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Incorrect calculation of medication dose leads to baby's permanent disability, $19.2M verdict
By Radha V. Bachman, Esq.
Buchanan Ingersoll & Rooney
Grena Porto, RN, ARM, CPHRM
QRS Healthcare Consulting
News: A woman gave birth to a baby at 24 weeks gestation. Physicians at the hospital ordered that the baby receive parenteral nutrition (PN). The amount to be administered to the child was documented in the child's birth as being calculated according to "standard protocol." For 11 days, the hospital administered the PN solution intravenously without incident. On the 13th day, the dose administered to the child was incorrect and resulted in an overdose. As a result, the child suffered catastrophic injuries, and the child's parents sued. The jury returned a verdict in favor of the plaintiff in the amount of $19.2 million.
Background: At 24 weeks gestation, a baby was born prematurely weighing 685 g. The child was immediately admitted to the hospital's Neonatal Intensive Care Unit with a diagnosis of low birth weight, respiratory distress syndrome, and possible sepsis. A day after birth, a physician order was received stating that the child should receive neonatal parenteral nutrition (PN) via a central venous line. The order sheet identified specific amounts of amino acids, carbohydrates, additives, and fat emulsion components to be included in the PN solution. The order sheet further stated that the vitamins and trace elements to be included in the PN solution were to be calculated by the hospital pharmacy in accordance with "standard protocol." Standard protocol was to be determined using the baby's body weight. For 11 days, the physician orders for the PN solution were updated daily, and the child received the intravenous PN solution without complication. Thirteen days after birth, an updated physician order sheet for the PN solution incorrectly listed the baby's weight as 720 kilograms. On the child's 15th day of life, the amount of vitamins and trace elements in the PN solution were improperly calculated. As a result, the child received an overdose of cysteine, zinc, copper, manganese, chromium, and selenium. The overdose caused the child to develop severe metabolic acidosis and suffer a severe cardiac and respiratory decompensation that required cardiopulmonary resuscitation and an exchange transfusion. Ultimately, the child developed an intraventricular hemorrhage and suffers from permanent injuries.
The child's parents sued the hospital on behalf of the minor and alleged that the hospital was negligent in the treatment of their daughter. Counsel for the plaintiff's argued that immediately following the overdose, the child suffered metabolic acidosis, decreasing pH levels, and cardiac arrest. In contrast to the 13 days prior that she had been receiving PN, on this day the child suffered a brain hemorrhage and other severe injuries.
The hospital conceded that the dosage was wrong but contended that the injuries suffered by the child were not a result of the mistake but rather the child's extreme prematurity. They also contended that based on placental pathology, a severe infection was passed from the mother to the baby in utero. Following delivery, the child's white blood count remained elevated despite antibiotics. Due to lack of growth of the child's head, she was diagnosed as microcephalic.
The child is 3 years old, is confined to a wheelchair, and is required to wear diapers. She is extremely developmentally delayed and requires around-the-clock care.
Plaintiff's counsel submitted a life plan totaling about $5 million. The jury found the defendant negligent and awarded the plaintiffs $19.2 million in total damages.
What this means to you: This tragic case perfectly illustrates the importance of a well-designed medication administration process that incorporates redundant checks and "failsafes" to prevent patient harm. Medication administration is a high risk process that is complex and, therefore, prone to failure. To extract lessons learned from this devastating case, we must first study how the system failed to protect this neonate.
First, the physician made a clearly erroneous entry regarding the baby's weight. He probably intended to write 720 grams, but instead wrote "kilograms," which would have meant that this neonate weighed about 1,584 pounds. It is possible that this mistake was prompted by the common practice of prescribing PN medications in terms of micrograms per kilogram of body weight, or mcg/kg. Thus, with the term "kg" already in mind, the physician inadvertently entered "kg" instead of "g" for the baby's weight.
Even this gross error in documenting the baby's weight should not have led to patient harm, however, if appropriate checks and balances were present and functioned properly. For example, upon reviewing this order, the nurse should have noted the use of "kilograms" rather than "grams" to describe the baby's weights, and this should have set off mental alarm bells. Yet, that apparently did not happen. Why? It is possible that the nurse committed the same mental "slip" as the physician when reviewing the order. It is also possible that the nurse was rushed or distracted when reviewing the order, or that he or she was interrupted when checking the order and thus failed to notice the mistake.
Furthermore, it is possible that none of these factors came into play as the nurse reviewed the order, and that instead "confirmation bias" played a role. Confirmation bias is a common failure of human cognition that causes us to look at something and see what we expect to see. Thus, in this scenario, it is possible that the nurse looked at this order expecting to see grams rather than kilograms and thought he or she saw exactly that.
We also must examine why the system of checks and balances in the pharmacy dispensing process failed. Upon receipt of this order in the pharmacy, it would normally be reviewed by a pharmacist and possibly entered into a computer system with automatic compounding software, which then would calculate the appropriate dose based on patient weight. Any questions or concerns about an order would normally be brought to the attention of the ordering physicians, and these would have to be addressed to the satisfaction of the pharmacist before he or she would approve the order for dispensing.
Why didn't this occur in this scenario? Again, we are left to speculate about what happened. Is it possible that the reviewing and dispensing pharmacist and/or pharmacy technician failed to appreciate the use of kilograms rather than grams? If automated compounding software was used, why did it generate no alert for this excessive dose? Furthermore, why did the pharmacy technician or pharmacist preparing the PN fail to notice that properly preparing the PN required multiple vials of highly toxic substances, a phenomenon that usually points to a dosing error in a pediatric patient? Were they excessively busy, understaffed, or just plain tired? Or, did this hospital pharmacy use larger vials that "masked" the excessiveness of the dose? Did everyone involved have appropriate training in the handling of PN and, just as importantly, in how to correctly perform an independent double check?
Although there are many unanswered questions in this scenario that prevent us from drawing definitive conclusions about what might have occurred, we can still extract some lessons learned by looking at similar errors. The Institute for Safe Medication Practices (ISMP) web site contains a detailed account of a similar error that may be useful for this purpose (ISMP Medication Safety Alert, Sept. 6, 2007. Web: ismp.org). In that case, PN was ordered for a baby born at 26 weeks gestation. The order included the addition of zinc to the PN, the dose of which was expressed in mcg/100 mL. However, the automatic compounding software required the order to be entered in terms of mcg/kg dose. The pharmacist had to manually convert the mcg/mL dose into mcg/kg, and in so doing, she accidentally wrote "mg" instead of "mcg." The PN bag then was checked by another pharmacist, who likewise failed to appreciate the conversion of "mg" to "mcg" by the original pharmacist, perhaps to due confirmation bias.
In addition, the 1,000-fold dose required the pharmacy technician who prepared the PN to use multiple vials of zinc many more than normally would be used yet this did not raise concerns in the mind of the technician and was not identified as a possible error until a change-of-shift review of the work. Thus, although the pharmacy technician viewed the dispensing process as unusual enough to mention to the oncoming technician at the end of the shift, he or she did not raise any concerns to the pharmacist at the time of dispensing. The result of this cascade of errors resulted in a 1,000-fold overdose, which led to the baby's death.
More recently, ISMP reported another case of a PN error involving a newborn (ISMP Medication Safety Alert, April 21, 2011). In that case, an infant had been born prematurely but thriving at 6 weeks was receiving PN. The physician prescribed a total of 14.7 mEq of sodium chloride and 982 mg of calcium in the infant's PN. The order was faxed to the pharmacy after midnight, at which time a pharmacy technician made an error when entering the order into automated compounder software. The technician accidentally entered the prescribed dose of calcium ("982" mg) into the mEq field for sodium. The technician then prepared the PN, which contained a total of 982 mEq of sodium, using an automated IV compounder. The technician affixed the printed label to the PN, which showed the erroneous sodium content. Unfortunately, the error was not detected when a pharmacist checked the final product. Furthermore, a different label that listed the sodium content as 14.7 mEq, the originally prescribed amount, was applied directly over the label produced by the compounder software that had listed the actual amount of sodium (982 mEq) in the solution. Thus, the nurse who eventually started administration of the PN solution was unable to detect the error. A few hours after the PN was started, routine lab studies showed that the infant's sodium level was abnormally high. The infant's physician assumed the study results were inaccurate and asked for the lab test to be redone. This lab test was never accomplished before the infant experienced a cardiac arrest and died.
Even without benefit of all of the facts in the original case mentioned above, we still can apply the systems solutions identified by ISMP:
Standardize the prescribing methods.
Standardize the method of ordering PN solutions (and other routinely compounded solutions) for neonates, pediatric patients, and adults, so that each prescribed ingredient matches the dosing templates used for entering the orders into the computer system and automated compounder. Use preprinted forms or standard order sets that list typical ingredients and prompt the correct dosing method. On the rare occasions that calculations are necessary, require two clinicians to calculate the dose independently and compare their answers for verification.
Prescribe and transmit PN orders during the day.
Policies that require prescribers to order PN daily during the day shift should be established and enforced to maximize the safety with which these solutions are prepared and dispensed. Pharmacy staff should be aware of patients who are receiving PN and check if orders have not been received by the established time.
Allow manual-only additions of low-volume ingredients.
For PN ingredients that typically require very small volumes, require staff to prepare, check, and inject those ingredients manually. Do not allow a trace element such as zinc to be loaded on a compounder for automated preparation.
Build, test, and heed automated warnings.
Install, test, and maximize automated dose-limit warnings in the pharmacy computer system and automated compounders, particularly for high-alert medications such as PN and its ingredients. Baxa, an automated compounder vendor with a large share of the hospital market, allows users to add soft warnings and hard stops if a dose limit is breached when entering an order. The company's more recent compounder software has "catastrophic" limits that stop the process completely when 100-fold or 1,000-fold overdoses caused by decimal point errors or mcg to mg selection errors occur.
However, DO NOT rely solely on the catastrophic dosing limits established by software vendors. Vendor-established dose limits, such as the Baxa Only Warning Limits, still will allow a potentially fatal dose to be entered into the software without issuing a warning. Organizations need to define more restrictive weight-based dosing limits applicable to their patient populations. These warnings should function as a hard stop without the ability to proceed until the dose has been reviewed via a peer review process.
Organizations also should print all alerts encountered during the order entry process so the person checking the order entry also can view and respond to the alerts. Reinforce the importance of reacting to the alerts with all staff. Print all alerts encountered during the order entry process so the person checking the order entry can also view and respond to the alerts. Reinforce the importance of reading and reacting to the alerts with all staff.
Heighten the suspicion of an error.
Continually emphasize that the following should trigger a full review of the patient's medications and treatment plan to ensure an error has not occurred:
the need to use more than a few dosage containers (whether it be tablets, capsules, vials, ampuls, etc.) to prepare or administer a single dose of any medication;
unexpected differences in the appearance of medications or solutions;
other unusual circumstances regarding a medication or solution;
unexpected patient response to a medication.
Technicians who compound products should be required to stop the process if they encounter situations which they need to add an electrolyte or mineral in large doses or in large volumes to complete a single preparation. A full review of the work label and order by a pharmacist should be required before proceeding. Nurses who work in pediatric and neonatal units should question products that are dispensed in larger quantities than typically supplied for children or neonates. Create a culture that encourages all staff, despite their level of experience or education, to speak up about unusual conditions.
Carry out effective redundancies.
Several verification processes should occur in the pharmacy:
before order entry into the automated compounding software to verify that the PN order is appropriate for the patient (e.g., based on weight, height, disease state, and lab values);
after initial order entry into the automated compounding software to match it to the verified order;
before injecting any additives that must be added manually;
once the PN has been compounded.
Verification of manual additives should include inspection of the actual vials and filled syringes prior to admixture. The "pullback" method is not recommended. Final verification of the compounded PN should include review of the original order, product label, and work label, as well as comparison of the expected weight/specific gravity with the actual weight/specific gravity. If different than expected or off by 3% or more, the product should be prepared again. If PN compounding is outsourced, a pharmacist should verify the appropriateness of the order before sending it to the pharmacy and verify that the product received matches the verified prescriber order. Before administering PN, nurses also should independently compare the label on the solution with the physician's order.
Label products and use critical thinking skills.
Produce product labels and associated work labels used by pharmacy staff to compound solutions that include the actual dose/strength of the base solution and each additive, not just the volume amounts needed to prepare the products. Encourage technicians who compound products to focus not only on the volumes needed to prepare the solution but also on the dose of the additives and the concentration of the solutions. Apply easy-to-read labels that print from the compounder order entry system to compounded products to ensure the label lists the actual contents. The label format should follow the prescriber's order.
Provide education and validate competency.
Establish a formal training process for pharmacy staff who are required to enter PN orders into the pharmacy computer, compound the solutions, or check the products after preparation. Designate and train specific staff members to function as preceptors and provide one-on-one supervision until trainees are comfortable providing the service and have demonstrated the skills and knowledge necessary to function independently. Training should focus on dose and dose concentration, not just the volume of additives, when preparing the solutions.
If compounding services are provided for neonatal and pediatric patients, include age-specific training emphasizing weight-based dosing, and validate the competency of all staff who serve the pediatric population. Develop learning modules and competency validation tools to expose trainees to a broad spectrum of responsibilities that they might not encounter during their on-the-job orientation. Plan adequate staffing with trained practitioners to cover vacations, illnesses, and other causes of planned and unplanned absences. Establish guidelines for closer supervision of work if emergency coverage with an inexperienced staff member is necessary.
Florida Circuit Court, Twentieth Judicial Circuit, Lee County, Case No. 09-CA-003963.