Physicians can now rely on the pharmacist’s expertise when managing total parenteral nutrition in patients
Pharm D PhD
APHP Hôpital Robert
Faculté de Pharmacie
Managing infants, children and adolescents, ranging from premature infants to 18-year old adolescents, on total parenteral nutrition (TPN) is a challenge. Nutritional requirements differ according to age, and unlike adults, endogenous nutrient reserves are limited in the young paediatric population and can be rapidly depleted by the metabolic stresses from surgical procedures or disease. A lack of adequate nutrition can have significant long term and short-term consequences such as immunosuppression, impaired tissue and muscle function, reduced respiratory and cardiac reserve, and impaired growth, particularly in very-low-birthweight infants.
In clinical practice, there are difficulties in establishing enteral feeds in preterm infants because of the immaturity of the gastrointestinal function, episodes of abdominal distension with presumed gastroesophageal reflux intolerance to early enteral nutrition and concerns regarding development of necrotising enterocolitis. Furthermore, there has been no greater advancement in managing intestinal failure than the use of TPN. Nevertheless, studies suggest that TPN practice is not optimal, and there are wide variations in practice among the various neonatal units around the world.
Unsatisfactory TPN practices are linked with limited knowledge of children’s nutritional needs. Some studies suggest that physicians’ mean learning about neonatal nutrition is inadequate. Therefore, a pharmacist involvement in a nutritional support team (NST) could explain the importance of nutrition and ensure there is adequate provision in all TPN regimens.
TPN admixtures are by far the most elaborate pharmaceutical preparations to be extemporaneously compounded each day. They are often given to the most seriously ill hospitalised patients and the specific needs of children make each TPN order unique in its composition. Moreover, risks are associated with this form of nutrition support so a high level of knowledge and expertise is required in the management of these patients.
Because of the lack of published scientific evidence to strengthen good practice related to ordering, compounding and administering TPN, Seres et al studied the discrepancies between reported practice and the Safe Practices for Parenteral Nutrition guidelines published by The American Society for Parenteral and Enteral Nutrition.
Physicians responsible for patients’ care were identified in 78% of TPN ordering. Several problems with the TPN ordering process were identified. Physicians reported variability in the ordering process. For example, there was a significant lack of consistency between the ordering methodology for base components, electrolytes and other additive components. The three most common interventions made by the pharmacists and the NSTs, which were heavily involved in the orderwriting process, were illegible writing, the omission of essential nutrients, and incorrect or unstable macronutrients.
NSTs generally consist of a clinician responsible for nutrition policy and prescriptions, a nurse, a dietitian and a pharmacist responsible for the formulation and preparation of parenteral feeds. The multidisciplinary team approach is seen as crucial in its ability to assess the patient’s nutritional status and prescribe the nutritional requirements.
There is growing evidence that the presence and activity of NSTs reduces the risk of prescribing inappropriate TPN formulas, reduces the costs associated with line infections, decreases metabolic complications and optimises the choice of the most appropriate feeding.[8,9]
In 1989, Driscoll stated the following: “As a member of the NST, the pharmacist plays a critical role in the provision of sterile admixtures, compatible nutritional formulations and cost-effective, therapeutically equivalent strategies.” Indeed, at the formulation stage, the hospital pharmacist must ensure both a germs-free environment and good aseptic technique (ie, laminar air flow cabinet, isolator). Pharmacists have to determine the compatibility and the stability of the mixture so that the prescription can be converted into a working formula, incorporating the most suitable ingredients, to ensure a stable and compatible mixture. One of the most lethal consequences of mishandling TPN admixtures is the formation of rigid and crystalline coprecipitates of calcium and phosphorus. It is important also that the pharmacist ensures the proper doses of nutrients are provided in order to avoid feeding- related complications. In children, overfeeding can be as harmful as not providing nutritional therapy.
Although the formulation and composition of parenteral feeds is the basis of the pharmacists’ function, involvement at every stage will ensure the smooth and efficient operation of artificial nutrition services. For example, by involving the pharmacist during patient assessment and the prescribing process, a number of important issues can be considered.
Two studies, both conducted in the US, specifically compared the use of a standardised TPN formulation with a pharmacist-assisted individualised programme of TPN in paediatrics. Mutchie et al found a significantly greater mean weight gain (17g/day) in the individualised group than the standardised group (4g/day). Dice et al reported that pharmacist monitoring of an individualised programme of TPN in neonates provided a greater mean daily weight gain, allowed a greater amount of nutrients to be provided and was cost-effective compared with the standardised solution without pharmacist monitoring.[10,11,12]
The success of the multidisciplinary approach in nutrition support within hospitals is well documented. Since the recommendations in 1992, more than a third of UK hospitals now have NSTs.
In their recent study, Maisonneuve et al describe hospital pharmacists’ practices in France, Switzerland and Belgium concerning TPN. NSTs were present in 45%, 33% and 42% of Swiss, French and Belgian hospitals, respectively. In Switzerland, 11% of NSTs did not include a pharmacist. NSTs were mainly in charge of developing TPN administration guidelines and choosing the TPN product in 80-90% of Swiss and Belgian hospitals. In France, NSTs also were involved in TPN prescription and in the follow-up of patients under TPN. In all countries, TPN administration was initiated mostly by the physician responsible for the patient. TPN prescriptions were checked more frequently by pharmacists in France (60%) and Belgium (66%) than in Switzerland (16%). However, their function in the direct management of TPN administration remained marginal everywhere except in France.
It seems clear that pharmacists need to be readily available on the ward at any time. Many studies showed the importance of a clinical paediatric pharmacist in detecting and preventing medication errors.
As Faber mentioned in 1991, and McDermott described in 1994, a way to increase staff pharmacists’ involvement in nutritional support and physician prescribing includes specialised training for staff pharmacists. All TPN patients were pharmaceutically monitored as pharmacists attended nutritional support rounds. Interventions and pharmacists’ involvement in the drug-usage evaluation process were recorded. The results of the increased influence of pharmacists on the prescribing process included more appropriate TPN therapy, earlier switch from parenteral to enteral nutrition, recognition of staff pharmacists as resources by the physicians and increased job satisfaction for pharmacists.[13,14]
Nowadays, computer software is being developed to assist pharmacists in the complex and time-consuming task of prescribing and preparing TPN in neonates. The software has proved its utility in improving nutritional care and effecting greater safety, accuracy and efficiency in the day-to-day clinical routine.[6,15]
For many clinical pharmacists, Greenlaw’s study in 1979 is still an objective: the pharmacist as the team leader of the TPN programme. To initiate TPN therapy, the attending physician requests a pharmaceutical consultation. Before initiating TPN, the pharmacist reviews the charts, performs a physical and nutritional evaluation of the patient, may order laboratory tests and then define the patient’s nutritional status. Then, the pharmacist orders all TPN-related matters, including laboratory tests and nursing care. Physicians who used to avoid TPN for their patients because of their lack of knowledge or the absence of a TPN consultant, can now rely on the pharmacist’s expertise for this service.
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