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Moritz Flick, Luisa Briesenick-Weskamm, Pawel Sierzputowski, Marie-Christin Süykers, Parisa Moll-Khosrawi, Linda Krause | The effects of maximizing stroke volume versus maintaining preoperative resting cardiac index on oxygen delivery, oxygen consumption, and microcirculatory tissue perfusion in patients having major abdominal surgery: The exploratory randomized CUSTOM trial

November 29, 2025

Background: Mechanistic effects of intraoperative blood flow-guided hemodynamic therapy remain poorly understood. Therefore, we aimed to determine the effects of a) maximizing stroke volume and b) maintaining preoperative resting cardiac index on oxygen delivery, oxygen consumption, and sublingual and abdominal microcirculatory tissue perfusion in major abdominal surgery patients.

Methods: We randomized 76 patients to maximizing stroke volume, maintaining preoperative resting cardiac index, or routine care during and for the first 6 h after surgery. We measured oxygen delivery index, oxygen consumption index, sublingual microvascular flow index, and urethral perfusion index.

Results: At the end of surgery and 6 h after surgery, the median (25th percentile, 75th percentile) oxygen delivery index was higher in patients assigned to stroke volume maximization (460 (404, 556) ml/min/m2 and 503 (466, 595) ml/min/m2) or to preoperative cardiac index maintenance (507 (460, 664) ml/min/m2 and 516 (403, 604) ml/min/m2) than in patients assigned to routine care (403 (338, 517) ml/min/m2 and 390 (351, 510) ml/min/m2). There were no important differences in oxygen consumption index and sublingual microvascular flow index among the three groups. The intraoperative average urethral perfusion index was slightly higher in patients assigned to stroke volume maximization or to preoperative cardiac index maintenance than in patients assigned to routine care.