low local venous pressure decreases blood loss. Ambiguity persists concerning the impact of local venous pressure on blood loss during open radical cystectomy. We determined the association between intraoperative blood loss and pelvic venous pressure as well as factors affecting pelvic venous pressure. In this single center, double-blind, randomized trial pelvic venous pressure was measured in 82 patients in a norepinephrine-low volume group and in 81 controls with liberal hydration. As secondary analysis patients from each arm were stratified into subgroups with pelvic venous pressure less than 5 mm Hg, or 5 or greater as measured after cystectomy, which is the optimal cutoff for identifying patients with relevant blood loss according to the Youden index. Median blood loss was 800 ml (range 300 to 1,600) in 55 of 163 patients (34%) with pelvic venous pressure less than 5 mm Hg and 1,200 ml (range 400 to 3,000) in 108 of 163 (66%) with pelvic venous pressure 5 mm Hg or greater (p <0.0001). Pelvic venous pressure less than 5 mm Hg was measured in 42 of 82 patients (51%) in the norepinephrine-low volume group and in 13 of 81 controls (16%) (p <0.0001). Pelvic venous pressure decreased significantly after removing abdominal packing and abdominal lifting in each group at all time points, that is at the beginning and end of pelvic lymph node dissection, and the end of cystectomy (p <0.0001). No correlation was detected between pelvic venous pressure and central venous pressure. Blood loss was significantly decreased in patients with low pelvic venous pressure. Factors affecting pelvic venous pressure were fluid management and abdominal packing.