Failure to use “low concentration” alerts properly leads to errors [ISMP Safety Alert]

When I read the headline in the most recent ISMP Medication Safety Alert! – Smart pump custom concentrations without hard “low concentration” alerts – I didn’t really get it. So what if a smart pump doesn’t stop you from programming “low concentrations”? Well after reading through the article, and the examples, it made perfect sense.

Failing to employ available dose error-reduction software (DERS) as intended and to heed important clinical alerts are common contributors to these errors. In particular, the misuse of custom concentration options (i.e., user must fill in the concentration) that do not employ a hard (requires reprogramming) minimum concentration limit is a prime example. This issue contributes largely to preventable errors with smart pumps given the counterintuitive, inverse relationship between concentration and volume. More concentrated drugs require less volume to deliver a specified dose; less concentrated drugs require more volume to deliver a specified dose. When using “fill-in-the-blank” custom concentrations, the concentration must be programmed into the pump so it can calculate the volume needed to deliver the prescribed dose. If the programmed concentration is lower than the actual concentration in the infusion bag or syringe, the pump will deliver an overdose. If the programmed concentration is higher than the actual concentration in the bag or syringe, the pump will deliver an underdose. Without a hard minimum concentration limit, the former scenario has led to life-threatening events, such as those described below.

Here’s a great example from the article that made the light bulb go off in my mind:

A physician prescribed IV HYDROmorphone 20 mg/100 mL (0.2 mg/mL) to infuse at 2.5 mg/hour. In this hospital, the standard concentration for this infusion was 0.1 mg/mL, so the custom concentration of 0.2 mg/mL had to be entered into the smart pump. The nurse selected the custom concentration option then mistakenly entered 2.5 mg/100 mL as the concentration instead of 20 mg/100 mL. Given the erroneously programmed concentration of 0.025 mg/mL, the pump issued a soft (can be overridden) low concentration alert. The nurse overrode the warning, mistakenly believing the warning was inconsequential. Based on the erroneous concentration, the smart pump infused the drug at a rate of 100 mL/hour, while the intended rate was 12.5 mL/hour. The pump delivered the entire bag of HYDROmorphone 20 mg to the patient in 1 hour.