Electronic Angiologist
Smartphones have surpassed people in the diagnosis of circulatory disorders
Natalia Pelezneva, Naked Science
Canadian scientists have tested how effectively a heart rate monitor application can detect blood flow disorders in the arteries using a smartphone camera. To do this, the method of photoplethysmography was used. The technique turned out to be more effective than the traditional way of controlling blood circulation, in which the doctor detects violations by changing the color of the patient's skin. The study was published in the Canadian Medical Association Journal (Di Santo et al., Photoplethysmography using a smartphone application for assessment of ulnar artery patent: a randomized clinical trial).
Today smartphones are widely used in medical diagnostics: such examinations are cheap and do not require sophisticated equipment. For example, in the USA, an application has been developed that can detect health disorders of infants by analyzing their cries. With the help of a relatively inexpensive diagnostic device, a smartphone can analyze blood, urine or saliva.
The study involved 438 patients who had to undergo elective cardiac catheterization – insertion of a catheter before therapeutic or diagnostic interventions. Before the procedure, the doctor evaluates the blood flow using a modified Allen test: the patient raises his hand and clenches his fist, then the doctor presses on the radial and ulnar arteries, and the patient's skin turns pale. The state of blood circulation is assessed by how quickly the normal skin color is restored.
Checking for blood supply disorders
© Canadian Medical Association Journal
The participants of the experiment were divided into two equal groups. The first one passed the Allen test, the other one was examined using the Instant Heart Rate heart rate app on the iPhone 4S. The program measures the pulse, recording small changes in the color of the skin on the finger: it changes with the expansion of blood vessels under the skin. The measurement was performed by pressing the radial artery of the patients. After the first check, all participants underwent an ultrasound examination of the vessels by Dopplerography. This allowed us to determine how accurate the first measurement was.
Allen's test gave the correct result in 84% of cases, the application – in 94%. Experts believe that such programs can become a reliable method of diagnosing blood flow disorders. At the same time, it is worth considering the difference in the sensitivity of cameras and the operation of different smartphone models in general. In order for tests using applications to be allowed to be used in medical practice, studies involving a larger number of patients and the use of different devices will be required.
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