From the Guidelines
The main source of fuel in sepsis is glucose (option A). During sepsis, the body undergoes significant metabolic changes characterized by hypermetabolism and increased energy expenditure. Despite adequate glucose availability, sepsis creates a state of insulin resistance, leading to hyperglycemia. The body preferentially uses glucose as fuel through aerobic glycolysis, even when oxygen is available (known as the Warburg effect). This metabolic shift occurs because inflammatory mediators and stress hormones like cortisol, catecholamines, and glucagon promote gluconeogenesis and glycogenolysis, increasing glucose production.
Key Points
- Glucose is the primary fuel source for cells, particularly immune cells, during sepsis 1.
- The body's metabolic changes during sepsis lead to increased glucose production and utilization.
- Fatty acid oxidation is impaired, and protein catabolism occurs, but glucose remains the main fuel source.
- The Surviving Sepsis Campaign guidelines recommend early initiation of enteral feeding, which includes glucose, rather than complete fasting or only IV glucose in critically ill patients with sepsis or septic shock who can be fed enterally 1.
Nutrition Recommendations
- Administer oral or enteral feedings, as tolerated, rather than complete fasting or provision of only IV glucose within the first 48 hours after a diagnosis of severe sepsis or septic shock 1.
- Avoid mandatory full caloric feeding in the first week, but rather suggest low-dose feeding, advancing only as tolerated 1.
- Use IV glucose and enteral nutrition rather than total parenteral nutrition alone or parenteral nutrition in conjunction with enteral feeding in the first 7 days after a diagnosis of severe sepsis or septic shock 1.
From the Research
Main Source of Fuel in Sepsis
- The main source of fuel in sepsis is glucose, as the body resorts to gluconeogenesis and amino acid oxidation for energy supply due to insulin resistance and decreased glucose utilization 2.
- Hyperglycemia is a common feature of sepsis, and maintaining normoglycemia has been shown to improve survival and reduce morbidity in critically ill patients 3.
- The availability of fuels in sepsis is limited, leading to increased muscle breakdown and nitrogen loss, with the body relying on glucose, amino acids, and other alternative sources for energy 2.
- Other sources of fuel, such as fatty acids and ketones, may also be utilized, but glucose remains the primary source of energy in sepsis 2, 4.
- Amino acids, particularly branched-chain amino acids, may play a role in energy metabolism in sepsis, but their primary function is to provide building blocks for protein synthesis and other metabolic processes 2.