Perioperative Energy Expenditure in Major Liver Resection

Rationale: Complication rates after major liver resections remain as high as 43%. Many initiatives have been taken to reduce postoperative morbidity. As such, prehabilitation programmes are increasingly used for patients undergoing major abdominal surgery. Improvement of aerobic fitness has been proven to reduce complication rates, especially in high-risk patients (those with a low preoperative aerobic capacity). Different conceptual hypotheses exist of the underlying mechanism of variability in postoperative complications and prehabilitation response. One of the complementary rationales focusses on homeostasis-allostasis before and after surgery, more specifically on the preoperative aerobic capacity to meet postoperative metabolic demands. However, more insight in postoperative metabolic demands (energy expenditure) during in-hospital recovery from major abdominal surgery in relation to preoperative resting metabolic demands and maximal aerobic capacity is essential to understand the increase in metabolic demands coinciding with major surgery in relation to the body's reserve capacity. This information can be used to better understand the rationale behind exercise prehabilitation, as well as to optimize the content of preoperative treatment for unfit patients, for instance by means of personalized prehabilitation programs that might improve postoperative outcomes. Objective: This study aims to explore the difference of pre- and postoperative energy expenditure in patients undergoing major elective liver resection and relate this to their preoperative aerobic capacity. Study design: The study will be a prospective observational study with thorough pre- and postoperative measurements of energy expenditure. Energy expenditure will be measured using the doubly labelled water method, as well as by indirect calorimetry. To assess aerobic capacity, cardiopulmonary exercise testing will be performed pre- and postoperatively. Additionally, accelerometers will be used to evaluate pre- and postoperative physical activity levels. Study population: Patients aged ≥18 years undergoing major liver resection (≥3 segments) will be asked to participate. The inability to perform cardiopulmonary exercise testing, neo-adjuvant chemotherapy, and cirrhotic liver are reasons for exclusion. Main study parameters/endpoints: The main study parameter is the difference of energy expenditure pre- and postoperatively, as measured with doubly labelled water and indirect calorimetry. Secondary endpoints: Additionally, as secondary endpoints, aerobic fitness, physical activity level, and postoperative complications will be assessed.