Pre- and Postoperative Energy Expenditure in Major Liver Resection: What do we Ask From a Patient?

The number of major surgical procedures performed in older patients has been rising in recent years. Older-aged patients have a higher risk of postoperative morbidity and mortality. A recent Dutch study reported that 43% of the patients had a complicated postoperative course after major liver resection (≥3 segments) performed for colorectal liver metastases. The risk of postoperative complications and mortality is related to the patient's age combined with a higher prevalence of comorbidities, which both decrease the physiological reserve capacity of organ systems. As such, preoperative aerobic capacity has been found to be independently and consistently associated with postoperative outcomes after liver surgery. Interestingly, exercise prehabilitation is known to preoperatively increase the aerobic fitness of patients scheduled for major elective abdominal surgery. High-risk patients will benefit most from this, with a reduction in postoperative complications of >30%.

The conceptual hypothesis of exercise prehabilitation as part of perioperative care in patients undergoing major abdominal surgery is clear and increasingly substantiated with evidence. However, when taking into account the variation in prehabilitation programs and the variability of individual prehabilitation outcomes, there is room for improvement by exploring different rationales subserving the conceptual hypothesis of prehabilitation. One of the complementary rationales focusses on homeostasis-allostasis before and after surgery, more specifically on the preoperative metabolic 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. Insight in this can subsequently be used to further optimize the content of preoperative preventive interventions for unfit patients (exercise prehabilitation) to improve patient- and treatment-related outcomes.

Study design:

This study will be an explorative prospective observational cohort study of 18 months, in which energy expenditure will be determined pre- and postoperatively in 20 patients undergoing major elective liver resection at the Maastricht University Medical Center+ (MUMC+). Patients undergoing major liver resection (≥3 segments) were chosen for this study given the magnitude of their surgery and high prevalence of postoperative morbidity.

This is a monocenter study, where all measurements will be performed at the Clinical Research Unit of the MUMC+. Energy expenditure will be quantified one week before and one week after surgery using the doubly labelled water (DLW) technique, as well as by using indirect calorimetry measurements during the hospital admission one day before surgery, at postoperative day 1, 2, and 3, and at hospital discharge. Moreover, aerobic capacity will be determined with cardiopulmonary exercise testing (CPET) preoperatively and at hospital discharge.