A smartphone application was shown to be diagnostically superior to a traditional physical examination for the assessment of ulnar patency in patients undergoing coronary angiography. Results of the CAPITAL iPhone-based evaluation of dual circulation before the transRadial Access for Diagnostic Angiography (CAPITAL iRADIAL) trial were published in the Canadian Medical Association Journal.
"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," according to Benjamin Hibbert, MD, PhD, of the University of Ottawa Heart Institute, Ottawa, Ontario, Canada. "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."
For this study, the researchers compared the use of a heart-rate monitoring application—Instant Heart Rate 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.
While color Doppler ultrasonography is the gold standard for assessing arterial patency and collateral competency, it is typically not feasible or cost-effective for routine practice. Bedside assessment using the modified Allen test is commonly accepted as standard practice, despite its diagnostic and prognostic shortcomings.
The Instant Heart Rate app was chosen because it is commercially available for free for both iOS and Android operating systems, and it allows direct visualization of the photoplethysmography tracing on the screen.
A total of 438 participants were recruited from the University of Ottawa Heart Institute’s coronary care unit, inpatient cardiology service, and the Regional Referral Centre/Day Unit. Patients were excluded if they were hemodynamically unstable, required emergency angiography, or had prior surgical removal of the radial or ulnar arteries.
Participants were split into two groups: one was assessed using the app, and the other using the modified Allen test. Patient characteristics were comparable between the groups, and nearly half of the participants in each group had undergone prior coronary angiography or had a history of arterial line insertion.
Results showed that the smartphone app had a diagnostic accuracy of 94%, while the traditional method had an 84% accuracy. The smartphone app also had a 10.1% greater accuracy for determining ulnar artery patency than the modified Allen test. Fifteen patients (6.8%) in the application group and 37 patients (16.9%) in the Allen group had false-positive results, and they would have been incorrectly excluded from radial artery access.
Additional investigation showed that the diagnostic accuracy of the application was comparable to conventional plethysmography.
"While [smartphones and apps] aren't designed as medical devices…it is important that they are evaluated in the same rigorous manner by which we assess all therapies and diagnostic tests," said Pietro Di Santo, MD, the study’s lead author. "When we designed the iRADIAL study, we wanted to hold the technology to the highest scientific standards to make sure the data supporting its use was as robust as possible."
Although this application is not currently certified for use in health care by any regulatory body, Dr. Hibbert said the study highlights the potential for smartphone-based diagnostics to aid in clinical decision-making at a patient's bedside.
To read more about this study, click here.