Medication Mix-Up at Karolinska University Hospital Puts Heart Surgery Patients in Critical Condition

Two heart surgery patients at Karolinska University Hospital in Solna suffered life-threatening complications after receiving calcium chloride instead of potassium chloride during their operations on August 18, 2026. The medication error prevented their hearts from restarting post-surgery, leading to critical injuries that may require heart transplants.

The mix-up occurred due to the similar appearance of medication bottles for potassium chloride and calcium chloride. While potassium chloride is typically used to stop the heart during surgery, calcium chloride can be lethal to the heart muscle if administered in this context. Eva Sundman Olofsson, head of intensive care and thoracic surgery at Karolinska, described the incident as "incredibly serious".

Following discovery of the error, the affected patients were transferred to another hospital for further care and evaluation. Karolinska University Hospital has expressed deep regret over the incident and is conducting an internal investigation. The hospital has already tightened protocols concerning medication deliveries to the thoracic surgery department to prevent recurrence. A formal Lex Maria report—a Swedish regulatory requirement for serious medical incidents—will be filed.

Additionally, Karolinska has contacted other thoracic surgery departments in Sweden as well as the suppliers and manufacturers involved, to address and mitigate the risk posed by the similar packaging of these critical medications.

This medication error highlights the significant risks associated with drug administration in high-stakes medical settings and underscores the importance of rigorous safety procedures. The hospital's swift actions to upgrade practices aim to prevent similar events in the future and to restore trust in cardiac surgical care.