## 5 The Role of Commercial Multi-Chamber Bags in Pediatric PN  
PN formulations for pediatric patients can either be individualized, tailored to meet the specific requirements of the patient, or standardized, which may be suitable for a broad range of patients [128; 129]. Individualized PN formulations are prescribed and prepared, usually on a daily basis, in the hospital pharmacy or in specialized compounding centers [129]. Individualized PN has long been regarded as the standard for PN in term infants, infants/toddlers, children, and adolescents. Nowadays there are concerns about hospital-compounded bags regarding the adequacy of nutrient delivery, as well as prescribing and compounding errors [130]. Individualizing PN in pediatric patients entails a large number of calculations, and numerous patient-specific characteristics must be accounted for. It is, therefore, particularly prone to errors, in particular concentration errors, with a reported error rate of 6% in a neonatal/pediatric ICU [131]. It is, moreover, unlikely that an expert in pediatric nutrition is readily available in each center [132]. With standardized PN formulations, in particular with ready-to-use, commercially manufactured multi-chamber bags (MCBs), this problem may be overcome since an expert nutrition care team can order the most common and suitable bags in advance [132]. Commercial MCBs can reduce infection risk, provide an adequate supply of nutrients, support adequate growth, provide ease of use, decrease prescription errors, and potentially reduce costs compared to individually compounded bags [133; 134]. Thus, they can provide important benefits in pediatric patients, particularly in smaller centers where automated compounding facilities are not available. A major advantage of standardized PN bags vs. individualized PN is related to their immediate availability on demand due to easy storage and longer shelf life of approximately 2 years, while individualized formulations cannot be prepared at any time and require highly aseptic conditions, specifically trained staff, and a longer lead time for provision [135; 136]. Indeed, roles for commercial MCBs have been proposed for emergency situations that make it impossible to acquire supplies, such as power failures interrupting the cooling chain or travel, or shortages of single PN components [137; 138]. According to current ESPGNAN/ESPEN/ESPR guidelines [128], standard PN solutions should generally be chosen over individualized PN solutions for the majority of pediatric and newborn patients [128]. Yet, although a wide variety of commercial MCBs are available for adults, these are not optimal for infants and children as their metabolic demands and nutritional needs differ significantly, depending on age, weight, underlying disease, nutritional and hydration status, and environmental factors [3; 129; 139]. Accordingly, standard PN formulations designed specifically to meet the varying nutritional requirements of newborn infants, infants/toddlers, children, and adolescents have been developed and made commercially available [129]. These modern commercial MCBs contain fixed amounts of nutrients conforming to current guidelines, thus enabling an improved compliance with guidelines [128; 136]. These MCBs should contain last-generation ILEs and amino acid solutions adapted for pediatric use. Vitamins must be added to the bag or delivered orally. However, there seem to be pediatric patients whose requirements cannot be met by standard regimes, especially among patients requiring PN for longer periods. As described in the current literature, only a few children receive standard formulas in the HPN setting. According to a large national survey from France, only 0.3 to 7.2% of HPN patients received standardized formulations between 2014 and 2019, mostly during holidays or during the period of the process of weaning from PN [9].