The goals for nutritional support are not only to supply the required amounts of macro- and micronutrients but also to achieve a balanced composition. The latter is especially important for energy and protein requirements.
Long et al1 correlated urinary nitrogen losses as a measure of protein requirements, and resting metabolic rates as a measure of energy requirements for different patient groups. They demonstrated that energy and protein (nitrogen) requirements increase with rising stress caused by disease (Figure 1). Both parameters increase as stress increases, with protein (nitrogen) needs increasing more than energy needs. These data demonstrated that different patient groups have different nutritional requirements.
Figure adapted from Long CL, Schaffel N, Geiger JW, Schiller WR, Blakemore WS. Metabolic response to injury and illness: estimation of energy and protein needs from indirect calorimetry and nitrogen balance. JPEN J Parenter Enteral Nutr 1979;3:452–456.
In a prospective, randomized, Australian study with 50 critically ill patients it was found that nitrogen balance is inversely related to energy expenditure, and positively related to protein intake (Figure 2).2 Scheinkestel et al found that in trial patients, nitrogen balance was positively related to protein intake (P=0.0075, adjusted for urea and repeated measures) and positive nitrogen balances were more likely to be attained with protein intakes larger than 2 g/kg/day (P=0.0001).2 The American Society for Parenteral and Enteral Nutrition (ASPEN) guidelines recommend protein requirements should be in the range of 1.2–2.0 g/kg actual body weight/day in patients with body mass index (BMI) <30, and may likely be even higher in burn or multi-trauma patients.3 In contrast, the European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines recommend, when PN is indicated, a balanced amino acid mixture should be infused at approximately 1.3–1.5 g/kg ideal body weight/day in conjuction with an adequate energy supply.4
Reproduced with permission from Scheinkestel CD, et al. Nutrition 2003;19:909–916.
The adequacy of administered energy and protein was examined in an international prospective, observational, multicenter cohort study by Alberda et al involving 2,772 mechanically-ventilated adult patients in an intensive care unit (ICU). BMI was used as a marker of nutritional status prior to ICU admission.5 Over the 12 days of follow-up, overall, patients received 59.2% (56–64%) of the prescribed energy and 56% (50–65%) of the prescribed protein amount,5 showing that neither the energy goal nor the protein goal was reached (Figure 3).
The energy and protein received on a per kg basis varied significantly across BMI groups (P<0.0001; Chi-square test).
Figures created using data from Alberda C, Gramlich L, Jones N, et al. The relationship between nutritional intake and clinical outcomes in critically ill patients: results of an international multicenter observational study. Intensive Care Med 2009;35:1728–1737.
The same study demonstrated that malnutrition has a direct impact on the mortality of patients in the ICU. This effect was particularly apparent in patients with BMI values <25 or ≥35.5
The E/N ratio represents an important parameter for providing nutritional support. The E/N ratio is based on the idea that any consumption of protein has to be accompanied by a certain amount of non-protein calories to guarantee the anabolic use of amino acids.6 A recent systematic review of the literature, based on 53 studies involving 1,107 subjects in 91 cohorts, provided insight into the nutritional needs of different patient groups with respect to energy expenditures and nitrogen loss.7 Correlation of energy expenditure and nitrogen loss revealed a decrease in the E/N ratio with increasing protein (nitrogen) loss, with patients separating into three distinct cohorts, as shown in Figure 4.7
Patients can be grouped into three cohorts: the blue area encompasses patients with high protein losses (≥1.2 g/kg/day), in the yellow area patients with moderate protein losses (0.8-<1.2 g/kg/day) are shown, and the green area depicts healthy individuals (<0.8 g/kg/day).7
Based on these cohorts, three different protein (nitrogen) demand groups can be identified. Healthy subjects and some surgical patients are in the 'normal' nitrogen demand group with a large E/N ratio. Patients admitted to the hospital ward due to elective surgery, cancer, or malnutrition, often belong to the 'moderate' nitrogen demand group. Critically ill patients (e.g. due to trauma, or patients with Crohn's disease) are often in the 'high' nitrogen demand group (Table 1).7
|Patients included*||Nitrogen Demand Group|
|Mostly healthy subjects and some surgical patients||Normal|
|Mostly patients admitted to hospital ward as a result of elective surgery, cancer, or malnutrition||Moderate|
|Critical (intensive) care, patients with trauma, inflammatory bowel disease||High|
*Based upon general classification, individual needs will need to be defined
In 2005, the European Society of Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and ESPEN, supported by the European Society of Paediatric Research (ESPR) published guidelines on parenteral nutrition of pediatric patients.8 ASPEN has also published guidelines on the parenteral nutrition of pediatric patients including enteral and PN for adult and pediatric patients (2002),9 guidelines specifically for the critically ill child (2009),10 and, most recently, parenteral multivitamins and trace elements in adult and pediatric patients (2012).11 Due to the limited availability of clinical studies in this patient group, the ESPGHAN recommendations are largely extrapolated from adult studies, and based on expert opinions.8 Nevertheless, children differ from adults in that their food intake must not only serve for the maintenance of body tissues, but also for growth.
To find out more about the nutritional recommendations for pediatric patients, please see Parenteral Nutrition Guidelines. According to the ESPGHAN guidelines, due to reduced physical activity, a hospitalized older child would have a reduced daily energy expenditure compared with active healthy older children.8 Given the poor reliability of the equations used to estimate energy expenditure in sick children receiving PN, it is important to consider indirect calorimetry, if available and clinically warranted.10 It is also important that body weight is monitored regularly to ensure that energy intake is at an appropriate level. Body weight should be regularly measured, usually daily, during the acute phase of disease or in unstable patients.8
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EUMP/MG17/15-0009 Aug 2015