What is the post-shock metabolic response described by Cuthbertson DP (David P.), also known as the catabolic response to shock?

From the Guidelines

The Cuthbertson post-shock metabolic response is characterized by an initial "ebb" phase of decreased metabolism, followed by a "flow" phase of hypermetabolism and catabolism, and a subsequent anabolic recovery phase, as described in the 2020 review of nutrition therapy in critical illness 1. The "ebb" phase, lasting 24-48 hours, is marked by haemodynamic instability, hormonal changes, and prioritization of energy substrate delivery to vital tissues, resulting in endogenous glucose production and lower energy expenditure compared to pre-injury 1. In contrast, the "flow" phase involves the breakdown of tissue, including lean muscle tissue, to provide substrates for the "fight or flight" response, and can last for days to weeks 1. A third, anabolic recovery phase has been described, during which resynthesis of lost tissue can occur and the body may be more metabolically able to process delivered nutrients 1. Understanding these phases is crucial for clinical management, as it guides nutritional support, fluid resuscitation, and metabolic interventions, with recent studies suggesting that less than 100% of energy expenditure should be targeted in the acute phases of critical illness due to endogenous glucose production 1. Key interventions to mitigate the catabolic effects of this post-shock response include early enteral nutrition when feasible, adequate protein provision, and careful glucose control, as supported by the 2021 ESPEN expert group recommendations 1. The current evidence suggests that nutrition interventions in the acute early and acute late phase of critical illness may not impact clinical outcomes and may cause harm in some groups, emphasizing the need for careful consideration of nutritional support in these phases 1. In particular, the EPaNIC trial found that late initiation of parenteral nutrition, started on day 8 of ICU stay, led to improved clinical outcomes, including increased proportion of patients discharged alive and earlier from ICU and hospital, and reduced infectious complications 1. Similarly, the TARGET trial found that augmented energy delivery in the early phase of illness did not improve clinical outcomes compared to standard care, highlighting the importance of tailored nutritional support in critically ill patients 1. Overall, the Cuthbertson post-shock metabolic response is a complex and dynamic process, and its management requires a nuanced understanding of the underlying physiological changes and the potential benefits and harms of different nutritional interventions.

From the Research

Post Shock Metabolic Response

• The post shock metabolic response, as described by Cuthbertson, involves protein and fat consumption and protection of body fluids and electrolytes due to hypermetabolism in the early period 2.
• This response is characterized by an increase in oxygen and energy requirements, which are proportional to the severity of the trauma 2.
• The main metabolic change in response to injury is the reduction of the normal anabolic effect of insulin, resulting in insulin resistance 2.
• Free fatty acids are the primary source of energy after trauma, with triglycerides meeting 50 to 80% of the consumed energy 2.

Cuthbertson's Response

• Cuthbertson reported that trauma patients experience a characteristic response, including protein and fat consumption and protection of body fluids and electrolytes due to hypermetabolism in the early period 2.
• This response is crucial in understanding the metabolic changes that occur after trauma, including the reduction of the normal anabolic effect of insulin and the increase in protein degradation 2.
• The awareness of these alterations in amino acid, lipid, and carbohydrate metabolism is essential in determining metabolic and nutritional support for surgical patients 2.

Metabolic Support

• The aim of glucose administration to surgical patients during fasting is to reduce proteolysis and prevent loss of muscle mass 2.
• In major stress, such as sepsis and trauma, it is essential to reduce the catabolic response and obtain a balanced metabolism in the shortest possible time with minimum loss 2.
• Oxandrolone, an anabolic androgenic steroid, has been used to promote anabolism in clinical settings, including the treatment of catabolic disorders, HIV-related muscle wasting, and severe burn injury 3, 4.