Doubling Calcium and Phosphate Concentrations in Neonatal Parenteral Nutrition Solutions Using Monobasic Potassium Phosphate

Parenteral Cysteine Supplementation in Preterm Infants: One Size Does Not Fit All

Due to their gastrointestinal immaturity or the severity of their pathology, many neonates require parenteral nutrition (PN). An amino acid (AA) solution is an important part of PN. Cysteine is a key AA for protein and taurine synthesis, as well as for glutathione synthesis, which is a cornerstone of antioxidant defenses. As cysteine could be synthesized from methionine, it is considered a nonessential AA. However, many studies suggest that cysteine is a conditionally essential AA in preterm infants due to limitations in their capacity for cysteine synthesis from methionine and the immaturity of their cellular cysteine uptake. This critical review discusses the endogenous synthesis of cysteine, its main biological functions and whether cysteine is a conditionally essential AA. The clinical evidence evaluating the effectiveness of the current methods of cysteine supplementation, between 1967 and 2023, is then reviewed. The current understanding of cysteine metabolism is applied to explain why these methods were not proven effective. To respond to the urgent need for changing the current methods of parenteral cysteine supplementation, glutathione addition to PN is presented as an innovative alternative with promising results in an animal model. At the end of this review, future directions for research in this field are proposed.

Parenteral Nutrition Overview

Parenteral nutrition (PN) is a life-saving intervention for patients where oral or enteral nutrition (EN) cannot be achieved or is not acceptable. The essential components of PN are carbohydrates, lipids, amino acids, vitamins, trace elements, electrolytes and water. PN should be provided via a central line because of its hypertonicity. However, peripheral PN (with lower nutrient content and larger volume) can be administered via an appropriate non-central line. There are alternatives for the compounding process also, including hospital pharmacy compounded bags and commercial multichamber bags. PN is a costly therapy and has been associated with complications. Metabolic complications related to macro and micronutrient disturbances, such as hyperglycemia, hypertriglyceridemia, and electrolyte imbalance, may occur at any time during PN therapy, as well as infectious complications, mostly related to venous access. Long-term complications, such as hepatobiliary and bone disease are associated with longer PN therapy and home-PN. To prevent and mitigate potential complications, the optimal monitoring and early management of imbalances is required. PN should be prescribed for malnourished patients or high-risk patients with malnutrition where the feasibility of full EN is in question. Several factors should be considered when providing PN, including timing of initiation, clinical status, and risk of complications.

Parenteral nutrition compatibility and stability: A comprehensive review

Several guidance documents support best practices across the stages of the parenteral nutrition (PN)-use process to optimize patient safety. The critical step of PN order verification and review by the pharmacist requires a contextual assessment of the compatibility and stability implications of the ordered PN prescription. This article will provide working definitions, describe PN component characteristics, and present a wide-ranging representation of compatibility and stability concerns that need to be considered prior to preparing a PN admixture. This paper has been approved by the ASPEN Board of Directors. This article is protected by copyright. All rights reserved.

WoCoVA consensus on the clinical use of in-line filtration during intravenous infusions: Current evidence and recommendations for future research

The need for filtering intravenous infusions has long been recognized in the field of venous access, though hard scientific evidence about the actual indications for in-line filters has been scarce. In the last few years, several papers and a few clinical studies have raised again this issue, suggesting that the time has come for a proper definition of the type of filtration, of its potential benefit, and of its proper indications in clinical practice. The WoCoVA Foundation, whose goal is to increase the global awareness on the risk of intravenous access and on patients' safety, developed the project of a consensus on intravenous filtration. A panel of experts in different aspects of intravenous infusion was chosen to express the current state of knowledge about filtration and to indicate the direction of future research in this field. The present document reports the final conclusions of the panel.

Automated system for kinetic analysis of particle size distributions for pharmaceutically relevant systems

Detailing the kinetics of particle formation for pharmaceutically relevant solutions is challenging, especially when considering the combination of formulations, containers, and timescales of clinical importance. This paper describes a method for using commercial software Automate with a stream-selector valve capable of sampling container solutions from within an environmental chamber. The tool was built to monitor changes in particle size distributions via instrumental particle counters but can be adapted to other solution-based sensors. The tool and methodology were demonstrated to be highly effective for measuring dynamic changes in emulsion globule distributions as a function of storage and mixing conditions important for parenteral nutrition. Higher levels of agitation induced the fastest growth of large globules (≥5 μm) while the gentler conditions actually showed a decrease in the number of these large globules. The same methodology recorded calcium phosphate precipitation kinetics as a function of [Ca(2+)] and pH. This automated system is readily adaptable to a wide range of pharmaceutically relevant systems where the particle size is expected to vary with time. This instrumentation can dramatically reduce the time and resources needed to probe complex formulation issues while providing new insights for monitoring the kinetics as a function of key variables.

Probability-based compatibility curves for calcium and phosphates in parenteral nutrition formulations

BACKGROUND

The information content of the calcium phosphate compatibility curves for adult parenteral nutrition (PN) solutions may benefit from a more sophisticated statistical treatment. Binary logistic regression analyses were evaluated as part of an alternate method for generating formulation compatibility curves.

MATERIALS AND METHODS

A commercial PN solution was challenged with a systematic array of calcium and phosphate concentrations. These formulations were then characterized for particulates by visual inspection, light obscuration, and filtration followed by optical microscopy. Logistic regression analyses of the data were compared with traditional treatments for generating compatibility curves.

RESULTS

Assay-dependent differences were observed in the compatibility curves and associated probability contours; the microscopic method of precipitate detection generated the most robust results. Calcium and phosphate compatibility data generated from small-volume glass containers reasonably predicted the observed compatibility of clinically relevant flexible containers.

CONCLUSIONS

The published methods for creating calcium and phosphate compatibility curves via connecting the highest passing or lowest failing calcium concentrations should be augmented or replaced by probability contours of the entire experimental design to determine zones of formulation incompatibilities. We recommend researchers evaluate their data with logistic regression analysis to help build a more comprehensive probabilistic database of compatibility information.

[Neonatal parenteral nutrition prescription practices in Portugal]

INTRODUCTION

The use of guidelines for neonatal parenteral nutrition (PN) improves its clinical efficiency and the safety of prescription.

OBJECTIVE

To evaluate the practices of neonatal parenteral nutrition prescription in Portugal, and the adherence to the National Consensus on neonatal PN (2008).

METHODS

A questionnaire based on a multiple choice response on parenteral nutrition prescription was conducted, and sent to the coordinators of the 50 public and private Portuguese neonatal special care units, 25 being level III and 25 level II.

RESULTS

Parenteral nutrition was prescribed in 32 neonatal units, 23 of which (71.9%) responded to the questionnaire. Of the respondents, 19 (82.6%) refer to follow the National Consensus, the remaining following local guidelines; 17 (73.9%) of units referred to using an electronic based system for prescription. In preterm neonates, most mentioned: administering judiciously the fluid intake during the first post-natal week; starting amino acids from the first post-natal day with 1.5-3g/kg/d, increasing up to 3-4g/kg/d; starting lipids from the first three post-natal days with 1g/kg/d, increasing up to 3g/kg/d; administering 40-70mg/kg/d of calcium and of phosphorus with the fixed calcium:phosphorus ratio of 1.7: 1 (mg:mg); and estimating the osmolality of the solutions, and weekly monitoring of serum triglycerides, blood urea, serum phosphorus and liver function.

CONCLUSIONS

The high response rate is probably representative of the practice of PN prescription in Portugal. Most of the units used the National Consensus on neonatal PN as a reference, thus contributing to better nutritional support for neonates.

Prediction of parenteral nutrition osmolarity by digital refractometry

BACKGROUND

Infusion of high-osmolarity parenteral nutrition (PN) formulations into a peripheral vein will damage the vessel. In this study, the authors developed a refractometric method to predict PN formulation osmolarity for patients receiving PN.

METHODS

Nutrients in PN formulations were prepared for Brix value and osmolality measurement. Brix value and osmolality measurement of the dextrose, amino acids, and electrolytes were used to evaluate the limiting factor of PN osmolarity prediction. A best-fit equation was generated to predict PN osmolarity (mOsm/L): 81.05 × Brix value--116.33 (R(2) > 0.99). To validate the PN osmolarity prediction by these 4 equations, a total of 500 PN admixtures were tested.

RESULTS

The authors found strong linear relationships between the Brix values and the osmolality measurement of dextrose (R(2) = 0.97), amino acids (R(2) = 0.99), and electrolytes (R(2) > 0.96). When PN-measured osmolality was between 600 and 900 mOsm/kg, approximately 43%, 29%, 43%, and 0% of the predicted osmolarity obtained by equations 1, 2, 3, and 4 were outside the acceptable 90% to 110% confidence interval range, respectively. When measured osmolality was between 900 and 1,500 mOsm/kg, 31%, 100%, 85%, and 15% of the predicted osmolarity by equations 1, 2, 3, and 4 were outside the acceptable 90% to 110% confidence interval range, respectively.

CONCLUSIONS

The refractive method permits accurate PN osmolarity prediction and reasonable quality assurance before PN formulation administration.

Surface activity of surfactant spiked with vitamin A

Background

Intramuscular injections of vitamin A decrease the risk of broncho-pulmonary dysplasia. Admixture of vitamin A with surfactant as a lipophilic vehicle might be a less invasive modality.

Aim

Test physical properties of surfactant + vitamin A.

Methods

Miscibility and surface activity were tested in surfactant supplemented with retinyl-acetate, -palmitate, 13-cis-, or all-trans-retinoic acid.

Results

Retinol acetate (5000 IU/mL) demonstrated miscibility with surfactant when premixing with ethanol. Its surface activity was 40% lower compared to surfactant alone.

Conclusion

These findings warrant preclinical studies to test whether administration of vitamin A in subjects requiring surfactant is associated with beneficial functional properties.