Auth0r: Rob Clemens, MD, MBA. PhD
A catastrophic medication error at Ascension Saint Thomas Hospital Midtown in Nashville, Tennessee, has become an important patient-safety lesson for every anesthesia department, hospital pharmacy, and operating room in the country.
On August 14, 2026, four patients scheduled for joint-replacement surgery mistakenly received potassium phosphate instead of mepivacaine, the local anesthetic intended for their procedures. Ascension Saint Thomas has confirmed that the error occurred in its pharmacy and that all four patients suffered adverse reactions requiring immediate medical treatment.
Local reporting indicates the consequences were devastating. NewsChannel 5 in Nashville reported that families of the affected patients said at least two patients were left paralyzed. One patient, 72-year-old Glenda Dorton, reportedly developed paralysis from approximately the chest down following what was expected to be a routine knee replacement.
The full long-term neurologic outcome of all four patients has not yet been publicly established.
What Happened?
According to Ascension Saint Thomas, the medication error originated in the hospital pharmacy. The four joint-replacement patients were supposed to receive mepivacaine, a local anesthetic commonly used for regional and spinal anesthesia. Instead, they received potassium phosphate.
Early news reports described the medication as potassium chloride and sometimes referred to the procedure as a spinal. The hospital’s August 21 statement provides the most specific information available: potassium phosphate was substituted for mepivacaine.
That distinction matters, but it does not lessen the seriousness of the event.
Potassium phosphate is a concentrated electrolyte preparation intended for carefully controlled intravenous administration after appropriate dilution. It has no role as a spinal anesthetic.
Why Can Potassium in the Spinal Space Be So Destructive?
The nervous system depends on extremely precise concentrations of potassium across neuronal cell membranes. Introducing a highly concentrated potassium solution into the neuraxial space can profoundly disrupt normal electrical activity and can produce severe neurotoxicity.
Although much of the published literature involves accidental neuraxial administration of potassium chloride, the experience demonstrates how dangerous concentrated potassium solutions can be when delivered near the spinal cord.
A review published in Regional Anesthesia and Pain Medicine identified 28 patients in previously reported cases involving accidental epidural or intrathecal potassium chloride administration. Twenty-two developed paraplegia, 11 required mechanical ventilation, and three died.
The Nashville event involved potassium phosphate rather than potassium chloride, so these historical cases should not be considered identical. They do, however, demonstrate why inadvertent neuraxial administration of concentrated potassium represents a medical catastrophe.
Potassium Phosphate Is a High-Alert Medication
This event is particularly troubling because the danger associated with concentrated electrolytes has been recognized for decades.
The Institute for Safe Medication Practices identifies potassium phosphate among concentrated injectable electrolytes requiring special safeguards. ISMP recommendations include physically separating concentrated electrolytes from other medications and keeping concentrated electrolyte vials out of routine patient-care and anesthesia stock whenever possible.
The Joint Commission and World Health Organization have similarly warned that concentrated electrolytes can cause death or permanent disability when the wrong product is selected, prepared, labeled, or administered. Potassium phosphate is specifically included among concentrated electrolyte preparations capable of causing lethal consequences when improperly administered.
This Is More Than a Medication Error
When four patients receive the same incorrect medication, the critical question should not simply be:
Who made the mistake?
The more important question is:
How did the healthcare system allow one mistake to reach four patients?
Modern medication-safety systems are specifically designed around the reality that human beings make errors. Hospitals therefore rely on multiple independent barriers—storage separation, barcode verification, pharmacy checks, labeling, electronic alerts, anesthesia medication verification, and independent double checks.
A catastrophic outcome generally means that several of those defenses either failed or were not capable of detecting the original error.
That is why this incident deserves attention well beyond Nashville.
Ascension Has Already Changed Its Procedures
Following the incident, Ascension Saint Thomas announced several specific corrective measures. The hospital says it has now:
- Physically isolated high-alert medications in separately marked storage areas.
- Established a mandatory hard stop whenever a spinal-medication scanning alert occurs.
- Required independent verification before such an alert can be overridden or resolved.
- Required a second trained pharmacist to perform final visual and physical verification of medications prepared for spinal administration.
- Engaged independent quality experts to review its corrective actions.
The hospital also reported the incident to Tennessee regulators on August 14. The Tennessee Bureau of Investigation subsequently opened an investigation, and state healthcare regulators are examining the event in coordination with federal authorities.
What Every Anesthesia Department Should Do Now
Anesthesia departments should not wait for the final Nashville investigation before examining their own systems.
Every hospital providing spinal or epidural anesthesia should immediately review how neuraxial medications are ordered, compounded, stored, labeled, transported, verified, and administered.
Particular attention should be given to pharmacy-prepared syringes. An anesthesia professional receiving a sealed, pharmacy-prepared syringe must ultimately rely heavily on the accuracy of the pharmacy’s preparation and labeling. That makes the safeguards upstream of the anesthesia provider extraordinarily important.
Hospitals should consider requiring independent verification of pharmacy-compounded neuraxial medications, physically separating concentrated electrolytes from local anesthetics, using barcode technology wherever technically possible, and treating any discrepancy or scanning alert involving a neuraxial medication as a hard stop—not merely another warning that can routinely be bypassed.
The Most Important Lesson
Spinal anesthesia is performed safely thousands of times every day. Yet medications placed directly into the neuraxial space have virtually no margin for certain types of error.
A medication that would be appropriate when correctly diluted and administered intravenously can become devastating when accidentally injected into the spinal space.
The four patients harmed in Nashville remind us why medication safety cannot depend on a single person recognizing a mistake.
The safest system assumes that someone, somewhere, eventually will make an error—and creates enough independent barriers that the error never reaches the patient.
The anesthesia community should study this event carefully. The appropriate response is not simply to ask whether this could happen at another hospital.
The question every anesthesia department should be asking today is:
Could this happen here—and what are we doing right now to make certain that it cannot?