SWEET REWARD: REDUCING ERRORS WITH IV INSULIN

This article appeared in the "ISMP MEDICATION SAFETY ALERT," Volume 3, Issue 23, November 18, 1998, published by the Institute for Safe Medication Practices (ISMP). Reprinted with permission.

PROBLEM: An ISMP study revealed that 11% of serious medication errors involve insulin misadministration (Cohen MR, et al., "Survey of Hospital Systems and Common Serious Medication Errors." "J Healthcare Risk Management" 1998; 18(1):16-27). Errors occur when insulin is mistakenly administered in place of other medications or when an overdose is given. We recently received four reports of both such error types. Two involve dose misinterpretations when using the abbreviation "u" for "units."

When a dietitian wrote an order to add "10U of regular insulin to each TPN bag," the pharmacist preparing the TPN misinterpreted the dose as 100 units.

In a similar case, a new pharmacy technician entering orders misinterpreted a sliding scale when insulin was ordered using "u" for units. Although the pharmacist checking the technician's order entry did not detect the error, a nurse intercepted the ten-fold overdose while reviewing the computer generated MAR.

The other two errors occurred when staff suffered a mental lapse and confused insulin with other products. In the first case, a verbal order to resume an insulin drip was transcribed incorrectly by a nurse as "resume heparin drip." A pharmacy technician entered the order and labeled a premixed heparin solution. The pharmacist caught the error when he noticed a flow rate of 1.5 units/hour and recognized the patient's name from a recent call for help calculating an insulin flow rate.

The other error resulted in significant patient harm when a double concentration of a critical care drug was ordered for a cardiac patient in ICU. A nurse called the pharmacy and inadvertently requested a double concentration of insulin. During order entry, the pharmacist failed to notice that diabetes mellitus was not listed as a patient diagnosis. Then, without seeing a copy of the order, he prepared and delivered the insulin infusion. While in ICU, he also did not obtain a copy of the order or review the patient's chart to verify hyperglycemia. When the nurse hung the insulin, a second nurse did not independently verify the drug, concentration, infusion rate and line attachment. No prominent cautionary labeling was present on the infusion to alert the staff that it contained insulin. The double concentration of insulin was administered at the rate intended for the critical care drug. The patient suffered permanent CNS impairment.

SAFE PRACTICE RECOMMENDATION: Insulin is a high alert medication with serious risk of causing injury when errors occur. As such, special safety considerations are essential. The first two errors described above are clear examples of the need to educate all practitioners, including dieticians and others who may communicate drug information, to always write out the word "units." The last two errors demonstrate the likelihood of mentally mixing-up products that are routinely used, especially if both are measured in units, such as heparin and insulin. Thus, measures must be implemented to make these errors visible. Verbal orders should not be accepted for IV insulin. Instead, orders should be faxed when the prescriber is off-site. If no other alternative exists, emergency telephone orders should be accepted with a second person listening, transcribing the order directly onto an order form and repeating it back for clarification. Also contributing to the last error described above, the standard insulin concentration (0.25 units/mL) used in this hospital was quite low. Using a concentration of 1 unit/mL can eliminate the need for most double concentrations, making such orders unusual and subject to scrutiny. Assure that all insulin infusions are prepared in the pharmacy. Insulin must never be dispensed or administered without an independent check, using the actual order and verifying that the patient needs insulin or has hyperglycemia. Special auxiliary labeling, such as "CONTAINS INSULIN" should be available to alert staff to its presence in IV solutions. Additionally, educate parents and include them in a double check system to detect any errors.