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Background Smartphone manufacturers offer mobile health monitoring technology to their customers, including apps using the built-in camera for heart rate assessment. This study aimed to test the diagnostic accuracy of such heart rate measuring apps in clinical practice. Methods The feasibility and accuracy of measuring heart rate was tested on four commercially available apps using both iPhone 4 and iPhone 5. 'Instant Heart Rate' (IHR) and 'Heart Fitness' (HF) work with contact photoplethysmography (contact of fingertip to built-in camera), while 'Whats My Heart Rate' (WMH) and 'Cardiio Version' (CAR) work with non-contact photoplethysmography. The measurements were compared to electrocardiogram and pulse oximetry-derived heart rate. Results Heart rate measurement using app-based photoplethysmography was performed on 108 randomly selected patients. The electrocardiogram-derived heart rate correlated well with pulse oximetry ( r = 0.92), IHR ( r = 0.83) and HF ( r = 0.96), but somewhat less with WMH ( r = 0.62) and CAR ( r = 0.60). The accuracy of app-measured heart rate as compared to electrocardiogram, reported as mean absolute error (in bpm ± standard error) was 2 ± 0.35 (pulse oximetry), 4.5 ± 1.1 (IHR), 2 ± 0.5 (HF), 7.1 ± 1.4 (WMH) and 8.1 ± 1.4 (CAR). Conclusions We found substantial performance differences between the four studied heart rate measuring apps. The two contact photoplethysmography-based apps had higher feasibility and better accuracy for heart rate measurement than the two non-contact photoplethysmography-based apps.

Novel mechanical chest compression devices offer the possibility to transport cardiac arrest patients with ongoing CPR and might shorten significantly the time delay to post-resuscitation care.We simulated an eight-minute cardiac resuscitation situation during ambulance transport using CPR training manikins. We compared teams consisting of two experienced resuscitators with the performance of a mechanical chest compression device (LUCAS).CPR-performance by two experienced resuscitators demonstrated ambivalent results. Whereas mean compression rate was within the recommended range (103/min, 95% CI: 93-113/min), mean compression depth was closely below the actually recommended compression depth of5 cm (49.7 mm, 95% CI: 46.1-53.3mm). Nevertheless, only a mean of two thirds (67%) of all compressions were classified as manually correct (defined as sternal compression depth5 cm). In contrast, the LUCAS device showed a constant and reliable CPR performance (99.96% correctly applied chest compressions correctly applied within the device programmed parameters, P = 0.0162) with almost no variance between the different sequences.The LUCAS CPR device represents a reliable alternative to manual CPR in a moving ambulance vehicle during emergency evacuation. Furthermore, it needs less human resources and is safer for the EMS personnel.