The FDA has issued Zoll Medical a warning letter outlining quality system regulation violations and violations of medical device reporting (MDR).
An inspection of the Chelmsford, Massachusetts-based company from Feb. 27, 2025, through April 15, 2025, identified the violations, according to the FDA letter issued on April 30, 2026.
Zoll develops a range of products, including AEDs, wearable cardioverter defibrillators (WCDs), monitor/defibrillator systems, ventilators and more. The company also appointed a new CEO earlier this year, promoting Eric Knudsen to the corner office in February.
The FDA said it determined that its devices are “adulterated” in that the methods, facilities or controls used for manufacturing, packing, storing or installation are not in conformity with the current good manufacturing practice requirements of the agency.
It also determined that the devices are “misbranded” in that Zoll failed or refused to furnish material or information respecting the device that is required by the FDA.
More on the quality system regulation violations
The FDA’s letter states that Zoll failed to establish and maintain procedures for implementing corrective and preventive action. This relates to correcting and preventing recurrence of nonconforming product and other quality problems.
One centered around a February 2025 documentation of burnt tin under the gel on the Onestep Pediatric GC Electrode, with air pockets surrounding the burn location. The FDA said a request form related to the nonconformity was not completely filled out.
It also said Zoll failed to analyze complaints and other sources of quality data to identify causes of the nonconformity or other quality problems. This related to 731 Series Ventilators with MRI compatibility nonconformities. A Corrective and Preventive Action (CAPA) was initiated on April 9, 2024, but a Class I recall not initiated until April 30, 2024.
The FDA also pointed to complaints with the X Series and inaccurate CO2 monitoring measurement, failure of the BVM feature of the Accuvent Sensor and more. It found that Zoll’s responses to the FDA’s claims that it failed to meet the quality standards, promising a revised complaint handling procedure, were not adequate.
Other quality system issues
The FDA also said Zoll failed to establish and maintain procedures for validating device design, again relating to the 731 ventilators. It found that the device’s labeling failed to specify how far the ventilator should be placed when using 1.5T MRI. The Zoll vent specification was for a 3T MRI, with the FDA finding no evaluation of specifications for the 1.5T MRI.
Further issues were found by the FDA with claims that the Z Vent ventilator and 731 Series were identical mechanically and different in cosmetic features only. However, the company says Zoll failed to assess MRI compatibility factors in testing. Again, it found company responses inadequate.
Then, the FDA said Zoll failed to establish and maintain procedures for validating the device design, which includes a risk analysis. It found failings in risk analysis processes for 731 ventilators, X Series defibrillators and One Step electrodes.
Finally, the FDA said Zoll failed to establish and maintain procedures to ensure that all purchased or otherwise received product and services conform to specified requirements. This relates to quality requirements that suppliers, contractors and consultants must meet.
The FDA said the company failed to categorize two suppliers, including one for the AccuVent Sensor on the X Series ventilator. It said this type of supplier was miscategorized as considered critical to business needs but not product safety or effectiveness. Similarly, the company categorized the supplier providing RescueNet software at the same level.
Zoll also failed to establish a supplier change control agreement with the RescueNet software supplier, the FDA said.
The FDA found the company’s responses inadequate. It said Zoll fails to
“Your firm continues to not take into account the effect the suppliers that deliver materials, components or other services may have on the safety or effectiveness of your finished devices,” the FDA wrote.
Medical Device Reporting (MDR) violations
The FDA said Zoll’s MDR failures relate to the failure to submit a report to FDA no later than 30 calendar days after the day that your firm receives or otherwise becomes aware of information, from any source, that reasonably suggests that a device that your firm markets has malfunctioned and this device or a similar device that it markets would be likely to cause or contribute to a death or serious injury, if the malfunction were to recur.
An incident with the ventilator MRI function would be considered reportable, the FDA said. However, the firm became aware of an event on June 20, 2024, but the MDR reached the FDA on March 10, 2025.
The FDA said that Zoll said it planned to revise its reporting process. However, it sees no evidence providing documentation of the completion of the activities in the company’s responses. It acknowledges completed updates to risk management files, though.
Additionally, the FDA said the RescueNet Live software analyzes data from a monitoring device and generates a secondary alarm. This makes it a medical device. The FDA said that means it requires FDA premarket approval (PMA), which Zoll failed to obtain. The company also failed to notify the FDA of its intent to commercially launch the device, the FDA said.
“Your firm should take prompt action to address any violations identified in this letter,” the FDA wrote. “Failure to adequately address this matter may result in regulatory action being initiated by the FDA without further notice. These actions include, but are not limited to, seizure, injunction, and civil money penalties.”
