Postoperative stress, metabolism, and catabolism

The number of older people undergoing major surgery has significantly grown over the last decades. In older adults, surgical procedures elicit a perturbed stress response, which may combine with preexisting conditions to increase the risk for perioperative complications and negative outcomes, including delirium, infections, functional decline, and mortality. Surgical stress in aging is characterized by altered peak response, which may be either exaggerated or blunted, followed by a slow (and often incomplete) return to baseline. Multiple age-related alterations in hypothalamic-pituitary axis and in inflammatory response have been described in older adults undergoing surgery and may be associated with abnormal surgical stress. Muscle atrophy frequently occurs after surgery due to prolonged bed rest and impaired anabolism/catabolism balance associated with anesthesia and surgical procedures. Muscle wasting may further hamper recovery and promote the development of adverse events. Postoperative stress response overstimulates the core biological processes of aging, the so-called “hallmarks of aging,” thereby inducing an accelerated aging phenotype. Currently, multimodal interventions, including nutrition and exercise, are the most effective strategies to contrast impaired perioperative stress response and preserve muscle in older adults. In the present chapter, the impact of aging on stress response to surgery will be summarized, with a specific focus on muscle anabolism/catabolism. Finally, current therapeutic options and novel intervention strategies, including the use of geroprotectors (i.e., molecules targeting biological pillars of aging), will be briefly introduced.