Amino Acid Metabolism in Fed Surgical Critically Ill Patients

Introduction Sarcopenia is defined as progressive generalized loss of skeletal muscle mass, strength and function. Sarcopenia due to lack of physical activity is a known phenomenon and is usually observed as a normal part of aging or in certain diseases and pathogenic processes. Major associated factors causing development of sarcopenia may be summarized as interactions of environmental and hormonal factors, underlying diseases, activation of inflammatory pathways, mitochondrial dysfunction, reduced satellite cell numbers, and loss of neuromuscular junctions. Intensive care acquired weakness (ICU-AW) known formerly as critical illness polyneuropathy, is a diagnosis that becomes more common as survival rates from long ICU hospitalization are more prevalent. It is characterized by a primary axonal degeneration, without demyelination, that typically affects motor nerves more than sensory nerves. ICU-AW affects the limbs (particularly the lower extremities) in a symmetric pattern. Weakness is most notable in proximal neuromuscular areas (e.g., the shoulders and hip girdle). In addition, involvement of the respiratory muscles can occur and can impede weaning from mechanical ventilation. The pathophysiological mechanisms of ICU-acquired weakness are believed to be multifactorial. Some suspected factors include dysfunctional microcirculation and hyperglycemia. It has been shown that tight glucose control in ICU patients reduces the risk for ICU-AW (although it has been associated with other adverse events). Sodium channels channelopathy is also a researched cause for ICU-AW. Muscle loss in the ICU are usually related to bedridden condition and lack of mobility, increase in ubiquitination and inadequate protein administration associated with large negative nitrogen balance. In addition mechanical ventilation contributes greatly to this problem. This has been particularly relevant in post trauma/surgical long stayer patients. In the past years great progress was made in