Smartphone-Based Diagnostics More Accurate than Traditional Examination Techniques

May 2018

Demonstration of the modified Allen test and the smartphone-based heart rate-monitoring application. For a detailed description, read the study titled 'Photoplethysmography using a smartphone application for assessment of ulnar artery patency: a randomized clinical trial,' as published in the CMAJ. Image source: CMAJ.
Demonstration of the modified Allen test and the smartphone-based heart rate-monitoring application. For a detailed description, read the study titled ’Photoplethysmography using a smartphone application for assessment of ulnar artery patency: a randomized clinical trial,’ as published in the CMAJ. Image source: CMAJ

A recent study published in the Canadian Medical Association Journal suggests smartphone technology is diagnostically more accurate than traditional physical examination techniques to assess blood flow in arteries found in the wrist.

The study was conducted at the University of Ottawa Heart Institute (UOHI) between July 2015 and March 2016. It sought to answer whether a smartphone application, namely the Instant Heart Rate app, produced more accurate results than the clinical standard for assessing blood flow in the wrist arteries of patients undergoing angiography.

Currently the Colour Doppler ultransonography is considered the “gold standard” for assessing arterial patency (that is, the condition of being open, expanded, or unobstructed) in a clinical setting, but is too resource-intensive and costly for routine use in practice. Therefore, the Allen test is widely accepted as the preferred approach for determining the openness of these arteries.  

Dr. Benjamin Hibbert, MD, PhD, is an Interventional Cardiologist and Director of the Vascular Biology and Experimental Medicine Laboratory at the UOHI, and the senior author of the study. “The current report highlights that a smartphone application can outperform the current standard of care and provide incremental diagnostic yield in clinical practice,” he wrote.

Dr. Benjamin Hibbert, MD, PhD
Dr. Benjamin Hibbert, MD, PhD, is an Interventional Cardiologist and Director of the Vascular Biology and Experimental Medicine Laboratory at the UOHI, and the senior author of the study.

Findings confirm version 4.5.0 of the Instant Heart Rate application has a diagnostic accuracy superior to that of the Allen test, at 94% compared to just 84% when using the traditional method. Researchers conducted the study using an iPhone 4S. The heart rate-monitoring application used for the study shows the changes in blood flow on the screen, is available for free on both Apple and Android operating systems, and is the most downloaded heart rate monitoring application worldwide.

To determine readings, the application is launched and the camera lens is pressed over the tip of a patient’s index finger. Changes in colour and brightness are captured via the lens and the data is interpreted and reflected as a numerical value and photoplethysmography tracing on the screen. (Photoplethysmography refers to a non-invasive and low cost technique used to detect blood volume changes at skin level).

Although the Instant Heart Rate application is not currently certified for use in health care by any regulatory body, Dr. Hibbert and his colleagues believe the findings of the study speak to the potential of smartphone-based diagnostics to aid in clinical decision-making at the patient bedside.

“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,” said Dr. Pietro Di Santo, the study’s lead author. “Built-in cameras with dedicated software or photodiode sensors using infrared light–emitting diodes have the potential to render smartphones into functional plethysmographs.”

For patients, Dr. Hibbert said this translates to their doctors making a more accurate assessment about the patency of the ulnar artery at the bedside. This may better guide physicians in selecting the wrist to be used for angioplasty, to monitor for complications from catheters being placed in arteries in the wrist or in a selection of a wrist artery as a conduit for bypass.

In total 438 patients participated in the study. It was published in the Canadian Medical Association Journal on April 3, 2018.

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