Types of IV Cannula Used in Healthcare Types of IV Cannula are different based on need of patients and treatment. This article discusses the uses of iv cannula and the importance of choosing right iv cannula size for various medical procedures. It also covers the situations in which an iv cannula may be needed for a blood transfusion. Medical buyers, students and healthcare professionals can learn a lot about IV access and patient care. GSTC provides clear, succinct information to help you make informed choices in health care settings.