A device used to heat and cool a patient’s blood during heart surgery has been linked to infections in 8 patients at a Pennsylvania hospital. The New York Times reports that four of those patients have died, but it is unknown whether their deaths were a direct result of the infections. On Monday, WellSpan York Hospital said it was warning some 1,300 current and former patients about the risk of bacterial infections during open heart surgery performed between Oct. 1, 2011 and July 24, 2015. The devices in question are heater-cooler devices, which use water in a closed circuit of warming and cooling blankets to maintain the appropriate temperature.
In a safety alert issued Oct. 15, the U.S. Food and Drug Administration (FDA) stated “Although the water in the circuits does not come into direct contact with the patient, there is the potential for contaminated water to enter other parts of the device or transmit bacteria through the air (aerosolize) through the device’s exhaust vent into the environment and to the patient.” The rate of infection among patients who underwent open-heart surgery during the period was less than one percent, according to WellSpan York Hospital.
The infections were caused by the bacteria nontuberculous mycobacteria (NTM), which can be found in soil and water. Most people are unharmed by NTM. However, infection can occur in rare instances, such as in individuals with a weakened immune system. NTM infection can lead to fever, weight loss, joint pain and lethargy; in some cases it can be fatal.
According to the FDA statement, the agency received 32 reports of bacterial infections linked to heater-cooler systems, 25 of which were reported this year alone. Eight of the reports occurred in the United States, and the rest happened in Europe. Whether those American cases were at York Hospital is unclear, NYT reports.
This summer, European researchers published reports on the link between heater-cooler devices and bacterial contamination. According to Joseph Perz, an epidemiologist at the Centers for Disease Control and Prevention, it is the first time NTM infections have been associated with the devices, although the bacteria has caused infections during treatment for decades.
Dr. Hal Baker, who oversees infection control at York Hospital, said that staff did not follow cleaning instructions outlined in a 2010 manual “to the letter”, according to NYT. Sorin Group, who manufactures the devices, issued a safety notice in June. The company gave a new set of guidelines to maintain the machines. The three machines at York Hospital have been replaced after the safety concerns arose, Dr. Baker said. In a statement, the hospital said the bacterial infection was “likely a contributing factor” in the four deaths.