Avoid Preparing Infusions Using the Rule of 6 or Broselow Tape

ISMP Medication Safety Alert. 2005;10(4) 

A calculation error related to the Rule of 6 may have contributed to an infant's death recently when it led to a misplaced decimal point and the preparation of a dopamine infusion that was 10 times more concentrated than required. Rule of 6 dosing is sometimes used in neonatal intensive care units (NICU). One multiplies the infant's weight in kilograms by 6, and then adds the resulting number as milligrams of drug to 100 mL of solution. This concentration allows a flow rate of 1 mL per hour to deliver 1 mcg/kg/minute. Thus, the mL per hour infusion rate delivers a corresponding mcg/kg/minute dose (3 mcg/kg/minute would be 3 mL/hour), making dose changes easily accomplished. However, as mentioned in our August 7, 2003 newsletter (Standard concentrations are safer than using the Rule of 6), using the Rule of 6 to prepare infusions results in varied concentrations. Thus, one key medication safety initiative - standardization of critical care drug concentrations - cannot be implemented.

Another obvious problem is that practitioners can misplace a decimal point during the calculation or make another type of arithmetic error, causing the wrong amount of drug to be added to the solution. This is what happened in the latest case. The decimal point error occurred in the pharmacy where the dopamine infusion was prepared using the Rule of 6. The premature infant became cyanotic during the infusion, but the exact role of the 10-fold overdose in the infant's death, if any, is unknown.

The anonymous reporter in this case wanted to share this story to help demonstrate the dangers of non-standard concentrations, especially in NICU with 500 g to 1,000 g babies and frequent use of high-risk drugs such as vasoactives and opioid infusions. Thus, we continue to recommend the use of standard concentrations for critical care drugs. We are also hoping that manufacturers will begin to provide more premixed pediatric solutions as the use of standard concentrations expands.

It should be noted that the Joint Commission National Patient Safety Goal (NPSG) related to improving the safety of high-alert medications requires the use of standardized drug concentrations. Thus, the Joint Commission, too, has openly discouraged use of the Rule of 6. Many hospitals with NICUs have abandoned reliance on the Rule of 6 and successfully converted to pharmacy-dispensed standardized solutions (or have used standard concentrations for many years). Neonatologists who have been educated to use the Rule of 6 have loudly supported its continued use.

A related safety issue is associated with preparing infusions using the Broselow Tape. Developed by Dr. James Broselow in the mid-1980s, the Broselow tape provides emergency equipment sizes and drug dosage recommendations based on a child's length. The tape was initially designed for children who presented with cardiac arrest but has now evolved to cover other pediatric emergencies. Since the Joint Commission NPSG requires hospitals to standardize drug concentrations, use of the tape is cause for concern because multiple infusion concentrations are listed on the tape. In fact, Joint Commission surveyors will determine whether infusions are being prepared using the tape, and consider its use as a sign of non-compliance with the NPSG.

We agree that use of standardized concentrations, rather than a concentration that varies depending on the child's length, reduces the risk of calculation and preparation errors. But another type of error could occur if the Broselow tape is used to prepare an infusion in the emergency department (ED). If the child is subsequently admitted to the hospital, the patient care unit may adjust the rate of infusion based on a standard concentration being used throughout the rest of the hospital. Nevertheless, the tape continues to be a valuable source of information for single doses of medications as well as medical supplies in an emergency situation, especially in EDs where children are treated infrequently. Consider covering the infusions listed on the tape with a label that redirects staff to a titration table using a standard concentration. According to Dr. Broselow, future revisions will remove the infusions from the tape.

The Joint Commission will also continue to consider requests for alternative approaches to this NPSG if specific conditions are met (see www.jcaho.org for details). However, it will also require ongoing evidence of progress toward full implementation of standard concentrations by December 31, 2008.


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