While many Luddites rail against the constant use of smartphones—often citing the devices as the downfall of society and calling for their discontinued use—scientists and engineers have decided to use these technological marvels to improve personal health. Now, a team of investigators at the University of Ottawa Heart Institute has published data from a recent randomized clinical trial that shows a smartphone application using the phone's camera function performed better than traditional physical examination to assess blood flow in a wrist artery for patients undergoing coronary angiography. Findings from the new study were published recently in the Canadian Medical Association Journal  (“Photoplethysmography Using a Smartphone Application for Assessment of Ulnar Artery Patency: A Randomized Clinical Trial”) and highlight the potential of smartphone applications to help physicians make decisions at the bedside.

Radial artery access is frequently performed for coronary angiography. Despite its precision limitations, the modified Allen test, which consists of the manual occlusion of radial and ulnar arteries followed by the release of the latter and assessment of the coloring of the patient’s hand (palmar blush) is used routinely for evaluating the collateral circulation and determining the patient’s suitability for radial artery access. The study investigators sought to evaluate whether a smartphone application may provide a superior alternative to the modified Allen test.

“Because of the widespread availability of smartphones, they are being used increasingly as point-of-care diagnostics in clinical settings with minimal or no cost,” explained Benjamin Hibbert, M.D., Ph.D., an interventional cardiologist and director of the vascular biology and experimental medicine laboratory at the University of Ottawa Heart Institute. “For example, built-in cameras with dedicated software or photodiode sensors using infrared light-emitting diodes have the potential to render smartphones into functional plethysmographs (instruments that measure changes in blood flow).”

In the current study, the researchers compared the use of a heart-rate monitoring application (the Instant Heart Rate application version 4.5.0 on an iPhone 4S) with the modified Allen test, which measures blood flow in the radial and ulnar arteries of the wrist, one of which is used to access the heart for coronary angiography. A total of 438 participants were split into two groups—one group was assessed using the app and the other was assessed using a gold-standard traditional physical examination (known as the Allen test). The smartphone app had a diagnostic accuracy of 94% compared with 84% using the traditional method.

“The current report highlights that a smartphone application can outperform the current standard of care and provide an incremental diagnostic yield in clinical practice,” Dr. Hibbert noted.

“While they aren't designed as medical devices—when smartphones and apps begin to be used clinically—it is important that they are evaluated in the same rigorous manner by which we assess all therapies and diagnostic tests,” remarked lead study investigator Pietro Di Santo, M.D. “When we designed the iRadialstudy we wanted to hold the technology to the highest scientific standards to make sure the data supporting its use was as robust as possible.”

While the application is not currently certified for clinical use, the study underscores the potential for smartphone-based diagnostics to aid in clinical decision-making. The healthcare profession and regulatory agencies should proactively address the challenges associated with bringing mobile health (mHealth) solutions into practice to maximize their benefits.

“Referred to as a new industrial revolution, the impact of digital technologies will be both disruptive and transformative,” concluded Kumanan Wilson, M.D., in a related commentary about the current study. “The continued maturation of technologies, such as artificial intelligence, virtual reality, and blockchain, will further expand the possibilities for mHealth in both diagnosis and treatment in health care.”

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