Death from Patient-Controlled Morphine Overdose

By ThinkReliability Staff

Could improving the reliability of the supply chain improve patient safety?

The unexpected death of a patient at a medical facility should always be investigated to determine if there are any lessons learned that could increase safety at that facility. A thorough analysis is important to determine all the lessons that can be learned. For example, the investigation into a case where a patient death was caused by a morphine overdose delivered by a patient-controlled analgesia (PCA) found that increasing the reliability of the supply chain, as well as other improvements, could increase patient safety.

The information related to this patient death was presented as a morbidity and mortality case study by the Agency for Healthcare Research and Quality. The impacts to goals, analysis, and lessons learned from the case study can be captured in a Cause Map, a visual form of root cause analysis that develops the cause-and-effect relationships in sufficient detail to be able to find solutions that will reduce the risk of similar incidents recurring.

Problem-solving methodologies such as Cause Mapping begin with defining the problem. In the Cause Mapping method, the what, when and where of the problem is captured, as well as the impact to the goals, which defines the problem. In this case, the patient safety goal is impacted due to the death of a patient. Because the death of a patient under medical care can cause healthcare providers to be second victims, this is an impact to the employee safety goal. A death associated with a medication error is a “Never Event“, which is an impact to the compliance goal. The morphine overdose is an impact to the patient services goal. In this case, the desired medication concentration (1 mg/mL morphine) was not available, which can be considered an impact to the property goal. Lastly, the response and investigation are an impact to the labor/time goal.

The analysis begins with one impacted goal and developing cause-and-effect relationships. One way to do this is by asking “Why” questions, but it’s also important to ensure that the cause listed is sufficient to have resulted in the effect. If it’s not, another cause is required, and will be joined with an “AND”. In this case, the patient death resulted from a morphine overdose AND a delayed response to the patient overdose. (If the response had come earlier, the patient might have survived.) It’s important to validate causes with evidence where possible. For example, the morphine overdose is a known cause because the autopsy found a toxic concentration of morphine. Each cause in the Cause Map then becomes an effect for which causes are captured until the Cause Map is developed to the point where effective solutions can be found.

The available information suggests that the patient was not monitored by any equipment, and that signs of deep sedation, which preceded respiratory depression, were missed during nurse checks. Related suggestions for promoting the safe use of PCA include the use of monitoring technology, such as capnography and oximetry, and assessing and recording vital signs, including depth of respiration, pain and sedation.

The patient in this case was given PCA morphine. However, too much morphine was administered. The pump settings were based on the concentration of morphine typically used (1 mg/mL).   However, that concentration was not available, so a much higher concentration (5 mg/mL) was used instead. The settings on the pump were entered incorrectly for the concentration of morphine used, likely because of confirmation bias (effectively assuming that things are the way they always are – that the morphine on the shelf will be the one that’s usually there). There was no effective double check of the order, medication and pump settings.

Related suggestions for promoting the safe use of PCA include the use of “smart” pumps, which suspend infusion when physiological parameters are breached, the use of barcoding technology for medication administration (which would have flagged the use of a different concentration), performing an independent double check, storing only one concentration of medications in a dispensing cabinet (requiring other concentrations to be specially ordered from the pharmacy), standardizing and limiting concentrations used for PCA, and yes, improving the supply chain so that it’s more likely that the lower concentration of morphine will be available. Any of these suggestions would improve patient safety; implementation of more than one solution may be required to reach an acceptable level of risk. Imagine just improving the supply chain so that there would be very few (if any) circumstances where the 1 mg/mL concentration of morphine is unavailable. Clearly the risk of using the wrong concentration would be lessened (though not zero), which would reduce the potential for patient harm.

To view a one-page downloadable PDF with the outline, Cause Map, and action items, click “Download PDF” above. Click here to read the case study.