Philips Respironics received thousands of complaints about a dangerous defect in its breathing machines but kept them secret for years as stock prices soared. The devices, including the popular DreamStation for sleep apnea, went to children, the elderly and veterans before the global giant announced a massive recall.

Congressional investigators are launching an inquiry into the Food and Drug Administration’s oversight of medical device recalls for the first time in years following reports that the agency failed to issue warnings about breathing machines capable of sending hazardous particles and fumes into the lungs of patients.

U.S. Sens. Dick Durbin, D-Ill., and Richard Blumenthal, D-Conn., urged the Government Accountability Office to investigate, citing reports by ProPublica and the Pittsburgh Post-Gazette that detailed the role of the FDA in an ongoing health crisis that has threatened millions of people in the United States and around the world.

The news organizations revealed that the agency had received hundreds of complaints about breathing machines manufactured by Philips Respironics long before the company announced a massive recall in 2021, but took no action to alert patients or doctors.

Philips withheld thousands of additional complaints over the course of 11 years while customers who relied on the machines to breathe reported respiratory problems, kidney and liver conditions, and cancer, the news organizations found.

“It’s clear from the Philips case that information about patient harm was known for years and not properly shared or addressed,” Durbin, who chairs the Senate Judiciary Committee, said in a statement. “We must ensure there is adequate oversight on medical device manufacturers so that Americans know the potential risks and can make informed decisions with their health care providers.”

In their request to the GAO, the watchdog arm of Congress, Durbin and Blumenthal said they needed far more information about the FDA’s oversight of the medical device industry, including how the agency ensures that companies initiate recalls and what happens when manufacturers fail to comply.

In an email, the GAO said it accepted the lawmakers’ request to conduct an inquiry.

Philips has said that it evaluated the early complaints about its sleep apnea machines and ventilators on a case-by-case basis and launched the recall after the company became aware that an industrial foam fitted inside the devices could break down and release potentially “toxic and carcinogenic” material.

The FDA has defended its handling of the crisis, saying it received complaints about “general contamination issues” before the recall but that the debris could have been caused by external sources unrelated to foam. At least 30 of the complaints described foam degradation, but the FDA said the reports did not indicate that any patients had been harmed.

“The FDA welcomes the opportunity for GAO review of the agency’s oversight of medical device recalls,” the agency said in a statement last week.

Durbin and Blumenthal said the GAO inquiry would follow up on a similar probe in 2011 that called for changes to better protect patients. Safety advocates said a new investigation is badly needed and long overdue.

In 2022, the FDA received 3 million reports about malfunctioning devices — nearly 30 times more than in 2005, government records show. Nearly one-third described injuries and deaths.

“At the end of the day, the public should have confidence in the products that are regulated by the FDA,” said Kushal Kadakia, a public health researcher at Harvard Medical School who has written about the Philips recall.

Device safety advocates said the GAO should review whether the FDA is regularly using information in health records, insurance claims, medical device registries and other sources — data they said would greatly improve the agency’s ability to track dangerous products. The FDA moved to create a center to bring together that data years ago, but a comprehensive new system is still not in place, records and interviews show.

Former FDA analyst Madris Kinard also said the FDA should do more to ensure the safety of devices before they are marketed and sold. A controversial process at the agency allows device makers to gain clearance for a new product by showing that it is substantially equivalent to one already on the market.

Kinard said the FDA should investigate whether those older models had any safety issues before newer versions are cleared.

“Simply getting a new device to market to me isn’t innovation,” she said. “Innovation is only good if it’s helping the patient.”

Durbin and U.S. Rep. Jan Schakowsky, D-Ill., have proposed legislation aimed at ensuring that doctors and patients receive vital information about recalls by requiring the FDA to create an electronic system of communication for the agency, device makers, hospitals and other providers. The bill would also require device makers to disclose more information about health risks and instruct hospitals and health care workers to pass the information to patients.

The proposal “will create an efficient, accountable system for ensuring patients are routinely notified about safety recalls for medical devices,” Chuck Bell, advocacy programs director at Consumer Reports, said in a statement. “As our health system operates today, consumers and providers may never receive any information ... or may receive it too late to avoid adverse consequences.”

Medicare claim forms should also include identifying information for devices — model numbers and names of manufacturers — to make it easier to detect troubled devices and contact patients in the event of a recall, Kadakia and others said.

“Right now, we rarely know what device has been used in what patient and when,” said Dr. Sanket Dhruva, a cardiologist and assistant professor at the University of California, San Francisco who has studied medical device safety and regulation. “Without this basic, really fundamental information about the device a patient has received, we can’t track the device.”

The GAO inquiry comes as a growing number of federal lawmakers call for investigations into Philips.

Schakowsky, the ranking member of the House Energy and Commerce subcommittee that oversees consumer product safety, said earlier this month that the company must be “fully held accountable and stopped from any future wrongdoing” if investigators determine that Philips failed to warn consumers in the years before the recall.

Schakowsky also cited new revelations, reported last month by ProPublica and the Post-Gazette, that a different foam placed inside replacement devices sent out by Philips after the recall was also found to emit hazardous chemicals, including formaldehyde, a known carcinogen.

“Americans should not be kept in the dark when it comes to the safety of their medical devices, and they certainly should not be forced to choose between a dangerous product and getting the care they need,” Schakowsky said in a statement.

Philips has said the new foam is safe and does not emit chemicals at dangerous levels. The FDA, which first reported that the foam failed emissions testing in 2021, said more tests are needed.

Philips said it regrets any “distress and concern” caused by the recall and is cooperating with authorities. The company also said testing on the original foam in the months after the recall found that the chemical emissions are not at levels that can cause “appreciable harm” to patients. The FDA has challenged Philips, saying in a statement in October that the studies were not adequate and that the company had agreed to conduct additional tests.

Debbie Cenziper with ProPublica and Michael D. Sallah with the Post-Gazette contributed reporting.