Safety Alert Abacus™ TPN Calculation Software - Baxa

20 January 2009
Safety Alert
Abacus TPN Calculation Software
Manufactured by Baxa Corporation
Overview
A number of medication errors have been reported by Abacus Software users as a result of
the confusion surrounding ordering salt-based parenteral nutrition (PN) ingredients on an ionbased
ordering template. One example is the ordering of calcium gluconate on an ion-based
template, which is detailed below. The problems associated with this practice, however, are
not exclusive to calcium gluconate.
Abacus TPN Calculation Software is designed and intended to allow ordering electrolytes in
only one of two ways:
1. As a salt (e.g., calcium gluconate 10%),
2. Or, as an elemental ion (e.g., calcium)
Continuing the calcium gluconate example, it is therefore possible to order the electrolyte
either in milligrams of calcium ion or milligrams of the calcium gluconate salt. For example,
ordering 500 mg of the 10% calcium gluconate salt will result in 5 mL of 10% calcium
gluconate. By contrast, ordering 500 mg of the calcium ion will result in 53.76 mL of 10%
calcium gluconate.
Recommendation
Due to the complexity of TPN order entry, Baxa recommends that users create individual
templates for salt-based ordering, OR for ion-based ordering. Currently, this
recommendation is emphasized during the initial installation of the Abacus TPN Calculation
Software.
Baxa does not recommend allowing salts to be ordered on an ion-based template,
because of the potential for an error and an unintended dose of the target ingredient.
In addition, please consider the following safe practices and the excellent list of safe
practices on the enclosed ISMP Safety Alert: 1
1 Provide detailed training and continuing education to pharmacists and pharmacy
technicians with emphasis on the differences between ion-based versus salt-based
ordering.
2 Establish clear and expected volumes for calcium gluconate and for ionic calcium so
that they can be checked and double checked prior to administration.
3 Check and double check calcium gluconate volumes on every order (especially
where templates allow both ions and salts to be used).
4 Establish ingredient warning limits in Abacus specific to your pharmacy. Have a
pharmacist sign off if a warning limit is exceeded.
5 Check the CalPhos curves in Abacus to ensure that calcium and phosphate are in
balance.
1 Reprinted with permission from the Institute for Safe Medication Practices, December 2000.

Reference 2
Page 2 of 4
Ordering Ions by Weight
The Abacus Software has inherent knowledge of ion properties, and it uses this knowledge to
translate the molar concentration to the equivalent gram weight of the ion that is delivered by
a salt. Using calcium gluconate 10% as an example, if the user requests that 100 mg of the
product be delivered, Abacus will multiply the 0.465 mEq/mL times the molecular weight of
calcium divided by its valence to arrive at the milligrams of ELEMENTAL calcium that will be
delivered per mL.
0.465 mEq/mL x 40.08 mg/mMol / 2 (valence) = 9.3 mg of Ca++/mL
Note: This is not the number of milligrams of SALT per mL of solution.
Users cannot order the amount of a salt in an ion-based formula, because the software will
convert the millequivalent concentration to the amount of the elemental ion. Therefore, if 100
mg/kg of calcium is ordered in the above example, the software will calculate the dose to be
10.75 mL of calcium gluconate solution per kilogram of body weight.
2 Abacus Operator Manual, page 137
Identification of Risk
To check your facility’s ordering practices, review the TPN order forms. If all electrolytes
(e.g., chloride, potassium, acetate, sodium, etc.) are listed as ions except calcium, which may
be listed as calcium gluconate, the Abacus software may be configured to allow the ordering
of salts on an ion-based template. Below is an example of this type of TPN order form:
Ordered
Normal
Drug Amount Unit Requirements
Sodium mEq/Kg 2 – 8 mEq/Kg
Potassium mEq/Kg 1.5 – 6 mEq/Kg
Calcium Gluconate mg/Kg 100 – 500 mg/Kg
Chloride mEq/Kg 1 – 4.5 mEq/Kg
Phosphate mM/Kg 1 – 3 mM/Kg
Magnesium mEq/Kg 0.25 – 1 mEq/Kg
NOTE: One possible indicator that a template allows a combination of salt- and ion-based
ordering is that ion-based ordering is in milliequivalents and millimoles of the ion while saltbased
ordering is in milligrams of salt. In the above example, calcium gluconate is ordered in
milligrams/kg.
If you suspect that your facility is using an ordering practice that is not recommended, check
your Abacus Formulary Ingredient Detail. The Abacus Administrator can determine this
software configuration by performing the following steps:
1. Log in to Abacus.
2. Access the “File � Formulary…” menu item.
3. Click on the calcium gluconate formulary item (for ion-based ordering it should look
similar to the screen shot on page 3).
a. Abacus uses the values in the attribute fields to perform ion balancing calculations.
b. For either ion-based or salt-based ordering, the Ion Attribute Value must be entered
correctly for all electrolytes.
c. In either ordering method, the Ion Attribute Value must be equal to the amount of
elemental calcium (or magnesium, potassium, etc.) contained in the source
ingredient.

Drug Concentration
must be correctly
entered here �
Page 3 of 4
i. For the most common commercially available calcium gluconate the
value to be entered in the attribute value field is one of the following:
1. 0.465 mEq/mL
2. 9.3 mg/mL
ii. The value entered here should NOT be the concentration of salt
contained in the calcium gluconate (i.e., it should not equal 100mg/mL).
Warning: These values may be different for the electrolyte in use at your facility. To
ensure safe practice, review and use the values provided by the drug manufacturer.
Ion Attribute
Value must be
correctly entered
� here
d. In either ordering method, the value for drug concentration in Abacus may be
practice-specific.
i. Abacus uses values in the concentration field to calculate based on
ingredient concentration and unit of measure.
ii. If your facility orders calcium gluconate by milligrams then the ingredient
concentration must be equal to the manufacturer’s value for calcium
gluconate in milligrams per milliliter (e.g. approximately 100 mg/mL).
iii. If your facility orders calcium gluconate by milli-equivalents then the
ingredient concentration must be equal to the manufacturer’s value for
calcium gluconate in milli-equivalents per milliliter (e.g. 0.465 mEq/mL)
Conclusion
It is easier than you may think to commit a dosing error, as reported incidents have
shown and the enclosed example demonstrates. This ISMP Safety Alert shows one example
of how ordering “calcium as gluconate” on an ion-based order can lead to a serious dosing
error (i.e., a tenfold or greater overdose).
This Safety Alert is intended as a reminder to you regarding the potential for these serious
types of errors, and to provide a recommendation for the best practice in safe compounding.

Page 4 of 4
If your Abacus TPN Calculation Software has been set up to allow the ordering of salts on an
ion-based template, please contact Baxa Technical Support (800-678-2292). Technical
Support for the Abacus TPN Calculating Software is available 24 hours a day, 7 days a week.
As always, contact Technical Support if you have any questions or require further assistance
with your Baxa hardware and software products.
Sincerely,
Patrick Hynes
VP Global Quality
Baxa Corporation
303-617-2121 Office
pat.hynes@baxa.com

Baxa Corporation Setup Verification Form
Please provide feedback on your current calcium and magnesium configurations to allow Baxa Technical Support
to determine and address any issues with your setup. Perform the steps below, complete this form and return it
to Baxa as soon as possible.
To do this, open your formulary using the instructions below and log the concentration and attribute value for each
calcium and magnesium ingredient. A screen shot of the formulary appears below.
1. Go to File � Formulary.
2. Single click on the first calcium ingredient.
3. Complete the information on the table below for the ingredient, and repeat for all instances of calcium and
magnesium in your formulary.
Ingredient Name Concentration Attribute Value
e.g., Calcium Gluconate 0.465 mEq/mL 0.465 mEq/mL
Your signature below acknowledges your receipt and understanding of this Safety Alert. It is your responsibility to
communicate this information to other users of the Baxa Abacus Software.
Printed Name Signature
Title/Date Facility Name
City/State Zip/Postal Code
Thank you for providing this information, which will help us update your system, if necessary. Return this form to
Baxa Corporation by fax attn: Anne Szilagy (303.690.4804), email (quality@baxa.com) or in the enclosed
business reply envelope.

ART IMITATES LIFE! ERROR PORTRAYAL REALLY HAPPENED
From the December 13, 2000 issue
PROBLEM: The opening general session at the recent ASHP Midyear Clinical Meeting in Las Vegas featured a
dramatic production that focused on a medication error and its wide-ranging effects on the patient, his family, and
the involved healthcare professionals. In "Anatomy of an Error," a pediatric patient received an overdose of IV
calcium gluconate. The drug was ordered as "calcium gluconate 1,200 mg." However, a seasoned pharmacist
prepared 1,200 mg of elemental calcium (nearly 130 mL using 10% calcium gluconate injection). Some in the ASHP
audience probably wondered how anyone could overlook such a large dose of calcium for a pediatric patient.
Coincidentally, just a few days prior to the meeting, an actual medication error report reached us that closely
resembled the dramatic presentation. In the actual incident, a 2-day-old infant with a serum calcium of 6.7 was
ordered "calcium gluconate 400 mg IV." Package labeling on the vial is a set-up for confusion. One label we recently
examined stated "0.465 mEq Ca ++ /mL" in bold print on the front of the label but also stated, "each mL contains
calcium gluconate 94 mg" in the fine print on the back. The label further mentioned "9.3 mg Ca ++ /mL" in bold in
another spot on the label. The nurse confused this statement about the mg amount of elemental calcium with the
mg amount of the salt, calcium gluconate. For the 400 mg dose of calcium gluconate that was ordered, she divided
it by 9.3 and calculated that she needed 43 mL. A 50 mL vial of calcium gluconate (approximately 1 g/10 mL) was
removed from a crash cart and 43 mL (approximately 4 g of calcium gluconate or 20 mEq of calcium ion) was
administered to the infant instead of around 4 mL or 400 mg. There was an immediate deterioration of the infant's
condition, but fortunately, as in the ASHP drama, the infant survived the error.
It is easier than you may think for staff to become confused by product labeling. Variations in the way prescribers
express the dose of calcium gluconate can also lead to dosing errors. Some prescribe the drug as mg of elemental
calcium while others express the dose in mEq of elemental calcium. Still others prescribe the drug in terms of
calcium gluconate and others in terms of volume and percent concentration (e.g., 10 mL of a 10% solution). The
lack of a standardized method for expressing doses of calcium gluconate (and calcium chloride), and the lack of a
standard dose expression in labeling, increases potential for serious medication errors.
SAFE PRACTICE RECOMMENDATION: The dosage of parenteral calcium should be standardized at each practice
site and based on the amount of elemental calcium rather than the mg strength of the salt. Develop protocols for
the use of electrolyte solutions, including calcium gluconate, to address proper dose expression in mEq of elemental
calcium, dose limits, labeling methods, infusion rates, and necessary monitoring parameters. Require independent
double checks of all calculations and dose preparations for concentrated electrolytes or electrolyte solutions.
Minimize the vial size (no 50 mL vials) and quantity of calcium gluconate available in patient care areas, including
storage in crash carts and automated dispensing cabinets. Whenever possible, have all IV infusions prepared in the
pharmacy. If calcium supplements must be a part of floor stock, use auxiliary labels that clearly state the total
contents of calcium (in mEq). In hospitals without 24-hour pharmacy service, a "night formulary" should be created
which allows minimal amounts and volumes of medications to be available for use after hours. Specific directions for
preparation of electrolyte solutions should be provided. On-call pharmacists should be contacted for any medicationrelated
questions. Each morning, pharmacy staff should immediately reconcile all drugs removed from the night
cabinet via comparison against the physician's orders. Educate the staff about the proper dosing of calcium during
orientation and through continuing education.
© 2009 Institute for Safe Medication Practices. All rights reserved