Calder PC, Waitzberg DL, Koletzko B (eds): Intravenous Lipid Emulsions. World Rev Nutr Diet. Basel, Karger, 2015, vol 112, pp 120–126 (DOI: 10.1159/000365667)
Intravenous Lipids in Adult Intensive Care Unit Patients Matthias Hecker · Konstantin Mayer University of Giessen and Marburg Lung Center (UGMLC), Justus-Liebig-University of Giessen, Giessen, Germany
Abstract Malnutrition of critically ill patients is a widespread phenomenon in intensive care units (ICUs) worldwide. Lipid emulsions (LEs) are able to provide sufficient caloric support and essential fatty acids to correct the energy deficit and improve outcome. Furthermore, components of LEs might impact cell and organ function in an ICU setting. All currently available LEs for parenteral use are effective in providing energy and possess a good safety profile. Nevertheless, soybean oil-based LEs have been associated with an elevated risk of adverse outcomes, possibly due to their high content of omega-6 fatty acids. More newly developed emulsions partially replace soybean oil with mediumchain triglycerides, fish oil or olive oil in various combinations to reduce its negative effects on immune function and inflammation. The majority of experimental studies and smaller clinical trials provide initial evidence for a beneficial impact of these modern LEs on critically ill patients. However, large, well-designed clinical trials are needed to evaluate which LE offers the greatest advantages concerning clinical outcome. Lipid emulsions (LEs) are a powerful source of energy that can help to adjust the caloric deficit of intensive care unit (ICU) patients. LEs possess various biological activities, but their subsequent impact on critically ill patients awaits further investigations. © 2015 S. Karger AG, Basel
Although nutritional demands and metabolism vary among critically ill patients, the onset of a trauma causes a generalized host response that is characterized by dynamic changes to their metabolic activity and thus energy requirements. This so-called
Downloaded by: UCSF Library & CKM 169.230.243.252 - 12/6/2014 6:32:49 AM
General Aspects of Nutritional Support for Intensive Care Patients
Lipids in Intensive Care Unit Patients Calder PC, Waitzberg DL, Koletzko B (eds): Intravenous Lipid Emulsions. World Rev Nutr Diet. Basel, Karger, 2015, vol 112, pp 120–126 (DOI: 10.1159/000365667)
121
Downloaded by: UCSF Library & CKM 169.230.243.252 - 12/6/2014 6:32:49 AM
stress response has been studied in detail in patients undergoing major surgery or after trauma [1]. The stress response also occurs in patients with sepsis, burn injury or onset of severe infection, although the timing and details of the reaction may differ. As the stress response has a direct impact on the nutritional regime of ICU patients, a simplified overview of the main features that are relevant for nutrition is presented in the following section. In general, the metabolic stress reaction can be divided into three phases. The first, so-called ebb phase, starts immediately after the initial insult and lasts for 1–2 days, depending on the extent of injury/stress [1]. This phase is characterized by an overall decrease in metabolic activity and energy requirements that are often accompanied by a decline in oxygen consumption and cardiac output. Although an individual in the ebb phase has a low basal metabolic rate, the individual initiates, in preparation for the following metabolic phases, a stress-hormone driven mobilization of endogenous energy stores (such as hepatic and skeletal muscle glycogen), which clinically translates into significant hyperglycemia. The onset of the flow phase is signaled by an increase in cardiac output, restoration of respiratory rate and escalation of the energy demand to adjust to the injury and stabilize the circulation. Metabolically, the flow phase is characterized by the provision of substrates (‘fuel’), which is basically achieved through catabolism and insulin resistance. The catabolic reaction encompasses protein breakdown (primarily skeletal muscle and later respiratory and gut musculature) to increase the availability of glucogenic amino acids as well as a rise in gluconeogenesis and impaired uptake of glucose in insulin-dependent tissues. Free fatty acids are provided to yield energy through lipolysis and the depletion of endogenous fat stores. The duration of the flow phase varies and might be up to weeks depending on the progress of healing and the occurrence of complications. In the final, so-called anabolic or recovery phase, restoration of lean body mass and weight is intended. Of special importance is the restoration of muscle tissue that was lost during the initial phases. The consideration of the above-mentioned stress response has a pivotal impact on the establishment of an adequate nutritional regime for the critically ill patient. First, it is of major importance that metabolic changes are dynamic depending, amongst others, on the extent of the injury, timing and complications. Second, the metabolic stress response impacts survival and has thus been evolutionarily programmed. Some features, such as hyperglycemia, could theoretically be influenced by massive intervention (e.g. excessive insulin application), but study data show that this might cause more harm than good. Third, except in the short time period of the ebb phase, where low metabolic rates are observed, the energy demand of critically ill patients is high, leading to a mobilization of the endogenous pool of substrates, especially in situations with insufficient exogenous provision of calories. By the provision of exogenous substrates, it is possible to reduce the adverse effects of catabolism, promote recovery and finally beneficially influence survival.
Parenteral Nutrition of Intensive Care Unit Patients
Given that malnutrition is a proven prognostic factor for a fatal outcome in intensive care patients, it is of major importance to provide adequate caloric intake. Enteral nutrition (EN) is regarded as the gold standard in an ICU setting, as it promotes the integrity of the intestine and thus reduces the rate of complications [2, 3]. However, two cohorts of patients may significantly benefit from the application of parenteral nutrition (PN). In the first group, the use of EN may be (temporarily) contraindicated (due to gut ischemia, peritonitis, major abdominal surgery), and thus PN is required to avoid malnutrition. Recommendations for the use of PN in ICU patients vary extensively among the national societies, with more liberal use in European guidelines and a restricted application regime in the USA and Canada [3, 4]. The role of PN as a supplement to EN is more controversial. Recent study data indicate that in critically ill patients, EN alone tends to underfeed and might lead to an undesirable energy deficit [5]. Cahill et al. could, for instance, demonstrate that, despite the international guidelines recommending early enteral feeding of ICU patients, only about 50% of the prescribed calories were applied in the first two weeks of ICU admission [6]. The main reasons for this were frequent interruptions of the enteral applications due to high gastric residual volume, vomiting, mechanical tube problems, diagnostic procedures or surgery [7]. The concept of supplemental PN encompasses the combination of PN and EN in ICU patients who do not meet the targeted caloric intake with EN alone. A recent study by Heidegger and colleagues could demonstrate that supplemental PN in patients receiving
Intravenous Lipids in Adult Intensive Care Unit Patients Matthias Hecker · Konstantin Mayer University of Giessen and Marburg Lung Center (UGMLC), Justus-Liebig-University of Giessen, Giessen, Germany
Abstract Malnutrition of critically ill patients is a widespread phenomenon in intensive care units (ICUs) worldwide. Lipid emulsions (LEs) are able to provide sufficient caloric support and essential fatty acids to correct the energy deficit and improve outcome. Furthermore, components of LEs might impact cell and organ function in an ICU setting. All currently available LEs for parenteral use are effective in providing energy and possess a good safety profile. Nevertheless, soybean oil-based LEs have been associated with an elevated risk of adverse outcomes, possibly due to their high content of omega-6 fatty acids. More newly developed emulsions partially replace soybean oil with mediumchain triglycerides, fish oil or olive oil in various combinations to reduce its negative effects on immune function and inflammation. The majority of experimental studies and smaller clinical trials provide initial evidence for a beneficial impact of these modern LEs on critically ill patients. However, large, well-designed clinical trials are needed to evaluate which LE offers the greatest advantages concerning clinical outcome. Lipid emulsions (LEs) are a powerful source of energy that can help to adjust the caloric deficit of intensive care unit (ICU) patients. LEs possess various biological activities, but their subsequent impact on critically ill patients awaits further investigations. © 2015 S. Karger AG, Basel
Although nutritional demands and metabolism vary among critically ill patients, the onset of a trauma causes a generalized host response that is characterized by dynamic changes to their metabolic activity and thus energy requirements. This so-called
Downloaded by: UCSF Library & CKM 169.230.243.252 - 12/6/2014 6:32:49 AM
General Aspects of Nutritional Support for Intensive Care Patients
Lipids in Intensive Care Unit Patients Calder PC, Waitzberg DL, Koletzko B (eds): Intravenous Lipid Emulsions. World Rev Nutr Diet. Basel, Karger, 2015, vol 112, pp 120–126 (DOI: 10.1159/000365667)
121
Downloaded by: UCSF Library & CKM 169.230.243.252 - 12/6/2014 6:32:49 AM
stress response has been studied in detail in patients undergoing major surgery or after trauma [1]. The stress response also occurs in patients with sepsis, burn injury or onset of severe infection, although the timing and details of the reaction may differ. As the stress response has a direct impact on the nutritional regime of ICU patients, a simplified overview of the main features that are relevant for nutrition is presented in the following section. In general, the metabolic stress reaction can be divided into three phases. The first, so-called ebb phase, starts immediately after the initial insult and lasts for 1–2 days, depending on the extent of injury/stress [1]. This phase is characterized by an overall decrease in metabolic activity and energy requirements that are often accompanied by a decline in oxygen consumption and cardiac output. Although an individual in the ebb phase has a low basal metabolic rate, the individual initiates, in preparation for the following metabolic phases, a stress-hormone driven mobilization of endogenous energy stores (such as hepatic and skeletal muscle glycogen), which clinically translates into significant hyperglycemia. The onset of the flow phase is signaled by an increase in cardiac output, restoration of respiratory rate and escalation of the energy demand to adjust to the injury and stabilize the circulation. Metabolically, the flow phase is characterized by the provision of substrates (‘fuel’), which is basically achieved through catabolism and insulin resistance. The catabolic reaction encompasses protein breakdown (primarily skeletal muscle and later respiratory and gut musculature) to increase the availability of glucogenic amino acids as well as a rise in gluconeogenesis and impaired uptake of glucose in insulin-dependent tissues. Free fatty acids are provided to yield energy through lipolysis and the depletion of endogenous fat stores. The duration of the flow phase varies and might be up to weeks depending on the progress of healing and the occurrence of complications. In the final, so-called anabolic or recovery phase, restoration of lean body mass and weight is intended. Of special importance is the restoration of muscle tissue that was lost during the initial phases. The consideration of the above-mentioned stress response has a pivotal impact on the establishment of an adequate nutritional regime for the critically ill patient. First, it is of major importance that metabolic changes are dynamic depending, amongst others, on the extent of the injury, timing and complications. Second, the metabolic stress response impacts survival and has thus been evolutionarily programmed. Some features, such as hyperglycemia, could theoretically be influenced by massive intervention (e.g. excessive insulin application), but study data show that this might cause more harm than good. Third, except in the short time period of the ebb phase, where low metabolic rates are observed, the energy demand of critically ill patients is high, leading to a mobilization of the endogenous pool of substrates, especially in situations with insufficient exogenous provision of calories. By the provision of exogenous substrates, it is possible to reduce the adverse effects of catabolism, promote recovery and finally beneficially influence survival.
Parenteral Nutrition of Intensive Care Unit Patients
Given that malnutrition is a proven prognostic factor for a fatal outcome in intensive care patients, it is of major importance to provide adequate caloric intake. Enteral nutrition (EN) is regarded as the gold standard in an ICU setting, as it promotes the integrity of the intestine and thus reduces the rate of complications [2, 3]. However, two cohorts of patients may significantly benefit from the application of parenteral nutrition (PN). In the first group, the use of EN may be (temporarily) contraindicated (due to gut ischemia, peritonitis, major abdominal surgery), and thus PN is required to avoid malnutrition. Recommendations for the use of PN in ICU patients vary extensively among the national societies, with more liberal use in European guidelines and a restricted application regime in the USA and Canada [3, 4]. The role of PN as a supplement to EN is more controversial. Recent study data indicate that in critically ill patients, EN alone tends to underfeed and might lead to an undesirable energy deficit [5]. Cahill et al. could, for instance, demonstrate that, despite the international guidelines recommending early enteral feeding of ICU patients, only about 50% of the prescribed calories were applied in the first two weeks of ICU admission [6]. The main reasons for this were frequent interruptions of the enteral applications due to high gastric residual volume, vomiting, mechanical tube problems, diagnostic procedures or surgery [7]. The concept of supplemental PN encompasses the combination of PN and EN in ICU patients who do not meet the targeted caloric intake with EN alone. A recent study by Heidegger and colleagues could demonstrate that supplemental PN in patients receiving
