The US Food and Drug Administration has issued a new warning about an “emerging safety issue” involving a Philips machine used for treatment of sleep apnea. 

The agency said it had had reports about thermal issues with the machine, “some of which cited patient injuries” including “fire, smoke, burns and other signs of overheating”. The warning applies to the DreamStation 2 CPAP.

“The FDA is in ongoing discussions with the company about mitigation strategies for this safety issue and will update the public accordingly,” the FDA statement said. 

The agency said it had noted a sharp increase (more than 270) in the number of reports about thermal issues since August. But prior to August, the agency had received fewer than 30 reports for the same issues since July 2020 when the device was cleared for marketing. 

The FDA the new issue was likely to be related to an electrical or mechanical malfunction, which may cause it to overheat in certain situations. It is unlikely, the FDA said, to be connected to the use of polyurethane foam, which has led to millions of the machines being recalled.

Nevertheless, “addressing these safety concerns remains a top priority for the FDA,” the agency’s medical equipment chief Jeff Shuren said. People do not need to stop using the machines but should monitor them carefully for signs of overheating.

The warning forced Philips’ share price down almost 7% in early trading in Amsterdam. 

The share price is currently some 60% down on early 2021, before the sleep apnea machine problems hit the headlines. 

Polyester foam used to dampen the noise from the machines was found to have degraded during cleaning, exposing patients who inhaled the particles to an increased risk of cancer.

Philips is currently embroiled in several lawsuits in the United States brought by patients who used its respirators to treat lung conditions and sleep apnea.

Philips said in September it would make an initial payment of $479 million (€448 million) to settle one of the class actions to “economic loss”, but continues to deny liability for the patients’ health problems.

In 2021 the company issued recall notices for 15 million devices that included polyester foam. More recent versions use polyether foam, which does not degrade in the same way.