A systematic review of the use of blockchain in Internet of Medical Things

International health organizations advocate for health care with greater quality and safety, reflecting population needs. However, current health services are inefficient, facing problems of inadequate treatment, human resources, infrastructure, and high costs. Digital health technologies play an increasingly important role in healthcare services such as remote care and vital signs monitoring. The Internet of Medical Things (IoMT), which is a customized version of the Internet of Things (IoT), is increasingly important as it interconnects different medical devices, sensors, patients, and doctors, among others. This brings several benefits in improving health services. Nevertheless, in the IoMT environment, there are several challenges to overcome. Blockchain technology, a distributed ledger, with its immutability, transparency, and anonymity features, is being used in IoMT to help overcome these challenges. In this paper, a systematic review was carried out to identify the research topics of blockchain application in IoMT, the challenges in IoMT, how blockchain helps to overcome them, and the maturity stage of those works. The review results allowed us to identify five research topics in which the main ones are authentication and intrusion detection. This review shows an overview of current research on this subject, giving the possibility of directing other research works, or optimizing the existing ones.