![]() ![]() “Satting 100,” Bickler called out as Caroline Hughes, a clinical Six researchers scurried about the small, one-room testing space as Taylor Swift’s music softly played. Blood gas measurements taken from blood are considered the gold standard. Her nose was pinched shut.įor the next 20 minutes, lab workers compared the oxygen readings on the devices with levels in the blood drawn intermittently from her arm and analyzed on the spot as she was “desaturated,” or given less and less oxygen to breathe. A pulse oximeter was placed on each of her fingers and a breathing tube was inserted in her mouth. Diamond Luong, a volunteer 23-year-old research coordinator at UCSF, sat upright in the gurney, her arm numbed with lidocaine, as Bickler gently guided a catheter into her radial artery while watching an ultrasound screen. Hypoxia Lab head Philip Bickler inserting a catheter during a pulse oximeter test. As the lab grappled with a host of issues - from how to assess skin tone to unpredictable variations in readings among different human subjects - one thing became immediately clear: Nothing about testing this simple device is simple. This month, its leaders allowed STAT to spend a day observing detailed testing procedures as they worked to determine how much of a factor skin pigment plays in the accuracy of the devices - a crucial unknown as regulators seek to understand how much those errors may affect treatment decisions. Now, with new attention focused on health equity and the devices, the lab’s profile has risen markedly. “There was no attention to health equity then.” ![]() ![]() “All the while, we were saying, ‘Yes, this is what we were trying to tell you.’ But it just wasn’t on people’s radar as a concern,” Bickler said. ![]() It’s been frustrating to Bickler, who was first author on a 2005 paper assessing the effect of skin tone on pulse oximeter readings, that it took a horrifying pandemic where pulse oximeters became critical in determining who received hospitalization and treatment, and numerous new studies, to raise widespread interest in the issue. When the devices got popular, he began to wonder how accurate they really were in people with darker skin,” said Philip Bickler, a professor of anesthesia and perioperative care at UCSF who took over running the lab when Severinghaus retired. The finding was something that nagged at him. Historical photos show Severinghaus testing the devices on Black patients decades ago, a time when clinical research subjects were predominantly white. That led to them publishing papers in the mid-2000s suggesting that pulse oximeters were less accurate in patients with darker skin. Courtesy UCSF AnesthesiaĪs blood gas monitoring evolved and pulse oximeters became ubiquitous in health care by the late 1980s, Severinghaus and his lab spent time evaluating how well they worked. John Severinghaus, a pioneer of blood gas analysis, in his lab in the 1960s. He had a deep interest in understanding how the human body copes with low oxygen he also studied subjects at a lab some call “the Hypoxia Hilton,” which is still in use at 12,470 feet in California’s White Mountains. Severinghaus went from designing radar systems in World War II to inventing the world’s first blood gas analyzer, a machine now housed in the Smithsonian. These instruments are critical for many aspects of medical care, from the treatment of Covid and pneumonia to neonatal monitoring, and the lab tests more than 60 each year for manufacturers and others in a small room packed with monitors, oxygen tanks, ultrasound machines, breathing tubes, and an operating room gurney.įounded in 1958 by John Severinghaus, a physicist turned anesthesiologist who’s been described as a “master tinkerer,” the Hypoxia Lab was one of the first to publish analyses questioning the accuracy of pulse oximeters on darker skin. For decades, the Hypoxia Lab at the University of California, San Francisco, has quietly worked to assess and improve the precision of this low-cost device that revolutionized health care by allowing fast, cheap, and non-invasive monitoring of blood oxygen levels. In the search for solutions, regulators from the Food and Drug Administration have turned to a single small lab in San Francisco whose visionary founder helped develop modern blood monitoring tools. SAN FRANCISCO - The discovery that fingertip oxygen-measuring devices might contribute to health disparities because they appear to work less well on patients with darker skin has roiled the world of pulse oximetry, a $2 billion industry that now faces stricter regulations and pressure to address bias in the development and testing of its devices. ![]()
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