Rationale: We previously reported outcome-associated decreases in muscle energetic status and mitochondrial dysfunction in septic patients with multiorgan failure. We postulate that survivors have a greater ability to maintain or recover normal mitochondrial functionality. Objectives: To determine whether mitochondrial biogenesis, the process promoting mitochondrial capacity, is affected in critically ill patients. Methods: Muscle biopsies were taken from 16 critically ill patients recently admitted to intensive care (average 1-2 d) and from 10 healthy, age-matched patients undergoing elective hip surgery. Measurements and Main Results: Survival, mitochondrial morphology, mitochondrial protein content and enzyme activity, mitochondrial biogenesis factor mRNA, microarray analysis, and phosphorylated (energy) metabolites were determined. Ten of 16 critically ill patients survived intensive care. Mitochondrial size increased with worsening outcome, suggestive of swelling. Respiratory protein subunits and transcripts were depleted in critically ill patients and to a greater extent in nonsurvivors. The mRNA content of peroxisome proliferator-activated receptor g coactivator 1-a (transcriptional coactivator of mitochondrial biogenesis) was only elevated in survivors, as was the mitochondrial oxidative stress protein manganese superoxide dismutase. Eventual survivors demonstrated elevated muscle ATP and a decreased phosphocreatine/ATP ratio. Conclusions: Eventual survivors responded early to critical illness with mitochondrial biogenesis and antioxidant defense responses. These responses may partially counteract mitochondrial protein depletion, helping to maintain functionality and energetic status. Impaired responses, as suggested in nonsurvivors, could increase susceptibility to mitochondrial damage and cellular energetic failure or impede the ability to recover normal function. Clinical trial registered with clinical trials.gov (NCT00187824).

The metabolic response to stress is part of the adaptive response to survive critical illness. Several mechanisms are well preserved during evolution, including the stimulation of the sympathetic nervous system, the release of pituitary hormones, a peripheral resistance to the effects of these and other anabolic factors, triggered to increase the provision of energy substrates to the vital tissues. The pathways of energy production are altered and alternative substrates are used as a result of the loss of control of energy substrate utilization by their availability. The clinical consequences of the metabolic response to stress include sequential changes in energy expenditure, stress hyperglycaemia, changes in body composition, and psychological and behavioural problems. The loss of muscle proteins and function is a major long-term consequence of stress metabolism. Specific therapeutic interventions, including hormone supplementation, enhanced protein intake, and early mobilization, are investigated. This review aims to summarize the pathophysiological mechanisms, the clinical consequences, and therapeutic implications of the metabolic response to stress.

French Ministry of Health and the Société Française d'Anesthésie Réanimation.

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A 48-h infusion of SL decreased the occurrence of raised ICP episodes in patients with severe TBI, while reducing fluid and chloride balances. These findings suggest that SL solution could be considered as an alternative treatment to prevent raised ICP following severe TBI.