Patent searches can tell you which companies are producing similar products, and they are also a good source for diagrams of similar products.
USPTO Patent Technology Monitoring Team (PTMT) report on Patents for Medical Devices.
Search the Cooperative Classification System codes.
Standards are generally set by industry associations or government agencies. When searching for standards, consider what types of standards might exist related to your product.
Additionally, be sure to consider the source of the standard -- both the organization and the country. Though the country of origin may not be the US, it may affect where you can sell your product.
VIEW THE STANDARDS GUIDE, including links to the full text of ASTM standards and the form to order standards.