Augmented reality (AR) has great potential for use in healthcare applications, especially remote medical training and supervision. In this paper, we analyze the usage of an AR communication system to teach a medical procedure, the placement of a central venous catheter (CVC) under ultrasound guidance. We examine various AR communication and collaboration components, including gestural communication, volumetric information, annotations, augmented objects, and augmented screens. We compare how teaching in AR differs from teaching through videoconferencing-based communication. Our results include a detailed medical training steps analysis in which we compare how verbal and visual communication differs between video and AR training. We identify procedural steps in which medical experts give visual instructions utilizing AR components. We examine the change in AR usage and interaction over time and recognize patterns between users. Moreover, AR design recommendations are given based on post-training interviews.