Category: Critical care

Intensive care unit (ICU) patients often experience significant metabolic and inflammatory stress that drastically alters their body's nutritional requirements. During such hypermetabolic periods, the body's synthesis of certain amino acids can no longer keep pace with the high demand, transforming previously nonessential nutrients into conditionally essential ones.

According to scientific literature, immunonutrients are specific dietary substrates that can modulate immune and inflammatory responses in the body. The crucial role of immunonutrients is to support and enhance the body's ability to fight off infections, heal from injury, and manage inflammatory conditions, especially in times of high physiological stress.

According to a 2021 review, energy expenditure is highly variable among critically ill patients, making static caloric estimates unreliable and emphasizing the risk of both underfeeding and overfeeding. Understanding what is the calorie requirement for critically ill patients is therefore crucial for improving their outcomes.

Recent clinical evidence suggests that underfeeding, specifically permissive underfeeding, may be tolerated during the acute phase of critical illness and potentially improve outcomes compared to aggressive, standard feeding protocols. This approach intentionally delivers fewer calories than estimated requirements.

According to a 2021 meta-analysis, the incidence of refeeding syndrome in Intensive Care Unit (ICU) patients can range from 17% to 52%, highlighting its significant prevalence and potential dangers. For critically ill patients, understanding what is refeeding syndrome is crucial, as the metabolic and electrolyte shifts following nutritional replenishment can lead to life-threatening complications.

In critical care, one serious but preventable metabolic disturbance is feeding tube syndrome, a potentially fatal condition caused by a feeding regimen that provides insufficient water relative to its high protein content. This metabolic imbalance can profoundly affect a patient's fluid and electrolyte levels, requiring urgent medical correction.

According to a study published in *Clinical Nutrition*, TPN can be a life-saving intervention for critically ill patients who cannot receive adequate nutrients via the digestive tract. In an intensive care unit (ICU), a patient may require Total Parenteral Nutrition (TPN) when their gastrointestinal system is non-functional or requires complete rest. This critical nutritional support is delivered directly into the bloodstream, bypassing the digestive process entirely.

The definition of a high gastric residual for tube feed has dramatically shifted in recent years, moving away from historical thresholds as low as 100-200 mL to modern guidelines that consider volumes over 500 mL more significant, especially in conjunction with other clinical signs. This change aims to prevent unnecessary feeding interruptions and improve patient nutrition.

According to the Cleveland Clinic, Total Parenteral Nutrition (TPN) is the delivery of complete nutrition intravenously for individuals whose digestive systems are non-functional. A definitive and absolute indication for TPN arises when patients are unable to obtain or process adequate nutrition through oral or enteral routes for a prolonged duration.

Malnutrition is common in critically ill patients, affecting up to 40% of those in the ICU and worsening with prolonged stays. In cases where a patient's gastrointestinal tract is non-functional, parenteral nutrition in the ICU becomes a life-saving method for delivering vital nutrients intravenously.