Purpose: High-quality cardiopulmonary resuscitation (CPR) affects survival after cardiac arrest. We aimed to investigate whether CPR quality can be improved by providing a smartwatch for healthcare professionals with real-time feedback instructions during resuscitation. 
Materials and methods: An app providing real-time audiovisual feedback was developed for use in an Android Wear with a built-in speaker. Emergency Department (ED) professionals (of ACLS-certified doctors and nurses) were recruited and randomly allocated to either the interventional group wearing a smartwatch with the preinstalled app, to a control group without the intervention. All participants were asked to perform a two-minute CPR on a Resusci Anne QCPR training manikin using the 30:2 compression-ventilation ratio. Beat-to-beat chest compression rate (CCR) and depth (CCD) were recorded using Laerdal PC SkillReporting software. Primary outcomes were CCR and CCD (mean±SD) measured on the manikin. Secondary outcome was the percentage (median and IQR) of chest compressions meeting both the guideline-recommended rate (100-120 min-1) and depth (50-60 mm) of high-quality CPR during the 2-minute period. Differences between groups were evaluated with the t-test or the Mann-Whitney U-test depending on the distribution. 
Results:  32 ED professionals were recruited in this preliminary trial. 15 people were assigned to the interventional and 17 to the control group. The compression rates (min-1) were significantly higher (but above the guideline recommendation) in the control group (123.9±15.1) than the interventional group (109.0±4.5) (P<0.05). The compression depths (mm) had significant difference between the interventional (50.0±7.0) and the control groups (41.6±7.6) (P<0.05). The percentage (%) of high-quality CPR was significantly higher in interventional (median 45.1, IQR 7.9-64.4) than in control group (median 0.0, IQR 0.0-0.2) (P<0.05). 
Conclusions: Without real-time feedback, chest compressions tend to be too fast and too shallow. CPR quality may be improved with the assistance of a smartwatch providing real-time feedback instructions in a simulated environment.

3 - Using a Smartwatch with Real-Time Feedback Instructions Improves the Delivery of High-Quality Cardiopulmonary Resuscitation