Metabolic alterations in critically ill patients

Abstract

The critically ill patient in intensive care often has to face significant metabolic alterations caused directly by the illness or secondary by complications (i.e. infections, organ failure or sepsis). Hyperglycemia during critical illness is an important clinical topic. As uncontrolled hyperglycemia in this setting is associated with a variety of adverse events, including morbidity and mortality, so that effective management of hyperglycemia in critically ill patients by intensive regimens of various insulin protocols is very important to achieve a significant reduction in mortality and morbidity in these patient. Intensive Insulin Therapy has the risk of hypoglycemia. That Severe or prolonged hypoglycemia can cause serious complications. Another complication of intensive insulin therapy is blood glucose variability which is defined as the standard deviation of each patient’s mean glucose level during ICU stay. In critically ill patients there is hypermetabolic response characterized by a hyperdynamic circulatory response with massive protein and lipid catabolism, total body protein loss and muscle wasting. Thyroid hormones have profound effects on many physiologic processes, such as development, growth and metabolism, and deficiency in thyroid hormones is not compatible with normal health. Thyroid hormones play an important role in the adaptation of metabolic function to stress and critical illness. So thyroid hormone alterations are very common, particularly in those of critical illness and by a large number of drugs there are used in ICU. Thus Nonthyroidal illness syndrome is characterized by alterations of thyroid status in critical ill patients who are clinically euthyroid and management of it is controversy. Hospital admission is a risk factor for further deterioration of nutrition status especially in Patients admitted to an ICU because of impaired organ function and those who cannot eat, is ventilated, and if not forcefed will progressively starve. Nutrition risk assessment is of great importance to identify patients who may benefit from nutritional intervention to prevent ICU starvation and avoid side-effects of nutrition care. Refeeding syndrome can be defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding (whether enterally or parenterally). These shifts result from hormonal and metabolic changes and may cause serious clinical complications Nutrition intervention plays a significant role in changing patient clinical outcomes in the intensive care unit and sufficient nutrients are needed for critically ill patients to meet metabolic requirements. Appropriate nutritional feeding and avoidance of under nutrition or over nutrition during critical illness improves the success in weaning patients from mechanical ventilation and in reducing the length of hospitalization needs. The daily energy requirements should be provided by calories derived from carbohydrates and lipids, and protein intake should be used to maintain the stores of essential enzymatic and structural proteins. Patients in the ICU are sedated, ventilated, so that Disabled that volitional oral feeding is either impossible or unlikely to successfully meet nutrient requirements. Under these circumstances, there are two options the first is tube feeding of a formulated nutrient mixture called enteral nutrition and the other is parenteral nutrition. Enteral and parenteral nutrition each have their own benefits and drawbacks, with advantages clearly outweighing the disadvantages when enteral nutrition is used.