Development and evaluation of VIE-PNN, a knowledge-based system for calculating the parenteral nutrition of newborn infants

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Abstract

Calculating the daily changing composition of parenteral nutrition for small newborn infants is troublesome and time consuming routine work in neonatal intensive care. The task needs expertise and experience and is prone to inherent calculation errors. We designed VIE-PNN (Vienna Expert System for Parenteral Nutrition of Neonates), a knowledge-based system (KBS) in order to reduce daily routine work and calculation errors. VIE-PNN was redesigned several times because the clinicians accepted the system only when it saved time. The most recent version of VIE-PNN uses an Hypertext Markup Language (HTML)-based client–server architecture and is integrated into the intranet of the local patient data management system. Since more than 3 years all parenteral nutrition plans are calculated using VIE-PNN. Evaluating the system’s performance and the users contentedness, we compared 50 nutrition plans calculated in parallel using VIE-PNN or a hand-held calculator, retrospectively analyzed more than 5000 nutrition plans stored in VIE-PNNs database and evaluated a user questionnaire. Nutrition plans were calculated in a mean time of 2.4 versus 7.1 min using VIE-PNN or the hand-held calculator. Errors and omissions in the nutrition plans were detected in 22% versus 56% and errors in the VIE-PNN’s plans occurring only with interactively changed values. Reviews of stored plans show that a mean of 4 out of 16 parameters were interactively changed. VIE-PNN was well accepted. Most important reasons for the successful operation of VIE-PNN in the daily routine work were time savings and robustness of the system.

Introduction

The planning and calculation of an adequate nutritional support for meeting the metabolic requirements of sick or premature neonates is an important daily routine task. It is time consuming, needs practical expert knowledge and experience, and involves the risk of introducing possibly fatal errors [5], [7], [15], [16]. The daily time required per patient is approximately 10 min summing up to more than 1 h for a eight beds neonatal intensive care unit (NICU). Approximately 5–50% of all parenteral nutrition solution (PNS) sheets contain calculation or omission errors requiring recalculation or even remixture of the nutrition solution. This is costly and requires additional time of physicians and nurses.

Computer programs supporting the calculation of parenteral nutrition plans are available at a few hospitals. Most of them are designed for adult or pediatric use (e.g. [10], [14]) without giving specific consideration to the specific needs of newborn infants. There are a few pediatric programs for parenteral nutrition planning covering also the group of newborn and premature infants [6], [11], [12].

Such programs, however, do not cover the specific metabolic and nutritional needs of extreme low birth-weight newborn infants (birth-weight: 500–1000 g). Only a few programs were specifically tailored for the needs of small newborn infants: there are simple calculation programs [2], [3], [8], [11] and more complex rule- and knowledge-based systems (KBSs) [4], [6]. Both types of programs reduce the routine work load, and lead to a more optimized nutrition supply. Most systems are tailored to the needs of a specific NICU, and their portability to other units is very limited because of differences in the clinical approach (policy of fluid supply, speed of increments, inclusion or exclusion of various minor nutrients, exactness of calculations, availability of various solutions and brands, etc.).

We designed VIE-PNN (Vienna Expert System for Parenteral Nutrition of Neonates) aiming to create a program for the routine support of our NICU combining standard textbook knowledge about neonatal nutrition with the practical knowledge of expert neonatologists.

In the year 1991, we started the implementation of VIE-PNN with the following main goals:

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    creating an interactive support system for calculating the daily nutritional plans (parenteral nutrition solution, PNS);

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    reducing the time needed for the calculation;

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    creating a system able to combine parenteral and enteral feedings;

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    providing a continuous increase of the daily nutrition supply and a forced change from parenteral to oral nutrition; this requires reasoning methods taking into account the data of the previous days;

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    output of a printed PNS schedule to become part of the case history. The PNS schedule is further used by the nurses to compose the daily mixture of the nutrition solution;

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    maintaining the hospital’s standard for neonatal nutrition management and providing adequate control of fluid, electrolyte, fat, nitrogen, and caloric needs. The standard is defined in terms of rules of expert neonatologists and

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    enabling the experts to keep the rules up-to-date.

Section snippets

The VIE-PNN system

VIE-PNN consists of three main modules: patient administration, computation of the daily PNS schedule, and maintenance of the knowledge base. Patient administration is needed for adding new patients (name, sex, date of birth, venous access) and for archiving the data of discharged infants. The maintenance module supports editing of nutrition rules, parameter limits, rounding factors, and updating of oral nutrition preparations.

The main module of VIE-PNN interactively calculates the daily PNS

Integrating VIE-PNN into the clinical intranet

The negative experiences with the stand-alone version of VIE-PNN motivated us to try a completely different approach. The NICU is equipped with an intranet of workstations. The workstations (two mirrored servers, a bedside workstation for each bed, and several workstations in the nurses’ and the physicians’ rooms) run the patient data management system (PDMS) Hewlett-Packard CareVue 9000. All patient records are handled electronically by this PDMS. Our goal was to integrate VIE-PNN into this

Routine use and evaluation of VIE-PNN

We installed the client–server intranet system of VIE-PNN at the NICU by end of June 1996. It was immediately accepted by the physicians of the NICU. Only a few minutes of initial training were required. After 2 years of successful operation, VIE-PNN was installed at a second NICU of the University of Vienna Medical School. VIE-PNN is now in continuous operation at these two NICUs. It calculates approximately 5000 nutrition sheets per year. There are no more PNS sheets calculated by hand. We

Discussion

The success of the HTML-based system has to be explained mainly by the ease of use and the benefits in terms of time savings and accuracy. Similar benefits were reported by Puangco et al. [13].

Comparing the stand-alone PC version and the client–server version there are no essential changes of the program flow and the knowledge used. Even the final printout of the PNS schedule is the same. Identifiable factors adding to the success of the HTML-based version are as follows.

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    VIE-PNN runs in the

Lessons learned

VIE-PNN is a KBS which solves a time-consuming problem in daily routine. It is less the amount and complexity of the knowledge covered which makes it a success, but its ability to implement practical clinical knowledge in the daily routine.

From this success story, we have learned the following.

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    A system containing textbook and clinical knowledge may be a success even if physicians do have that knowledge at hand. Our experience shows that successful KBS are not restricted to complex domains of

Acknowledgments

We greatly appreciate the support given to the Austrian Research Institute of Artificial Intelligence (ÖFAI) by the Austrian Federal Ministry of Education, Science and Culture.

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